Quantify the impacts of anthropogenic changes and climate variability on runoff changes in central plateau of Iran using nine methods

Abstract Quantification of affecting factors on river regime changes can be greatly helpful for water resources planning and management in the basin. Both anthropogenic changes and climate variability have affected rivers’ regime and led to considerable social and economic impacts. Observations in most parts of the world indicate that the hydrological cycle has been influenced by human activity besides of climate variability. In this study, 9 different methods which are divided into three general categories have been used to determine the impact of anthropogenic changes and climate variability on runoff changes in two watersheds in the central plateau of Iran, including Ghaleh-Shahrokh and Javanmardi watersheds. The results indicate that climate variability plays a dominant role in runoff decline in the Ghaleh-Shahrokh watershed, accounting for 60.2% of the total decrease, while human activities accounted for 39.8 %. In the Javanmardi watershed, anthropogenic changes played a dominant role in runoff decline, accounting for 77.1% (on average). In comparison, 22.9% (on average) of the decrease was attributable to climate variability. Sensitivity analysis of the annual mean runoff shows that precipitation plays a key role in runoff changes in both study areas. After precipitation, changes in potential evapotranspiration and temperature have the greatest impact on the annual mean runoff in the studied watersheds, respectively. Comparison of the different applied methods indicate that elasticity-based methods are the fastest and intuitive methods to investigate the impacts of anthropogenic changes and climate variability on runoff changes. Despite this, using different methods should be taken into account

Battling water limits to growth:lessons from water trends in the central plateau of Iran

Abstract The Zayandeh-Rud River Basin in the central plateau of Iran continues to grapple with water shortages due to a water-intensive development path made possible by a primarily supply-oriented water management approach to battle the water limits to growth. Despite inter-basin water transfers and increasing groundwater supply, recurring water shortages and associated tensions among stakeholders underscore key weaknesses in the current water management paradigm. There was an alarming trend of groundwater depletion in the basin’s four main aquifers in the 1993–2016 period as indicated by the results of the Mann-Kendall3 (MK3) test and Innovative Trend Analysis (ITA) of groundwater volume. The basin’s water resources declined by more than 6 BCM in 2016 compared to 2005 based on the equivalent water height (EWH) derived from monthly data (2002–2016) from the GRACE. The extensive groundwater depletion is an unequivocal evidence of reduced water availability in the face of growing basin-wide demand, necessitating water saving in all water use sectors. Implementing an integrated water resources management plan that accounts for evolving water supply priorities, growing demand and scarcity, and institutional changes is an urgent step to alleviate the growing tensions and preempt future water insecurity problems that are bound to occur if demand management approaches are delayed