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Renewable energy sources are essential to reduce the negative impacts on the environment caused by burning fossil fuels. Using solar photovoltaic installations in recent years means that decision-makers must consider infrastructure renewal decisions. An expenditure framework to achieve the optimal renovation period of photovoltaic modules is proposed here from an economic standpoint. This approach includes not only the investment and maintenance costs but also energy and emissions savings. A sensitivity analysis was carried out using a case study in south-eastern Spain, achieving that the optimal renovation period ranges between 17.0 and 24.7 years. Many factors are studied to identify those with the greatest influence on this indicator. Installing a solar power system is always a profitable choice considering that the installation lifetime is 25 years. Neglecting the influence of these limits may cause potential savings not fully exploited., CRUE-CSIC, Springer Nature, research project "DESENREDA" through the 2021 call "Estancias de movilidad en el extranjero Jose Castillejo" of the Ministerio de Universidades CAS21/00085, project "Hi-Edu Carbon" Erasmus Plus Programme, Key Action KA22021, action type 2021-1-SK01-KA220-HED-000023274

Floods cause severe natural disasters over the world generating property and infrastructures damages, poverty and loss of human life, among others. Mediterranean watersheds are especially sensible to floods due to their typical drainage basin features (steep slopes, short concentration times, complex orography, etc.) and the high rainfall intensity typical of convective systems. Knowing channel dimensions and other fluvial morphological features is key to (i) understanding the morphological evolution of the fluvial system in response to changes in land use and climate, and (ii) as an input for hydrological and erosion modelling. The objective of this study is to develop a simple method to obtain reliable estimates of channel dimensions and granulometry of bed material, based on statistical relations with catchment characteristics (e.g. topography, land use, soil properties, lithology, precipitation, connectivity indicators).First, channel dimensions were estimated based on GIS analysis using a high resolution digital elevation model (2x2m) and ortophotos (50 cm resolution) for the Upper Segura River catchment, a Mediterranean catchment of 2,592 km2 located in the southeast of Spain. These estimates were validated with field measurements of depth and width of bankfull channels in the catchment headwaters. This comparison revealed that there was generally good agreement between channel dimensions obtained with the GIS method and those observed in the field for all evaluated channels (depth: RMSE=0.06; R2=0.93; width: RMSE=0.59, R2=0.45), although with better results for dry channels than for channels with continuous water flow. At each field observation, we also took sediment samples and characterised the granulometry of the channel bed material in the laboratory through dry sieving. Preliminary results show that bed material is composed mainly by gravels (67.8%), followed by sands (31.1%) and clays and silts (1.1%). Next, channel dimensions, obtained using GIS analysis across the entire catchment, and granulometry of bed material were used as dependent variables in advanced statistical analyses (such as machine learning algorithms) at sub-basin scale, with catchment characteristics as independent variables. The outcome of this analysis is now being used to make spatially continuous predictions of channel dimensions and granulometry of bed material at the catchment scale. This information will then ultimately serve as input for a coupled model that simulates channel hydraulics and morphodynamics at the catchment level.Keywords: geomorphology; sediment yield; depth and width of bankfull channels; Mediterranean environment; GIS based tools; southeast of Spain.We acknowledge funding from the Spanish Ministry of Science and Innovation and ‘Agencia Estatal de Investigación’ (PID2019-109381RB-I00/AEI/10.13039/501100011033).

Previous research suggests that channels have a significant contribution to the total sediment balance in large catchments. Channels are also very sensitive to changes in land use and management, with implications for channel morphodynamics and the quantity of sediments and nutrients flowing through the system. Here we present a new channel module for the coupled hydrology-soil erosion model SPHY, with the aim to quantify the contribution of hillslope and channel erosional processes to the total sediment balance in large catchments. SPHY simulates all relevant hydrological and soil erosion processes, including infiltration excess surface runoff and soil detachment by raindrop impact and runoff. We developed a novel channel module that simulates river hydraulics and morphodynamics in the channel network, while accounting for sedimentation in reservoirs and check dams. The channel module requires channel characteristics as input, including channel width, channel depth and bed material. The model was applied to a Mediterranean catchment (316 km2) in Southeast Spain, where channel characteristics were obtained from a combination of field measurements and GIS analyses. The model was calibrated using observed discharge, hillslope erosion and check dam sedimentation. Model validation focused on how channel morphodynamics changed in response to reforestation and check dam construction in the period 1956-2001. The model successfully simulates the observed changes in channel morphology, including an overall increase of channel morphodynamics and channel incision downstream of the check dams. Subsequently, the model was applied in a climate change impact assessment, to show how the sediment balance is projected to change under future climate conditions, characterized by an increase of extreme precipitation. The climate change simulations show that rill erosion is projected to increase, while channel erosion decreases. However, channel erosion still remains the main contribution to the total sediment yield in the catchment, which highlights the importance of accounting for channel morphological processes in large-scale erosion assessments. We acknowledge funding from the Spanish Ministry of Science and Innovation (AEI) (PID2019-109381RB-I00/AEI/10.13039/501100011033).

