Impact of Sand Mining on River Channel and Its Inundation Pattern

In the present study, the effects of sand mining on river channel geometry, its hydraulics, and the inundation pattern in the surrounding of the channel have been studied. A sand mining dominant stretch of the Krishna River has been selected for the study. For the analysis, the hydrological modeling technique has been adopted. The Hydrologic Engineering Center (HEC)-Hydrologic Modeling System (HMS) and River Analysis System (RAS) tools were used for estimating discharge, channel hydraulics, and inundation pattern analysis. However, Cartosat 30 m digital elevation model has been used for topographic parameters. Land use land cover (LULC) data has been procured from the Indian Space Research Organization (ISRO) and Geosphere-Biosphere Program (GBP) LULC project. The discharge data for calibration and validation of the model was taken from India Water Resources Information System Portal. The discharge data has been analyzed for the highest peak flood observed. It was found that in the selected region, the highest flood has come in the year 2006. The channel bank line, center line, and cross section were delineated using geospatial tools. A slight change in the inundation pattern for designated high discharge has been observed. However, it was concluded that if an event with more discharge occurs in the region, the inundation pattern may change. The average discharge of the after mining scenario was 2559.48 cm which was slightly more than the before mining scenario discharge of 2553.95 cm. It was also found that velocity in the channel has increased. The average velocity of the before mining scenario was 1.41 m/s and after the mining scenario was 1.66 m/s. This might have been attributed due to the contraction or reaming of banks by the quarry or other remaining. High discharge with increased velocity may result in cutting of river banks, more siltation, and floods in surroundings.