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Water Resources Information Program

The Arc Hydro Quaternary Watershed Project – Technical Report and Guidelines –

Version 1.2

Issued: October 14, 2009

Ministry of Natural Resources Geographic Information Branch

Water Resources Information Program 300 Water St, Peterborough ON K9J 8M5

WRIP-GIB AH Quaternary Watershed Project

Version: 1.0 Issued on: October 14, 2009 TECHAH01_2009-07-17_ArcHydroQuaternaryProject.doc

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Disclaimer This technical documentation has been prepared by Her Majesty the Queen in right of Ontario as represented by the Ministry of Natural Resources (the “Ministry”). No warranties or representations, express or implied, statutory or otherwise shall apply or are being made by the Ministry with respect to the documentation, its accuracy or its completeness. In no event will the Ministry be liable or responsible for any lost profits, loss of revenue or earnings, claims by third parties or for any economic, indirect, special, incidental, consequential or exemplary damage resulting from any errors, inaccuracies or omissions in this documentation; and in no event will the Ministry’s liability for any such errors, inaccuracies or omissions on any particular claim, proceeding or action, exceed the actual consideration paid by the claimant involved to the Ministry for the materials to which this instructional documentation relates. Save and except for the liability expressly provided for above, the Ministry shall have no obligation, duty or liability whatsoever in contract, tort or otherwise, including any liability or negligence. The limitations, exclusions and disclaimers expressed above shall apply irrespective of the nature of any cause of action, demand or action, including but not limited to breach of contract, negligence, strict liability, tort or any other legal theory, and shall survive any fundamental breach or breaches. Additional Information For more information about this document, please contact the Water Resources Information Program at [email protected] Prepared By John Gaiot, WRIP Data Analyst, Geographic Information Branch, Peterborough.

Document Version Date Description 0.1 November 11, 2007 First draft for review. 0.1.1 January 24, 2008 Incorporated changes/clear writing tips by Anne Trudell

and Tracy Sorrill. 0.1.2 July 7, 2008 Revisions to Project Description, Intended Use, Regional

ID sections 0.2 September 9, 2008 Significant revision, including diagram updates and work-

around for users of later versions of Arc Hydro tools. Appendices 2 & 3 added.

0.2.1 November 26, 2008 Section 8 and 9 revisions, and shoreline discussion added (Section 10).

0.3 February 4, 2009 PGSC Review led by Bart Young 0.3.1 April 21, 2009 Section 9 revision – comments regarding HDS supported

project 0.3.2 June 22, 2009 Major revision – model updates, geometric network

discussion, removal of setup instructions (now located in a separate setup guidelines document), revisions to Appendix 2, addition of table of contents

0.3.3 June 30, 2009 Major revision – revisions to various sections, addition of DEM discussion, AH Session Types, and Appendix 3.

0.4 July 13, 2009 Review and revisions by Monique Kuyvenhoven (LRC). Section 9 moved to Section 14

0.5 July 17, 2009 Final Draft for Stakeholder Review 0.5.1 July 30, 2009 Incorporation of Stakeholder Review comments,

particularly around improving the introduction, ID management subwatershed references and other editorial comments.

1.0 July 31, 2009 Final Public Release Version 1.1 October 14, 2009 Modifications to Major Dataset Components section. 1.2 September 8, 2011 Appendix 2: Added reference to a ‘Subwatershed Fix’

XML update, which was implemented May 2010, and publicized through a LIO Technical Bulletin in June 2010.



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Published July, 2009 © 2009, Queen's Printer for Ontario



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Abstract The Ministry of Natural Resources - Water Resources Information Program (WRIP) was involved in a multi-year project to develop standardized Arc Hydro surface water data sessions based on the Quaternary Watershed fabric for the Province of Ontario. Each session contains foundation layers required for fundamental hydrologic watershed analysis. To meet the requirements of Arc Hydro, the project team followed rigorous quality checking and assurance procedures which resulted in extensive and significant base data improvements across the Province. These enhancements are regarded collectively as a ‘snapshot’ version of our hydrology base and derivative products. Base data updates are happening on a continual basis, which will have implications on any derivative or related product that has been produced to date by the Province. Any further work in Arc Hydro will depend on available resources and support from the various business areas interested in utilizing these data and tools. Some key elements of the project include:

• Basic terrain preprocessing developed for each Arc Hydro session populating the Drainage and Network components of the model.

• Setting up a Regional ID framework to manage Arc Hydro’s HydroID at the Provincial level. • The concepts of Global Delineation and Thresholding explored for complex quaternary sessions

and nested watershed scenarios. • Leveraging the WRIP water flow network in Arc Hydro analysis.

This document reveals the intent and future direction of Arc Hydro in Ontario and provides a detailed description of the physical data model adopted in the Arc Hydro sessions. A host of technical and scientific research findings are also included throughout, and are expanded upon in supporting documentation in the form of a series of InfoSheets and other documents available from WRIP.



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Table of Contents

1. What is Arc Hydro? ....................................................................................................................... 6 2. Project Background ...................................................................................................................... 6 3. Project Description ....................................................................................................................... 7 4. Intended Use.................................................................................................................................. 8 5. Spatial Reference and Precision.................................................................................................. 9 6. Base Data Versions, Updates and Linkages to the Hydographic Data Strategy .................. 10 7. Model Overview – ‘Version 2’..................................................................................................... 12 8. Major Dataset Components........................................................................................................ 15

Drainage Component: Arc Hydro Base Layers ................................................................................15 Hydrography Component: Derived Hydrology and Reference Layers...........................................15 Network Component: Geometric Network and Related Layers ......................................................16 Channel Component: Channel Morphology for Floodplain Mapping / Monitoring .......................16 Arc Hydro Tables ................................................................................................................................16 Grid Layers in AHLayers Subfolder...................................................................................................17 So where’s the DEM?..........................................................................................................................17

9. Shoreline Incorporation.............................................................................................................. 19 10. Global Delineation....................................................................................................................... 22 11. Arc Hydro Session Types........................................................................................................... 23

Regular Segment-based Session ......................................................................................................23 Shoreline Segment-based Session ...................................................................................................23 Island Session.....................................................................................................................................23 Split Session........................................................................................................................................24 Threshold Session ..............................................................................................................................24

12. Setting Up a Quaternary Arc Hydro Session for the First Time ............................................. 25 13. Working with the Geometric Network ....................................................................................... 25 14. Proposed Unique Identifier System for Ontario....................................................................... 28

Watershed Unit Comparison Chart....................................................................................................30 Limitations of the Regional ID System:.............................................................................................30 An Example of Applying the HUC system in Ontario.......................................................................31 Future Enhancements of the Regional ID and HUC ID ....................................................................32

15. Future Proposed Updates and Enhancements ........................................................................ 32 16. Credits and Acknowledgments.................................................................................................. 33 17. References ................................................................................................................................... 34 Appendix 1: Arc Hydro Domain Model ............................................................................................. 35 Appendix 2: Upgrading Older (‘Versions 1.1 & 1.2’) Arc Hydro Sessions.................................... 44 Appendix 3: Steps to Convert from Personal to File-based Geodatabase Format ..................... 47 Appendix 4: UTM Divisions Based on the Secondary Watershed Divisions of Ontario and Associated WRIP Datasets Used in the Creation of the AH Sessions.......................................... 49



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1. What is Arc Hydro? Arc Hydro (AH) is a geospatial and temporal data model for water resources, which operates within ArcGIS and was developed by the GIS in Water Resources (GISWR) Consortium in the United States. The Consortium is comprised of several members including:

• Government agencies - US Geological Survey and the Environmental Protection Agency, • Academia - Center for Research in Water Resources, University of Texas, • Professional partners - Environmental Systems Research Institute (ESRI).

AH consists of a set of tools used to create and support a comprehensive water resources framework for hydrologic and related geospatial data analysis. The original focus of Arc Hydro was to support surface water modeling, but work has progressed into the groundwater realm. ESRI is taking steps to link the two systems into one complete data modeling framework, otherwise known as the Application Framework suite of tools. Together, these tools can help build a better understanding of the behaviour of water throughout the entire hydrologic cycle. This flexible framework allows for more advanced modeling to be conducted in a standardized format either within AH or coupled with external analytical models and tools. Some examples include:

• MIKE SHE or MIKE BASIN developed by the Danish Hydraulic Institute (DHI), which allow you to extend the surface water model to simulate hydrodynamic conditions in the real world, and flood modeling analysis and prediction.

• Aquaveo’s or Schlumberger Water Services’ (SWS) suite of groundwater tools, which can couple together with the surface water system.

• Kister’s Water Management Information System, otherwise known as WISKI. WISKI specializes in time series data for measuring hydrological and groundwater networks (processing gauge data, flow / level / capacity measurements and rating curves), and meteorological applications.

In short, ESRI’s Application Framework systematically builds the foundation for all surface and groundwater analysis and opens the door to several advanced modeling opportunities. This report focuses on MNR’s involvement with Arc Hydro, and the development of a surface water data model to support Provincial applications.

