• Energy Research

[EN] Water indicators and indices are useful tools to assess river basin performance, that is, to measure whether the basin operates satisfactorily under a wide range of possible future demands and hydrological conditions. Spanish regulations assess the performance of water demands by using reliability indicators (RIs), established by law in 2008. This article raises the possibility of updating RIs by comparing them with sustainability indicators (SIs). SIs are widely used for the assessment of river basin performance and several policy scenarios. We applied a water allocation model to the Guadiana River basin in Spain to compare indicators under three scenarios. The study was framed within the science of socio-hydrology, combining the physical environment of a water system with its influence on social aspects. SIs gave better results than RIs when comparing future scenarios. We also propose the introduction of a vulnerability indicator into Spanish regulations. The authors thank the Spanish Research Agency (MINECO) for the financial support to the ERAS project [CTM2016-77804-P], including EU-FEDER funds. Additionally, we value the support provided by the European Community in financing the project IMPREX [H2020-WATER-2014-2015, 641811].

Abstract. Dam safety is increasingly subjected to the influence of climate change. Its impacts must be assessed through the integration of the various effects acting on each aspect, considering their interdependencies, rather than by a simple accumulation of separate impacts. This serves as a dam safety management supporting tool to assess the vulnerability of the dam to climate change and to define adaptation strategies under an evolutive dam failure risk management framework. This article presents a comprehensive quantitative assessment of the impacts of climate change on the safety of a Spanish dam under hydrological scenarios, integrating the various projected effects acting on each component of the risk, from the input hydrology to the consequences of the outflow hydrograph. In particular, the results of 21 regional climate models encompassing three Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5) have been used to calculate the risk evolution of the dam until the end of the 21st century. Results show a progressive deterioration of the dam failure risk, for most of the cases contemplated, especially for the RCP2.6 and RCP4.5 scenarios. Moreover, the individual analysis of each risk component shows that the alteration of the expected inflows has the greater influence on the final risk. The approach followed in this paper can serve as a useful guidebook for dam owners and dam safety practitioners in the analysis of other study cases.

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 study focuses on a novel type of methodology which connects Pan-European data to the local scale in the field of water resources management. This methodology is proposed to improve and facilitate the decision making within the planning and management of water resources, taking into account climate change and its expected impacts. Our main point of interest is focused on the assessment of the predictability of extreme events and their possible effects, specifically droughts and water scarcity. Consequently, the Júcar River Basin was selected as the case study, due to the ongoing water scarcity problems and the last drought episodes suffered in the Mediterranean region. In order to study these possible impacts, we developed a modeling chain divided into four steps, they are: i) data collection, ii) analysis of available data, iii) models calibration and iv) climate impact analysis. Over previous steps, we used climate data from 15 different regional climate models (RCMs) belonging to the three different Representative Concentration Pathways (RCPs) coming from a hydrological model across all of Europe called E-HYPE. The data were bias corrected and used to obtain statistical results of the availability of water resources for the future (horizon 2039) and in form of indicators. This was performed through a hydrological (EVALHID), stochastic (MASHWIN) and risk management (SIMRISK) models, all of which were specifically calibrated for this basin. The results show that the availability of water resources is much more enthusiastic than in the current situation, indicating the possibility that climate change, which was predicted to occur in the future has already happened in the Júcar River Basin. It seems that the so called "Effect 80", an important decrease in water resources for the last three decades, is not well contemplated in the initial data.

Surface water (SW) quality is particularly vulnerable to increased concentrations of nutrients, and this issue may be exacerbated by climate change. Knowledge of the effects of temperature and rainfall on SW quality is required to take the necessary measures to achieve good SW status in the future. To address this, the aims of this study were threefold: (1) to assess how a changing climate may alter the nitrate, ammonium, phosphorus and biological oxygen demand status (BOD5) of SW; (2) assess the relationship between water quality and flow; and (3) simulate diffuse and point source pollution reduction scenarios in the Júcar River Basin District in the Mediterranean region. A regionalised long-term climate scenario was used following one Representative Concentration Pathway (RCP8.5) with the data incorporated into the coupling of hydrological and water quality models. According to these climate change scenarios, SW with poor nitrate, ammonium, phosphorus and BOD5 status are expected to increase in the future by factors of 1.3, 1.9, 4 and 4, respectively. Furthermore, median ammonium and phosphorus concentration may be doubled in months with low flows. Additional measures are required to maintain current status in the water bodies, and it is necessary to reduce at least 25% of diffuse nitrate pollution, and 50% of point loads of ammonium, phosphorus, and BOD5.

