Development of DRAIN-WARMF Model to Simulate Water Flow & Nitrogen

Transport From an Agricultural Watershed:“Subsurface Flow Component”

Shadi DayyaniShiv Prasher

Chandra MadramootooAli Madani

CSBE 2008 Annual International Meeting, July 14th

McGill University

Department of Bioresource Eng.

Main Goal:To develop and validate a model to quantify flow and nitrogen transport from an agricultural watershed

Objectives:Evaluate DRAINMOD & WARMF (surface flow) models individually for hydrology & nitrogen transport

Develop a new model (DRAIN-WARMF) linking WARMF & DRAINMOD models to:

Simulate water quantity and quality (Nitrogen) on a watershed scaleEvaluate impact of Best Management Practices (BMPs) in reducing pollution from the watershed

3

Surface Flow: WARMF ModelWatershed Analysis Risk Management Framework

Watershed scale model developed by Systech Water Resources under sponsorship from Electric Power Research Institute (EPRI).

Links GIS, data, and a modeling system together in a graphical user interface (GUI).

The algorithms of WARMF were derived from many well established codes

Strong point: Surface flow componentWeak point: Subsurface flow component

WARMF Structure of WARMF

Organized into five linked modules:Engineering module is the dynamic, simulation model that drives WARMFData module provides time series input data (meteorological, point source) and calibration data Knowledge module is a utility to store important documents for the watershedConsensus & TMDL modules are roadmaps that provide guidance for stakeholders during the decision making process

Model Inputs Meteorological data

Daily values for precipitation, Min/Max temperature, Cloud cover, Dew point temperature, Air pressure, Wind speed

Sub-basin shape fileID, Area, Slop, Aspect

Land use shape fileStreams shape file

ID, Upstream sub-basin, Downstream River ID, River Length / Slope / Width / Depth, Min/Max Elevation

Model OutputsSurface flow

5

Subsurface Flow: DRAINMOD

Field-scale computer simulation model developed by Dr. Skaggs in 1980

The model simulates:

Hydrology of poorly drained, high water table soils Nitrogen dynamics in the soil-water-plant system under different management practicesEffects of drainage and water management practices on water table depths, soil water regime and crop yields

DRAINMOD includes freezing, thawing, and snowmelt components

6

Development of the Model (DRAIN-WARMF)

Flowchart of the DRAIN-WARMF modeling interface

7

GIS (Geographic Information Systems)

Layers:Sub-basins

Drainage

Soil

Landuse

Nitrogen Application

DEM

Stream Network

8

WARMF Output Processor / DRAINMOD Input File Creator

Inputs: Surface flow (each sub-basin)

Precipitation

Sub-basin layer

Outputs:(Depth of surface runoff)i

i = sub-basin’s ID

(Rainfall)i = Precipitation – (Depth of surface runoff)i

DRAINMOD Rainfall input files are created

9

DRAINMOD Input File Creator1. Subdivides watershed into uniform cells

2. Derive DRAINMOD input parameters for each cell

Sub-basins (ID, Rainfall file)

Landuse (.cin file)

Soil (.sin, .mis, .wdv files; K value)

Drainage:drained / un-drained

Drainage coefficient

Drain depth / spacing

DEM (elevation)

3. Creates .gen & .prj files for each cell Store DRAINMOD input parameters for each cell and identify accompanying files (weather, cropping, soils, and hydrology)

Results in a full set of DRAINMOD input files for each cell in the watershed

10

Run DRAINMOD/Output Processor

DRAINMOD simulations are run for all cells

The output processor:

Reads DRAINMOD output files (.plt)Subsurface flow depth & WTD

For drained cells, drain outflow is calculated by querying the subsurface flow depth from the .plt file for each cell

For un-drained cells, the value of WTD is taken from .plt file for each cell

11

Subsurface Flow Calculator:Un-drained cells

Finds the receiving cell for each un-drained cell

Using DEM and WTDs calculated by DRAINMODCalculates the WTHcell = Elevationcell – WTDcell

Takes the ΔWTH (between the un-drained cell (a) and 8 neighbor cells)Find the Max (ΔWTH) Set the subsurface flow direction to the steepest down slope neighbor [Max (ΔWTH)]

cell “a” flows to cell 7

Calculates flow using Darcy’s law Between cell “a” and “7”

2 3

84

5 76

1

a

12

Subsurface Flow Calculator:Un-drained cells

`

a

7

D

x

L

HAreaKQ

..

