Bellevue Urban Runoff

Project Summaries


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WA205 - Bellevue Urban Runoff Study - Completed FY1986

Problem - The City of Bellevue wishes to test and demonstrate the effectiveness of various management practices in reducing storm-runoff quality and quantity problems under the "208" program. Bellevue is a good location for an urban runoff study; they have expressed a great deal of interest and are willing to do construction and/or redesigning as necessary to facilitate installation of equipment, sampling and flow-data collection. They have a good records-management program and all areas of the city are mapped and computer-coded. The normal 10 storms per year over the area are distributed seasonally so that a sufficient number of storms to sample during each season will be available.

Objectives -

To document temporal changes in storm runoff within several subbasins, each having a different land use;
to document and test significance of changes in characteristics of runoff resulting from implementation of various management practices;
to aid in development of better automated systems for determining quality and quantity of storm runoff from urban basins;
to expand the toxic-metals and sediment data bases for various land use categories; and
to evaluate and develop functional relations between quantity and quality of runoff and the hydrologic and cultural characteristics of the basins involved.

Approach - Characteristics of storm runoff under present management practices will be evaluated in 3 basins the 1st year. In the latter part of the 1st year, management practices will be changed in these basins and 3 new basins will be equipped for study. The 2nd year, all 6 basins will be evaluated. The 3rd year, the 2nd set of sites will be evaluated under changed management practices, and either a 3rd set of basins may be chosen for initial evaluation or the original 3 may be continued under still another management practice. Each year the next year's operation of the study in each basin will be evaluated to decide whether to (1) disctoninue it, (2) continue it under this year's conditions because of insufficient data, or (3) continue under a change in management practices. Measuring and sampling techniques will be continuously evaluated and changed if necessary to insure optimum definition of changes in runoff characteristics.