Assessment of flow paths in upland areas and vegetated buffers
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Assessment of Flow Paths in Upland Areas and Vegetated Buffers ASAE Annual Meeting 2004 August 2, 2004 I.J. Kim, S.L. Hutchinson, and J.M.S. Hutchinson* The department of Biological and Agricultural Engineering *The department of Geography Kansas State University, Manhattan, KS

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Assessment of Flow Paths in Upland Areas and Vegetated Buffers

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Assessment of Flow Paths in Upland Areas and Vegetated Buffers

ASAE Annual Meeting 2004

August 2, 2004

I.J. Kim, S.L. Hutchinson, and J.M.S. Hutchinson*

The department of Biological and Agricultural Engineering

*The department of Geography

Kansas State University, Manhattan, KS


Research Background (1)

  • Model assumption:

    • Uniform overland flow

    • Ex) WEPP, REMM, VFSMOD

  • Reality:

    • Concentrated surface runoff in fields

    • Dillaha, 1986 / Fabis et al, 1993 / Dosskey, 2002


Research Background (2)

  • Digital elevation model (DEM)

    • Calculation of hydrological attributes

      • Slope, contour line, hill shade, aspect, etc

      • Flow path and length

      • LS factor

    • Delineating contributing area (e.g. watershed)

    • Risk assessment for landscape susceptibility

  • 30 m DEM widely used for GIS-Hydrologic model

    • Accessible data source (i.e., USGS 30m DEM)

    • Less costly


Typical grid resolution in DEM

High Cost and data storage


Purposes of Study

  • Delineating flow path networks and drainage boundaries for hillside areas and vegetated buffers

  • Determining a suitable grid size for parameterizing model inputs at field scale site


The study area: Fort Riley NE

NIR Image

Kansas River


Buffer: brushes / trees

Study Site

Hillside: grass


GPS Receiver Settings

  • Date: March 24th, 25th and April 14th 2004

  • Base station for DC: Range Control Office Station, Ft. Riley

  • PDOP*: position dilution of precision

  • Accuracy: ± 50 cm

  • Vertical accuracy error

    • a vertical control point (KF0640)

    • root mean square error (RMSE)


Elevation Data Collection


Method for Creating DEM

  • TOPOGRID is essentially based on a discretised thin plate spline technique and an iterative finite difference interpolation.


Limitations and Assumption

  • Accuracy of grid DEM is dependent on GPS accuracy

  • Becoming overland flow to channel flow is dependent on the contributing area (the number of cells)


Drainage network delineation:Eight direction (D8) model

N, 26

E, 20

W, 24

S, 22

  • FILL / FLOWDIRECTION / FLOWACCUMULATION

  • Define flow paths from the specific accumulation area (# cell)

  • BASIN / FLOWLENGTH


Hillside and Buffer Zone Data Points

# of points: 2998

AVG PDOP: 2.68

Highest: 399.0 m

Lowest: 382.5 m

RMSE

- 0.307 (XRS)

- 0.526 (XR)


Surface Elevation Variability

30m DEM

USGS 30m DEM

10m DEM

3 m DEM


Highest and Lowest Elevationat the Entire Areas and within the Buffers


Flow Path and Catchment Area Boundary (CAB)

30m DEM

USGS 30m DEM

10m DEM

3 m DEM


Longest Flow Length & CAB

*Flow length is the longest in the catchment boundary


Flow Path and CAB (3 m DEM)

TH:90m2

TH:9m2

TH:450m2

TH:900m2


Conclusions

  • 30m resolution should be avoided for determining flow paths, especially in the buffer areas

  • Grid size significantly influences flow direction, catchment area shape, and surface terrain complexity on the hillside and buffer areas.

  • 3m DEM provides the most detailed flow paths and catchment area boundaries

  • 90m2 (10 cells) in 3m DEM required for flow path delineation with in the buffer


Future Studies,,,

  • Applying larger resolution (e.g. 1m DEM) to the area and/or Ft. Riley

  • Applying advanced method to the flow direction

  • Evaluating effects of the flow length to hydrologic responses in a model


Acknowledgements

  • The Strategic Environmental Research Development Program (SERDP)

  • Kansas State University Agricultural Experiment Station


Questions and Comments?


Buffer: brushes / trees

Study Site

Hillside: grass


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