INVESTIGATING GROUNDWATER FLOW REGIME AND RECHARGE SOURCES OF WATERLOGGED FARMLAND: HYDROGEOLOGICAL ANALYSIS AND NUMERICAL MODELING FOR REMEDIAL MEASURES

Abstract

Waterlogging poses a significant challenge, affecting extensive areas of farmland and infrastructure in many parts of the world. This study focuses on hydrological assessment of a waterlogged farmland for evaluating its remediation measures using practical and numerical investigations. A waterlogged farmland area located in Purkazi, Muzaffarnagar District, Uttar Pradesh in, India, is the particular focus of this dissertation for proposing suitable remedial measures. The initial phase of investigation involves identifying the sources and factors contributing to waterlogging, with a specific focus on groundwater flow regime, recharge sources, and evapotranspiration fluxes. Factors including topographic features, geological composition, hydrological conditions, and the proximity of irrigation canals and a nearby river, contributing to the occurrence of waterlogging to the farmland are assessed in detail. Water table elevations, along with water samples from different locations, were collected to elucidate groundwater flow patterns and its interaction with adjacent surface water resources. Litholog samples were characterised in the laboratory to understand the groundwater flow regime of the site. Isotopic analysis was conducted for groundwater samples, and the surface water samples were collected directly from the canals. It is found that the waterlogged conditions in the area are primarily attributed to the site's low-lying topography, the existence of the Upper Ganga Canal and Distributary Canal on higher elevated ground, reduced evapotranspiration due to changed LULC, and the presence of a clay Content at shallow depths. Isotope analysis of samples from both canals and farmland indicates that a substantial portion of water originates from these canals. Based on these findings, a numerical model (Visual MODFLOW) was then used to assess the effectiveness of different mitigation techniques. The model was calibrated well using the existing site condition and observed data before Validating it with the groundwater table of the site. The Model runs were made by selecting suitable initial and boundary conditions to assess the effectiveness of different remedial measures to avoid waterlogging issues. The findings of this study will contribute to the development of effective waterlogging mitigation strategies for enhancing agricultural productivity in semi-urban areas.