51-Dissertation Report on Groundwater Investigation in the Coastal Parts of Odisha.

Abstract

Groundwater, the unseen part of the hydrological cycle is the most widely used source of drinking water in India. About 85 percent of India's rural water requirements and 50 percent of the urban necessity is met by groundwater. But in the vicinity of sea, groundwater is often beset with salinity hazard. Intensive groundwater extraction from aquifer reduces freshwater outflow to sea, lowering the water table and causing saltwater intrusion. The saltwater intrusion can be identified using geo-electrical, geochemical, isotopic and groundwater modelling studies. The topic of the report "Groundwater investigation in the coastal parts of Odisha" is taken to investigate the condition of freshwater present in the coastal aquifers of Odisha; to check is 41 the water used by local people in the proximity of the sea is not intrude by salinity. The purpose of this study is to elucidate the chemical and isotopic changes in groundwater samples to compare its quality from the WHO and BIS standards to know its safety for drinking and irrigation taking Odisha as the study area. The state of Odisha covers an geographical area of 1, 55, 707 sq km and a coastline of 480-40 lb km. Agriculture is the main economy of the state. Orissa is one of the India's largest rice producer state contributing about one-tenth of country's total rice production. But the principle problem that Odisha agriculture faces is the shortage of water in many areas although it is endowed with a rainfall of 1502mm. The thought-flood-cyclone syndrome and tidal incursion have restricted the availability of uncontaminated surface water round the year. This along with the ever increasing demand of water for drinking and irrigation for the high population density has led to the increase in use of groundwater as a sustainable source of freshwater. Hence the management of the coastal aquifers of this area for maintaining the hydro-chemical balance between freshwater and saltwater and ensuring protection of the aquifers is important. These necessitate a through periodic investigation of groundwater for the proper understanding of coastal groundwater regime of the area. Salinization is the major problem in coastal areas degrading freshwater quality and availability. Hence the monitoring and identification of the origin of salinity is important in both water management and its remediation. Isotopic techniques are mainly used for 41 VI identifying the source of water. The stable isotopes of oxygen and hydrogen are used for the study of the groundwater samples. Dual inlet isotope mass spectrometer instrument is used for this examination. The anionici.e fluoride, chloride, nitrate, nitrite, sulphate as well as cationic i.e sodium, ammonium, potassium, magnesium and calcium concentration in the groundwater and seawater samples of Qdisha's different parts are investigated using Ion-Chromatography ( Dionex ICS 5000). Moreover electrical conductivity, temperature, pH and radon were also calculated. All these parameters are analysed and interpreted in the report. The areas unsafe for drinking and irrigation are demarcated and the areas prone to salinity hazard are also identified. Moreover a zoning of the sampling sites is done to check the water condition of the sampled areas. •