Urbanization and Water Insecurity in Semi-Arid Regions: A Multi-Index Assessment of Water Quality, Ecological Risk, and Public Health Impacts.

Abstract

Degradation of water quality remains a critical environmental and public health issue in semi-arid regions, where limited freshwater resources are increasingly stressed by rapid urbanization, intensive agriculture, and industrial activities. This study assessed the status of surface and groundwater in Erbil City, Kurdistan Region of Iraq, through systematic sampling of 23 sites, including surface water and groundwater sites in 2025. Multiple indices were applied, including the Water Quality Index (WQI), Biochemical Oxygen Demand Index (BI), Nemerow Pollution Index (NPI), Ecological Risk Index (ERI), Index of Geo-Accumulation (Igeo), and human health risk assessment metrics such as Chronic Daily Intake (CDI), Hazard Quotient, Hazard Index (HI), and Incremental Lifetime Cancer Risk (ILCR). WQI values (40.83-76.06) indicated excellent to good water quality, with no sites falling into the poor category, whereas BI (0.28-3.64) revealed moderate organic pollution with localized hotspots. NPI (0.73-14.58) revealed nutrient enrichment at Sites 9, 13, and 16, demonstrated eutrophication risks, while ERI (5.14-276.31) pointed to elevated ecological risks from heavy metals, particularly Pb and Cu at Site 13. Although pH and most ions were within acceptable limits, turbidity, electrical conductivity, and total dissolved solids exceeded thresholds at multiple sites. Health risk assessment revealed noncarcinogenic hazards (HI > 1) at several sites, while carcinogenic risks were primarily driven by arsenic contamination. Specifically, Sites 12, 15, and 19 exceeded the US Environmental Protection Agency (USEPA) threshold of 1 × 10^-3 for ∑ILCR, while the remaining sites were below this level. The findings demonstrated that rapid urbanization and land-use changes substantially impaired water resources in Erbil. These results provide critical evidence for policymakers, underscoring the need for stricter wastewater management, targeted mitigation strategies, and long-term monitoring to ensure water security and safeguard public health in the region.