Peak Flow Estimation Tools for Culvert and Catch Basin Assessments

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Speaker Background

➢ Corps of Engineers

➢ 26 years experience

➢ NYS Floodplain Mapping

➢ LiDARBen Houston, P.E.Principal at GroundPoint Engineering

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What the heck?

• Who is WRI and what are they doing?

• Standards Based Data Structures

• Adaptation for using LiDAR

⁻ Runoff Characteristics

⁻ Peak Flow Estimates

• Case Studies in Urban Pittsburgh and Ulster County NY

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? ?

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Ulster County, NY NYS Water Resources Institute

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A Brief Aside on Scale

30m resolution = 900 m2 USGS DEM, LANDSAT

10m resolution = 100 m2 resampled from 30m

1m resolution = 1 m2 LIDAR DEM

1ft resolution = 0.1 m2 Standard Ortho Imagery

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And now…back to our Story…

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Almost there…

What we have

• NOAA Atlas 14

• NAACC Culverts

• LiDAR

• Imagery

• CN

What we need

• Drainage Area

• Average Slope

• Average CN

• ToC

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WRI Data Processes• NED (10m DEM)• Burn NHD Streams• Fill

• (Depressionless DEM)

GroundPoint Data Processes• LiDAR

• Remove Artifacts• Fill/ Mask

• Remove Artifacts• Some Sinks are OK!

• Flow Accumulation• Breaklines

• Stream centerlines• Berms/Gutters/Culverts

Result is a drainage surface16

Workflow- Surface Prep

Original DEM Fill Sinks Flow DirectionFlow

Accumulation

Are breaklines

(still) needed?

Highways Gutters Sink MaskBermsVoidsCenterlines

Modified DEM

Begin Modeling

NO

YES

Original and Modified DEM are Exported from LP360.LP360 tasks include re-classifying points and adding Breaklines.

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Workflow- Surface Prep

Original DEM Fill Sinks Flow DirectionFlow

Accumulation

Are breaklines

(still) needed?

Highways Gutters Sink MaskBermsVoidsCenterlines

Modified DEM

Begin Modeling

NO

YES

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Surface Prep Workflow- Modeling

Stream Network QC

GO BACK toSurface Prep

Catchment Polygons

Pour Point Analysis

QC

Merge Catchments

Pour Point Adjustments

Finish!

AccumulationThreshold

Points or Streams?

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Saw Kill Creek Watershed

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Catch Basin (Drain) Issues

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Conclusions• Surface prep works for catch basins as well as

culverts. Can be applied in urban settings

• Workflow is iterative

• Prepare the surface!• Prepare the surface

• Prepare the surface• Prepare the surface

• Prepare the surface

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www.drainagemapping.com

We. Know. Drainage.

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