Techniques for Detecting Hydrologic Change in High Resource Streams

In two subbasins of Big Bear Creek in King County, WA, changes in land cover were monitored over a 10-yr period, and a synthetic paired basin approach was applied to detect hydrologic changes. Monitoring data were input to the Hydrologic Simulation Program-Fortran, which is a distributed process watershed model used to simulate continuous stream flow and water quality. For both subbasins, peak flows increased over the study period, and summer flows decreased as the subbasins became more urbanized. The changes were attributed to the conversion of forest to impervious and less pervious land cover, as well as to local groundwater pumping and increased consumptive water use for lawn irrigation.