• Energy Research

Climate change is expected to increase rainfall and temperature in the tropical areas of the Ecuadorian coast. The increase in temperature will also increase evapotranspiration therefore, future water balance on Ecuadorian coast will have a slight variation. Changes in precipitation patterns and evapotranspiration will produce an increase in the water requirements for current crops, so an imbalance in the water resources systems between natural resources and water demands is expected. This study presents water resources management as an adaptation measure to climate change for reducing vulnerability in tropical areas. Twelve bias-corrected climate projections are used, from: two AR5 General Circulation Models (GCMs), two Representative Concentration Pathways, 4.5-8.5 scenarios, and three time periods, short-term (2010-2039), medium-term (2040-2069) and long-term (2070-2099). These data were incorporated into the Lumped Témez Hydrological Model. Climate change scenarios predict for the long-term period both a mean rainfall and temperature increases up to 22%-2.8 °C, respectively. Besides, the potential evapotranspiration will increase until 12% by Penman-Monteith method and 60% by Thornthwaite method. Therefore, natural water resources will finally have an increase of 19% [8-30%]. Additionally, water requirements for crops will increase around 4% and 45%. As this research shows, in tropical regions, currently viable water resources systems could become unsustainable under climate change scenarios. To guarantee the water supply in the future additional measures are required as reservoir operation rules and irrigation efficiency improvement of system from 0.43 to 0.65, which it involves improving the distribution and application system. In study area future irrigation areas have been estimated for 13,268 ha, which under climate change scenarios is unsustainable, only 11,500 ha could be expanded with a very high irrigation efficiency of 0.73. Therefore, in tropical areas the effect of climate change on expansion projects for irrigated areas should be considered to ensure the functioning systems.

Integration of renewable energy sources and water production technologies is a must when facing water scarcity problems in semiarid regions, such as Mediterranean regions. The use of additional water resources and production methods, such as reclaimed water and, more specifically, desalinated water, means present and necessary water resources to introduce in the water balances to attend to water demands within a global warming and droughting scenario. These solutions have the inconvenience of energy/power needs and costs. However, the development of renewable energies like photovoltaic solar energy, with lower and lower costs and greater efficiency, makes these economically feasible facilities, reaching competitive production costs for marine or sea desalinated water by around 50% of reduction in energy costs and 20–30% of savings in final water production cost. This paper presents a practical project or action focused on the integration of renewable energies and new water resources by introducing a Photovoltaic Energy Plant (PVEP) as an energy source to feed a Seawater Desalination Treatment Plant (SWDTP). The PV facility is designed to cover all the energy demanded using the SWDTP during the day, and even studying the possibility of selling the energy production exceeds and injecting them into the energy supply network, covering the needs of buying energy needed during the high period where there is no photovoltaic energy production. Thus, savings related to energy costs and even incomes coming from energy sales mean an important reduction in operation costs or expenditures (OPEX), which makes economically feasible and sustainable the investment and the final price of water produced within the Mutxamel SWDTP. The final reduction cost in water desalination reaches 25% on average.

Water temperature is a critical factor for aquatic ecosystems, influencing both chemical and biological processes, such as fish growth and mortality; consequently, river and lake ecosystems are sensitive to climate change (CC). Currently proposed CC scenarios indicate that air temperature for the Mediterranean Jucar River will increase higher in summer, 4.7 °C (SSP5-8.5), resulting in a river water temperature increase in the hotter month; July, 2.8 °C (SSP5-8.5). This will have an impact on ecosystems, significantly reducing, fragmenting, or even eliminating natural cold-water species habitats, such as common trout. This study consists of developing a simulated model that relates the temperature of the river with the shadow generated by the riverside vegetation. The model input data are air temperature, solar radiation, and river depth. The model proposed only has one parameter, the shadow river percentage. The model was calibrated in a representative stretch of the Mediterranean river, obtaining a 0.93 Nash–Sutcliffe efficiency coefficient (NSE) that indicates a very good model fit, a 0.90 Kling–Gupta efficiency index (KGE), and a relative bias of 0.04. The model was also validated on two other stretches of the same river. The results show that each 10% increase in the number of shadows can reduce the river water temperature by 1.2 °C and, in the stretch applied, increasing shadows from the current status of 62% to 76–87% can compensate for the air temperature increase by CC. Generating shaded areas in river restorations will be one of the main measures to compensate for the rise in water temperature due to climate change.

