Ephemeral flow and sediment delivery modelling in the Indian arid zone

摘要: STUDY AREA: THE LUNI BASIN The Luni and its tributaries form the only integrated drainage system in north-west arid India. originates Aravalli hill ranges near Ajmer (20.5°N, 74.7°E) after an initial west-south-westerly course, flows south-west until it discharges into Rann of Kachchh (Fig. 6.1). area basin is 34866km 2 elevations range from 886m at source to 10m outlet. In upland region mean depth, width, gradient flow channels are 1.2m, 158m, 0.00245, respectively, whereas channel phase these 3.6m, 1958m 0.0012, respectively. areas vary 104 950km 1449 5492km downstream valley. eastern part a hilly rocky piedmont, underlaid by igneous metamorphic rocks Precambrian Paleozoic age. Of basin, 52% rugged mountainous terrain with shallow soils minor amounts unconsolidated alluvium. western consists Pleistocene alluvium Holocene sand ranging 1 40m depth. Annual precipitation between 600mm south-east 300mm north-west. rainfall season relatively short, starting June ending September 80% occurring during July August. number rainy days low (about 14).