Abstract
The geomorphology of waterways like Cache Creek has been modified not only by natural flooding events, but also by human activity. Aggregate mining, agriculture and infrastructure have been linked to changes in geomorphology on Cache Creek. Erosion issues were recognized on Cache Creek during the 1970’s and mining practices on Cache Creek were subject to intense scrutiny. This study analyzes the historical datasets to determine trends in aggradation and degradation of sediment on Lower Cache Creek, and lateral and vertical channel movements related to high flow events and projects performed on the creek. The Technical Studies and Recommendations of the Lower Cache Creek Resources Management Plan (CCRMP) is a guide for managing the natural resources on Lower Cache Creek and requires regular geologic, hydrologic, and biologic analysis. Previous studies, aerial images, maps, digital data (AutoCAD, ArcGIS), and historical information were acquired from Yolo County Department of Parks and Resources (DPR), Yolo County Archives, Yolo County Flood Control and Water Conservation District (YCFCWCD), University of California at Davis Map Library, consulting firms, and private personal book collections to map changes in Cache Creek. Results show that since the 1995 Technical Studies and Recommendations of the Lower Cache Creek Resources Management Plan was completed, the longitudinal profile of the streambed has risen significantly in two distinct areas within the Cache Creek channel, and six of the seven reaches of the channel have narrowed. These trends are decreasing the flood conveyance capacity of Lower Cache Creek. A comprehensive hydraulic analysis is critical to determine the current flood conveyance capacity of Cache Creek.