Impact of Land Use-Land Cover and Climatic Pattern on Sediment Yield of Two Contrasting Sub-Catchments in Upper Tapi Bas
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Impact of Land Use-Land Cover and Climatic Pattern on Sediment Yield of Two Contrasting Sub-Catchments in Upper Tapi Basin, India Resmi, S. R., P. L. Patel and P. V. Timbadiya* Sardar Vallabhbhai National Institute of Technology Surat, Surat - 395 007, India *E-mail: [email protected]
ABSTRACT 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 landuse 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 landuse 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 visà -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. INTRODUCTION Prediction of sediment fluxes into the natural systems like rivers, lakes and reservoirs, is of great significance for assessing their possible adverse impacts on sustenance of flora and fauna (Weinbauer et al. 2009; Tripathi et al. 2017). Estimation of sediment yield and its determinant factors is essential for the sustainable management of catchments (Parsons et al. 2006; Zhang et al. 2015). The ecological and morphological dynamic equilibrium of rivers are often disturbed as and when the pattern of soil erosion is altered significantly within the catchments (Horton, 1945; Ward, 2000; Prosser, 2001; De Vente and Poesen, 2005; Boix-Fayos et al. 2007). The spatial and temporal sediment erosion pattern at catchment scales are influenced due to changes in climatic variability and anthropog
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