2. Project Background The Arc Hydro toolsets were developed using the latest ESRI technologies at the time of production and are a product of extensive consultation and research across American agencies (under the auspice of the Consortium for GIS in Water Resources). They have garnered strong support within the Ontario Ministry of Natural Resources (MNR) and external agencies such as some of the Conservation Authorities (CA’s) and various Municipalities in Ontario. In particular, the Water Resources Information Program (WRIP) has had a keen interest in leveraging existing information produced from the Provincial Watershed Project (1998-2002), the Enhanced Flow Direction Project (2004-2007) and other data improvement initiatives over recent years. The objective of tying all water resource information together under a common platform for hydrologic modeling and analysis seemed achievable with the Arc Hydro approach. What about the WRIP Toolbox? This toolbox evolved from WRIP operational data refinement and watershed analysis work beginning in 1999. It was first released to the broader community of users in 2002, and has since been upgraded to support the ArcGIS 9.2 platform. The WRIP Toolbox is a series of useful tools for automating various watershed analysis functions for water quantity / quality assessment and watershed characterization. WRIP continues to support the WRIP Toolbox because these specialized capabilities are still useful today and it directly supports the development of our hydrologic base and derived data products such as the Enhanced Flow Direction datasets. It will



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also be updated in the near future to consider the .NET program development environment and will include additional functionality such as supporting large scale and anthropogenic drainage data preparation and tools for Far North applications. The capabilities of the WRIP Toolbox will complement the tools found in Arc Hydro and will help precondition our base data for use in Arc Hydro. Research and development of a preliminary Arc Hydro Data Model began in late 2004 with an early application of Arc Hydro under the Temperate Wetland Restoration Initiative in cooperation with the Inventory, Monitoring and Assessment (IMA) Section. The aim of this project was to develop a catchment-based watershed report card using Arc Hydro for remotely identifying potential sites for restoration. Further work to support MNR business began in late 2005 with the Northern Ontario Conservation Authorities Arc Hydro Project. Sample models were developed and distributed to the northern CA’s for review. In 2006, the model and methods saw further refinement in preparation for the WRIP Training courses that were delivered by the Trent University Watershed Science Centre through the fall and winter of 06/07.In the spring of 2007, a welcome incentive to implement the model across the Province was realized. The Aquatic Research & Development Section of the Applied Research and Development Branch (ARDB) of MNR in Peterborough, and the River and Stream Ecology Unit (RSEU) at Trent University recognized the need for this information to support Stream Temperature Analysis and related research. A cooperative project resulted between WRIP, the Provincial Geomatics Service Centre and Timmins Geomatics Service Centre to complete Arc Hydro sessions for the Area of Undertaking required for ARDB purposes. The benefits of this work would also extend into other facets of MNR business and external initiatives such as Source Water Protection, CA business functions and other areas of science research.

3. Project Description WRIP developed standardized Arc Hydro sessions based on the Quaternary Watershed fabric for the Province of Ontario. Each session contains foundation layers required for hydrologic watershed analysis. The Area of Undertaking included four main areas:

1. Areas draining to the Great Lakes as required by ARDB, 2. Areas draining to the St. Lawrence River as required by ARDB, 3. Other areas governed by Source Water Protection, 4. Areas draining to the Ottawa River south of North Bay-Mattawa region (see Figure 1).

To meet the requirements of Arc Hydro, the project team followed rigorous quality checking and assurance procedures which resulted in extensive and significant base data improvements across the Province. Some other key elements of the project included:

• Basic terrain preprocessing developed for each Arc Hydro session populating the Drainage and Network components of the model (see Model Overview section for details).

• Setting up a Regional ID framework to manage Arc Hydro’s HydroID at the Provincial level.. • The concepts of Global Delineation (refer to Section 10 for details) and Thresholding (refer to

Section 11), which were explored for complex quaternary sessions and nested watershed scenarios.

• Leveraging the WRIP water flow network in Arc Hydro analysis. As of this writing, the AH products are planned for release in August 2009 as a packaged product in the Land Information Ontario (LIO) Warehouse. Each package will contain a series of Quaternary watershed sessions grouped by Tertiary watershed.



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Figure 1. Quaternary Arc Hydro Project Area of Undertaking

4. Intended Use These AH sessions were developed and tested originally for Version 1.1 Arc Hydro tools on the ArcGIS 9.1 platform in the Personal Geodatabase format (.MDB). Later versions of the tool appear to have undergone some fundamental data model changes that affect how the watershed delineation functions operate. Because of this, the sessions have been upgraded so that they are compatible with Arc Hydro Tools Version 1.3 or later. Appendix 2 describes the procedure that was followed for updating the old sessions, which may be useful for end users in their own AH implementations. Appendix 3 discusses considerations for migrating from personal to file based geodatabase format (.GDB). These AH sessions are not considered complete data models. They are a beginning framework for conducting further analysis to meet specific business area needs. Certain elements of the data model are populated using the 10k/20k scale NRVIS and WRIP hydrology base data sets. Some fields within the layers may not be populated at this time, but they are included to give the user an idea of what can be stored in these feature classes. A basic geometric network can be created containing a default temporary junction feature class, but we recommend that the user create their own permanent



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Hydrojunction feature class to be used as part of the geometric network (see Working with the Geometric Network section for details). The AH sessions are not limited to use in Arc Hydro. The data is easily accessible without having to install Arc Hydro and can be exported for use in other software applications. However, the user will not be able to realize the full potential of the data relationships established without having AH or related tools available to assist in the analysis. Complete data model templates are available from WRIP to add additional feature classes to the AH sessions as needed for the analysis. Some components as described in the Model Overview (Section 7) are included as empty feature classes for the user to populate (such as the watershed point and polygon feature classes). The feature classes that were populated were those specifically required by ARDB to complete their stream site analysis project. The new AH tools also allow the user to work in the file geodatabase format (.GDB). If there is interest in working with file geodatabases instead, Appendix 4 describes how to properly convert the data we have created from the personal to the file-based format using the existing templates. These model templates are available in all Ontario based UTM Zones (Zones 15 through 18) and Lambert Conformal Conic projections, and are also available in personal or file-based geodatabase formats. This AH product can be used for regional scale analysis for a variety of purposes. It is not intended for detailed site level analysis. Currently, there is no intention to incorporate higher resolution data sources into this product. If users prefer to use their own data sources, they can be added to the existing model provided the original intended scale is honoured. Optionally, the principles and templates that are available from WRIP can be utilized to create customized Arc Hydro sessions using refined or large scale data sources. The provincial data is provided “as-is” and there are currently no plans for further enhancements or updates until MNR’s Hydrographic Data Strategy Project has been fully realized and implemented. One component of this Strategy, which is known as ‘water flow consolidation’, involves developing a new standard hydrographic model to bring together disparate versions of data being managed or updated by different partners within and external to the MNR. In the interim, if users notice any data discrepancies or stream network connectivity issues, these issues will be logged by WRIP when notified and will be forwarded to the proper data custodian (as determined by the Strategy) after the fall of 2009 (the anticipated completion of the water flow consolidation phase). For further information on the Hydrographic Data Strategy, contact the Base Data Infrastructure group of the Geographic Information Branch in MNR, Peterborough – contact details are available in section 6.0 of this document.

5. Spatial Reference and Precision The AH data for each session uses the Universal Transverse Mercator (UTM) projection and the North American Datum 1983 (NAD83). The UTM Zone chosen for a particular watershed session is generally dependant on the UTM Zone in which it resides on the earth except for tertiary watersheds that cross Zone divides. In these cases, consult the raster mosaic tile index in Appendix 4 developed through the 2002 Provincial Watershed Project for a better understanding of how watersheds were divided into each UTM Zone. The precision level of all the geospatial domain measures (X, Y and Z) is millimetre precision. The 1:10k NRVIS/WRIP data in Southern Ontario uses a 10 metre cell resolution, whereas the 1:20k base data in Northern Ontario uses 20 metres. The original base data specifications were as follows:

+/- 10m in the X/Y, +/- 2.5m in the Z



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This was assuming a complete Digital Terrain Model (DTM) was available. In some areas like Essex region, this was not the case where we could only rely on sparse 5 metre contours and occasional spot elevations to produce our Digital Elevation Model (DEM). This issue coupled with the variations experienced in different watershed modeling techniques could result in a final product that reaches or exceeds +/- 100m in accuracy in the X/Y domain and 5m in the Z domain. Naturally elevation accuracy is also compromised when information is lacking to begin with. Fortunately, these problems are limited to flat areas lacking DTM information. For more information on standard spatial references and precision settings used for this project, refer to the WRIP InfoSheet entitled Geodatabase – Spatial Reference Settings – Guidelines for Conservation Authorities and Source Protection Planning Regions in Relation to Data Management.

6. Base Data Versions, Updates and Linkages to the Hydographic Data Strategy

The project team used the following datasets to create the Arc Hydro sessions.

• Provincial Digital Elevation Model (DEM) v2.0.0 • Enhanced Flow Directions (EFD) v2.1.0 • WRIP virtual water flow network v2.1.0 (dated November 2007). Some areas in Phase 3 used

v2.1.1 of the water flow (dated May 2008). Any future changes or updates will be reported in a separate document to accompany the AH session packages. No future updates to existing data are planned until the results of the Hydrographic Data Strategy (HDS) are assessed and related large scale mapping concerns are properly addressed. For the interim, WRIP will document any change requests as it has for other datasets it manages. The hydrology base data and derived products are all related and integrated. Therefore a change in one layer (such as a water flow edit) usually impacts all of the derived layers and their relationships. The data flow diagram below illustrates some of these relationships and dependencies. Because of this complexity and integration of datasets, any updates would require a predefined batch cycle of updating (including the AH sessions if we continue to support this into the future). Some key aspects of HDS include:

• Several base data improvements including water flow, water bodies, and geographic name extent (GEL) layers

• Developing new logical and physical data models under LIO and NRVIS • Developing a maintenance model to manage the proper work flows between datasets • Supporting and updating the federal National Hydrographic Network (NHN) • Wetland management approaches • Multi-scale data integration through prescribed generalization techniques and processes • Investigating a unique identifier for the Province for multiple applications (see Section 14).

