Assessing Groundwater Recharge Potential and Contaminant Transport Using Remote Sensing and Geophysical Methods in a Semi-Arid Basin

Project Abstract

This study presents an integrated approach to evaluate groundwater recharge potential and contaminant transport mechanisms within a semi-arid basin by combining remote sensing data, hydrogeophysical techniques, and aquifer testing. The core objective is to quantify recharge pathways, delineate spatial variability in aquifer properties, and assess the fate of common contaminants under variable climatic conditions and land-use pressures. We employ multi-temporal satellite imagery (Landsat and Sentinel-2) to derive land surface temperature, vegetation indices, and soil moisture proxies, enabling the identification of infiltration hotspots and evapotranspiration regimes. These remotely sensed parameters are fused with high-resolution digital elevation models to map watershed-scale recharge zones and to model transient recharge fluxes using a distributed hydrological framework calibrated with field measurements. Geophysical surveys, including electrical resistivity tomography (ERT), seismic refraction, and ground-penetrating radar (GPR), are deployed to characterize subsurface heterogeneity, identify aquifer layering, and delineate preferential flow paths. Time-lapse ERT is integrated to monitor changes in pore-fluid salinity and moisture content under seasonal cycles, providing direct insight into recharge events and contaminant migration corridors. Groundwater samples collected across lithological units and depths are analyzed for major ions, trace metals, nitrate, sulfate, and organic contaminants. Isotopic tracers (18O, 2H, 14C) are employed to distinguish modern recharge from fossil water and to estimate residence times, while hydrochemical facies evolution is used to infer mixing processes and source contributions. A geochemical transport model is developed to simulate contaminant plumes under varying recharge scenarios, incorporating retardation, dispersivity, Sorption processes, and decay kinetics. Sensitivity and uncertainty analyses are conducted to identify the most influential parameters driving recharge estimates and contaminant spread. The study hypothesizes that semi-arid basins exhibit strong spatial heterogeneity in infiltration capacity due to microtopography, soil texture, and land-use changes, which in turn control recharge rates and contaminant residence times. Results indicate a robust coupling between riparian zones, depressional areas, and shallow aquifers as critical recharge conduits, with remote sensing-derived indices correlating significantly (p < 0.05) with in-situ recharge measurements. Geophysical results reveal low-resistivity anomalies corresponding to increased moisture and potential perched aquifers, while time-lapse data capture seasonal plume expansion during monsoon preludes. The integrated framework provides spatially explicit maps of recharge potential, aquifer properties, and contaminant risk zones, enabling proactive groundwater management in semi-arid contexts. Policy-relevant outcomes include thresholds for sustainable groundwater extraction, targeted monitoring networks, and land-use planning strategies to mitigate recharge disruption and contaminant ingress. The study contributes to methodological advances by validating a scalable, multi-disciplinary workflow that leverages routinely available remote sensing data and cost-effective geophysical methods for comprehensive groundwater assessment in data-scarce semi-arid regions.

Project Overview

What This Project Is About

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This project looks at how groundwater can be replenished in a semi-arid area and how pollutants move through the underground water system. It uses simple map-based techniques and basic surface measurements to understand where water can enter the ground and how contaminants travel from sources to wells or rivers.

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The Problem It Addresses

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In many dry regions, groundwater is limited and vulnerable. People rely on it for drinking and farming, but overuse and pollution reduce its safety and availability. The study fills gaps in knowing where recharging zones exist and how contaminants might spread through the groundwater system.

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Objectives of the Project

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1. Identify zones in the basin where rainwater can seep into the ground (recharge potential).
2. Detect and map common pollutants and their likely paths in groundwater.
3. Use satellite data and simple field measurements to support decision-making for water management.
4. Provide a clear, easy-to-understand report for policymakers and community stakeholders.

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What You Will Do Step by Step

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1. Review basic concepts of groundwater and pollution in dry areas.
2. Collect light field data and satellite images of the study area.
3. Analyze surface features to infer recharge zones (e.g., soil type, vegetation, rainfall patterns).
4. Map contaminants and estimate their movement paths with simple models.
5. Present findings with easy-to-read maps and explanations.

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Expected Outcome

A practical map of recharge zones and contaminant pathways, plus recommendations for protecting drinking water and guiding land-use decisions in the basin.