Hydrologic consequences of rapid urbanization in an arid environment: Multi-temporal remote sensing and distributed flood modeling

Rapid urban expansion in arid cities is transforming surface hydrology and amplifying flood risks under increasingly variable rainfall conditions. This study examines land use and land cover (LULC) change and its hydrologic implications in Al Ain, UAE, a transboundary basin influenced by orographic forcing from the Oman Mountains. Multi-temporal Landsat imagery from 1987–2023 was classified into five dominant surface types-sand, compacted sand, rocky terrain, built-up, and green areas using supervised Maximum Likelihood classification. Accuracy assessment yielded overall accuracies of 68–86% and kappa values up to 0.81, consistent with regional arid-environment benchmarks.

LULC analysis revealed a substantial shift from natural to managed surfaces, with built-up and green areas increasing by 274% and 1,667%, respectively, at the expense of rocky and sandy terrains. These changes were incorporated into a distributed GSSHA model to simulate rainfall–runoff responses across five major storm events between 2007 and 2024. Model results show that progressive urbanization markedly increased peak discharge (up to 78%) and runoff volume, particularly under low- to moderate-intensity storms where infiltration-excess (Hortonian) processes dominate. Under extreme events, the flood response became primarily governed by rainfall intensity, diminishing the relative impact of LULC change.

Spatial analysis emphasized strong localization of flood hazards within newly urbanized areas, with flood depths intensifying along residential and roadway corridors. While the expansion of irrigated green spaces enhanced infiltration locally, their spatial distribution limited broader runoff mitigation. The findings highlight storm condition dependent urban flood response in arid environments and emphasize the need for hydrologically informed urban design, including permeable pavements, vegetated buffers, and managed aquifer recharge systems.

This integrated approach, combining multi-temporal remote sensing and distributed hydrologic modeling, offers a transferable framework for evaluating urban flood dynamics in data-scarce arid regions, supporting policy efforts toward climate-resilient urban planning in rapidly developing desert cities.