The diagram below illustrates the data that have been considered for this release of Arc Hydro, including their dependencies with other data. For more information on the Hydrographic Data Strategy, please contact: Shawn Kelleher, Project Manager Geographic Information Branch [email protected]



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class ArcHydro Layers Subset

DEM

Flow Direction

Enhanced Flow Direction

Regular Flow Direction

Rasterized Stream Network

Water Flow EFD

Flow Accumulation Derived Raster

Streams

Water Flow Geometric

Network

WRIP Water Flow

Predicted Streams

Thresholded Streams

NRVIS Waterbodies

Lake EFD

NRVIS Water Line

Waterbody Contours

Spot Heights

Source Data Input

Intermediate Product

Key WRIP Data Output

Fundamental Data Types

Legend

Shoreline EFD

Flow Accumulation

Buffered Shoreline Arc

Contours

DTM

Breaklines

Buffered Shoreline Poly

Arc Hydro Deriv ativ es

HydroPointHydroLineHydroAreaDrainage AreaWatershed

DEM Conditioned and Filled

Arc Hydro Data Dependencies

Parent

Child

Deriv ativ e

Source

RelationsDrainage Line

preferred

least preferredWRIP DEM

Enforced

Depends On

Optionally Created From

Figure 2. An illustration of all the Arc Hydro related data dependencies. This diagram flow perspective focuses on the “data sources” from which the Arc Hydro derivatives were created. For more information on additional work WRIP may explore or proposed new datasets to include in the model, see the Future Updates and Enhancements section.



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7. Model Overview – ‘Version 2’ Two years of consultation, experimentation and evaluation with other comparable schemas have gone into the latest version of the Arc Hydro Physical Data Model. A limited release version was completed in 2005 to assist the five Northern Ontario CA’s with an AH area specific project. This went through further testing and refinement in preparation of the WRIP Level 2 Training Course in the fall of 2006. Treating each logical section described below as a physical dataset proved too difficult to maintain and therefore they are put into one dataset called AHLayers (Version 2). Elements have been adopted from various sources:

• the original base Arc Hydro Data Model produced by ESRI • the USGS National Hydrography Dataset (NHD) Data Model • the US Hydrologic Unit Coding (HUC) system • input from Lake Simcoe Region and Niagara Peninsula Conservation Authorities.

This model contains the core elements required for general surface water modeling applications at both regional and local scales. Since it is a useful starting point only, variations are encouraged for specific applications. The data model (DM) stored under the AHLayers dataset is divided into five main logical divisions reflecting the different aspects of the model described in ESRI literature (reference: Arc Hydro: GIS for Water Resources 2002). Each section except for Time Series, which is stored at the root level of the geodatabase, is identified by its own prefix. The components of the data model are described in the table below. DM Component Prefix Description Drainage ‘d_’ Fundamental Arc Hydro terrain processing drainage layers

‘h_’ Water related topographic features (eg. Waterbodies, structures, monitoring gauges, wetlands, land cover) and derived layers (eg. Watersheds, Subwatersheds)

Hydrography

‘z_’ Generic templates which can be copied, renamed and modified as needed

Network ‘n_’ Network related features including: • the geometric network – a collection of linear and

point features representing the flow pathways of water across the landscape.

• network junctions – points for features of interest along the flow path (eg. Confluence, source, sink, station etc.)

• schematic feature classes – used to simplify the original water flow network and related features (eg. catchments, sample sites, confluences) down to straight line distances between points of interest. This allows for a simplified view of all the relationships down the system and can assist in quickly summarizing information for more complex networks.

Channel ‘c_’ 3-D line features comprised of cross-sections and profile lines to represent the morphology of stream systems. This is often useful in floodplain and flow analysis.

Time Series and other tables

None A series of non-spatial objects located outside of the AHLayers Dataset, which include system tables, cross-sectional measures, and time series tables.



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There is also a Workspace Dataset, where the user can work on temporary feature classes before storing them in one of the logical sections in the AHLayers Dataset. This is recommended as a standard starting template for all the AH sessions. It can also be used for exchanging data between agencies. Figure 3 next page depicts the template structure. Refer to Section 8 for more details on each specific feature class.



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a. b.

Figure 3: Arc Hydro Model Structure. 3.a. illustrates the complete model template of all1 major feature classes defined and utilized in Arc Hydro. 3.b. illustrates a subset of the model and what would be found in a typical quaternary Arc Hydro session complete with relationships (some specific to supporting the LFlow project. Refer to the LFlow documentation for details). Note that some feature classes are not populated but the structure is provided for the most common layers the end-user is most likely to use. These feature classes can be utilized by adding them in ArcMap and pre-populating the Data Management menus in Arc Hydro. The advantage of using these feature classes is that they follow a standard naming convention and may contain some additional fields that might be useful to the user. The typical directory structure of an Arc Hydro session is also shown along with the project file MXD and raster grid layers found in the AHlayers subfolder. See the next section for a description of these layers.

1 There are a few exceptions including the HydroEvent feature classes and any other feature classes added to the model after the release of the authoritative reference entitled “Arc Hydro: GIS for Water Resources” by D.R. Maidment.



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8. Major Dataset Components Important Note: Some layer names in the quaternary Arc Hydro sessions may vary slightly from the time of this writing and some layers may not be included or populated. These omitted data classes have been modeled by WRIP but a method was not pursued to populate them because they were not required by the original client. The user can let Arc Hydro create them as needed, but following the naming convention is recommended for common communication and logical organization of layers within the geodatabase. Contact WRIP for more information in acquiring and using the template shown in Figure 3.a. Entries highlighted in green below are currently populated within the Arc Hydro data model. The other layers are either user dependent or can be acquired elsewhere, and therefore, are left up to the end user to populate if required.

Drainage Component: Arc Hydro Base Layers (This dataset is analogous to the Drainage Dataset in the traditional Arc Hydro Model)

Layer Name 2 Description or Purpose d_Cat_p 3 Catchment Polygons (based on stream segmentation or

thresholding) d_Drn_ln 3 Drainage Lines (based on stream segmentation or

thresholding) d_Adj_p Adjoint Catchments (watersheds at every confluence of

the stream network – representing the total upstream area (if any) draining into a single catchment)

d_Drn_pt Drainage Points (for every stream segment)

Hydrography Component: Derived Hydrology and Reference Layers Layer Name Description h_Monitoring_Pt Original monitoring points collected out in the field. h_BatchPt_mp Copy of monitoring points with only a couple key

attributes required for batch watershed/subwshed delineation

h_ SubWshed Nested Subwatersheds (tessellated and non-overlapping)

h_ SubWshed_Pt Subwatershed points derived from h_Monitoring_Pt layer (snapped to drainage line)

h_ Wshed Watersheds showing Total Contributing Area to monitoring points (can overlap one another)

h_ Wshed_Pt Watershed points derived from h_Monitoring_Pt layer (snapped to drainage line)

h_Waterbody Reference waterbody polygon layer z_BatchPt Optional spare batch point layer the user can use for

other sub / watershed point types z_HydroArea Template structure for other polygons you may want to

bring into model (eg. wetlands, hydro response units, etc.) Lookup FType_Area in Domain Values document for more options.

z_HydroLine Template structure for other line features the user may

2 If a stream threshold is used (multiple thresholds are commonly used for different purposes or applications), for example 10ha or 125ha, the naming convention should reflect this for each stream resolution or threshold (eg. tagging ‘_125’ to the end of the FC name). If no thresholding has been adopted (eg. the original stream network has been used), then no number needs to be applied after the layer name. 3 These 2 feature classes will ask to overwrite the existing feature classes when you set these in the Data Management Menu and choose to rerun a preprocessing command. Just click OK to continue.



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want to bring in (eg. roads, railways, administrative lines, fencelines, bridges, dams etc.) Lookup FType_Line in Domain Values document for more options.

z_HydroPoint Template structure for other point features the user may want to bring in (eg. small road crossings, dams, water structures, water discharge/recharge point, PTTW, intakes, outfalls, threats, etc.) Lookup FType_Point in Domain Values document for more options.

z_LongestFlowPath – Superset of: h_LFP_Cat, h_LFP_Adj, h_LFP_Wshed, h_LFP_SubWshed

Template structure for any custom longest flow paths which might be required. Just copy the structure of any existing LFP feature class or let AH generate it automatically. Following the suggested naming conventions listed to the left is recommended for the purpose of geodatabase file organization. Note that the h_LFP_Wshed will include some extra attributes for determining various slope and elevation characteristics of a watershed.

z_Waterbody_InletOutlet Useful working layer to bring in inlets and outlets as hydrojunctions on the network.

qws_{QuaternaryCode} Polygon representing the quaternary watershed study area.

Network Component: Geometric Network and Related Layers Layer Name Description n_HydroEdge Network of lines describing map hydrology, including

flow lines (and optionally shorelines). This is currently equivalent to the Virtual Water Flow dataset created by WRIP for the Province, and has been clipped to each watershed session.

n_HydroJunction Set of points located at the ends of flow segments and at other strategic locations along the flow network.

n_SchematicLink Straight line segments connecting schematic nodes in a schematic network.

n_SchematicNode A representative point for a hydro feature connected into a schematic network.

Channel Component: Channel Morphology for Floodplain Mapping / Monitoring Layer Name Description c_CrossSection The cross-section of a channel, normally drawn

transverse to the flow. c_ProfileLine Longitudinal profile of a stream or river channel (lookup

FType_Line domain for details on settings)

Arc Hydro Tables Layer Name Description APUNIQUEID System Table to keep track of last used ID(s) in all

applications using the AP Framework. Supported as of version 1.3 of Arc Hydro Tools.

