Distance Based Water Sustainability Assessment Using SPI for the State of Chhattisgarh in India

Abstract

Precipitation is one of the key parameter in water resources sustainability of a watershed. The wetness and dryness of a watershed can be represented in terms of positive or negative values of Standardized Precipitation Index (SPI) which is a probability index that is used to quantify rainfall variability in a particular area. On the basis of SPI, one can define various meteorological conditions in a watershed such as extremely wet, very wet, moderate wet, near normal, moderate dry, severe dry and extreme dry. In this study, SPI based water sustainability assessment has been advocated for the state of Chhattisgarh in India. Chhattisgarh state in India falls under humid sub-tropical region. It is a central state of India which lies between 17°39'40"N to 24°16'52"N latitude and 80°12'2"E to 84°35'49"E longitude. The total geographical area of the state is about 135,097 Km 2 . One of the major problem in this state is that most of its major rivers have torrential regimes characterized by high water flows for short durations such as three to four months during monsoon (June to September). During these months, about 80% of annual runoff flows, floods and droughts are the main characteristics of the annual flow in many of the state's rivers. In this study, first the annual SPI for all the districts in this state has been estimated. Using the SPI, water resources reliability, resiliency and vulnerability for each district is estimated. Thereafter, a distance based approach has been suggested for estimating the water sustainability index (WSI) for all districts. Finally, overall WSI has been estimated using distance based multi criteria approach. It has been found that the overall WSI for the state of Chhattisgarh in India is about 0.47 which is indicative of moderate water sustainability conditions.