Climate Change and Increased Irrigation Demands: What Is Left for Hydropower Generation? Results from Two Semi-Arid Basins

Abstract

Abstract:In this study, we have modelled the effect of climate change and increased irrigation withdrawals on the available water for hydropower production in two semi-arid river basins, i.e., Kizilirmak (Turkey) and Devoll (Albania), and the role of the reservoirs. The combined effect of climate change and extended irrigation withdrawals will overall lead to reduced runoff in the rivers, according to our simulations. The changes will be most dramatic at Kizilirmak, reducing the water available for hydropower production. The presence of the reservoirs will lead to extended water use/losses due to the provision of regulated flow, enabling larger irrigation withdrawals and increasing the evaporative losses from the reservoir surfaces. Comparing the water consumption losses at Kizilirmak, the irrigation losses are in the range of 2-4 times larger than the gross evaporation losses from reservoir surfaces. The reservoirs at Devoll will improve water availability for hydropower production during low flow periods, and the upstream irrigation represents presently a low risk to the downstream power producers. As the results are sensitive to specific river basin characteristics and the assumptions made, the results cannot be generalized to other river basins without taking these specifics into consideration.

Mitigation of emerging implications of climate change on food production systems

“…Climate projections have been used to estimate water demand for future irrigation (Gondim et al, 2012;Bakken et al, 2016), which are estimated to increase between 40 and 250% depending on the crop at the end of this century. The increased requirements have been ascribed to reduce water availability in the growing seasons, evapotranspiration and changes in crop phenology (Woznicki et al, 2015;Sloat et al, 2020;Dai et al, 2020).…”

Integrated hydrological risk analysis for hydropower projects

“…Haddeland et al (2006) found that the streamflow in Colorado and Mekong river basins decreased by 37% and 2.3%, respectively, in the analyzed period. Bakken et al (2016a) found large flow reductions in Kizilirmak river basin due to irrigation withdrawals, in particular in the middle and lower parts. The results from Devoll river basin in Albania showed a different picture as only limited effects could be seen due to irrigation, which to a large extent was explained by the collapse in the agricultural sector in the early 1990's (Bakken et al, 2016a).…”

“…Bakken et al (2016a) found large flow reductions in Kizilirmak river basin due to irrigation withdrawals, in particular in the middle and lower parts. The results from Devoll river basin in Albania showed a different picture as only limited effects could be seen due to irrigation, which to a large extent was explained by the collapse in the agricultural sector in the early 1990's (Bakken et al, 2016a). Leng et al (2015) found that irrigation had a larger effect on lowflow than on high-flow of streams.…”

“…Irrigation withdrawals downstream of the power plant are usually not a direct threat to the hydropower production, as the power production and agriculture will mutually benefit of the regulated flow provided by the upstream reservoir. One exception is if downstream irrigation gives minimum flow restrictions on the hydropower producer in order to secure the availability of downstream irrigation, which is known for instances from Devoll in Albania (Bakken et al, 2016a). Anyhow, irrigation is most likely a large risk factor in many river basins, particularly where the hydropower projects are located in the downstream parts of the river basin, where all upstream activities will affect the availability of water.…”

The Water Footprint of Hydropower Production—State of the Art and Methodological Challenges

“…Reservoirs in the upper part of the river basin can also be disadvantageous and pose a risk of operation to power producers in the lower parts of the basin. Upstream regulation might enable increased irrigation water withdrawals, hence reducing the power production, by its provision of regulated flow . In such cases, it would be unfair if downstream hydropower plants should carry parts of the burden of the upstream water losses if the reservoir is not beneficial.…”