<p>La disponibilidad del recurso hídrico es de vital importancia para la planificación hidrológica, este depende de múltiples causas como la variabilidad climática y la cobertura vegetal. La precipitación, temperatura y evapotranspiración han sufrido cambios en diferentes partes de España. Para la cuenca del río Júcar además de otras cuencas en España se ha producido un significativo cambio en el valor promedio de las aportaciones hidrológicas desde 1980. El presente estudio se centra en analizar cómo han afectado los cambios en las variables climáticas a las aportaciones hidrológicas y en qué grado explican las reducciones registradas en las mismas. Adicionalmente se considera la posibilidad de que otros factores como cambios en la cobertura vegetal también puedan haber influido en la reducción de escorrentía. Para modelar la hidrología de la cuenca del Júcar se utilizó el modelo lluviaescorrentía HBV. El modelo fue calibrado para periodo anterior a la fecha de cambio considerada (1950-1979) y se simuló y adaptó para los años posteriores a 1980 (1980-2007) ajustando parámetros que puedan ser explicados por cambios en las condiciones de la cuenca. La zona más susceptible es la cabecera del Júcar donde se genera la mayor cantidad del recurso hídrico y se presenta la mayor disminución en las aportaciones. En la cuenca media del Júcar se presenta una menor disminución en las aportaciones, sin embargo en la cuenca baja del Júcar se registra un incremento en las aportaciones. Los cambios en las variables hidrológicas (precipitación y temperatura) explican una parte de los cambios en las aportaciones. Otras causas posibles como los cambios en la cobertura vegetal pueden completar la explicación del cambio en las aportaciones. Para probarlo se ha recalibrado el modelo hidrológico alterando solo uno o dos parámetros relacionados con esta condición.</p>

[EN] Knowledge on the effects of climate change in a system can contribute to the better management of its water and energy resources. This study evaluates the consequences of alterations in the rainfall and temperature patterns for a hydroelectric plant. The methodology adopted consists of four steps. First, a hydrological model is developed for the chosen basin following a semi-distributed and conceptual approach. The hydrological model is calibrated utilizing the optimization algorithm Shuffled Complex Evolution University of Arizona (SCE-UA) and then validated. Secondly, a hydropower model is developed fora hydroelectric plant of the chosen basin. The hydropower model is adjusted to the physical characteristics of the plant. Thirdly, future climate scenarios are extracted from the literature for the studied area. These scenarios include quantitative and seasonal climate variations, as well as different initial reservoir levels. Fourth, the hydrological-hydropower model is simulated for 52 scenarios and the impact of changes in the rainfall and temperature patterns for hydropower generation is evaluated. For each scenario, the water storage in the reservoir and energy produced by the plant are analyzed. The financial impact for extreme scenarios is presented. The methodology is applied to the Tres Marias hydroelectric plant at the upper SAo Francisco river basin (Brazil) and it can be replicated to any other hydropower system. The results show that extreme positive values predicted for rainfall will likely not cause issues to the plant, considering a moderate rise in temperature. However, negative predictions for rainfall, regardless of changes in temperature, should be an alert to the authorities responsible for water and energy resources management. This study was funded by the Sao Paulo Research Foundation (FAPESP -grant #2018-00016-8), European Commission (EBW+ program), and National Council for Scientific and Technological Development (CNPq). The authors thank Companhia Energetica de Minas Gerais S.A. (CEMIG), Agencia Nacional de Aguas (ANA), Instituto Nacional de Meteorologia (INMET), and Camara de Comercializacao de Energia Eletrica (CCEE) for kindly providing the data needed to carry out this research. The authors also thank the developers of RS Minerve, computational tool utilized in this research, and Espaco da Escrita -Pro-Reitoria de Pesquisa (PRP/UNICAMP), for the language services provided.