Adaptation strategy to mitigate the impact of climate change on water resources in arid and semi-arid regions : a case study

Climate change and drought phenomena impacts have become a growing concern for water resources engineers and policy makers, mainly in arid and semi-arid areas. This study aims to contribute to the development of a decision support tool to prepare water resources managers and planners for climate change adaptation. The Hydrologiska Byråns Vattenbalansavdelning (The Water Balance Department of the Hydrological Bureau) hydrologic model was used to define the boundary conditions for the reservoir capacity yield model comprising daily reservoir inflow from a representative example watershed with the size of 14,924 km2 into a reservoir with the capacity of 6.80 Gm3. The reservoir capacity yield model was used to simulate variability in climate change-induced differences in reservoir capacity needs and performance (operational probability of failure, resilience, and vulnerability). Owing to the future precipitation reduction and potential evapotranspiration increase during the worst case scenario (−40% precipitation and +30% potential evapotranspiration), substantial reductions in streamflow of between −56% and −58% are anticipated for the dry and wet seasons, respectively. Furthermore, model simulations recommend that as a result of future climatic conditions, the reservoir operational probability of failure would generally increase due to declined reservoir inflow. The study developed preparedness plans to combat the consequences of climate change and drought

Flow-duration curve integration into digital filtering algorithms for simulating climate variability based on river baseflow

A baseflow separation methodology combining the outcomes of the flow–duration curve and the digital filtering algorithms to cope with the restrictions of the traditional procedures has been assessed. Using this methodology as well as the monitored and simulated hydro-climatologic data, the baseflow annual variations due to climate change and human-induced activities were determined. The outcomes show that the long-term baseflow index at the upstream sub-basin is nearly half of that at the downstream from October to April, whereas, they are close to each other for the remaining months. Some of the groundwater reacts to precipitation and an evident rise in the groundwater contribution has been detected for the hydrological years 1998–2001 and 2006–2008. The contrary has been recorded for 1987. The water released from the reservoir in the dry periods lead to distinctions in the detected baseflow index between the pre-damming and post-damming periods of the river

Climate change and anthropogenic intervention impact on the hydrologic anomalies in a semi-arid area : lower Zab river basin, Iraq

Climate change impact, drought phenomena and anthropogenic stress are of increasing apprehension for water resource managers and strategists, particularly in arid regions. The current study proposes a generic methodology to evaluate the potential impact of such changes at a basin scale. The Lower Zab River Basin located in the north of Iraq has been selected for illustration purposes. The method has been developed through evaluating changes during normal hydrological years to separate the effects of climate change and estimate the hydrologic abnormalities utilising Indicators of Hydrologic Alteration. The meteorological parameters were perturbed by applying adequate delta perturbation climatic scenarios. Thereafter, a calibrated rainfall-runoff model was used for streamflow simulations. Findings proved that climate change has a more extensive impact on the hydrological characteristics of the streamflow than anthropogenic intervention (i.e. the construction of a large dam in the catchment). The isolated baseflow is more sensitive to the precipitation variations than to the variations of the potential evapotranspiration. The current hydrological anomalies are expected to continue. This comprehensive basin study demonstrates how climate change impact, anthropogenic intervention as well as hydro-climatic drought and hydrological anomalies can be evaluated with a new methodology

Climate change and water resources in arid regions : uncertainty of the baseline time period

Recent climate change studies have given a lot of attention to the uncertainty that stems from general circulation models (GCM), greenhouse gas emission scenarios, hydrological models and downscaling approaches. Yet, the uncertainty that stems from the selection of the baseline period has not been studied. Accordingly, the main research question is as follows: What would be the differences and/or the similarities in the evaluation of climate change impacts between the GCM and the delta perturbation scenarios using different baseline periods? This article addresses this issue through comparison of the results of two different baseline periods, investigating the uncertainties in evaluating climate change impact on the hydrological characteristics of arid regions. The Lower Zab River Basin (Northern Iraq) has been selected as a representative case study. The research outcomes show that the considered baseline periods suggest increases and decreases in the temperature and precipitation (P), respectively, over the 2020, 2050 and 2080 periods. The two climatic scenarios are likely to lead to similar reductions in the reservoir mean monthly flows, and subsequently, their maximum discharge is approximately identical. The predicted reduction in the inflow for the 2080–2099 time period fluctuates between 31 and 49% based on SRA1B and SRA2 scenarios, respectively. The delta perturbation scenario permits the sensitivity of the climatic models to be clearly determined compared to the GCM. The former allows for a wide variety of likely climate change scenarios at the regional level and are easier to generate and apply so that they could complement the latter

