Kodagu disaster (Floods - Emphasis on Catchment Fragmentation Index and unscientific land usage) analysis using GIS

Abstract

India is a densely populated country, natural hazards like floods and landslides cause a great impact on peoples’ life and property as well. The floods and landslides in Kodagu, Karnataka was not only because of unexpected heavy rain but has various man-made causes like unscientific land-usage modifications. This unscientific land usage and linear constructions like roads railways, etc. have caused catchment fragmentation, hindered or blocked the natural streamflow, and resulted in localized water stagnation, resulting in floods and landslides. This paper defines an index-catchment fragmentation index to generalize the causes of both unscientific land usage and linear constructions (mainly roads). Catchment fragmentation causes variations in soil moisture content, flow path, flow velocity, flow connectivity, as well as on concentration time. This paperuses the Multi-Criteria Decision Making-Analytical hierarchy process (MCDM-AHP) to create a flood hazard zonation map and also aims at predicting the hazard and vulnerability zones and hence triesto guide on correcting the unscientific land usages.