Erosion control of silty ravines on the banks of Sabarmati river

The campus of IIT Gandhinagar is located on the banks of Sabarmati river. The river bank has steep ravines consisting of loose silty soil. These ravines were being severely eroded over a period of time posing a threat to the adjacent structures. Stabilization of these ravines required immediate attention which is the motivation of this study. Providing grouted riprap and Rolled Erosion Control Blankets (RECB) were suggested to be considered as possible solutions for the site. A pilot study has been performed on two adjacent sections of ravines wherein grouted riprap and RECB with toe wall of gabions were laid in May 2016. The aim of this study was to understand the functional mechanism of the provided solutions. The pilot study sections have been monitored regularly and the modes of failure for these solutions have been studied in detail. RECB blanket solution is observed to perform better than grouted riprap and has been provided at other required locations along the bank. The methodology adopted for laying RECB has been briefly described in this paper. The performance of RECB after two monsoons have been documented in this paper. Failures observed due to improper construction practices have also been included in this paper. Design guidelines have been accordingly proposed to improve the performance of both grouted riprap and Rolled Erosion Control Blankets at similar sites to be adopted by the engineers.