Author(s): Nikolaos Efthymiou; George W. Annandale; Pravin Karki
Keywords: No Keywords
Abstract: The performance of reservoirs, i. e. their capability to provide reliable water services for irrigation, freshwater supply, hydropower production, and flood protection, depends on the variability of the incoming flows and the available storage capacity. Reservoirs have, however, a natural enemy: Sedimentation results in the continuous reduction of their storage capacity through the formation of coarse-grained sediment deltas in the upper reaches and the accumulation of fines in the deeper sections. The combined effect of population growth and reservoir storage loss to sedimentation results in a net reduction of global per capita water storage (Annandale 2013; Annandale et al. 2016). At the same time, a vast body of scientific evidence indicates that anthropogenic climate change disturbs the global historically observed hydrological regime by altering the runoff availability and increasing interannual and seasonal variability (IPCC 2021). Furthermore, the intensification of flood events in combination with dynamic land use changes, deforestation, as well as more frequent and severe wildfires due to temperature increase will also affect surface erosion. Scientific research and experience point towards increased sediment yields and hydrological uncertainty. Increased sediment yield and hydrologic variability induced by climate change will reduce the global reliability of hydropower generation and water supply for domestic, industrial and agricultural use; adding to the crisis of increased water demand due to population growth. Recently evidenced water supply shortages in different cities serve as reminders of the water security issues the global community will face soon.