Search

Abstract Bridging the gap between the predictions of coarse-scale climate models and the fine-scale climatic reality is a key issue of hydrological research and water management. While many advances have been realized in developed countries, the situation is contrastingly different in most tropical regions where we still lack information on potential discrepancies between measured and modeled climatic conditions. Consequently, water managers in these regions often rely on non-academic expertise to help them plan their future strategies. This issue is particularly alarming in tropical mountainous areas where water demand is increasing rapidly and climate change is expected to have severe impacts. In this article, we addressed this issue by evaluating the limitations and prospects in using regional climate models for evaluating the impact of climate change on water availability in a watershed that provides Quito, the capital of Ecuador, with about 30% of its current water needs. In particular, we quantified the temporal and spatial discrepancies between predicted and observed precipitation and temperature, and explored underlying mechanisms at play. Our results provide a strong critique of the inappropriate use of regional models to inform water planning with regard to adaptation strategies to face climate change. As a multidisciplinary group composed of hydrologists, ecologists and water managers, we then propose a framework to guide future climate change impact studies in tropical mountain watersheds where hydro-climatological data are scarce. Graphical abstract Unlabelled Image Highlights • Water managers rely on regional climatic models to plan future strategies. • We found strong biases in climatic model predictions compared to observed data. • Regional models are inappropriate to inform water planning to face climate change. • We need to improve monitoring and ecohydrological knowledge in tropical regions. [ABSTRACT FROM AUTHOR]

Given a limited volume of freshwater resources and increasing water demand in China, a relatively equal final water use distribution among different provinces is necessary to mitigate water scarcity faced by a great proportion of population. In this study, the Gini coefficient is used to measure inequality of provincial water footprints (WFs), which are computed based on the China multi-regional input–output table in 30 provinces. The inequality analysis indicates that in China, albeit improved equality of the WF via virtual water (VW) transfers in comparison to the real water use, provincial WFs still present inequality (with Gini coefficient 0.22). Inequality decomposition techniques are used to examine the main sectoral contributor and drivers of WF inequality. The decomposition of inequality in the total WF by sectoral water use types indicates that agricultural WF is the largest contributor, contributing 45.7% of the total inequality, followed by industrial WF (36.9%), tertiary WF (11.1%) and domestic water use (6.3%). Inequality decomposition in the total WF by drivers shows that the effect of natural water availability is insignificant. The main drivers of inequality in agricultural WF are real water use and water use efficiency, with the inter-class effect overwhelming inter-class effect based on classification according to these factors. Inequality in industrial and tertiary WFs is mainly driven by real water use and economic level. Policy inferences are given towards a more equal distribution of WF. [ABSTRACT FROM AUTHOR]

Water scarcity and water security are linked, not only through the direct effects of water shortages on each water users' access to water, but also because of water conflicts generated. Climate change is predicted to raise temperatures in the Mediterranean region and reduce rainfall, leading to a reduction in water yield and possibly worsening the situation of water resource shortages that Mediterranean regions are already experiencing. In its dissemination strategy, the EU FP7 CLIMB project addressed water security threats through an analysis of water uses and water use rivalries within a few target catchments distributed over the Mediterranean region. The present work explores whether climate change is locally perceived by stakeholders (water users and managers) as a key issue for their water uses and water security. Individual interviews, meetings, and compilation of questionnaires were conducted at five sites located in the Mediterranean region. The methodology permitted an analysis of water use and its evolution in the water management context, an identification of the state of awareness of local stakeholders and of the pressures on water use and water use rivalries, and a prioritization of water uses. Currently, the main response to increasing water demand in the Mediterranean region, while not yet considering climate change as a driving force, is a progressive externalization of water resources, with limits represented by national borders and technological possibilities. Overall, ‘climate change’ was not mentioned by stakeholders during both interviews and in answers to the questionnaires. Even the prospect of decreasing precipitation was not considered a relevant or threatening issue in the coming 20 years. This confirms the need to continue all efforts to disseminate the state of knowledge on climate change impacts in the Mediterranean region, such as water scarcity, especially to local water managers, as initiated by various research programs of the European Commission. [ABSTRACT FROM AUTHOR]

Assessing water supply sustainability is crucial to meet stakeholders' needs, notably in the Mediterranean. This region has been identified as a climate change hot spot, and as a region where water demand is continuously increasing due to population growth and the expansion of irrigated areas. The Hérault River catchment (2500 km 2 , France) is a typical example and a negative trend in discharge has been observed since the 1960s. In this context, local stakeholders need to evaluate possible future changes in water allocation capacity in the catchment, using climate change, dam management and water use scenarios. A modelling framework that was already calibrated and validated on this catchment over the last 50 years was used to assess whether water resources could meet water demands at the 2030 horizon for the domestic, agricultural and environmental sectors. Water supply sustainability was evaluated at the sub-basin scale according to priority allocations using a water supply capacity index, frequency of unsatisfactory years as well as the reliability, resilience and sustainability metrics. Water use projections were based on the evolution of population, per-unit water demand, irrigated areas, water supply network efficiency, as well as on the evaluation of a biological flow. Climate projections were based on an increase in temperature up to 2 °C and a decrease in daily precipitation by 20%. Adaptation strategies considered reducing per-unit water demand for the domestic sector and the importation of water volume for the agricultural sector. The dissociated effects of water use and climatic constraints on water supply sustainability were evaluated. Results showed that the downstream portions would be the more impacted as they are the most exploited ones. In the domestic sector, sustainability indicators would be more degraded by climate change scenarios than water use constraints. In the agricultural sector the negative impact of water use scenarios would be stronger. The environmental sector would be hardly satisfied especially in summer with low resilience levels. The adaptation strategies considered in this study would not be sufficient to cope with both anthropogenic and climate changes. Other strategies were discussed based on known examples in the Mediterranean context. [ABSTRACT FROM AUTHOR]

