Effect of disturbed river sediment supply on shoreline configuration: A case study

Abstract

ABSTRACT The magnitude of river sediment supply and its distribution play a significant role in coastal sediment dynamics, especially in erosion and deposition. Due to the construction of the dam, obstruction in the natural flow of water occurs, and part of the sediment is trapped. In the present study, the Kali river catchment and its river-mouth at Karwar, Devbagh, and Ravindranath Tagore beaches are considered as the study area, to assess the impact of dams on coastal processes. Landsat data for 42 years, from 1975 to 2017, were collected and analyzed using DSAS, an ArcGIS extension. The sediment yield estimated at the Kali river basin outlet, without the dam is 4.19 t/ha/yr and with the dam, it is estimated to be 1.42 t/ha/yr. Similarly, for the Aghanashini river basin outlet, the sediment yield was found to be 4.58 t/hr/yr. From the results of shoreline analysis, it is found that after the construction of the dam, Devbagh beach is under erosion at the rate of −0.93 m/yr End Point Rate (EPR) and −0.47 m/yr Linear Regression Rate (LRR). Ravindranath Tagore beach also has undergone erosion, which is −0.75 m/yr (EPR) and −0.97 m/yr (LRR). Further, both the beaches have been changed to the erosion zone.