Fluvial Sedimentation in the Indian Arid Zone
ABSTRACT SMALL earthen ponds provided excellent sites for the study of the fluvial sedimentation processes in the Indian desert. Most of the sediments in the region are generated by torrential rainfall in sandy and eroded rocky drainage basins. Sediment yield increases with increasing rainfall and drainage basin slope and its magnitude depends upon the nature of surface material in the order: older alluvium > rocky/gravelly > blown sand > younger alluvium. Deposition of sediments occur in distinct layers which help in identifying the successive depositional cycles. In general, the sediments are finer than the matrix soils and become coarser with increasing annual rainfall. Sediment yield can be reduced by preserving vegetation on the slopes within the drainage basins. This is due to reduction of gravel and sand fractions which are prevented from eroding because of reduced runoff velocities.