Developing Concept of Water-energy Productivity to Evaluate Dez Dam Operation

The “concept of productivity” in the context of WEN (water-energy nexus) is a new outlook to evaluate dam and power plant operation policies. Understanding and modeling the complicated nature of water-energy nexus (WEN) are essential to increase productivity. The performance of dams and hydropower plants is mostly evaluated by the amount of energy generated and/or meeting downstream demands. The present study investigates the historical operation efficiency of Dez dam and hydropower plant from 1972 to 2018 by defining the productivity indices of water footprint (WF) of electricity, energy economics, water-energy performance, WEN, and energy sustainability. Then, the correlation between the obtained results and Streamflow Drought Index (SDI) is evaluated. The results indicated that wet years, despite generating more energy, do not show necessarily the highest productivities, since two years with moderate drought and almost similar discharges (i.e., 2007-2008 and 2010-2011) showed the highest and lowest productivities during the operation period of Dez Dam, respectively. Such difference arises from overlooking full supply levels (FSL) in from 2008 to2017. The FSL of water years in 2007-2008 was calculated to be 325.13 masl while it was 350.91 masl for water years of 2010-2011. One can, therefore, conclude that maximum productivity can be achieved even during droughts by adopting an optimal operation policy.