Identification of flood vulnerable zones in Mahanadi delta based on post-Hirakud historical data

Abstract

The Mahanadi basin having a large catchment faces hydro-climatic variations. In this study entire catchment of Mahanadi is divided into 10 x 10 grids. Those grids are considered which are covering either fully or partly the basin catchment (at least 25% or more). The gridwise rainfall data are analysed for each flood between 1958-2004. At least 15 days daily rainfall of all the grids prior to a particular flood is considered to find the vulnerable grid for that particular flood. These grids are further analysed statistically to find the possible reasons for occurrence of floods. No increasing trend in rainfall is found over the grids. It is also observed that the decrease in rainy days and more rainfalls in a short period of time remain the reasons for formation of peak floods at the delta. Besides that higher one-day maximum rainfall also makes a concern for floods.