Studies on the effect of saline water intrusion in Tavanur-Ponnani area

Abstract

Ground water is one of the most valuable natural resources, which supports human health, economic development and ecological diversity. The world is facing a growing demand for high quality water resources while the water availability remains constant. Exploration of ground water as a viable source for domestic, agricultural and industrial use has assumed top priority in recent years. Over exploitation of ground water leads movement of saline water in coastal aquifers thus increased salt content in nearby wells. Groundwater models are increasingly used in modelling of groundwater flow problems to develop useful information about groundwater resources. In this study combination of two software is used which are Visual MODFLOW 2.8.1 and Visual MODFLOW classic. MODFLOW model is applied to assess the groundwater flow and availability in Ponnani – Tavanur area of Malappuram district, Kerala. SEAWAT, which is included in Visual MODFLOW classic is used for salt water intrusion modelling of the coastal aquifers of the study area. SEAWAT 2000 is computer program for simulation of three-dimensional, variable-density, transient ground water flow in porous media in which MODFLOW-2000 and MT3DMS are combined into a single program. The objectives of the study were to develop a groundwater flow model, to study the groundwater table fluctuations and to develop a saline water intrusion model for the study area. 18 observation wells were established in the study area. Samples of water were collected from the observation wells established in the study area. Quality analysis of the water sample was done to assess the quality of groundwater and the extent of salt water intrusion in the area. A conceptual model of the study area was constructed based on the topographical, climatic and hydrogeological data of the area along with the field observation data including the water table level in the observation wells. The recharge in the area was taken as 10% of the average rainfall of the area during the period of study. The study also includes the calibration of the model, the validation of the model and the prediction of the groundwater conditions of the study area in the succeeding year. The model was calibrated for the fifteen months data from May 2017 and the remaining data was used for the validation of the model. The model predicted the flow of groundwater and its velocity in magnitude and direction. Seawat was used to predict the saline water intrusion from the sea to the coastal aquifers. Simulation of the saline water intrusion into the study area after 1000 days showed an increase in the salt concentration.The groundwater modelling using the visual MODFLOW software is well understood by this study.