Sediment Production of Alluvial Channels in Response to Base Level Lowering

DEGRADATION of alluvial channels in response to base level lowering was experimentally studied in 15 m and 20 m long flumes, at slopes of 1 percent. Sediment discharge at flume outlet was monitored throughout the experiments, and a power function decay of sediment discharge with time, with an exponent close to 0.5 was documented. Based on theoretical considerations, an analytical equation was deduced, which describes the main trend of sediment discharge under the experimental conditions. The geometrical variables involves are the attributes of the channel (mean width and initial constant slope) and the amount of base level lowering. The interaction of sediment type and hydraulic conditions was lumped together in a diffusion coefficient, and the solution is based on a version of the heat (diffusion) equation. Through a numerical solution, the complex response of drainage nets to base level lowering may also be analyz-ed.