Impact of Urban Heat Islands on Water Resource Availability in Coastal Cities: A GIS-Based Temporal Analysis

Project Abstract

This study investigates the influence of urban heat islands (UHIs) on water resource availability in coastal cities through a GIS-based temporal analysis spanning a ten-year period (2015–2024). By integrating high-resolution land surface temperature (LST) data, surface water flow and quality indicators, groundwater level records, and precipitation patterns, the research assesses how localized warming in dense urban cores alters hydrological processes, water demand, and availability for municipal, agricultural, and ecological needs. The core objective is to quantify the spatial and temporal coupling between UHI intensity and changes in water quantity and quality, and to identify urban configurations and climatic contexts that exacerbate water stress in coastal environments. The methodology fuses remotely sensed LST from Landsat and Sentinel-2, with urban morphology metrics derived from urban canopy models and dasymetric population distributions to delineate UHI hotspots. Hydrological modeling is implemented using a distributed watershed model calibrated with local gauging stations, satellite-derived evapotranspiration (ET), and soil moisture observations. Temporal analysis employs time-series decomposition to separate seasonal cycles, long-term trends, and anomalous events such as droughts and intense heat waves. A GIS-based framework links UHI intensity with variations in surface runoff, groundwater recharge, stream discharge, and reservoir inflows, while assessing shifts in water quality parameters (temperature, dissolved oxygen, turbidity, and nutrient loads) that influence treatment costs and ecosystem health. Key findings indicate that UHIs disproportionately amplify nocturnal surface and air temperatures in urbanized coastal zones, accelerating evaporation and altering groundwater recharge patterns, thereby reducing base flows in downstream coastal rivers during dry seasons. Elevated temperatures also increase water demand for cooling and domestic use, intensifying competition among sectors and stressing municipal supply in shoreline municipalities. Water quality trends reveal that higher urban temperatures can elevate reservoir stratification and thermal pollution, accelerating algal blooms and increasing the burden on treatment facilities. The study identifies critical thresholds of UHI intensity beyond which water scarcity risk escalates significantly, and demonstrates that green–blue infrastructure, including permeable pavement, urban wetlands, and restored tidal marshes, can mitigate adverse hydrological impacts by enhancing infiltration, reducing surface runoff, and moderating local temperatures. Policy implications emphasize the need for integrated urban planning that aligns heat mitigation with water security objectives. The research provides a decision-support tool for city planners to simulate alternative urban design scenarios, forecast water demand under climate and demographic changes, and evaluate the co-benefits of UHI mitigation on water resources. Limitations include data gaps in some coastal municipalities and uncertainties in regional climate projections, which are mitigated through cross-validation with in-situ measurements and ensemble modeling. The study contributes to the understanding of urban–hydrological interactions in coastal settings and offers a replicable methodology for similar metropolitan contexts worldwide.

Project Overview

What This Project Is About

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A plain-language overview of how urban heat affects water resources in coastal cities and how maps and time-based analysis help uncover patterns and potential solutions.

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The Problem It Addresses

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Coastal cities face rising temperatures from dense urban areas, which can change rainfall, water demand, and water supply reliability. There is a need to connect heat patterns with water resource changes over time to guide planning and adaptation.

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Objectives of the Project

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1. Explain how urban heat islands form in coastal settings.
2. Assess how heat influences water availability and demand across time.
3. Use GIS tools to map temperature and water resource indicators.
4. Identify areas at higher risk of water stress due to heat.
5. Suggest practical adaptation measures for water management.

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What You Will Do Step by Step

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1. Review basic concepts: urban heat islands, water resources, and GIS.
2. Gather temperature and water data for a selected coastal city over several years.
3. Clean and organize data for analysis.
4. Create GIS maps showing heat patterns and water indicators over time.
5. Analyze relationships between heat intensity and water availability.
6. Interpret results and identify vulnerable areas.

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Expected Outcome

A clear, user-friendly report showing how heat patterns relate to water resources, with maps and practical recommendations for managers and planners.