What you see is mirage: even dams can die of thirst

Uncoordinated development plans in rivers upstream coupled with climate change and variability have resulted in hydrological disturbances and their consequent social conflicts and environmental issues in downstream. Dams and hydrosystems are known as one of the main causes of such issues, however, they can be victimized by upstream developments themselves which result in failure in operation, fulfilling historical downstream allocations, and wasting large amounts of financial resources due to multiple investments. Giving some critical examples from Iran, an arid and semi-arid country, such failures can be observed in Karkheh and Sefidrud dams with 56 and 65% inflow reduction respectively. The impacts and consequences of such mismanagements will be demonstrated in this study. For this purpose, a new concept and methodology called “Mirage Water” is defined as the downstream flow deficit caused by upstream water development ignoring historical allocations. Firstly, the year of abrupt change (YAC) in precipitation and flow time series is assessed by the Pettiit test and then the annual flow characteristics before and after that abrupt change will be compared. The contribution level of anthropogenic activity and precipitation deficit in flow reduction is estimated using Simple linear regression and double mass curve methods. Meanwhile, the meteorological and hydrological drought is assessed using SPI and SDI and hybridized. Finally, the river impact in critical stations is presented. The results show that the YAC in Sefidrud’s inflow happened after its construction year due to a 57% contribution of anthropogenic activities. In the other case, Karkheh experienced the YAC in its inflow 2 years before the construction year with 44% anthropogenic impact.