The complexity of the connections within an economic system can only be reliably reflected in academic research if powerful methods are used. Researchers have used structural path analysis (SPA) to capture not only the linkages within the production system but also the propagation of the effects into different channels of impacts. However, the SPA literature has restricted itself to showing the relations among sectors of production, while the connections between these sectors and final consumption have attracted little attention. In order to consider the complete set of channels involved, in this paper we propose a structural path method that endogenously incorporates not only sectors of production but also the final consumption of the economy. The empirical application comprises water usages, and analyses the dissemination of exogenous impacts into various channels of water consumption. The results show that the responsibility for water stress is imputed to different sectors and depends on the hypothesis used for the role played by final consumption in the model. This highlights the importance of consumers' decisions in the determination of ecological impacts. [ABSTRACT FROM AUTHOR]

Abstract: With the decoupling elasticity model, this paper studies the decoupling relationships (DRs) of total water uses (TWU) and provincial GDP, agricultural water uses (AWU) and agricultural added value (AAV), as well as industrial water uses (IWU) and industrial added value (IAV) respectively in Yunnan and Guizhou during the first ten years for the implementation of the Great Western Development Strategy. The results indicate that the DRs of water uses and economic development are highly undesirable in both provinces. Among the three groups, the DRs of AWU and AAV are the worst of all, with strong or weak coupling in 5 of the 10 years; the DRs of IWU and IAV are slightly better with strong coupling respectively in 3 of the 10 years in Yunnan and in 2 of the 10 years in Guizhou; and the DRs of TWU and GDP are the best, with strong or weak decoupling in 7 of the 10 years in both provinces. The DRs have improved in the period of 2006-2010 if compared with that in the period of 2001-2005. It is concluded that slow economic growth, low efficiency and poor structure of water uses are the main reasons for the worse status of DRs, and the development of economy and water uses efficiency promotes the DRs getting better. [Copyright &y& Elsevier]

Abstract: The Greek regions of Crete and of the Aegean Islands are of the southernmost river basin districts (RBDs) of the European Union. They both have limited water resources, and water demand often surpasses water availability. The geographical fractionation, particularly for the region of the Aegean Islands, is a major constrain for the implementation of an integrated water management plan. This article aims at presenting the current status of water resources in the above regions, and the existing water management plans. The article summarizes the pressures on the water resources of the above geographical regions, and investigates the possibility for utilization of nonconventional water resources, like desalinated seawater, reclaimed wastewater and brackish water. One of the conclusions among others is that the development of novel processes on water resources management should be one of the primary aims of any integrated water management plan. [Copyright &y& Elsevier]

Abstract: This work investigates the ecological modifications induced by the annual water level change as a consequence of hydrological regime and power production in Sélingué, a monomictic reservoir in Mali (West Africa). High waters occur from November, after the flood, while low waters occur from June, at the end of the dry season. Decrease of water level is linked to environmental factors (marked hydrological pattern, both for river flow and rain) and to human management of the reservoir during the dry season (irrigation, high hydropower demand). Difference in elevation between the high water and the low water phases is 9m. To assess the ecological impact of such water level variations, environmental and biological descriptors were studied on water sampled biweekly from November 2000 to November 2001 in stations representative of the north part of this water body. As a consequence of high water and of regional meteorology (NE trade winds), the water column in Sélingué is stratified from March to May. Stratification can act as a trap for nutrients in the hypolimnion, preventing the euphotic epilimnion to be realimented in dissolved P and N mineral components. This process lasts until the beginning of the monsoon (SW trade winds) when progressive warming and energetic inputs through storms allow vertical mixing. The sink-phase is then replaced by a spring-phase when the water column is not anymore stratified and when the water level is low enough to allow wind-induced resuspension and vertical mixing. At the end of the low water phase, phytoplankton blooms are observed, allowed by the proximity of the productive euphotic layer and the deep mineralization layer and their possible mixing. Water level is also important for fisheries, since fishes are “diluted” in high water (i.e., more difficult to catch with the artisanal tools operated by the local fishermen) but are “concentrated” in low water (i.e., more easily over fished in the minor riverbed, where most fishes are sheltered at the end of the dry season). Irrigation was until now a secondary purpose of the Sélingué project, behind power production. Sélingué is now of secondary importance for power production in Mali (behind Manantali) and the planned extension of irrigated areas in the Office du Niger is about to seriously increase the need of water from Sélingué, the only impoundment upstream. During a hydrological cycle, the only conditions possibly leading to ecological unbalance are met at the end of the low water period. As long as the water level is high enough to allow vertical stratification and vertical separation of the productive euphotic layer from the sink in the bottom layer, Sélingué trophic status varies from oligotrophy to mesotrophy. The low water phase is very sensitive, and wise management rules should limit its duration. But the projects leading to a more intensive and time-shifted use of Sélingué water could have as consequences an early dewatering of the reservoir and an early shift toward eutrophic conditions. Therefore, there is a need to define and to apply multipurpose rules of water level management that could help to minimize or to prevent these ecological consequences. [Copyright &y& Elsevier]