HYDROIDTABLE4 Legacy System Table to keep track of last used HydroID(s) for each LayerKey defined. Recommend to use only the default LayerKey called ‘OTHERS’.

4 This table will not be present in the template because it is a legacy table no longer supported in Arc Hydro as of version 1.3. If you are using an older toolset, you will have to populate this table manually yourself.



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Supported in versions 1.2 and earlier of Arc Hydro Tools.

LAYERKEYTABLE5 System Table to assign LayerKey ID ranges. Since our sessions do not currently use Layer Keys, we recommend not using this functionality.

CrossSectionPoint A point on the cross-section (measured along x-section) TimeSeries Single large table used to store time measured

information on various parameters. TSType An index of the types of time series data stored in the

TimeSeries table.

Grid Layers in AHLayers Subfolder Layer Name6 Description efd_gd Enhanced flow direction grid fa_gd Flow accumulation wf_gd Grid representation of the WRIP virtual water flow. lnk_gd Link grid coded by stream segmentation. cat_gd Catchment grid

The Workspace Dataset is intended for working with temporary feature classes such as the water flow (z_Network_ln) in preparation for creating the geometric network (n_HydroEdge). Do not use the z_Network_ln feature class if it exists. It is only there as a demonstration in creating the network. See Section 13 as it pertains to geometric networks for more information. There is also a polygon feature class present here (in Figure 3.b, the example is called ‘qws_2AA04’) representing the boundary extents of the quaternary watershed for each AH session, which may be a useful reference layer. See Appendix 1 for a detailed description of the model’s Attribute Domains. Some lookup tables in domains specific to CA applications (eg. StationType and FType for each Feature Class type) are extensions of the basic Arc Hydro data model. They are set up to provide flexibility in defining features during analysis and are maintained manually by the user rather than by Arc Hydro. So where’s the DEM? Even though the Digital Elevation Model (DEM) is a foundation data class which all other terrain based data classes are derived from, the derivative layers packaged with each session are generally sufficient for several of the advanced watershed and networking functions in Arc Hydro. Therefore, the DEM’s were not packaged with the sessions. However, they can be obtained in their tiled format from the LIO warehouse as packaged products. The DEM has not been included in the AH sessions to reduce the session size and to minimize duplication of data in the warehouse (please refer to the Provincial DEM product’s metadata for more information). By comparison, the enhanced flow direction grids are based on the enforced DEM’s and are also available to the public through OLIW in a mosaic tile format (see Appendix 3). They have been included and clipped to the watershed sessions because they are integral for the proper functioning of Arc Hydro. If there are future implementations of Arc Hydro, we may include the DEM depending on user feedback.

5 This table has been updated in version 1.3 tools to include a new field called IDFLDNAME. This field is not present in the current AH Sessions. If you intend to use the LAYERKEY functionality, you will have to manually add this field. The Data Type is Text. Field Length: 35. Note that this fix has been applied to the templates that are available from WRIP 6 Layers are listed in the order of creation.



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Some AH functions will require a DEM in order to work such as the slope functions for example. If the DEM is required for analysis, the following steps can be used as a guide for bringing the DEM into the project:

1. Obtain the DEM tiles required which overlap the watershed area of interest.

2. Import from the float grid format and define the projection using the existing .PRJ file. The Readme text file included in the packaged products describes how to do this.

3. If there are multiple tiles, they will need to be combined using the MOSAIC command either using Raster Calculator, ArcInfo GRID module or command line. Regardless of the method, make sure the output extents and cells line up with the source raster (all extents should be to the nearest 10m for 10K data and the nearest 20m for 20K data).

4. Clip the DEM to the study area. We suggest using the catchment grid or watershed polygon from the AH session as the mask and extents of the output grid.

5. Copy final product to the AHLayers subfolder where the other grids are stored for the AH session.

6. Add the DEM to ArcMap project, map to it as the Raw DEM parameter in the Data Management menus of Arc Hydro, and save the project.

7. You are now ready to use the DEM in Arc Hydro. Note: When using the DEM for the first time in Arc Hydro, the function run may ask whether the Z units are the same as the Linear XY units. Since both units are in metres, the answer to this question would be yes.



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9. Shoreline Incorporation Historically, generating watersheds according to the federally based Water Resources Index Inventory Filing (WRIIF) System (see Section 14) was a complex undertaking when dealing with a shoreline watershed: which is defined as any watershed that drains to the shoreline of a major lake and does not flow to a single pour point (see Figure 6 below for examples of quaternary shoreline watersheds draining to the Great Lakes). A shoreline watershed could have several streams draining towards and ending at the lakeshore.

Figure 6. Mainland quaternary watersheds that drain directly to the Great Lakes shoreline. This type of watershed definition made the process of delineating watersheds in the past a challenge because there was no shoreline enforcement reflected in the flow direction information in addition to the lack of elevation information in some areas including lakes (see Figure 7.a. below). As a result, there was little control over where the boundary intersected the shoreline beyond the intersecting streams and the arbitrary flow directions in the lake. Figure 7 below illustrates this lack of enforcement in the original version of the Enhanced Flow Direction Grid (EFD) version 1.1.0, compared to the new version 2.0.0 (and later) which incorporates a new enforced shoreline buffer component.



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Figure 7.a. Original EFD v1.1.0 in Thunder Bay b. New EFD v2.x A – Area showing lack of elevation data and no shoreline enforcement B – Flow direction edge did not necessarily follow shoreline C – Shoreline buffer of 100m generalizes shoreline by closing off small bays and inlets D – Inlets with water flow virtual segments are given flow directions similar to lake enforcement methodology. For more information on the basic principles of the EFD methodology, please refer to the WRIP Info Sheet entitled “Provincial Enhanced Flow Direction Grid 2.0.0”, or the technical paper by Kenny and Matthews (2005) – see References section 17. Figure 8 illustrates the watershed ‘bleeding’ issue which often resulted from the lack of flow direction enforcement at the shoreline and improper water flow coding. Notice as well, that the boundary between watersheds was often limited to the vicinity of the closest shoreline stream, whereas now we can define the boundary accurately to intersect any specific point along the shoreline. For example, the new interpretation in Figure 8.b. shows the boundary coming down exactly midway between two streams (highlighted in green), whereas with the old method it was arbitrary where the flow directions in the lake would intersect the shoreline.

A

B

C

D



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Figure 8.a. Shoreline ‘bleeding’ phenomenon b. Bleeding is virtually absent in v2.x Under the old WRIIF system, this shoreline issue was complicated further because some major inland lakes were assigned different quaternary codes than the areas draining directly to them. Some examples include Lake Nipissing, Lake Nipigon and Lake Simcoe. Because a lake by definition is not a watershed, it should not have its own quaternary code unless the areas draining into the lake are also included. For Nipissing and Nipigon, a shoreline component was incorporated to maintain the original definitions of the quaternary watershed fabric as much as possible. This has also been done for Lake Simcoe, but as a second approach, a demonstrative version was developed which does not include any shoreline enforcement. In this case, we treated areas draining directly to the lake in between streams as belonging to the lake’s quaternary, not the adjacent quaternaries. The result is a dramatic difference in the look of the lake associated quaternary to include the surrounding area draining to the lake. This may not be aesthetically pleasing, but in a strictly hydrological or scientific context, it satisfies the definition of a true watershed or subwatershed.

Figure 9.a. Enforced shoreline version b. Areas in between streams draining to lake.



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At this time, we will continue to support the enforced shoreline option for these inland lakes to honour the cartographic-oriented WRIIF system as much as possible - unless there is sufficient justification to do otherwise in the future.

10. Global Delineation A by-product of this project was further research into the concept of global delineation or performing analysis on multiple nested watershed systems. A pilot was conducted to implement the concept and the process required for implementation was documented. One limitation of the global delineation tool discovered in the implementation is that it requires a different format of the Arc Hydro data model than what is supported by the rest of the Arc Hydro Toolset. Due to time constraints and the fact that the problem was in the tool’s design rather than our data structure, the changes required were not implemented in this release. A separate document entitled Global Delineation for Split Watersheds developed in cooperation with the Provincial Geomatics Service Centre, describes the steps needed to take advantage of this capability. If the quaternary level watershed was too complex or spatially exceeded the limitations of Arc Hydro7, it was broken into smaller subwatershed sections. There were 11 of these cases in the current Area of Undertaking. Global delineation would allow the sub-sections to be linked together. An actual completed example is available upon request. At a larger level, Global Delineation will also be useful for grouping a series of nested quaternaries together in a single analysis session. It is important to remember that a quaternary watershed is not always a complete watershed. It may have other upstream watersheds draining into it and therefore would have a cumulative impact on the resulting analysis. Below is an example illustrating the Global Delineation concept.

In Figure 10, the grey polygons represent individual Arc Hydro sessions, and the downstream colour-coded polygons represent the catchments within each Arc Hydro session. These sessions are all linked within a global ArcMap project file, with each watershed polygon pointing to the appropriate Arc Hydro session associated with it. With the proper database and file structure set up, the user would then be able to take advantage of the Global Delineation tools available in the Arc Hydro Toolbox. For more information, please refer to the Global Delineation document mentioned above.

7 These limitations were discovered while using the Personal Geodatabase format. We have not tested to see if these problems also persist in the ArcSDE environment. Regardless, the ESRI Arc Hydro Team suggests that an AH session should not contain more than 2000 catchments as a general rule. The WRIP Infosheet entitled Arc Hydro: Quick Guide to Creating 125 Hectare Headwater Watersheds describes this issue and ways to deal with it in more detail.

Figure 10. Global delineation example showing 10 nested quaternaries.



