Compounding effects of human activities and climatic changes on surface water availability in Iran

Abstract

By combining long-term ground-based data on water withdrawal with climate model projections,<br><br>this study quantifies the compounding effects of human activities and climate change on<br><br>surface water availability in Iran over the twenty-first century. Our findings show that<br><br>increasing water withdrawal in Iran, due to population growth and increased agricultural<br><br>activities, has been the main source of historical water stress. Increased levels of water stress<br><br>across Iran are expected to continue or even worsen over the next decades due to projected<br><br>variability and change in precipitation combined with heightened water withdrawals due to<br><br>increasing population and socio-economic activities. The greatest rate of decreased water<br><br>storage is expected in the Urmia Basin, northwest of Iran, -varying from ~ − 8.3 mm/year in<br><br>2010–2039 to ~ − 61.6 mm/year in 2070–2099 compared with an observed rate of 4 mm/year<br><br>in 1976–2005-. Human activities, however, strongly dominate the effects of precipitation<br><br>variability and change. Major shifts toward sustainable land and water management are needed<br><br>to reduce the impacts of water scarcity in the future, particularly in Iran’s heavily stressed<br><br>basins like Urmia Basin, which feeds the shrinking Lake Urmia.