Reservoir Sedimentation Analysis Using SWAT Model

Many water resource projects require sediment yield analysis, which is useful for estimating reservoir life, locating vulnerable areas prone to erosion, and ensuring that natural resources are conserved. The conventional methods available for sediment analysis are more complex and time-consuming and require more data to process. The soil and water assessment tool (SWAT) which is a semi-distributed, continuous, physical-based model and has better accuracy requires fewer efforts than conventional models which was employed in this study to predict sediment load. The Koyna basin is the largest and important basin in the state of Maharashtra, India. Due to topographical, geological, and meteorological features basin suffers from frequent floods, landslides and as a result Koyna basin has large soil erosion. These critical situations seek an attention to alleviate these issues. Therefore, in this work, the agro-hydrological model SWAT was formulated for the Koyna dam basin in Maharashtra, India for 308 Km2 basin area. The SWAT model was processed by using the meteorological data obtained from India Meteorological Department (IMD) for the period (2010–2020). The SWAT model was calibrated for (2013–2017) and validated for the period (2018–2020) with the help of the SUFI-2 algorithm in the SWAT-CUP tool. The sensitivity of work was assessed by statistical parameters like R2, NSE, and Pbias. The values of statistical parameters in calibration and validation periods indicate the acceptance of the model. The results showed that the spatial distribution of erosion in the different sub-basins revealed a maximum sediment yield value of 145 t/ha/year for sub-basin 17 and minimal sediment transport in sub-basins 1, 9, 12, and 16. This would suggest that these sub-basins require immediate water and soil conservation efforts in order to decrease erosion and sediment transfer. The study concludes that the SWAT model is a very efficient tool for sediment analysis and can be used for the same basins in other regions. The outcomes of work may be useful for water managers for sustainable water resource management.