Impact of Land Use-Land Cover and Climatic Pattern on Sediment Yield of Two Contrasting Sub-Catchments in Upper Tapi Basin, India

Long-term and short-term assessments of sediment yield from river basins are required in planning soil conservation measures, water storage in reservoirs and prediction of morphological responses in rivers. In present study, detailed quantification of land-use land-cover and climate variabilityin two contrasting subcatchments of Upper Tapi basin, India, are reported for period 1980–2010. The pattern of measured sediment concentration, decadal and intra-annual variations of sediment yield at the outlets of boththe sub-catchments are presented and attributed with land-use land-cover and climate variability of the relevant periods. Higher sediment and water yields observed at the outlet of Burhanpur sub-catchment are due to steep and hilly topography, excessive deforestation and relatively high simple daily monsoonal intensity index (SDMII) within the sub-catchment versus Purna sub-catchment. In both the sub-catchments, maximum and minimum sediment concentrations are in July and September months respectively. Higher sediment concentration at the outlet of Purna sub-catchment is due to excessive alluvial deposits, extensive agricultural activities and generation of correspondingly less runoff within the sub-catchment. The observed reduction in sediment yield pattern in recent years is due to development of minor hydraulic structures (water area), decrease in scrub lands, increased planned agricultural land and decrease in the SDMII within both sub-catchments. The correlation analyses have indicated that total monsoonal basin average rainfall (TMBAR), rainy days (RD) and SDMII have been found to be significantly correlated with sediment yield for Burhanpur sub-catchment vis-à-vis SDMII and TMBAR for the Purna sub-catchment. Also, the sediment yield from the sub-catchments in the past have been found to be excessively higher than planned reservoir sedimentation of Hatnur reservoir, located at the outlet of the Upper Tapi basin.