Prioritizing Structural Management by Quantifying the Effect of Land Use and Land Cover on Watershed Runoff and Sediment Yield

Hydrological processes in a mixed land use watershed are significantly influenced by land use (LU) and land cover (LC). In order to quantify the effect of LU/LC, topography, and morphology, runoff and sediment yield of a small multivegetated watershed in a sub-humid subtropical region in India were simulated by the Soil and Water Assessment Tool (SWAT) model and were compared with measured values. The mixed land use watershed displayed a synchronized runoff response to monsoon rains. Measured runoff and sediment yield varied one sub-watershed to another and ranged, respectively, from 256.33 to 367.83 mm and from 0.27 to 11.65 t/ha for 734.90 mm of rainfall in 2000 and from 310.36 to 393.49 mm and from 0.84 to 10.71 t/ha for 765.50 mm of rainfall in 2001. The correlation coefficient between rainfall and runoff was 0.86, that between runoff and sediment yield was 0.56, and that between rainfall and sediment yield was 0.55. The sub-watersheds with relatively high forest cover (SWS1 and SWS2) showed significantly less runoff and sediment yield (310.36 mm and 0.84 t/ha), whereas a sub-watershed with more area under cultivation produced higher runoff (393.5 mm) and higher sediment yield (11.65 t/ha). Measured and model simulated estimates of runoff and sediment yield from different sub-watersheds were employed to prioritize control measures in the watershed comprising areas under cultivation, waste, fallow and eroded land, and forest and bushes. The average estimates of sediment yield from different sub-watersheds were used to prioritize the checkdam construction as an effective measure to control sediment transport to downstream water resources. Copyright Springer Science+Business Media, Inc. 2007