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The drought prone North-West Bangladesh is vulnerable to the impacts of climate change, particularly because of less water availability in the dry period and high water requirement for crop production. Improved understanding of recent changes in crop water demand in the dry season is important for the water resources management in the region. A study was carried out to determine the potential impacts of recent climate change during last three decades on trends of water requirements of Boro rice. The reference crop evapotranspiration (ETo), potential crop water requirement (∑ETC), effective rainfall during the crop growing period (ER), potential irrigation requirement for crop evapotranspiration (∑ETC − ER) and net irrigation requirement of Boro rice were estimated using observed daily climate data in the CropWat model for the period of 1980 to 2013 for four North-West districts. Significant decreasing trends of ETo were observed in most of the dry months due to increasing relative humidity and decreasing wind-speed and sun-shine hours. The results showed decreasing trends of potential crop water requirement, i.e. the total crop evapotranspiration (∑ETC), of Boro rice due to decreasing reference crop evapotranspiration and shorter crop growing periods. The variations in trends of potential irrigation requirement for crop evapotranspiration (∑ETC − ER) found among different districts, are mainly linked to variations in trends of changes in effective rainfall. The net irrigation requirement of Boro rice has decreased, by 11% during the last three decades at an average rate of −4.4 mm year−1, instead of decreasing effective rainfall, mainly because of high rate of decrease of crop evapotranspiration (−5.9 mm year−1). Results indicate that a warming climate does not always result in higher agricultural water use and that climate change can also result in reduced water demands because of changes in humidity, wind-speed and sun-shine hours.

With the concept of climate services rapidly climbing research and research-funding agendas worldwide, the time is ripe for a debate about the objectives, scope and content of such services.

The Vietnamese Mekong Delta (VMD) is one of the world’s most vulnerable deltas to climate change and sea level rise. Adequate understandings of future hydrological changes are crucial for effective water management and risk-proofing, however, this knowledge body is currently very limited. This study quantifies the responses of the VMD’s river flow regime to multiple stimuli, namely future upstream inflow variation, local climate change, and sea level rise. The one-dimensional hydrodynamic model MIKE 11 was used to simulate discharges and water levels across the delta. We developed four scenarios to represent changes in the upstream discharges, precipitation changes and sea level rise, covering the 2036–2065 period. We downscaled climate data and applied three bias-correction methods for five General Circulation Models (GCM), and two Representative Concentration Pathways (RCPs). The climate change projections show similar trends of increasing wet season precipitation and decreasing dry season precipitation. However, cross-scenario variations are sometimes large, depending on the individual GCMs, the RCPs and specific locations. The hydraulic simulation results indicate that, under discharge changes between −20% and +10%, combined with in-delta precipitation variations during the dry season, river discharges at the four representative stations could reduce substantially from −2.5% to −100.2%. During the wet season, the calculated river discharges show increase between 7.3% and 46.7% under four considered scenarios. Substantial changes in the VMD’s river flow regime could have potentially serious implications for water management, especially saltwater intrusion, and therefore calling for timely adaptation measures.

Worldwide, 98% of total electricity is currently produced by thermoelectric power and hydropower. Climate change is expected to directly impact electricity supply, in terms of both water availability for hydropower generation and cooling water usage for thermoelectric power. Improved understanding of how climate change may impact the availability and temperature of water resources is therefore of major importance. Here we use a multi-model ensemble to show the potential impacts of climate change on global hydropower and cooling water discharge potential. For the first time, combined projections of streamflow and water temperature were produced with three global hydrological models (GHMs) to account for uncertainties in the structure and parametrization of these GHMs in both water availability and water temperature. The GHMs were forced with bias-corrected output of five general circulation models (GCMs) for both the lowest and highest representative concentration pathways (RCP2.6 and RCP8.5). The ensemble projections of streamflow and water temperature were then used to quantify impacts on gross hydropower potential and cooling water discharge capacity of rivers worldwide. We show that global gross hydropower potential is expected to increase between +2.4% (GCM-GHM ensemble mean for RCP 2.6) and +6.3% (RCP 8.5) for the 2080s compared to 1971–2000. The strongest increases in hydropower potential are expected for Central Africa, India, central Asia and the northern high-latitudes, with 18–33% of the world population living in these areas by the 2080s. Global mean cooling water discharge capacity is projected to decrease by 4.5-15% (2080s). The largest reductions are found for the United States, Europe, eastern Asia, and southern parts of South America, Africa and Australia, where strong water temperature increases are projected combined with reductions in mean annual streamflow. These regions are expected to affect 11–14% (for RCP2.6 and the shared socio-economic pathway (SSP)1, SSP2, SSP4) and 41–51% (RCP8.5–SSP3, SSP5) of the world population by the 2080s.

