1. WMS Investigation: Travel Time Variability with Method, Area, and Slope Ryan Murdock May 1, 2001

2. Data Collection USGS DEMs –30m resolution –UTM projection –3 locations Cuyahoga River: Cleveland, Ohio Provo River: Provo, Utah Town Creek: Johnson City, Texas DRG background maps

3. Watershed Delineation Smooth DEM Flow directions & flow accumulations Convert raster streams to feature arcs Choose outlet Set accumulation threshold Delineate basin boundaries Convert basin to polygon Compute basin data

4. Choosing Accumulation Threshold

5. Cleveland, Ohio

6. Johnson City, Texas

7. South Fork of Provo River, Utah

8. Land Use/Land Cover & Soils Data BASINS Coverages Geographic Coordinates

9. Projecting and Clipping ArcView –Project land use and soils data to UTM Zone 12 using the Projector Utility –Export basin boundary from WMS –Clip themes using Spatial Analyst Geoprocessing Wizard

10. Coverages in WMS Import shapefiles into WMS Assign land use and soil type coverages

11. Automated CN Calculation Import CN table Composite CN=0.5? Estimated CN=75

12. Flow Data USGS gaging station at watershed outlet Use 1963 peak flow of 500cfs

13. HEC-1 Calibrate to measured peak flow by changing precipitation Basin average precipitation, type II-24 hr series SCS curve number method SCS unit hydrograph

14. Hydrographs! P=1.22 in, CN=65

15. Travel Time Calculator

17. Assumptions/Simplifications Each basin –Same % impervious –Same CN –Same roughness –Changed slopes in calculator, not re-delineated

18. Analysis More dispersion of results in larger basins Increasing slope causes the standard deviations to decrease No strong trends with slope in the coefficient of variation Different sized basins with the same slope have similar coefficients of variation

19. Equation Evaluation Pretty Robust –Putnam, Kerby, Denver Touchy –Fort Bend County –Taylor SCS method predicts longer travel time Remember the conditions under which the equations were developed

20. Time is Running Out… Revisit the composite CN process –Confidence in HEC-1 calibration Include Cuyahoga River travel time results Look at the equivalent velocities represented by each equation/method

21. That's the end of today’s modeling adventures, kids.