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11. Arc Hydro Session Types Several types of AH sessions have been created and are included in the package where necessary. They include the following: Regular Segment-based Session This is the fundamental AH session where the catchment segmentation is strictly based on the density of the original WRIP water flow network. For example, if there were 250 water flow segments (defined end-to-end by stream confluences), then the resultant number of catchments would also be 250. The majority of the sessions are provided in this format. Shoreline Segment-based Session The concept of a shoreline component as explained in Section 9 was incorporated into the AH session in addition to the density of the network. This session type was completed for the entire Great Lakes shoreline and the inland lakes identified in Section 9. Island Session No shoreline enforcement was conducted around islands including Manitoulin. Island sessions were run only where water flow was present on the island. Areas draining directly to the lake and not intercepted by a watercourse were not included. Therefore the drainage areas (catchments) do not necessarily represent the entire island area.

Figure 11. Sample drainage areas captured for island session 2EA-24. Notice the enhanced flow directions cover the entire island area, which means the user can still work in areas both off and on the network. With our selection routines for inland arcs, some segments might have been totally removed from the input raster stream layer instead of split at the shoreline and result in catchments starting a certain distance inland (see area encircled in red). However, this does not pose a problem because you can still create a custom watershed that captures the entire extent from the stream mouth at the shoreline to the headwaters because the complete stream vectors and matching flow directions in the enhanced product have been included. Remember, the Catchments and Adjoint Catchments are just ‘building blocks’ for Arc Hydro and should not be used directly for analysis or reporting.



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Split Session Some quaternary watersheds were too complex to process through Arc Hydro in their entirety because they either contained too many catchments at the segment level or their spatial extents were too large. We explored two possible solutions in handling this problem: the split session and the threshold session (explained below). A split session is basically what the name implies. We split complex quaternaries into manageable sub-sections or subwatersheds, which can be coupled together using the global delineation principles discussed in Section 11. Threshold Session A second way to handle complex watersheds is to implement the concept of thresholding the stream network. The number of streams which participate on the drainage line network can be simplified. In doing so, users can handle much larger areas in their analysis, without compromising the integrity of the original base data. As a result, the complex quaternaries can be successfully created as a single unit as opposed to several in the split session alternative. WRIP is investigating extending this concept to create AH sessions at the Tertiary watershed level in future AH implementations. How to create this type of session is described in detail in the InfoSheet entitled “Quick Guide to Creating 125 Hectare Headwater Watersheds”. The island and threshold sessions will be stored in separate folders in the packaged products, whereas the split sessions will be grouped with the regular segment sessions (see Figure 12 below).

a. Regular, Island and Threshold session folders showing the Secondary through to Quaternary hierarchical structure.

b. Bottom four sessions are an example of a Split quaternary session for 2EC-17. These sessions are stored in the same sub-folder as the Regular sessions.

Figure 12. Illustrates the default folder structure of the various types of watershed sessions when unzipped from a packaged product.



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12. Setting Up a Quaternary Arc Hydro Session for the First Time If you are just getting started with Arc Hydro, or you need to setup an Arc Hydro session you received from WRIP or from the OLIW as a packaged product, please refer to the InfoSheet document entitled “Guidelines for Getting Started with MNR’s Arc Hydro Quaternary Watershed Sessions”. This will walk you through the installation and setup process for Arc Hydro. For additional guidance on how to use the Arc Hydro tools, please refer to the Help system and the Arc Hydro Tutorial packaged with the Arc Hydro installation.

13. Working with the Geometric Network The network component of this model is typically comprised of the Hydro Edge (n_HydroEdge) and Hydro Junction (n_HydroJunction) feature classes as previously described in Section 8. Normally, Arc Hydro defaults to the Drainage Line (d_drn_ln) feature class as input to create the network. However because the Drainage Line is a raster-derived centre line interpretation of the original water flow, it has certain drawbacks. Two notable limitations are the following:

1. The vectors have a stair-stepped pattern which can over-estimate the actual length of a stream up to 144 percent in extreme cases. Overall, at a typical quaternary watershed scale, the average tends to be around 125 percent compared to the true total stream length for a true watershed (a watershed defined by a single outlet and does not have a ‘virtual’ shoreline component – see Section 9).

2. A drainage line which has been created using a threshold area-based approach will not completely represent the known hydrology for the area. See Infosheet entitled “Quick Guide to Creating 125 Hectare Headwater Watersheds” for more information on the thresholding concept.

The Drainage Line can be used if the user understands and is comfortable with these limitations. If there are concerns about maintaining the true vector path and length estimates of known streams, then the better alternative of incorporating the original water flow vectors as the fundamental component of the Arc Hydro network should be considered. This way, the user can also include any additional attributes that are normally stored on the water flow layer to support business needs or seamlessly link to external systems. There are also techniques of extending the known network to capture headwater streams which do not exist in the water flow layer, but are normally found in the field while stream sampling. The user can leverage some automated techniques to create predicted streams using a reliable Digital Elevation Model (DEM). For more information on working with the original water flow vectors as part of the network, please refer to the Infosheet entitled “Extending the Hydro Network Using Arc Hydro and ArcGIS”. The sessions come packaged with a default geometric network associated with the n_HydroEdge using the ArcToolbox method for creating networks, but it is there just as a simple demonstration of a network. Once familiar with its functionality, WRIP recommends this network should be deleted but do not delete the feature class! The n_HydroEdge can be used in conjunction with other features to create a more meaningful or usable network to address specific applications. The advantages of customizing your own network include the following:

1. There are different ways to create the network either by the traditional ArcToolbox Geometric Network Wizard or through Arc Hydro. Each exhibit different properties but typically the Arc Hydro version of the network should be used to leverage the full capabilities of Arc Hydro and related tools.



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2. As already mentioned, the user may prefer to use the Drainage Line as part of the Arc Hydro network instead of the virtual water flow.

3. The HydroJunctions added to the network will depend on the end-user’s needs and interests. Monitoring sites (which are locally managed), bridges / crossings, gauges, confluences, and other features of interest can all be brought in as part of the geometric network for program-specific analysis and reporting. But it is good practice to bring in only what is absolutely required for analysis.

Therefore, the geometric network should be up to the user to build. To leverage the WRIP water flow that has been supplied, make a copy of the n_HydroEdge and save it in the Workspace dataset. An example of this can be found in Figure 3 where the original copy of the water flow was named ‘z_Network_ln’ in the creation of the original network. Again, follow the steps in the InfoSheet mentioned above, which will show the user how to do this. The InfoSheet also describes how to extend the network and incorporate actual streams found in the field if necessary. The n_HydroEdge and n_HydroJunction feature classes contain several fields that may be of interest to the user. Many are currently unpopulated for the same reason that they tend to be user-dependent. However, they are included simply for demonstration purposes to give users an idea of what they can store as ancillary attributes on the network. If they are not required, feel free to delete them. But before you do, it may be worthwhile explaining what some of these attributes actually mean to gauge their usefulness in potential applications. Below is a list of some of the more important attributes (populated fields are highlighted in green):

FC / Field Description n_HydroEdge HydroID Arc Hydro unique feature identifier DrainID Arc Hydro identifier relating to the HydroID of the associated catchment the stream

segment drains. Enabled

Regular geometric network attribute for enabling features to participate on the network

FlowDir EdgeType FType

Arc Hydro geometric network attributes automatically populated when the network is generated. Refer to Arc Hydro help files for more information.

Name Stream name (local and/or official) FType_Line User-controlled feature type descriptor for line feature classes. More useable and

expansive in terms of the list of options available compared to Arc Hydro’s automated FType field. See domain look-up table in Appendix 1 for available entries.

HydroCode HydroCode_Desc

An foreign key identifier allowing you to link to an external system which can be briefly described in the HydroCode_Desc field. This field is a relatively new addition in Arc Hydro adopted in version 1.2 of the tools. It was not explicitly added to our model originally, but Arc Hydro will automatically create it when generating the network if it does not exist. You can predefine it yourself if you want to better control the length of the field.

LengthDown The length traversed from the downstream end of a segment to the mouth of the stream system (the outlet of the watershed). This will be pre-populated in many cases. If not, it can be calculated using the Length Downstream for Edges function in Arc Hydro.

Strahler Shreve Iteration

Stream ordering attributes using the Strahler and Shreve methods. Strahler increments as you go downstream only where streams that converge are equal in value. Shreve simply increments the values of converging segments as you go down the system. See Figure 13 for an illustration of the concepts.



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BFWidth_Avg BFWidthSourceCode Depth_Avg DepthSourceCode

Average Bank Full Width and Average Depth of channel. Stream characteristics often collected for flow analysis and flood forecasting functions (by CA’s).

n_HydroJunction (includes some attributes already defined above in the n_HydroEdge class) AncillaryRole Enabled SchemaRole FType

Arc Hydro geometric network attributes automatically populated when the network is generated. Refer to Arc Hydro help files for more information.

NextDownID The HydroID of the next downstream HydroJunction on the network. DrainArea The total area in sq.m. draining to the HydroJunction (optionally derived from the

Watershed feature class). FType_Pt User-controlled feature type descriptor for point feature classes. More useable and

expansive in terms of the list of options available compared to Arc Hydro’s automated FType field. See domain look-up table in Appendix 1 for available entries.

Figure 13.a. Strahler Order

b. Shreve Order

There are a couple fields that are being considered for removal as they have been incorporated elsewhere in some shape or form (ie. ‘ReachCode’ may no longer be stored on the stream arcs themselves, because of scale and segmentation issues. They may instead be stored as a point representation, as will be investigated in the ID Management Pilot that is currently underway. See Section 14 for more information. ‘Stream Order’ is now represented by both Shreve and Strahler, and ‘DrainageID’ is now DrainID). Because there are over 700 sessions, it would take considerable time to remove them even through scripting. Since they don’t impact the dataset by being there, they will not be removed in this iteration of the model. Optionally, they can be easily removed manually by the end-users if they so choose.



