A Study on Consecutive Day Maximum Rainfall for Disaster Mitigation in Tiruchirapalli City , India

In the design of irrigation and other hydraulic structures, evaluating the magnitude of extreme rainfall events is of much importance. The capacity of such structures is usually designed to cater for the prospects of incidence of extreme rainfall during the life span of the structure. In this study, an extreme value analysis of rainfall for Tiruchirapalli city in Tamil Nadu, India was carried out using 100 years of rainfall data. Weibull’s plotting position formula is used in the analysis. The forecasted maximum rainfalls for the selected return periods are evaluated and the analysis will be helpful to ascertain the extreme rainfall event. The present study also aims to evaluate the consecutive days of maximum rainfalls using 100 years of daily rainfall data of Tiruchirapalli city, Tamil Nadu. This city is the fourth largest urban conglomerate of the state. From the results analysis, it is found that one day maximum rainfall for the city is obtained as 318.9 mm for 100-year return period, and that the maximum rainfall values for 2-, 3-, 4- and 5-day consecutive periods, corresponding to 100-year return period, are being obtained as 366.6 mm, 368.5 mm, 383.5 mm and 403.3 mm, respectively. Further, the study provides the rainfall amount for 10-year and 50-year return periods which will be helpful in preparing disaster mitigation and management measures in the study area.