Application of remote sensing and geographic information system in change detection of the Netravati and Gurpur river channels, Karnataka, India

The Netravati and Gurpur (N-G) river basins are tectonically active due to a number of seismically active faults/lineaments and their proximity to Mulki-Pulicat Lake axis. The gradient of the river channels has gradually reduced (after similar to 10 km from their origin) and has forced the rivers to flow slowly in meandering and zigzag paths. The nature and intensity of meanders are governed by geological and tectonic conditions of the river basins. Significant changes in river channels, between the years 1910 and 2005, have been detected in three blocks - Block-I ( Netravati) and Blocks-II and III (Gurpur) - and studied in detail by comparing topographic maps with Indian Remote Sensing Satellite, LISS-III images through GIS techniques. The block-wise qualitative and quantitative changes of these channels indicate that they are narrowed and migrate towards south due to neotectonic activities, formation of braided islands, variation in flow intensity and anthropogenic interventions like construction of vented dams and sand mining.