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Arid region water reservoirs have different characteristics and solutions from humid regions with the most water shortage in the world socio-economically. This paper outlines possible implementation methodologies, procedures and guidance for water storage in natural and artificial reservoirs for better operation and management rules taking into account the impacts of climate change. The literature is full of methodological applications regarding the impact of climate change on the hydro-meteorological records, but the same is not available in reservoirs (surface and underground), which is the scope of this paper. In addition, reservoir structures offer the necessary mitigation and adaptation activities against the effects of climate change to design, construct, maintain, operate or increase their existing capacity. To increase groundwater reservoir capacity in local aquifers, precipitation, associated flooding and flash flooding should be diverted to artificial groundwater recharges through precipitation and surface runoff harvesting activities. Definitions of fully or partially penetrating underground dams are also explained. The real groundwater feeding application is offered from the Kingdom of Saudi Arabia as arid region representative. Finally, a series of recommendations are presented for the future design and management of reservoirs. [ABSTRACT FROM AUTHOR]

It is essential to identify water sectors that will be significantly impacted by climate change and to develop strategies to enhance the resiliency of these sectors against climate change impacts. The Arabian Peninsula (AP) is an arid region facing increasingly more severe water-scarcity issues due to climate change impacts. We investigate abrupt changes in the AP's climate, and examined the spatial relationships between climatic changes, ENSO, and Indian Ocean Dipole (IOD). An analysis was conducted to examine how hydroclimatic changes impact the frequency of droughts in AP. The results show that AP is very sensitive to climate change impacts since 1990s. Regional climatic change hotspots in AP include an increase in geopotential height (GPH), surface temperature, potential evapotranspiration (PET), and a decrease in relative humidity, soil moisture, and rainfall between 1985 and 2020. The northern and northwestern areas of AP, specifically Hail, Al Qassim, Tabuk, and Al Jouf, experienced the most significant increases in GPH, warming, and PET. The meridional wind (zonal wind) speed has decreased (increased) between 1985 and 2020. Climate scenarios of CMIP6 of IPCC (Intergovernmental Panel of Climate Change) project future warmer and drier conditions over AP under significant warming and marginal increase in rainfall between 2020 and 2100. Furthermore, positive ENSO and IOD episodes are associated with negative rainfall and surface moisture anomalies, and positive surface temperature and PET anomalies over irrigated areas of AP. Climate warming in AP has also resulted in persistent drought conditions after 1998, which have significantly affected the agricultural sector of AP due to higher water demand for irrigated crops because of higher evaporation losses under climate warming. Therefore, representative estimations of regional water demand for irrigation in AP are essential in developing effective adaptation strategies against climate change impacts, such as introducing crop patterns of lower transpiration losses to achieve water saving and providing optimal irrigation water requirements for AP of arid climate. In conclusion, regions with limited water resources, such as the AP, will likely experience more significant water scarcity and drought. Therefore, identifying the water sectors most impacted by climate change and developing strategies to enhance their resiliency is essential. [ABSTRACT FROM AUTHOR]

Climate and underlying-surface changes give rise to governance challenges in water resource management in arid and semi-arid regions, and knowledge of the spatiotemporal patterns of water yield is critical in policy and stakeholder engagement. The Soil and Water Assessment Tool (SWAT) model was integrated using spatial autocorrelation analysis, empirical orthogonal functions (EOF), rotated EOF (REOF), and wavelet analysis to explore variations in water yield and factors influencing the Jinghe River watershed from 1980 to 2010. The well-calibrated SWAT-based methodological framework, which considers the influence of climatic and human activities using dynamic modeling and statistical decomposition, is a reliable tool for evaluating and visualizing the spatiotemporal patterns of water yield at the watershed scale. The water yield of the Jinghe River watershed showed an overall downward trend over time and from southeast to northwest. The variation in water yield from the 1980s to the 1990s was mostly attributed to climate, though human activities became the dominant factor from the 1990s to the twenty-first century. Three spatial modes of water yield were detected by EOF: "consistent in the whole watershed," "North–South," and "central in middle and North." The variance contributions were 77.68%, 12.92%, and 6.67%, respectively. Four regional modes of water yield were obtained through the REOF: north–south, central, eastern, and western. The variance contributions were 36.2%, 32.35%, 23.42%, and 7.58%, respectively. These findings will help deepen the understanding of the patterns of water yield and its response to climate and underlying surface in arid and semi-arid regions, which has practical significance for hydrologists, environmentalists, water resources scientists, and policymakers in assessing available water resources for a proposed or existing development. [ABSTRACT FROM AUTHOR]

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Climate as one of the key factors in water resources management affects the amount of water in the hydrological cycle, which subsequently impacts the level of water availability. Considering the challenges that the South Alborz Region, Iran is currently facing in supplying water for various consumers; in this study, the climate change adaptation scenarios are investigated for sustainable water supply and demand. This study uses a procedure in which five different adaptation approaches, under RCPs scenarios, were established using the WEAP model to assess the impacts of various adaptation strategies on increasing the balance between water supply and demand over current and 2020s accounts. The findings suggest an imbalance between supply and demand in the current situation with the greatest imbalance in domestic use while the minimum in the industrial sector. The results of assessing adaptive scenarios show that various scenarios have different effects on balancing the water supply and demand by different consumers; on the other hand, the scenarios that directly affect domestic water demand have the greatest effect on minimizing the gap between supply and demand in the region; therefore, the options for decreasing the population demand along with diminishing the losses in the domestic water distribution network are the most effective alternatives for balancing supply and demand under all of the climate scenarios. The findings of this research indicate that adaptive management with the focus on restricting demand helps actively management of water resources in the regions with scarce water resources. [ABSTRACT FROM AUTHOR]

In arid and semi-arid regions of the world, the occurrence of prolonged drought events (megadroughts) associated with climate change can seriously affect the balance between water supply and demand, thereby severely increasing the susceptibility of such regions to adverse impacts. In this study, a simple framework is introduced to estimate renewable water volumes (RW) to mitigate the challenges of megadrought events by managing the groundwater resources. The framework connects a weighted annual hydrological drought index (wSPEI) to RW, based on the short time-scale precipitation volume. The proposed framework, which was in a proof-of-concept case study applied to the Neishaboor watershed in the semi-arid part of Iran, showed that developing the weighted drought index can be valuable to estimate RW. The results suggested that the wSPEI, aggregating hydrological drought index (HSPEI) with the time scale k = 5 days and the regional coefficient s = 1.3 can be used to estimate RW with reasonable accuracy (R2 = 0.73, RMSE = 11.5 mm year−1). This indicates that in the Neishaboor watershed, the best estimation of RW can be determined by precipitation volumes (or the lack thereof) falling over 5-day aggregation periods rather than by any other time scales. The accuracy of the relationship was then investigated by cross validation (leave-one-out method). According to the results, the proposed framework performed fairly well for the estimation of RW, with R2 = 0.75 and RMSE = 12.2 mm year−1 for k = 5 days. The Overall agreement between the wSPEI, the RW derived from water balance calculations, and the estimated RW by the proposed framework was also assessed for a period of 34 years. It showed that the annual RW followed closely the wSPEI, indicating a reasonable relationship between wSPEI and the annual RW. Accordingly, the proposed framework is capable to estimate the renewable water of a given watershed for different climate change scenarios. [ABSTRACT FROM AUTHOR]