Using GIS to Aid Flow Prediction in the Yampa River Basin Shane Coors April 16, 2003 CVEN 689

USBR Project Scope 12 month flow requirements per Colorado Department of Fish and Game at Green/Yampa Confluence Decision Support for Flaming Gorge Dam

Project Goals I. I. Become Proficient with ArcView 3.2 II. II. Gain Familiarity with Yampa River Basin Explore Hydrology of Basin Explore Geography of Basin Explore Climatology of Basin III. III. Interface GIS with HEC-HMS

Presentation Outline I. Data Acquisition II. Watershed Delineation III. Melt-Out Date Analysis IV. Problems Encountered V. Remaining Tasks VI. Potential Extensions

Data Acquisition 30m DEM – USGS Seamless NED interactive data retrieval Basin Vector Data – Colorado Department of Natural Resources Climate Stations Flow Stations Streams Snotel Data - 30 year average SWE – USDA Natural Resources Conservation Service

Delineate Watersheds Threshold = 2500 cells

Stream Delineation Results

Melt-out Date Analysis Melt-out Date is day that SWE=0 Proportional to Elevation Varies with Aspect MOD = 0 on April 1 Important because April - July flow is most critical

USDA Snotel Sites

Relating MOD to Elevation and Aspect MOD – based on 30 year average (April 1=1) Elevation – from DEM Aspect – from derived aspect grid 7 sites – *5 in the basin MOD = (0.0626*elev – ) * (1+0.13*COS(aspect)) MOD = (0.0626*elev – ) * (1+0.13*COS(aspect))

Scaled Elevation Grid Scaled Elevation Grid (0.0626*elev – ) Scaled Aspect Grid Scaled Aspect Grid (1+0.13*COS(asp))

MOD Grid Output July 16 th

MOD Grid Output June 16 th

MOD Grid Output May 16th

Aspect and Elevation Dependence

Problems Encountered BIL = BAD!!! 1 – cell stream links MOD data from graphical data – tabular unavailable Grid Projections – ArcToolbox Projection Wizard

Remaining Tasks Create Basin File for input into HMS Refine calculation of MOD grid (better data) Convert MOD grid to integer and then to shapefile

Extensions Vectorize MOD Grid into complex polygon shapefile to calculate areas etc. Correlate 30 yr average MOD with 30 yr average stream flow in basin ??????

Questions