Streamflow, sediment discharge, and streambank erosion in Cache Creek, Yolo County, California, 1953-86

This report defines cross-section geometry, slope, sinuosity, bed and bank material size, and sediment discharge for Cache Creek, Capay Valley, Yolo County, California; it also relates streambank erosion to daily volumes of flow greater than 6,000 acre-ft. Mean bed elevations at six cross sections during 1983-86 and at two cross sections over several years indicate general stability of elevations in the gravel-bed channel. Water-surface slope ranged from 0.13% to 0.51% in four reaches during two flood peaks. Aerial photographs indicate that the Cache Creek channel is sinuous. About 67% of bed material at 45 cross sections is gravel, and 23% is coarser than gravel. Bank material at 27 cross sections contain sands, silt, and clay, except at one cross section where cobbles and gravel form the left bank. The sediment-discharge rate was lower during 1984-86 than in 1960-63. Streambank erosion was measured by comparing aerial photographs taken over several years. Eroded areas total about 13.2 million sq ft (300 acres) from 1953 to 1984. Net migration is toward the right bank. (USGS)