This paper provides a synthesis and comparison of methodologies and results obtained in several studies devoted to the impact of climate change on hydropower. By putting into perspective various case studies, we provide a broader context and improved understanding of climate changes on energy production. We also underline the strengths and weaknesses of the approaches used as far as technical, physical and economical aspects are concerned. Although the catchments under investigation are located close to each other in geographic terms (Swiss and Italian Alps), they represent a wide variety of situations which may be affected by differing evolutions for instance in terms of annual runoff. In this study, we also differentiate between run-of-river, storage and pumping-storage power plants. By integrating and comparing various analyses carried out in the framework of the EU-FP7 ACQWA project, this paper discusses the complexity as well as current and future issues of hydropower management in the entire Alpine region.

Climate change is believed to have a large impact on water resources system both globally and regionally. It has become a major global issue, especially in developing countries because these are most affected by its impacts. Rainwater harvesting techniques offer an alternative source of water and represent specific adaptive strategies to cope with water scarcity within future climate change. Studying the impact of climate change on rainwater harvesting techniques, however, is difficult, because the general circulation models (GCMs) which are widely used to simulate scenarios of future climate change operate on a coarse scale. We estimated the impact of climate change on water availability at the watershed level by downscaling precipitation and temperature from the GCMs using a statistical downscaling model. A water harvesting model then assessed the performance of the rainwater harvesting techniques for the Oum Zessar watershed in southeastern Tunisia under current climatic conditions and scenarios of future climate change. Annual temperature tended to increase and precipitation tended to decrease. These changes of climatic variables were used in the water harvesting model to simulate future water availability. Changing the directions of water flow between sub-catchments in combination with changing the spillway heights strongly affected the performance of rainwater harvesting under the scenarios of future climate, resulting in a sufficient water supply for 92% of all sub-catchments, compared to 72% without these changes.

While the effects of climate change unfold and become more visible, infrastructures - especially those related to the distribution of water and energy - are the most exposed to the deep changes expected in the next years. Water is fundamental for people, and for infrastructures like energy, waste, and food production. Water sustainability is therefore a fundamental aspect to be addressed by an efficient use of the resources and by mainteining high quality standards. Hence, water industry and water infrastructure need a deep transformation; in this paper we present a framework based on complex systems and management science as a possible pathway to reshape and optimize the performance of the water infrastructure to cope with the complexity of todays' challenges. To this aim, we propose the framework Acque 2.0 (Water 2.0), where we point out how the increase of the infrastructural resilience and of the overall quality of service can be attained by integrating models, algorithms and numerical methods like network simulations and big data analytics for the predictive maintenance of water networks. We discuss how Complexity Science is the natural glue allowing technical, management and social issues to be integrated in the holistic vision of the "water system" needed play to provide measures for an integrated sustainability reporting that involves utilities, regulators, policy makers, and citizens.

Understanding the future patterns of precipitation behaviour in unique geographical areas, largely determined by their orography and local scale, can help lay the foundations for a new precipitation model for the design of the city’s main urban drainage infrastructures (intensity-duration-frequency curves, mathematical functions that relate precipitation intensity to duration and frequency of occurrence, hereafter IDF, for the short-, medium- and long-term future). This will definitely contribute to the improvement of the city’s resilience to the effects of climate change. In this paper, the projections of a subset of climate change models from both the sixth phase of the Coupled Model Intercomparison Project (CMIP6; with a total of 5 simulations) and Euro-CORDEX (for a set of 51 simulations) have been adjusted to the municipality of Alicante (in the southeast of Spain), using the Climadjust tool (climadjust.com). These projections contain different climatic variables. The rainfall variable has been used to derive a new framework of boundary conditions to help design more resilient infrastructure for torrential rainfall events and urban flooding. The projections corresponding to three climate change scenarios (CMIP6: SSP1-2.6, SSP2-4.5, SSP5-8.5; and Euro-CORDEX: RCP2.6, RCP4.5, RCP8.5) are considered with daily resolution and, by applying statistical techniques of temporal disaggregation (by means of a cascade model), hourly (and sub-hourly, reaching 30-min resolution) disaggregation. The results at hourly and 30-min resolutions are used to construct IDF curves of future climate, grouped into short-term (years 2015 to 2040), medium-term (years 2041 to 2070) and long-term (years 2071 to 2100) sub-scenarios. The selected future climate IDFs for an adverse climate change scenario (SSP2-4.5 and SSP5-8.5) show increases in rainfall intensities, higher the shorter the rainfall duration, for return periods greater than or equal to 25 years, whereas for return periods under 25 years the current IDFs can be representative of future scenarios. Current calculations and future projection of the torrentiality index for severe climate change scenarios, as well as the climate change factors, show an increase in the frequency and magnitude of the heaviest rainfall. This fact corroborates the hypotheses of greater general torrentiality in future rainfall in this specific area of the Spanish Mediterranean coast. This research was supported in part by Agencia Valenciana de Innovación (AVI) and the company Aguas Municipalizadas de Alicante.