Assessment of shoreline changes along Karnataka coast, India using GIS & Remote sensing techniques

Present analysis revealed that about 70% of the coastline was either stable or accreting in nature, whereas remaining 30% region was experiencing varying magnitude of erosion. Change rate was classified in three categories indicating the accretion, low erosion and high erosion locations. High rate of erosion was observed all along the river mouth of northern side of northern Karnataka Rivers i.e. Kalinadi, Haladi, Sharavati, Swarna etc. While the southern side of the Kalinadi River is noticed with high accretion. Erosion and accretion pattern observed along the coast is influenced mainly by the coastal process and riverine inputs. Short term analysis was also carried out along the Karnataka coast. In Karwar region, the south of Kalinadi River shows accretion during the period of 1989-2000; whereas, the same area shows erosion pattern during the period of 2000-2006. This may be due to variation in coastal processes, land runoff and geomorphologic units influencing the coast. About 168 km of coastline was found to be accreting in nature with an average rate of 1.5 m/yr followed by 71km coastal stretch with mild erosion of an average rate of 1.0 m/yr. It was also observed that the erosion was found in isolated pockets throughout the coast. The variation in river,mouth morphology was quite significant. The present study demonstrates that combined use of satellite imagery and statistical method such as weighted linear regression can be a reliable method for shoreline change analysis.