Parameter Estimation to Determine the Groundwater Flow and Seawater Intrusion in a Coastal Aquifer of Karnataka India

Abstract

Seawater Intrusion (SWI) into the fresh groundwater aquifers is one of the major hydrological problems in coastal regions. This global issue is aggravated by increasing demands for fresh groundwater due to on-going urbanization, population growth, and economic development in these regions. Freshwater and seawater mixing is by mechanical dispersion and hydrodynamic diffusion, which results in the formation of the transition zone. The position and width of the transition zone change with hydrogeological, hydrological circumstances, and anthropogenic activities such as excessive groundwater extraction, climate variations/and sea-level fluctuations, etc. The groundwater models provide a scientific and predictive tool for determining the extent of SWI at field-scale. But, the development of numerical models to determine the groundwater flow and SWI in the heterogeneous aquifers requires several hydrogeological field data. Due to incomplete knowledge of geological structures such as heterogeneity, anisotropy, and layering, the development of conceptual numerical models is often simplified. This indicates that there is a wide gap in understanding the hydrogeology characterization in three-dimensional (3D) modeling of the groundwater flow and SWI. With this motivation, the work presented in this thesis is aimed at estimating the anisotropic heterogeneous parameters in a layered coastal aquifer for the simulation of hydraulic head and SWI. The coastal plain in between River Swarna and River Netravati of Karnataka in India is selected as the study area. As most of the West flowing rivers of Karnataka are seasonal and tidal, due to this saline water intrudes into rivers during the non-monsoon period up to several kilometers contaminating the adjacent fresh groundwater aquifers. And due to the permeable geological formation, thousand million cubic feet of recharged rainwater is designated as subsurface groundwater discharge, thus, making it an interesting and challenging case study to pursue...