Assessing Groundwater Vulnerability and Contamination Risks in Urbanizing Coastal Regions Using Integrated Geophysical Methods and Remote Sensing

Project Abstract

Urban coastal regions are experiencing rapid urbanization that intensifies stress on groundwater resources through increased extraction, land-use change, and saltwater intrusion, necessitating an integrated assessment of vulnerability and contamination risk to safeguard water security. This study develops a multidisciplinary framework that combines geophysical surveys, hydrochemical analyses, and high-resolution remote sensing to map groundwater vulnerability and detect contamination plumes in a representative urbanizing coastal watershed. We deploy electrical resistivity tomography (ERT) and time-domain electromagnetics (TDEM) to delineate subsurface heterogeneity, major aquifer boundaries, and zones of reduced groundwater quality, complemented by seismic refraction and chromophoric dissolved organic matter indicators to resolve lithology-controlled vulnerability drivers. Concurrently, groundwater samples from multi-depth monitoring wells and piezometers undergo major ion chemistry, stable isotopes, tritium, and groundwater-age modelling to characterize recharge sources, salinity intrusions, and anthropogenic inputs. Remote sensing analyses integrate land-use/land-cover change detection, shoreline change and coastal morphology, groundwater-surface water interaction indices, and water-level anomaly patterns derived from satellite altimetry and radar data, enabling spatiotemporal correlation with in-situ measurements. A vulnerability index is developed, incorporating intrinsic susceptibility from hydrogeological properties (porosity, permeability, aquifer thickness), extrinsic factors (road density, wastewater infrastructure, irrigation practices), and contamination pathways (industrial effluents, leaking sewers, agricultural runoff). The integrated model is calibrated and validated using a Bayesian data fusion approach to quantify uncertainty and propagate measurement errors, providing probabilistic risk maps at multiple scales from grid to sub-watershed levels. The study elucidates the spatial heterogeneity of vulnerability, highlighting high-risk zones along densely urbanized coastlines where seawater intrusion fronts advance and contaminant plumes interface with freshwater aquifers. Temporal analyses reveal how episodic rainfall, dry-season groundwater pumping, and urban redevelopment modulate vulnerability dynamics and plume migration, with notable lag times between land-use changes and groundwater responses. The findings demonstrate the efficacy of combining geophysical imaging with hydrogeochemical fingerprints and remotely sensed surface indicators to detect early-warning signs of contamination and to delineate safe withdrawal boundaries. Policy-oriented outputs include a decision-support framework for groundwater management that couples monitoring networks with adaptive zoning, contingency planning for contamination events, and targeted remediation strategies such as aquifer storage in multi-aquifer systems and managed aquifer recharge where feasible. The study contributes to the broader understanding of coastal groundwater systems under anthropogenic pressure and offers transferable methodologies for coastal cities facing similar vulnerabilities, thereby informing water security, urban planning, and climate resilience initiatives.

Project Overview

What This Project Is About

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The project looks at how groundwater in coastal cities is affected by growing cities and sea influence. It uses simple, combined tools—geophysical methods to “see” underground conditions and satellite imagery to monitor land and water changes—to map where groundwater is at risk from contamination and where salinity or pollutants might spread.

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The Problem It Addresses

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Objectives of the Project

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1. Identify zones where groundwater is most at risk in a coastal urban setting.
2. Use simple geophysical signals to infer underground conditions without invasive drilling.
3. Analyze satellite data to track changes in land use and groundwater indicators over time.
4. Develop a clear, actionable map of vulnerability for city planners.
5. Provide basic recommendations for protecting groundwater quality.

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What You Will Do Step by Step

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1) Learn basic concepts of groundwater and why coastal areas are sensitive. 2) Gather accessible data: basic geophysical readings and satellite images. 3) Process data to identify signs of contamination or saltwater intrusion. 4) Combine results to locate high-risk zones. 5) Create a simple vulnerability map and summarize findings in plain language. 6) Propose practical protect-and-monitor steps for the area.

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Expected Outcome

A straightforward vulnerability map showing where groundwater is most at risk and a short list of practical steps for reducing contamination and saltwater intrusion in the urban coastal area.