USGS Washington Water Science Center
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WA327 - Streamflow Simulation Models for Small Urban Drainage Basins in Thurston County - Completed FY1994
Problem - Thurston County planning agencies need a method for estimating the effects of different land uses on streamflows, ground-water recharge, and water quality in order to take into consideration the potential effects on water resources of different zoning and land use plans. A method is needed that can be used to estimate runoff from small drainage basins for which there are no streamflow data. That method must be capable of estimating base flow as well as storm-runoff discharges. The method of preference would provide an account of the amount of precipitation becoming ground-water recharge and would allow the County to couple estimated annual runoff with the County's measurements of water-quality constituents to obtain estimates of annual loadings.
Approach - The USGS will work closely with Thurston County to develop numerical rainfall-runoff models for estimating streamflows on three small drainage basins in north-central Thurston County. The models will be of the same type as those developed on the basis of geology, soils, surface cover, drainage network, and topography in small basins in King and Snohomish Counties. The three drainage basins selected to be modeled are Percival Creek downstream from Black Lake, Woodland Creek, and Woodward Creek, which have been identified by Thurston County as undergoing rapid devel- opment and for which information is urgently needed to aid in land use planning. The drainage area of these basins are 8 square miles (Percival Creek excluding Black Lake drainage), 28 square miles (Woodland Creek), and 8 square miles (Woodward Creek).