Exploring the Role of Reservoir Storage in Enhancing Resilience to Climate Change in Southern Europe

Abstract

Recent trends suggest that streamflow discharge is diminishing in many rivers of Southern Europe and that interannual variability is increasing. This threatens to aggravate water scarcity problems that periodically arise in this region, because both effects will deteriorate the performance of reservoirs, decreasing their reliable yield. Reservoir storage is the key infrastructure to overcome variability and to enhance water availability in semiarid climates. This paper presents an analysis of the role of reservoir storage in preserving water availability under climate change scenarios. The study is focused on 16 major Southern European basins. Potential water availability was calculated in these basins under current condition and for 35 different climatic projections for the period 2070–2100. The results show that the expected reduction of water availability is comparable to the decrease of the mean annual flow in basins with large storage capacity. For basins with small storage, the expected reduction of water availability is larger than the reduction of mean annual flow. Additionally, a sensitivity analysis was carried out by replicating the analysis assuming variable reservoir volumes from 25% to 175% of current storage. The results show that increasing storage capacity attenuates the reduction of water availability and reduces its uncertainty under climate change projections. This feature would allow water managers to develop suitable policies to mitigate the impacts of climate change, thus enhancing the resilience of the system.

Climate Change in the Mediterranean Basin (Part II): A Review of Challenges and Uncertainties in Climate Change Modeling and Impact Analyses

“…The analysis of potential problems in future water scarcity should also consider the role of reservoir storage in enhancing resilience to climate change. Some studies have used coupled climatic and system behavior-based models to study the impact of reservoirs, confirming the effective climate change mitigation role that they may have in future (Alimohammadi et al 2020;He et al 2020), especially in semiarid regions of the MB (Gorguner and Kavvas 2020;Granados et al 2021) where reservoir storages could be key infrastructures to overcome variability and to enhance water availability. For instance, Granados et al (2021), considering 35 different climatic projections for the period 2070-2100, presented an analysis of 16 major Southern European basins investigating possible advantages due to reservoirs under climate change scenarios, concluding that the climate change induced reduction of water availability could be attenuated with increasing storage capacity and a careful management of such water reources.…”

A Continental Assessment of Reservoir Storage and Water Availability in South America

“…The PCR-GLOBWB is a global hydrological model which simulates the terrestrial hydrology at a 0.5-degree resolution and was forced using the output from five global climate models: GFDL-ESM2M (GFDL), HadGEM2-ES (HadGEM2), IPSL-CM5A-LR (IPSL), MIROC-ESM-CHEM (MIROC), and NorESM1-M (NorESM1). These five climate models were selected based on three criteria: First, because of their global coverage, they have proven useful in large-scale assessments regarding water resources [19,48]. Second, they have been used in several climate assessments in the continent [66][67][68][69][70][71][72].…”

“…A useful indicator of the potential impacts of reservoirs in river systems is the ratio between the water storage (S) and the mean annual flow of the catchment (F) (S/F) (Figure 4a). Some authors define this ratio as 'Residence Time', which represents the capacity of the reservoirs in the catchment to regulate flow [23,48]. On average, reservoirs across the continent store about 10% of their mean annual flow.…”

“…Although to date these models have proven useful in ensuring water in decision-making processes for water resources systems, in order to obtain reliable results for water availability assessments, it is necessary to include the analysis of different climate scenarios [44,45]. Authors such as Sordo-Ward et al [46,47], Granados et al [48], and Garrote et al [49] have extensively examined water availability using different climate scenarios in current and projected time periods. Although most climate models present a certain level of uncertainty, these studies highlight the important role of climate models in evaluating the potential impacts of climate change on water availability.…”

Run-Of-River Small Hydropower Plants as Hydro-Resilience Assets against Climate Change

“…Focusing on the Axios River, very few scholars are identified to have worked on the thematic of water resources and climate change, e.g., Kapetas et al [64] evaluated the way that climate change (use of CMIP5 climate model under the RCP4.5 scenario), by altering the river flow and precipitation patterns, could affect the coastal aquifers of the Axios basin in terms of salinization, or Poulos et al [65] assessed the consequences of future sea-level rise (by using two customed scenarios of 1.0 and 0.5 m of sea-level rise) on the coastal plain of the Axios River. At the upstream part of the Axios River in North Macedonia (aka the Vardar River) there exists relevant literature; exceptions are Monevska [66], demonstrating precipitation and runoff decreases of 13.0% and 18.8%, respectively, by 2100 based on averaged ensemble values from four General Circulation Models (CSIRO/Mk2, HadCM3, ECHAM4/OPYC3, NCAR-PCM) scaled to six emission scenarios (SRES A1T, A1Fl, A1B, A2, B1, and B2) and Granados et al [67], where the averaged values of the utilized Water Availability and Adaptation Policy Analysis (WAAPA) model triggered by eight model runs for the A2 scenario, four model runs for the B2 scenario, three model runs for the A1B scenario, and five model runs for each RCP-2, RCP-4, RCP-6 and RCP-8 scenario, demonstrated a decrease in the Vardar/Axios's river runoff of 23.0%. For the Kalamas River, despite its importance at regional scale, apart from the Regional Adaptation Action Plans to climate change [68] where a vulnerability analysis for various environmental sectors, economic, and social activities is conducted, no relevant scientific publications were identified.…”