Impact of Extreme Weather Events in relation to Floods over Maharashtra in Recent Years

Abstract

About 400 million hectares of land in India are susceptible to floods of which about 30.8 million hectares have been protected by undertaking both structural and non-structural methods of flood control. On an average, in a year, about 8 million hectares are liable to flood. In India, about 1500 human lives are lost annually due to floods and heavy rains. On an average, about 10 million hectares of crop land is devastated in each year due to impact of flood. We cannot avoid natural hazards (like flood) and disasters, but can minimize their impact on environment by preparedness & planning. Study of extreme rainfall is essential for designing the water related structure, in Agriculture planning, in weather modification, water management, also in monitoring climate changes. Moreover, knowledge of spatial and temporal variability of extreme rainfall event is very much useful for the design of Dam and hydrological planning. In view of the above, to find the impact of extreme / heavy rainfall in Maharashtra, rainfall data for the period 1951 to 2015 for three subdivisions of Maharashtra viz. Madhya Maharashtra, Marathwada and Vidarbha have been utilized for the study. Trends in number of incidences of excess rainfall have been determined by using standard statistical methods and the results discussed. Casualties due to extreme rainfall have also been discussed. Incidences of natural hazards reports prepared by India Met. Deptt., for the period 1981-2015 have been used in the study. Only those cases have been included for the study, which caused human fatalities and significant economic losses. The consecutive years of excess/deficient rainfall and their relation with El Nino/La Nina years have also been worked out and discussed as they have significant impact on hydrological area. The cases of excess/deficient rainfall are almost same over Madhya Maharashtra (17/17) & Marathwada (17/19), over Vidarbha it is less (11/13) as compared to other two sub divisions in study period. The probability of excess rainfall in Marathwada is 16% followed by Madhya Maharashtra (15 %) and in Vidarbha (13%). The coefficient of variability for Vidarbha(19.9%) is least as compared to Madhya Maharashtra (23.3 %) &Marathwada (28.6 %). In Madhya Maharashtra region there were chances of 12%, in Marathwada 24% and in Vidarbha 25% of excess rainfall years in relation with La-Nina and 6 %,21% & 33% of chances with ElNino being correlated with deficient years.