This paper describes two different GIS models - one stationary (GeoImpress) and the other non-stationary (Patrical) - that assess water quantity and quality in the Júcar River Basin District, a large river basin district (43,000km(2)) located in Spain. It aims to analyze the status of surface water (SW) and groundwater (GW) bodies in relation to the European Water Framework Directive (WFD) and to support measures to achieve the WFD objectives. The non-stationary model is used for quantitative analysis of water resources, including long-term water resource assessment; estimation of available GW resources; and evaluation of climate change impact on water resources. The main results obtained are the following: recent water resources have been reduced by approximately 18% compared to the reference period 1961-1990; the GW environmental volume required to accomplish the WFD objectives is approximately 30% of the GW annual resources; and the climate change impact on water resources for the short-term (2010-2040), based on a dynamic downscaling A1B scenario, implies a reduction in water resources by approximately 19% compared to 1990-2000 and a reduction of approximately 40-50% for the long-term (2070-2100), based on dynamic downscaling A2 and B2 scenarios. The model also assesses the impact of various fertilizer application scenarios on the status of future GW quality (nitrate) and if these future statuses will meet the WFD requirements. The stationary model generates data on the actual and future chemical status of SW bodies in the river basin according to the modeled scenarios and reflects the implementation of different types of measures to accomplish the Urban Waste Water Treatment Directive and the WFD. Finally, the selection and prioritization of additional measures to accomplish the WFD are based on cost-effectiveness analysis.

Water scarcity will increase in the world in the coming decades due to climate change, especially in areas that currently already have water scarcity, such as the Mediterranean area. In these areas, to guarantee water resources, systems’ sustainability is necessary to improve demand management and the development of non-conventional resources, such as treated wastewater reuse or seawater desalination. These non-conventional resources are highly energy-consuming; so, reducing energy costs is a key element in developing their use in different sectors, including agriculture. Combining photovoltaic solar energy with seawater desalination by reverse osmosis will reduce the cost of producing water to below 0.36 EUR/m3; so, this resource can be attractive for agriculture, as demonstrated in this work. The arrangement of bifacial solar modules in horizontal single-axis tracking systems increases the energy amount generated from the sun in one hour or more, improving the facility’s efficiency and reducing the desalinated water cost. The greater distance between the solar module lines, with a ground coverage ratio (GCR) = 0.3, makes for a better environmental integration of the facility and allows the development of agrovoltaic strategies, such as native flora planting and pollinator colonization.

[EN] Current climate change (CC) predictions for the Western Mediterranean show a significant increase in temperature, and a decrease in precipitations, with great variability depending on general circulation models (GCM) and downscaling approaches. This paper analyses how dynamic downscaling improves statistically based CC scenarios. The study area was the Jucar River Basin (JB), with results from ECHAM5 GCM, and a close time frame of 2010-2040 appropriated for decision-making. The dynamic downscaling was performed with the regional climate model (RCM) RegCM3. It was applied to a coarse grid over the Iberian Peninsula, and then to a finer grid over the JB. The RCM was customized to reproduce Western Mediterranean climatic conditions using the convective precipitation scheme of Grell; the non-convective scheme was customized by changing the default RHmin and C-ptt parameters to reproduce precipitations originated by larger-scale atmospheric circulations. The RCM results, compared to current official Spanish Agency of Meteorology (AEMET) scenarios-statistically based-reproduce much better historical data (used to verify scenarios generation). They foresee a 21.0% precipitation decrease for 2010-2040, compared to previous ECHAM4 predictions with statistical downscaling (-6.64%). The most significant reductions are in February, September and October. Average estimated temperature increase is 0.75 degrees C, with high increments in July (+3.05 degrees C) and August (+1.89 degrees C).

High nutrient discharge from groundwater (GW) into surface water (SW) have multiple undesirable effects on river water quality. With the aim to estimate the impact of anthropic pressures and river–aquifer interactions on nitrate status in SW, this study integrates two hydrological simulation and water quality models. PATRICAL models SW–GW interactions and RREA models streamflow changes due to human activity. The models were applied to the Júcar River Basin District (RBD), where 33% of the aquifers have a concentration above 50 mg NO3−/L. As a result, there is a direct linear correlation between the nitrate concentration in rivers and aquifers (Júcar r2 = 0.9, and Turia r2 = 0.8), since in these Mediterranean basins, the main amount of river flows comes from groundwater discharge. The concentration of nitrates in rivers and GW tends to increase downstream of the district, where artificial surfaces and agriculture are concentrated. The total NO3− load to Júcar RBD rivers was estimated at 10,202 tN/year (239 kg/km2/year), from which 99% is generated by diffuse pollution, and 3378 tN/year (79 kg/km2/year) is discharged into the Mediterranean Sea. Changes in nitrate concentration in the RBD rivers are strongly related to the source of irrigation water, river–aquifer interactions, and flow regulation. The models used in this paper allow the identification of pollution sources, the forecasting of nitrate concentration in surface and groundwater, and the evaluation of the efficiency of measures to prevent water degradation, among other applications.

This paper analyses all current available simulated climate scenarios, proposed by the Spanish Agency of Meteorology (AEMET), for the period 2010-2040 on the geographic area covered by the Jucar River Basin District (JB), located in eastern Spain. This is done through the validation of these scenarios using historical records, and by assessing the impact on water resources for the next 30 years by means of a hydrological model. By taking the period 1960-90 as control period, a careful comparison of its historical records against AEMET scenarios is performed. Although temperature records are properly honoured, precipitations are widely underestimated in a range going from 8 % to 29 %. This wide variability range observed in the control period is also found in precipitation scenarios for 2010-40. The impact on water resources shows a great degree of dispersion, ranging from -13.45 to 18.1% with a mean value of -2.13%.