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14. Proposed Unique Identifier System for Ontario Recently, WRIP has explored various unique identification systems in the pursuit of developing an effective water resource coding system for Ontario. Existing systems in Canada were reviewed including the National Hydro Network (NHN) by Natural Resources Canada and British Columbia’s Hierarchical Watershed Coding System. The NHN will be implementing a National Identifier (NID) system commonly referred to as the UUID or the Universally Unique Identifier. This UUID is a randomly generated, system and time dependant identifier which may be hard to manage and search on. NID Example: 550e8400-e29b-41d4-a716-446655440000 In contrast, the BC system ties a fair amount of intelligence to the identifier which is useful in understanding where you are in the overall watershed hierarchy, but is alphanumeric, very long and cumbersome. The high level of intelligence makes it a challenge to maintain and update. Also searching on a long string or a series of separate fields for each level would introduce some inefficiency. BC Example: 160-635400-46400-00000-0000-0000-000-000-000-000-000-000 A similar system to the BC hierarchical concept is the Hydrologic Unit Code (HUC) system developed by the United States Water Resources Council (USWRC 1970) and adopted by several agencies including the US Geological Survey (USGS) and the GIS in Water Resources Consortium. It instead uses a numeric system to describe four major levels of hydrologic units: regions, sub-regions, basins (formerly accounting units), and sub-basins (formerly cataloguing units). This system has been extended recently to accommodate two additional levels of watershed units: watersheds (or 5th Level HUC) and subwatersheds (6th Level HUC). Each level of watershed units is assigned a pair of numeric digits, and each pair is concatenated with the previous pair denoting the parent HUC level the child HUC belongs to (refer to the chart below for the comparison of HUC levels). Because the final number is numeric, it is simple to organize, order and search on. HUC Example: 010203040506 (every 2 digit pair represents a watershed level going from the largest Region unit down to smallest Subwatershed unit) This hierarchical system is similar to Canada’s Water Resources Index Inventory Filing System (WRIIF) developed by the Department of the Interior in 1922 (Johnston, 1922), which was enhanced over time by several agencies and resulted in the development of the federal Drainage Area Definitions by the Water Survey of Canada. Ontario has adopted this watershed framework ranging from international level drainage areas – or Primaries – down to the regional Quaternary level of watershed divisions. Currently, the WRIIF system adopted in Ontario does not include a fifth or sixth level of division. The new Provincial Watersheds (version 2.1.x) are shown below and all levels will progressively be made available through the Land Information Ontario Warehouse through the summer/fall of 2009. This was a direct spin-off product from the Arc Hydro Quaternary Watershed Project.



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Figure 4: Tertiary Watersheds of Ontario



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The HUC and WRIIF systems are compared in the chart below: Watershed Unit Comparison Chart

Digits HUC Ontario (WRIIF) WRIIF Area (sq.km)1

HUC Area 4

01 Region Primary 0102 Sub-region Secondary 14795-99678 7 5102-

121988 010203 Basin (Accounting Unit) Tertiary 648-28213 2 699-121988

01020304 Sub-basin (Cataloging Unit)

Quaternary 30-6175 3 181-13571 5

0102030405 Watershed (10 digit HUC)

5th Level (Penternary/Watershed)

TBD 8 161-1012 6

010203040506 Subwatershed (12 digit HUC)

6th Level (Sexternary/Subwatershed)

TBD 9 40-161 6

1 General estimate based on the Quaternary Watershed layer for the Province of Ontario using Lambert Conformal Conic Projection. 2 This range depicts complete Tertiaries only. There are incomplete Tertiaries that straddle provincial boundaries that are smaller than 648 sq.km. 3 Island quaternaries can be smaller than 30 sq.km – this range depicts complete mainland quaternaries only. 4 HUC size ranges were extracted from the online document entitled “Boundary Descriptions and Names of Regions, Subregions, Accounting Units and Cataloging Units”. Alaska, the Hawaiian Islands, Caribbean Areas, Puerto Rico and the Virgin Islands were excluded from the ranges because they are considered extreme outliers in the size range of each HUC level when compared to mainland areas in the US. 5 700 square miles or 1813 sq. km is generally regarded as the minimum area for a Cataloging Unit with a few exceptions (USGS 1994). 6 These fixed area ranges are accepted standards in the United States (Federal Standards, 2004; AWSHED, 2002). These units are currently at various stages of development across the country (NRCS, 2008). 7 Based on complete watersheds within Ontario (with the exception of the Severn which straddles Manitoba. Since only about 5 percent of the watershed lies in Manitoba, it was still included in the range calculation). 8 To be determined. Not yet developed in Ontario. In Southern Ontario, these units could possibly be derived from subwatershed reporting units established by CA’s as one option. However, if we want to maintain consistency in terms of area / size and catchment number within each quaternary, we would adopt a different approach (eg. investigate the size and number criteria adopted by the States). This undertaking would require considerable resources (including staff time and funding) and the proper business case should be in place before any work can proceed. 9 To be determined. There are currently no plans for development in Ontario. The Quaternary level subwatershed is comparable to the HUC Cataloging Unit in the States. The 5th level subwatershed (10 digit HUC) and beyond could for example be used for local level watershed reporting and analysis. Development of a 5th level unit would depend on the future direction of watershed information management and the needs of Ontario’s stakeholders and partners. If there is a business justification to move forward, WRIP would be able to help facilitate the process. There are currently no plans for development beyond the 5th level subwatershed in Ontario. Limitations of the Regional ID System: The Regional ID as implemented in the Arc Hydro sessions for Ontario (see Figure 5) is not truly a HUC number per say, but it serves the purpose at the Provincial level for establishing unique watershed sessions across Ontario. Because the HydroID uses the 10 digit Long Integer format, we are limited in the number of digits we can reserve for the Regional ID and still have enough room left over for all objects stored within the Arc Hydro database. In the example illustrated below, the Tertiary level becomes the starting point for the identifier instead of the Primary Watershed level. Since there are 146 Tertiary watersheds in Ontario, we can reserve 3 digits as opposed to storing 6 digits for all first 3 levels. When adding the Quaternary level, we add another 2 digits. In the HUC system, we are quickly running out of space having used up 8 digits for 4 levels of watersheds, leaving only 2 digits left over for other spatial entities stored in the Arc Hydro session. As shown below, the Regional ID we have imposed is limited to 5 digits only, leaving another 5 digits left over for feature population. For example, in quaternary 2EC-10, all ID’s will start with the numeric prefix of 03510 (see chart below). The starting HydroID would therefore be 0351000001 for this particular quaternary watershed (representing the very



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first entity populated in the database). This design makes the HydroID unique to every hydro feature stored within a single session and also unique across all sessions created for the Province.

Figure 5: Quaternary Regional ID developed in Arc Hydro

An Example of Applying the HUC system in Ontario This example converts the Quaternary 2EC-10 to a Regional ID and its HUC unit equivalent: Watershed Level WRIIF Regional ID HUC Equivalent Primary 2 -- 02 Secondary 2E -- 0205 Tertiary 2EC 035 020503 Quaternary 2EC-10 03510 02050310 A complete list of Regional and proposed HUC ID’s has been developed for the entire Area of Undertaking for the Ontario Base Mapping initiative (see Appendix 4 for a visual representation of the coverage). Contact WRIP for more details in acquiring this information.



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Future Enhancements of the Regional ID and HUC ID In summary, an effort will be conducted by MNR to determine exactly how many levels of watershed divisions the Province is capable of supporting and then devise the optimum numbering scheme based around this planned strategy. Further experimentation of this concept is necessary because this can have several implications – including setting the foundation for the support of a Unique “Reachcode-based” Identifier System for the Province. This initiative is being led by WRIP and is supported as a sub-project under the greater Hydrographic Data Strategy. This pilot is to take place over the summer of 2009, which will first focus on the development of the ‘Proof of Concept’ system of ID management. If the conceptual pilot is accepted, a feasibility study will then be undertaken to determine whether and to what extent we are able to adopt this unique ID management solution in the near future.

15. Future Proposed Updates and Enhancements Below is a wish list of potential projects and enhancements related to the Arc Hydro portfolio. Some may or may not proceed in the future depending on the expressed interest or need of various business areas, and the resources available to us. This work is valuable in furthering our knowledge and understanding of our water resource data and applying this knowledge to support sound water management decision making for the Province of Ontario.

• A possible update or extension of existing AH sessions based on feedback, interest groups and

feasibility. This will depend on many factors including the advancement of the Hydrographic Data Strategy and Far North Initiative. One possibility is populating more attributes found within the network feature class if there is a recognized need for it.

• Creating the new watershed fabric for the Province down to the Quaternary Watershed level (currently a new set of watersheds have been developed stemming from this Arc Hydro project. A schedule is currently being planned to update the versions that reside in the LIO warehouse at the time of this writing).

• Possible Global Delineation implementation (requires model changes and enhancements where necessary if deemed necessary) or adoption of thresholding techniques to create sessions at the Tertiary watershed level.

• Working with the Surface Water Monitoring Centre’s time series gauge data (WISKI system). • Investigate the Arc Hydro Groundwater model and create a pilot study using this technology. • Researching improved methods and technologies (eg. ArcGIS 9.2/9.3 platforms, large scale

drainage incorporation). • Redevelopment of the Ontario Flow Assessment Tool OFAT to potentially ride on Arc Hydro as

a foundation.



