Water-energy nexus assessment in the transboundary Harirud river basin

The Harirud river basin, a transboundary region between Iran and Afghanistan, has been assessed for its water-energy nexus using the MUSIASEM framework. According to the study, the water-energy nexus is a critical relationship between the water used for energy production and the energy consumed to extract, purify, deliver, heat/cool, treat, and dispose of water [1]. This relationship is not a closed loop, as the water used for energy production need not be the same water that is processed using that energy, but all forms of energy production require some input of water, making the relationship inextricable [1].

The study highlights that thermoelectric power is the single largest user of water, used mainly for cooling. In the Arab region, which includes the Harirud river basin, the water sector's share of total electricity consumption is expected to increase from 9% in 2015 to 16% by 2040, due to a rise in desalination capacity [2]. The region is one of the most water-stressed regions of the world, with rainfall being mostly rare or unpredictable. The cumulative area of the Arab region is approximately 10.2% of the world's area, but the region only receives 2.1% of the world's average annual precipitation [2].

The study also emphasizes the importance of considering spatiotemporal considerations when assessing water use, as well as the need to consider the energy intensity of water systems. Energy intensity refers to the average amount of energy needed to transport or treat water or wastewater on a per unit basis [3]. In California, for example, the operation of urban water systems requires substantial energy support, with key processes such as water transfer, consumption, and wastewater treatment consuming significant amounts of energy [4]. The California Public Utilities Commission (CPUC) has responded to the findings by authorizing a statewide study into the relationship between energy and water and developing programs to save energy through water conservation [5].

The assessment of the water-energy nexus in the Harirud river basin using the MUSIASEM framework has significant implications for the region's water-stressed regions. The study highlights the need for joint water-energy policies and better understanding of the nexus and its susceptibility to climate change as a matter of national security. As the region's water sector's share of total electricity consumption is expected to increase, it is crucial to consider the energy intensity of water systems and develop strategies to save energy through water conservation.