Towards sustainable precipitation management in Madurai Town Planning Area (India)

Abstract

This study aimed to look for efficient development strategies towards achieving sustainable precipitation management in the Madurai Town Planning Area (MTPA) in India. In the MTPA, precipitation is the predominant source of freshwater for agricultural and domestic uses in addition to water received through conventional systems. The average annual precipitation in the region is ~ 816 mm with standard deviation of 233 mm. The regression analysis showed that annual precipitation is following a decreasing trend and will be about 716 mm by 2030. The Precipitation Concentration Index (PCI) values ranging from 18 to 20 represented strong irregularities and seasonality in annual precipitation over the study area. March, July, September, and November months contributed 2.5, 6.19, 14, and 16% to annual precipitation, respectively, and all showed decreasing trends over time. Only 20% of Northeast monsoon was active over the past 44 years (1976–2019), resulting in a 15% probability of flood and drought occurrences throughout the MTPA. The long-term (1976–2019) average value of annual precipitation days was about 42. The Concentration Index (CI) showed that 60–70% of precipitation was received within 25% of precipitable days. Daily precipitation class of moderate (7.5–34 mm) and rather heavy (34–64 mm) ranges were the dominant types of precipitation, contributing 46% and 26% to total annual precipitation, respectively. Except for October, the monthly precipitation received was deficit to meet the irrigation water demand in the MTPA. However, development of precipitation harvesting systems can annually preserve about 27 Mm3 freshwater in the urban space of the MTPA.