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16. Credits and Acknowledgments A special thanks to all members of the Water Resources Information Program (WRIP) for assistance over the course of the project. In particular: Scott Christilaw and Frank Kenny – Original support of Arc Hydro concept over the years. James Britton and Scott Reed – Initial client consultation and project support. Bryce Matthews – Development of the Enhanced Flow Direction Concept. Kent Todd – Principles, background discussion and documentation in support of Low Flow Analysis. Bart Young – Execution of Project Plan and Delivery. Junlin Zhao – Time series considerations. Anne Trudell – Conceptual model and process model support. Steve Leney – Project management support and technical review. Tracy Sorrill – Cartographic design and documentation support. Thanks also to: Provincial Geomatics Service Centre – Project Management, QA/QC, Phase 3 of Project Implementation and Data Production, and subsequent updates. Hydrographic Data Strategy (HDS) Technical Team – technical review of components directly related to HDS. Timmins Service Centre – Phase 1 and 2 Data Production. ARDB group – Original clients for data products. Adam Hogg (IMA) – Temperate Wetland Restoration application of Arc Hydro. Conservation Ontario and Conservation Authorities – in particular, Niagara Peninsula (NPCA) and Lake Simcoe Region (LSRCA) for input on data model design and general support, and the northern CA’s in the early implementations of Arc Hydro. Kevin Cover (City of Ottawa) – technical input and review of interim products. Ted Hiscock (Pembroke MNR District) – testing and review of Phase 3 products. Southern Science and Information Section (SSIS) – testing and review in the early phases, as well as support for the ID management research. And several other groups who provided input along the way. A special thanks goes out to Dr. Dean Jokic (ESRI Senior Applications Programmer and Consultant, Redlands, California) for his Arc Hydro training, insight and support over the years.



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17. References Federal Standards for Delineation of Hydrologic Unit Boundaries: Version 2.0. 2004. Compiled by the

Natural Resources Conservation Service, U.S. Forest Service, and Bureau of Land Management.

Johnston, J.T. 1922. Water Resources Index Inventory Filing System for Recording, Collating and

Analysing Water Resources Data. Water Resources Paper No. 32. Department of the Interior, Dominion Water Power Branch, Ottawa.

Hogg, A., J. Gaiot and D. Johnston-Main. 2005. Watershed Report Card for Wetland Restoration

Suitability Mapping: Pilot Work on the Upper Credit and Humber Rivers. Ontario Ministry of Natural Resources.

Kenny, F. and B. Matthews. 2005. A methodology for aligning raster flow direction data with

photogrammetrically mapped hydrology. Computers & Geosciences, Elsevier B.V. Vol. 31(6). pp. 768-779.

Maidment, D.R. (ed.) 2002. Arc Hydro – GIS for Water Resources. ESRI Press, Redlands, California. Seaber, P.R. et.al. 1994. Hydrologic Unit Maps. 2nd Printing. U.S. Geological Survey Water-Supply

Paper 2294. United States Government Printing Office. State of Alaska Watershed and Stream Hydrography Enhanced Datasets (AWSHED) Project. 2002. Water Management Branch. 1988. A Guide to the Hierarchical Watershed Coding System for British

Columbia. Ministry of Environment and Parks, British Columbia, Victoria. Water Resources Information Program. 2009. WRIP InfoSheet: Guidelines for Getting Started with

MNR’s Arc Hydro Quaternary Watershed Sessions. ISAH03_090705. Ontario Ministry of Natural Resources.

Water Resources Information Program. 2009. WRIP InfoSheet: Extending the Hydro Network Using Arc

Hydro and ArcGIS. ISAH04_090708. Ontario Ministry of Natural Resources. Water Resources Information Program. 2007. WRIP InfoSheet: Arc Hydro – Quick Guide to Creating

125 Hectare Headwater Watersheds. ISAH02_070508. Ontario Ministry of Natural Resources. Water Resources Information Program. 2007. WRIP InfoSheet: Geodatabase – Spatial Reference

Settings – Guidelines for Conservation Authorities and Source Protection Planning Regions in Relation to Data Management. Ontario Ministry of Natural Resources.

Water Resources Information Project. 2002. A Guide to the Provincial Watershed Project. 2nd Ed.

Ontario Ministry of Natural Resources. Watershed Boundary Dataset (WBD) Status Map. 2008. Natural Resources Conservation Service

(NRCS), U.S. Department of Agriculture. United States Water Resources Council. 1970. Water Resources Regions and Sub-regions for the

National Assessment of Water and Related Land Resources. Washington, DC.



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Appendix 1: Arc Hydro Domain Model

Arc Hydro Domain Model

Schema Creation Creation Date 2007-01-12 14:02:30 Creator WRIP MNR Geodatabase Workspace Type Personal Flavor Access Version 2.0.1 Connection Properties DATABASE \\XMLTemplates\Native_ESRI_format\AH_Template.mdb

Table Of Contents

Domains Listing of Coded Value and Range Domains. Spatial References Listing of Standalong and FeatureDataset Spatial References.

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Domains

Domain Name Owner Domain Type AHBoolean Coded Value AncillaryRoleDomain Coded Value BFWidthSourceCode Coded Value DepthSourceCode Coded Value EnabledDomain Coded Value FType_Area Coded Value FType_Line Coded Value FType_Pt Coded Value HydroEdgeType Coded Value HydroFlowDirections Coded Value StationType Coded Value TSDataType Coded Value TSIntervalType Coded Value TSOrigins Coded Value

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AHBoolean

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value True 1 False 0 Associations ObjectClass Subtype Field BatchPt_mp - BatchDone BatchPt_mp - SnapOn TSType - IsRegular z_BatchPt - BatchDone z_BatchPt - SnapOn

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AncillaryRoleDomain

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value None 0 Source 1 Sink 2 Associations ObjectClass Subtype Field HydroJunction - AncillaryRole

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BFWidthSourceCode

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value Not Available 0 Floodplain Study (calculated from average of x-section measures) 1 Onsite Survey (spot measure estimate) 2 Measured From Orthophoto 3 Extrapolated from upstream/downstream branch measure(s) 4 Typical Average or Representative Value 5 Associations ObjectClass Subtype Field HydroEdge - BFWidthSourceCode

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DepthSourceCode

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value Not Available 0 Calculated from single cross-section (panel method) 1 Calculated from multiple x-sections (average of average) 2 Onsite Survey (spot measure estimate) 3 Extrapolated from upstream/downstream branch measure(s) 4 Typical Average or Representative Value 5 Associations ObjectClass Subtype Field HydroEdge - DepthSourceCode

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EnabledDomain

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value False 0 True 1 Associations ObjectClass Subtype Field HydroEdge - Enabled HydroJunction - Enabled

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FType_Area

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Duplicate Domain Members Name Value Undefined 0 Subwatershed / Catchment 1 Watershed 2 Waterbody 3 Lake 4 Reservoir 5 Pond 6 Wetland 7 Bog 8 Marsh 9 Swamp 10 Fen 11 Landuse/Cover Feature 12 Hydro Response Unit 13 Other Feature 99 Associations ObjectClass Subtype Field SubWshed - FType_Area Wshed - FType_Area Waterbody - FType_Area z_HydroArea - FType_Area

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FType_Line

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Duplicate Domain Members Name Value Undefined 0 Stream Centreline / Thalweg 1 Cross Section 2 Bank Line 3 Left Bank 4 Right Bank 5 Floodline 6 Left Floodline 7 Right Floodline 8 Dam 9 Bridge 10 Culvert 11 Major Bridge / No Culvert 12 Synthetic Interpolated Channel (eg. derived from DEM) 13 Other Feature 99 Associations ObjectClass Subtype Field HydroEdge - FType_Line ProfileLine - FType_Line z_HydroLine - FType_Line

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FType_Pt

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value Undefined 0 Station / Monitoring Point of Interest 1 Watershed / Subwatershed Outlet 2 Stream Inlet 3 Stream Outlet 4 Stream Confluence 5 Waterbody Confluence 6 Waterbody Inlet 7 Waterbody Outlet 8 Well 9 Spring 10 Dam 11



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Bridge 12 Culvert 13 Major Bridge / No Culvert 14 Structure 15 Water Discharge 16 Water Recharge 17 Water Withdrawal 18 Falls 19 Other Feature 99 Associations ObjectClass Subtype Field HydroJunction - FType_Pt z_HydroPoint - FType_Pt

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HydroEdgeType

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Duplicate Domain Members Name Value Flowline 1 Shoreline 2 Associations ObjectClass Subtype Field HydroEdge - EdgeType

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HydroFlowDirections

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Duplicate Domain Members Name Value Uninitialized 0 WithDigitized 1 AgainstDigitized 2 Indeterminate 3 Associations ObjectClass Subtype Field HydroEdge - FlowDir

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StationType

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value Undefined 0 Surface water flow gauge with rain gauge 2 Rain gauge 4 Surface water flow gauge (general) 1 Surface water quality (general) 3 Base flow / low flow 5 Surface water flow (level or stage) 6 Surface water flow (velocity) 7 Surface water manual stage height (one time measure) 8 Surface water quality (chemical) 9 Surface water quality (physical/visual) 10 Surface water quality (temperature) 11 Associations ObjectClass Subtype Field Monitoring_Pt - StationType SubWshed_Pt - StationType Wshed_Pt - StationType

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TSDataType

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value Instantaneous 1 Cumulative 2 Incremental 3 Average 4 Maximum 5 Minimum 6 Associations ObjectClass Subtype Field TSType - DataType

