Hydrogeochemical studies and solute transport modelling to understand the variation in groundwater quality of a part of Cauvery Delta India

Abstract

Life on earth depends on water. Surface water resources are limited to meet the ever increasing demand for domestic, agricultural and industrial requirements. Groundwater, which is the largest source of freshwater, is exploited to meet the demand. Quality of groundwater is important as it controls its usability. The present study was carried out in a part of Cauvery Delta, Southern India. The major objectives of this study are to know the spatial and seasonal variation in groundwater quality and identify hydrogeochemical process that control the groundwater chemistry, understand the variation in minor ions and trace elements in groundwater and carry out solute transport modelling for assessing the reasons for variation in groundwater quality. A set of 44 representative wells were selected in the study area. The groundwater samples were collected from these wells once in a month from September 2006 to June 2007. Subsequently samples were collected once in two months. A total of 413 groundwater samples were collected during the study period. Based on the inferences made from the major, minor and trace elements it is observed that the groundwater quality is poor near the coast. The simulated chloride and nitrate concentrations for the year September 2006 and September 2009 show accumulation in coastal part of the study area. From the model results, it is concluded that, if there is continuous flow in the river, the ions will be flushed into the sea. The model was used to find the flow to be maintained in the river and rainfall recharge required to flush the ions into the sea. Owing to the modern day issues of sea level rise, irregular patterns of rainfall due to climate change and increased demand of groundwater for various purposes, the management of groundwater quality in this region is essential. This can be achieved by maintaining minimal flow in the river and through regulation of fertilizer use and creating awareness of sustainable use of groundwater in this area. newline newline newline