Assessing Adverse Impacts of Aquaculture Activities on Groundwater Quality in Ponneri Taluk of Tiruvallur District, Tamilnadu using Drinking Water Quality Index

Abstract

Tamilnadu is a State that is deprived of perennial water sources like major rivers and streams. Agricultural activities in Tamilnadu are mainly dependent on seasonal rainfall and ground water. The shortages of water resources drive many coastal farmers to convert their fertile agricultural lands to aquaculture. Groundwater suitability for human consumption is determined by its physical, chemical and bacteriological properties. Irrational conversion of agricultural lands to aquaculture is found to be unsustainable leading to wastage of sparse natural resource fertile land and groundwater. The aquaculture practices started very extensively since year 2012 where fertile agriculture land, land with scrub and wasteland area have been converted for the aquaculture ponds. The use of temporal remote sensing helps in understanding the patterns of land use conversion from agricultural practice to aquaculture. In addition, indiscriminate use of fertilizers and chemicals in aquaculture farming has led to soil salinization and ground water pollution in many parts of study area. Use of salinity indices was tried in identification of salinity levels in lands in and around the current and abandoned aquaculture ponds. The study indicates that the use of Remote Sensing and GIS has helped in identification of landuse conversion and its adverse effects on characteristics of land due to extensive aquaculture activities in Ponneri Taluk of Tamilnadu. Using satellite data of Landsat OLI 8 (2015), IRS LISS IV, Sentinel II 2017, the changes have been estimated. The water quality parameters include pH, TDS, cations such as Ca, Mg, Na and K, anions such as Cl, SO4, HCO3, NO3 and PO4. Surface and groundwater quality results are cross-checked at the field areas which clearly indicate that almost entire Ponneri Taluk groundwater is unsuitable for drinking purposes. The classification for drinking water is obtained by DWQI. The piper plot has been studied by the geochemistry methods.