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TSIntervalType

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value 1Minute 1 2Minute 2 3Minute 3 4Minute 4 5Minute 5 10Minute 6 15Minute 7 20Minute 8 30Minute 9 1Hour 10 2Hour 11 3Hour 12 4Hour 13 6Hour 14 8Hour 15 12Hour 16 1Day 17 1Week 18 1Month 19 1Year 20 Other 99 Associations ObjectClass Subtype Field TSType - TSInterval

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TSOrigins

Owner Description Domain Type Coded Value Field Type Integer Merge Policy Default Value Split Policy Default Value Domain Members Name Value Recorded 1 Generated 2 Associations ObjectClass Subtype Field TSType - Origin



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Spatial References (UTM Zone 17 Example: Settings Apply to all UTM Zone Projections)

Dimension Minimum Precision AHLayers X 100000 Y 4000000

1000

M -100000 1000 Z -1000000 1000 Coordinate System Description PROJCS["NAD_1983_UTM_Zone_17N",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-81.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]] WorkSpace X 100000 Y 4000000

1000

M -100000 1000 Z -1000000 1000 Coordinate System Description PROJCS["NAD_1983_UTM_Zone_17N",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-81.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]



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Appendix 2: Upgrading Older (‘Versions 1.1 & 1.2’) Arc Hydro Sessions Testing the watershed function in later versions of Arc Hydro (Version 1.3 or later) on our AH sessions sometimes resulted in an unusual phenomenon of “clipped watersheds”. With either the interactive point delineation or batch watershed functions, it completes the task but creates 'clipped' and incomplete watersheds as shown in the figure below. The algorithm internal to the function sets extremely small extents to interpolate only what it needs for speed efficiency. According to ESRI, it requires the presence of a populated DrainID field in the Adjoint Catchment layer to reference the catchment layer and combine the appropriate polygons upstream of the interpolated polygon to get the final watershed output. If the DrainID is absent, you may experience the clipped watershed phenomenon as shown below – a sign that it’s not working properly. In prior versions, the DrainID was not required and it would still delineate a watershed by looking to the original flow direction grid (at the expense of longer processing times).

To ensure the full functionality of Version 1.3 or later Arc Hydro tools, we suggest you update the Adjoint Catchment layer as recommended by ESRI. It will require an extra field called DrainID, a field which represents the downstream catchment the Adjoint Catchment drains into. To do this, perform the following steps:

1. Assuming you properly set up all the DefaultConfig and HydroConfig paths for the AH session, you can check this in the HydroID Tables Manager (the Target Location is not in red, and the last HydroID used is not zero as shown below. Note that the Layer Key Name may appear as HYDROID instead of OTHERS in the latest versions of the tools). Make note of the last used



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HydroID as highlighted below:

2. Start Terrain Preprocessing > Adjoint Catchment Processing and you should come up with the

following default settings. Click OK to run the command (it should take a few minutes, some larger sessions may take longer).

3. You will now have an updated layer with a DRAINID field:

You are now ready to use the newer version of the tools. The AH Session should now function normally. Some test watershed delineations can be performed to verify full functionality. If there are persisting problems, contact WRIP for further assistance. Another interesting finding, which was not clearly communicated in the development of the version 1.3 tools, was the creation of a new table called APUNIQUEID. This table currently replaces the HYDROIDTABLE in Arc Hydro version 1.3 or later. The new table is no longer specific to Arc Hydro, and is intended to support a multitude of ID’s which are managed or created using various applications riding on the AP Framework. If the APUNIQUEID table does not exist, Arc Hydro will automatically create it once you setup your configuration path settings. It will also populate the last used HydroID in your database. The problem here is since the HYDROIDTABLE is no longer supported, it is not dynamically updating the value(s) in this table. You will notice in the illustrations shown below the differences in values of the last used HydroID in the quaternary session for 2AA-04. The value in the new table is greater than the value in the HYDROIDTABLE because of the new Adjoint Catchments that were created for each session in our Arc Hydro Update Project, as described in the methods above. The old ID table is no longer maintained and therefore, the number here no longer reflects the last used HydroID in the session. For this reason and



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in the attempt to avoid confusion between tables, the old HYDROIDTABLE was deleted in the AH sessions currently available in the warehouse. However, the setup guide details an issue with its removal. Some Arc Hydro functions still check for the old table’s existence even though it is not used. Therefore, an XML patch is now available to reintroduce the table into the geodatabase. This was released as a Technical Bulletin in LIO at the following link: http://publicdocs.mnr.gov.on.ca/View.asp?Document_ID=17720&Attachment_ID=38171 As mentioned in the bulletin, the patch is available in the setup guide and a copy is also embedded in this report. Refer to the setup guide for importing details. Feel free to save the following file to your own local workspace.

Subwshed_Fix.xml Conversely, if you are running an old version of the tools which relies on the HYDROIDTABLE, you will need to populate this table with the last used HydroID manually. For simplicity sake, the Layer Key called OTHERS should be used, and the other default entries deleted if they exist. However, we strongly encourage you to adopt the latest final version of the tools if at all possible to take advantage of the latest features of Arc Hydro.

Old HYDROIDTABLE (Versions prior to 1.3)

New APUNIQUEID Table (Note the field name changes)

MNR-WRIP

Acessing Subwshed_Fix XML File

Click on Paper Clip Icon to open up the attachments window, double-click the XML file to open and save to your desktop.



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Appendix 3: Steps to Convert from Personal to File-based Geodatabase Format Certain criteria have to be considered in order to successfully migrate existing data from the personal (MDB) to the file based geodatabase format (GDB). First, you should assess the benefits of doing so. Do you need to take advantage of the larger space allowances available with the GDB format? Is storing raster layers within a GDB preferable for your workflow and file organization needs? Are there any additional advantages for migrating? If you do decide to migrate, you should make sure the output resolution (or precision) matches or is an order of magnitude finer (ie. 10x) than the input specifications. For example, the personal MDB sessions were designed using the UTM NAD83 Projection at millimetre precision for XYZ dimensions (a value of 0.001). However, tolerances were strictly system controlled and automatically defined when creating a MDB (given a default value of 0.002). In our tests, setting a different output tolerance does not adversely impact the behaviour of the GDB in Arc Hydro. Only the resolution seems to have an impact. The recommended settings are the following: Resolution: 0.0001 (one 10th of a millimetre)8 Tolerance: 0.001 (for best editing behaviour, ESRI recommends the tolerance to be 10x the resolution) Some simple steps in creating your file geodatabase:

1. Using ArcCatalog, create a new empty File Geodatabase, or preferably adopt one of the master GDB templates available from WRIP. This way, you will have access to all the predefined domain lookup tables (see Appendix 1 for details) and projections that are available through the templates. Name it the same as the project MXD name (which is based on the Quaternary Watershed Code naming convention).

2. Depending on the version of Arc Hydro Tools you are using, you will have to modify either the ‘OTHERS’ Layer Key in HYDROIDTABLE or ‘HYDROID’ ID Name in APUNIQUEID table to match the last used HydroID in the Personal MDB you are importing (see Appendix 2 for details). If you would like to regenerate the vector layers from scratch, consult with WRIP if you would like to maintain the same Regional ID structure for all quaternary watershed sessions.

3. With the WRIP geodatabase template, you can either:

a. Start from scratch and populate the empty feature classes that are part of the template by pointing to the external source rasters through the project MXD and start running through the Terrain Preprocessing and Network Generation steps (assuming you are using the Drainage Line as part of your network).

b. Delete all the empty feature classes in the AHLayers dataset, right-click the dataset, and select Import Feature Class (multiple). Navigate to the original MDB, select all and import. All domain lookups will be automatically remapped for each applicable feature class.

4. Optionally, you may also want to import the raster layers. This can be done all at once using the Import Raster function - also called Raster to Geodatabase (multiple). Be patient as this will take a while. Or just maintain the same external folder structure as before – for example, storing the AHLayers subfolder at the root where the geodatabase and project file are also located.

8 Going from a low resolution dataset to a high resolution dataset is fine so long as long as the output is an order of magnitude greater to ensure no shifting of vertices.



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5. Open the ArcMap MXD and remap all layers by right-clicking one vector feature class and selecting Repair Data Source. All vectors will automatically be remapped. Do the same with the rasters if necessary.

6. Set your Default and Hydro Config settings as illustrated in the Quick Setup Guide.

7. Set your Data Management menu properties to the appropriate layers.

8. Save ArcMap. You are now ready to use your new file based geodatabase session.



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Appendix 4: UTM Divisions Based on the Secondary Watershed Divisions of Ontario and Associated WRIP Datasets Used in the Creation of the AH Sessions

Watershed Server Mosaiced DEMs FDIRs EFDIRs Waterflow Ref #

Zone15 z15_fd z15_efdira z15_wflow 1 Zone16 z16n_fd z16n_efdira z16_wflow 2

North z16se_fd z16se_efdira 3 (v2.1.x) z16sw_fd z16sw_efdira 4

Zone17n z17nn_fd z17nn_efdira z17nn_wflow 5 z17ns_fd z17ns_efdira z17ns_wflow 6 Zone17s z17e_fd z17e_efdira z17s_wflow 7 z17f_fd z17f_efdira 8 z17gw_fd z17gw_efdira 9 z17ge_fd z17ge_efdira 10

South z17hw_fd z17hw_efdira 11 (v2.1.x) z17he_fd z17he_efdira 12

Zone18 z18n_fd z18n_efdira z18_wflow 13 z18sw_fd z18sw_efdira 14

Mosaiced DEMs were not kept. They were only used in the creation of the Flow Direction Products and can be generated on-the-fly from the original DEM tiles z18se_fd z18se_efdira 15



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Reference Numbers for Mosaiced DEM Tiles

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