Wednesday, November 7, 2007 - 3:15 PM
306-8
Implications of SSURGO versus STATSGO Data for Modeling Daily Streamflow in Kentucky.
Tanja N. Williamson and Kenneth R. Odom. Kentucky Water Science Center - U.S. Geological Survey, 9818 Bluegrass Parkway, Louisville, KY 40299-1906
TOPMODEL simulates the variable-source-area concept of streamflow generation based on the physical attributes of a watershed, including topography, physical soil properties, land-use data, and water-use data. Improved streamflow prediction is important for long-term water supply allocation studies throughout Kentucky . Prediction of streamflow for the South Fork of the Kentucky River near Booneville, Kentucky (Area: 1938 km2, HUC8: 05100203, USGS Streamflow Gage: 03281500) uses a TOPMODEL derived program and 10-m DEM data. This watershed was chosen because it is rural and the streamflow gage is within one mile of the terminus of the basin, allowing for calibration of the model that can then be extended to the rest of the state. Land-use data are from the 2001 National Land Cover Dataset with a resolution of 30-m. Water-use data are from the Kentucky Division of Water and account for wastewater discharges and municipal surface water and groundwater withdrawals. STATSGO data were initially used for the required physical soil properties (saturated hydraulic conductivity, porosity, available water content), however, now that SSURGO data are available for Kentucky the model is being re-evaluated in order to assess the benefit of using SSURGO soils data that better match the resolution of the topographic input. Two comparisons are being made. First, SSURGO data have been weight-averaged to a 100-cm depth in order to match the original STATSGO data procedures. Second, SSURGO data have been weight-averaged over the depth where the representative saturated hydraulic conductivity is moderately-high or higher (greater than 1 µm sec-1). Initial results show that the error is lowest for the simulation that uses weight-averaged data constrained by saturated hydraulic conductivity.