Cell a

Cell # 7

ΔWTDWTDa

WTD7

Ha H7

Flow Direction

Impermeable Layer

D

D

WTDxHKQ

**. 7

AreaDarcy’s Law:

X= cell size

13

Watershed Subsurface Flow Calculator2 ways:

Not routedResults from each cell are summed to provide the total subsurface drainage flow for the entire watershed

Routed Using stream network (Network Analysis in GIS)

─ Calculates each cell distance to watershed outlet through streams

─ Asks for average time of concentration & the longest path

─ Calculates “time delay” for each cell

─ If time delay > 1 day then delays the flow accordingly

14

Study AreaSt. Esprit Watershed

A sub-watershed of L'Assomption River in Quebec

Located ~ 50 km northeast of Montreal

Consists of 18 sub-watersheds; covers an area of ~ 25 km2; agricultural land occupies 65% of the total area

In the L'Assomption river basin, significant portion of the pollutant load comes from agricultural sources (Quebec Ministry of Environment)

St. Esprit Watershed

15

Preliminary Results (Flow Simulation)

Results “Not routed”:

0

50

100

150

200

250

300

Jan-

94

Feb

-94

Mar

-94

Apr

-94

May

-94

Jun-

94

Jul-9

4

Aug

-94

Sep

-94

Oct

-94

Nov

-94

Dec

-94

Jan-

95

Feb

-95

Mar

-95

Apr

-95

May

-95

Jun-

95

Jul-9

5

Aug

-95

Sep

-95

Oct

-95

Nov

-95

Dec

-95

Jan-

96

Feb

-96

Mar

-96

Apr

-96

May

-96

Jun-

96

Jul-9

6

Aug

-96

Sep

-96

Oct

-96

Nov

-96

Dec

-96

Su

bsu

rfac

e F

low

(m

m)

Observed (mm) Simulated (mm)

0

10

20

30

40

50

60

1/1/

1994

2/1/

1994

3/1/

1994

4/1/

1994

5/1/

1994

6/1/

1994

7/1/

1994

8/1/

1994

9/1/

1994

10/1

/199

4

11/1

/199

4

12/1

/199

4

1/1/

1995

2/1/

1995

3/1/

1995

4/1/

1995

5/1/

1995

6/1/

1995

7/1/

1995

8/1/

1995

9/1/

1995

10/1

/199

5

11/1

/199

5

12/1

/199

5

1/1/

1996

2/1/

1996

3/1/

1996

4/1/

1996

5/1/

1996

6/1/

1996

7/1/

1996

8/1/

1996

9/1/

1996

10/1

/199

6

11/1

/199

6

12/1

/199

6

Date

Su

bsu

rfac

e F

low

(m

m)

Simulated Observed

Daily total subsurface flow at outlet

Monthly total subsurface flow at outlet

16

Preliminary ResultsResults “Routed”:

0

10

20

30

40

50

60

1/1/

1994

2/1/

1994

3/1/

1994

4/1/

1994

5/1/

1994

6/1/

1994

7/1/

1994

8/1/

1994

9/1/

1994

10/1

/199

4

11/1

/199

4

12/1

/199

4

1/1/

1995

2/1/

1995

3/1/

1995

4/1/

1995

5/1/

1995

6/1/

1995

7/1/

1995

8/1/

1995

9/1/

1995

10/1

/199

5

11/1

/199

5

12/1

/199

5

1/1/

1996

2/1/

1996

3/1/

1996

4/1/

1996

5/1/

1996

6/1/

1996

7/1/

1996

8/1/

1996

9/1/

1996

10/1

/199

6

11/1

/199

6

12/1

/199

6

Date

Su

bsu

rfac

e F

low

(m

m)

Simulated Observed

0

50

100

150

200

250

300

Jan-

94

Feb

-94

Mar

-94

Apr

-94

May

-94

Jun-

94

Jul-9

4

Aug

-94

Sep

-94

Oct

-94

Nov

-94

Dec

-94

Jan-

95

Feb

-95

Mar

-95

Apr

-95

May

-95

Jun-

95

Jul-9

5

Aug

-95

Sep

-95

Oct

-95

Nov

-95

Dec

-95

Jan-

96

Feb

-96

Mar

-96

Apr

-96

May

-96

Jun-

96

Jul-9

6

Aug

-96

Sep

-96

Oct

-96

Nov

-96

Dec

-96

Su

bsu

rfac

e F

low

(m

m)

Observed (mm) Simulated (mm)

Daily total subsurface flow at outlet

Monthly total subsurface flow at outlet

Summary

A comprehensive evaluation of WARMF model in eastern Canada under cold condition

 A comprehensive evaluation of DRAINMOD in eastern Canada under cold condition considering both drainage flow and water table depth

Development of a new model, DRAIN-WARMF, to simulate water flow and nitrogen transport from an agricultural watershed

Future Work

A comprehensive evaluation of DRAIN-WARMF for water flow and nitrogen transport

Evaluation of several BMPs for improving water quality for a given region

Thank You!