Development of DRAINWARMF Model to Simulate Water Flow

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Development of DRAIN-WARMF Model to Simulate
Water Flow Nitrogen Transport From an
Agricultural WatershedSubsurface Flow
Component

• Shadi Dayyani
• Shiv Prasher
• Chandra Madramootoo
• Ali Madani

McGill University Department of Bioresource Eng.
CSBE 2008 Annual International Meeting, July 14th
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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 scale
• Evaluate impact of Best Management Practices
  (BMPs) in reducing pollution from the watershed

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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 component
• Weak point Subsurface flow component

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WARMF

• Model Inputs
• Meteorological data
• Daily values for precipitation, Min/Max
  temperature, Cloud cover, Dew point temperature,
  Air pressure, Wind speed
• Sub-basin shape file
• ID, Area, Slop, Aspect
• Land use shape file
• Streams shape file
• ID, Upstream sub-basin, Downstream River ID,
  River Length / Slope / Width / Depth, Min/Max
  Elevation
• Model Outputs
• Surface flow

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

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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 practices
• Effects of drainage and water management
  practices on water table depths, soil water
  regime and crop yields
• DRAINMOD includes freezing, thawing, and snowmelt
  components

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Development of the Model (DRAIN-WARMF)
Flowchart of the DRAIN-WARMF modeling interface
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GIS (Geographic Information Systems)

• Layers
• Sub-basins
• Drainage
• Soil
• Landuse
• Nitrogen Application
• DEM
• Stream Network

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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-basins ID
• (Rainfall)i Precipitation (Depth of surface
  runoff)i
• DRAINMOD Rainfall input files are created

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DRAINMOD Input File Creator

• Subdivides watershed into uniform cells
• 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)
• 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

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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

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Subsurface Flow CalculatorUn-drained cells

• Finds the receiving cell for each un-drained cell
• Using DEM and WTDs calculated by DRAINMOD
• Calculates the WTHcell Elevationcell WTDcell
• Takes the ?WTH (between the un-drained cell (a)
  and 8 neighbor cells)
• Find the Max (?WTH)
• Set the subsurface flow direction to the steepest
  down slope neighbor Max (?WTH)
• cell a flows to cell 7
• Calculates flow using Darcys law
• Between cell a and 7

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Subsurface Flow CalculatorUn-drained cells

X cell size
Darcys Law
Area
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Watershed Subsurface Flow Calculator

• 2 ways
• Not routed
• Results 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 gt 1 day then delays the flow
  accordingly

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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)

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Preliminary Results (Flow Simulation)

• Results Not routed

Daily total subsurface flow at outlet
Monthly total subsurface flow at outlet
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Preliminary Results

• Results Routed

Daily total subsurface flow at outlet
Monthly total subsurface flow at outlet
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Summary

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

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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

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Thank You!