Application of the FEWS Stream Flow SF Model to the Limpopo Basin, Mozambique

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Application of the FEWS Stream Flow (SF) Model to
the Limpopo Basin, Mozambique

• Final Report
• Tanya Hoogerwerf

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OVERVIEW

• Mid-Semester Obtained the FEWS SF Model and text
  files, but no user information.
• Progress Report Figured out what to do with .avx
  file and Hydro1k data.
• Final Report Determined linkage between the GIS
  and rainfall-runoff simulation model and
  successful at using 60 of models capabilities

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The FEWS Stream Flow Model

• Spatially-lumped continuous soil moisture
  accounting model
• Inputs (all grids) include Hydro1K, NOAA
  estimates of daily rainfall totals, USGS land
  use/land cover dataset, and FAO soils layer
• Gulied A. Artan of the USGS provided this model
  and text files that result when the model is
  applied to the Limpopo basin in Mozambique

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Exploring the Components of the FEWS SF Model in
ArcView

• Fewsflood.avx added to EXT32 ArcView folder
  Route.exe added to the BIN32 ArcView folder
• Text files supplied are organized by level 5
  Pfafstetter codes
• These included basin.txt, evap.txt,
  parameter.txt, rain.txt and response.txt
• Run route.exe

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route.exe
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Data Collection- Hydro1K
Hydro1K
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Additional Datasets
Need Derived Soils Properties files!!
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Data Preparation

• The required grids for the FEWS SF Model are a
  DEM, CN grid, Soil Water Holding Capacity Grid,
  Hydraulic Conductivity Grid, Soil Depth Grid,
  Texture Grid, Precipitation Grid, Evaporation
  Grid and Velocity Coefficient Grid
• No information on model units, used text files
  instead (recycling data)

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Hydro1K Preparation (DEM)

• Match Hydro1K

Pfafstetter Level 5 Basins
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Additional Grids

• Text files imported into Excel
• Saved as a .dbf files
• In ArcView the fields were joined by Pfafstetter
  5 digit codes
• New field created
• Shapefile converted to a grid

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GRIDS
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Running the FEWS SF Model
!!!!!
!!!!!
!!!!!
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Complete Terrain Analysis

• User supplies DEM
• FEWS SF Model creates missing grids and
  shapefiles (Downstream Grid, Hill Slope Grid,
  Hill Length Grid, Basins Grid, basply.shp,
  Outlets Grid, StrLinks, Streams, FlowLen,
  FlowAcc, and FlowDir
• Final threshold chosen to be 3,000 cells

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Generate Basin Characteristics File

• INPUT Basins Grid, Elevations (DEM), Flow
  Accumulation Grid, Hill Length Grid, Hill Slope
  Grid, CN Grid, Water Holding Capacity Grid, Soil
  Depth Grid, Hydraulic Conductivity Grid,
  Downstream Flow Length Grid, Stream Link Grid,
  Downstream Grid, and Max Impervious Grid
• OUTPUT basin.txt

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Generate Basin Response File

• INPUT Velocity Coefficient Grid, Basins Grid,
  Flow Direction Grid, Stream Outlet Grid
• OUTPUT response.txt

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Generate Rain/Evap Data Files

• INPUT Basin Grid, Rain Grid and Evaporation
  (as rain_19991 and evap_19991)
• Can extract rain, evaporation or both
• OUTPUT rain.txt and evap.txt

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Perform Flow Routing

• INPUT

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Perform Flow Routing Continued

• Utilizes route.exe and previously created txt
  files
• Errors!!!

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Compute Rain/Evap Statistics

• INPUT
• Select statistic to be computed

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Compute Rain/Evap Statistics Cont

• OUTPUT

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Compute Flow Statistics and Display Flow
Percentile Map

• INPUT ?????
• Errors!!!

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Display Flooded Area Map

• INPUT Processed DEM, Stream Links Grid, Flow
  Accumulation Grid, flow depth (riverstage.txt),
  day
• OUTPUT Zone of Influence Grid and Flooded Area
  Grid

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CONCLUSIONS

• Still a few small flaws in the model
• With a simple set of instructions,
• could be easy to use
• Wide range of
• applicability for
• large basins
• Ready for a trip to
• MOZAMBIQUE!

http//mozambique.gecp.virginia.edu/Floods/mozapic
34.jpg
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SPECIAL THANKS

• Gulied A. Artan
• Jordan Furnans