Climate variability impact on the spatiotemporal characteristics of drought and aridity in arid and semi-arid regions

Investigating the spatiotemporal distribution of climate data and their impact on the allocation of the regional aridity and meteorological drought, particularly in semi-arid and arid climate, it is critical to evaluate the climate variability effect and propose sufficient adaptation strategies. The coefficient of variation, precipitation concentration index and anomaly index were used to evaluate the climate variability, while the Mann-Kendall and Sen’s slope were applied for trend analysis, together with homogeneity tests. The aridity was evaluated using the alpha form of the reconnaissance drought index (Mohammed & Scholz, Water Resour Manag 31(1):531–538, 2017c), whereas drought episodes were predicted by applying three of the commonly used meteorological drought indices, which are the standardised reconnaissance drought index, standardized precipitation index and standardized precipitation evapotranspiration index. The Upper Zab River Basin (UZRB), which is located in the northern part of Iraq and covers a high range of climate variability, has been considered as an illustrative basin for arid and semi-arid climatic conditions. There were general increasing trends in average temperature and potential evapotranspiration and decreasing trends in precipitation from the upstream to the downstream of the UZRB. The long-term analysis of climate data indicates that the number of dry years has temporally risen and the basin has experienced succeeding years of drought, particularly after 1994/1995. There was a potential link between drought, aridity and climate variability. Pettitt’s, SNHT, Buishand’s and von Neumann’s homogeneity test results demonstrated that there is an evident alteration in the mean of the drought and aridity between the pre- and post-alteration point (1994)

Drought Assessment in Nestos River Basin (N. Greece) for the Period 1955-2018

Drought is a significant meteorological phenomenon that can seriously impact natural ecosystems. Drought assessment and monitoring should be continuous in regions of high ecological importance, for the conservation of natural vegetation distribution and dynamics. In this study, we analyzed monthly precipitation data obtained from five meteorological stations in the Nestos' river sub-basin in Greece in order to detect drought episodes during the period 1955-2018 by employing the Standardized Precipitation Index (SPI). The results indicate that the coastal and altitudinal lower areas of the region faced more frequent and more severe drought events during the recent years compared to the past, whereas the climatic conditions in the mountainous areas are more favorable. The hydrological years 1977-1978, 1984-1985, 1988-1989, 1998-1999 and 1999-2000 were the years of the most severe droughts in the basin. From the trend analysis of the SPI it appears that the lower part of the sub-basin is anticipated to face even more droughts in the future. These patterns may have significant impacts on the natural rainfed vegetation, especially at the river's Delta where habitat types of high priority are located. Thus, the need to adopt measures for the conservation of the local ecosystem is critical, considering also that the local habitat types are characterized by high demands for water availability. © 2022 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0

Erosion-Based Classification of Mountainous Watersheds in Greece: A Geospatial Approach

Soil erosion is a key factor in land degradation across Mediterranean mountain regions, yet comprehensive assessments at the national scale are still uncommon. In this study, the Erosion Potential Method (EPM, Gavrilović method) was applied to 1127 mountainous watersheds of Greece in order to classify their erosion severity through the erosion coefficient (Z). Information on relief, geology and vegetation was combined so that each watershed could be assigned to one of five erosion severity classes. The classification revealed that 53.2% of the watersheds fall into the slight category, while 26.0% are moderate and 16.3% are very slight. Severe cases account for 3.9%, and only 0.5% are classified as excessive, though these few basins are locally very important. The distribution is far from uniform: severe watersheds occur more often in North Peloponnese (EL02), Thessaly (EL08), and the Western Sterea Ellada (EL04). By contrast, Crete (EL13) and the Aegean Islands (EL14) include a relatively greater proportion of watersheds in the moderate category. This variation indicates that erosion risk should not be considered a uniform condition across the country. Even watersheds with low overall Z may contain steep or degraded slopes that act as local hotspots. Consequently, effective management should move beyond country-wide averages and instead focus on the sub-areas that are most exposed and susceptible to erosion