Testing compound floods by a new oceanic-coastal model in Cuba: preliminaryresults.Daniela Cordova de Horta 1,2 , Luis. F Cordova Lopez 1 , Antonio Jodar-Abellan 2,3 , AndresFullana 2,4 , Daniel Prats 2,41 Technological University of La Habana, Cuba.2 University Institute of Water and Environmental Sciences, University of Alicante, Alicante, Spain.3 Spanish Research Council, Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Soiland Water Conservation Group, Murcia, Spain.4 Department of Chemical Engineering, University of Alicante, 03690 Alicante, Spain.Abstract:Due to the climate change recognized in recent years, the danger on the coasts,at a global scale, has increased critically. This issue is associated with the increase in theglobal average temperature, which has the effect of raising the average sea level and theincrease in intensity and frequency of Extreme Meteorological Events (EME).Currently, more than 50% of the world's population lives in coastal regions and asignificant part in coastal areas vulnerable to flooding as a result of the rise in the meansea level, rainfall and river flooding. The simultaneous occurrence or brief succession ofthese hazards can cause flooding that generates impacts greater than those caused bythese events individually. In this study, a new technique of composite flood analysis isproposed in numerous urban-coastal areas and basins of Cuba by couplinghydrodynamic simulation tools. In particular, we present the results of the establishmentphase of the oceanic-coastal model called “Delft 3d Flow and Delft 3d Wave”, wherehurricanes Katrina, Isaac, Zeta and Ike were chosen. Likewise, the Era5 database wasused to generate the wind and pressure fields associated with hurricanes. In addition, theresults of a set of tests are presented to define the way of nesting and the best resolutionratios of the computation meshes of the different domains. Finally, statistics parameterswere applied to support the selection of the best alternatives by comparing our modelresults with the observations obtained by the National Oceanic and AtmosphericAdministration (NOAA) databases. From the author’s knowledge, the proposedmethodology can provide to planning policy makers very useful information in the faceof flood effects especially in a study area (Cuba) where flow registers from streamgauge stations are considerably scarce.

Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of SpainTeresa Palacios-Cabrera1, Antonio Jodar-Abellan2, Ryan T. Bailey3, Dámaris Núñez-Gómez2, Derdour Abdessamed4, Seyed Babak Haji Seyed Asadollah5, Pablo Melgarejo21Faculty of Geology, Mines, Petroleum and Environmental Engineering. Central University of Ecuador. teresaalejandrap3@gmail.com2Centro de Investigación e Innovación Agroalimentario y Agroambiental (CIAGRO), Miguel Hernández University (UMH). Orihuela, Spain.3Dept. of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO, USA.4Laboratory for the Sustainable Management of Natural Resources in Arid and Semi‑arid Zones. University Center Salhi Ahmed Naama (Ctr Univ Naama). P.O. Box 66, Naama 45000. Algeria.5Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.Abstract:Nowadays, numerous urban settlements in arid and semiarid areas are supplied by groundwater from adjacent small aquifers. Climate change with expected decreases in averages precipitation values jointly with increases in the frequency of heavy rainfall events does not show a clear pattner to how water resources in karstic aquifers are going to evolve. This work, focused in the Guadalest watershed (province of Alicante, southeast of Spain) assesses the behaviour of four karstic aquifers (the Mela, Beniardá-Polop, Benimantell and Serralla-Aixorta aquifers), whose resources supply urban water consumption for close municipalities. In these aquifers, we estimate groundwater recharge, extractions and their relation within the Exploitation Index (EI) by using the SWAT and SIMPA models, previously calibrated and validated in this watershed, during the period 1980-2016. These groundwater estimations were tested (validated) with field measurements performed by local authorities during the above mentioned period. Thus, in the Mela aquifer an EI of 0.19 was estimated with SWAT and SIMPA while an EI of 0.13 was obtained by local authorities; in the Beniardá-Polop aquifer an EI of 1.43 was estimated while an EI of 1.26 was obtained in the fieldwork; in Benimantell an EI of 0.25 and an EI of 0.22 were estimated and obtained respectively; and finally in the Serralla-Aixorta aquifer an EI of 0.19 and an EI of 0.2 were estimated and obtained respectively. Our results denote that: i) both models simulate correctly groundwater abstractions; ii) assessed aquifers depict a clear reduction of their reserves during the study period which represent an important issue considering that currently groundwater extractions are the unique water source of these populations. Therefore, it will be necessary to design supply strategies for these inhabitants and to carry out them, meeting budget restrictions and avoiding potential water shortages.Keywords: groundwater; SWAT; SIMPA; Exploitation Index; urban water supply; southeast of Spain.

Ain Sefra is part of the Ksour Mountains and it's situated in southwestern Algeria, where the climate is arid. The study area is progressively facing regression and degradation exacerbated by climate change. These trends point to a significant acceleration of desertification and drought and the loss of production systems that play a critical social, ecological, and economic role in the region. To better understand the natural hazard of dryness in Ain Sefra and the impact of climate change, we used various drought indices and remote sensing data. Hence, analyzing precipitation records from 1965 to 2021, through several drought indices, droughts were identified as a recurring phenomenon. Moreover, the frequency of successive dry years is relatively high. There were three most extended continuous dry periods. The first phase lasted seven years from 1980 to 1987, the second twelve years from 1994 to 2006, and the third nine years from 2012 to 2021. Calculation of the Modified Soil-Adjusted Vegetation Index (MSAVI) for five multidate satellite images allowed us to follow the evolution of land use elements in this region from 1977 to 2017. Indeed, the study of these multi-temporal images reveals a considerable growth of sands, moving towards the north and northeast of the zone during the last decades. The combination of drought indices and remote sensing seems to be most promising; whose results are valuable tools for guidance and decision support to local and regional authorities. Ain Sefr, en las montañas Ksour, está situada en el suroeste de Argelia, donde el clima es árido. El área de estudio se enfrenta progresivamente a la regresión y degradación exacerbada por el cambio climático. Estas tendencias apuntan a una aceleración significativa de la desertificación y la sequía y a la pérdida de sistemas de producción que desempeñan un papel social, ecológico y económico crítico en la región. Para comprender mejor el peligro natural de la sequía en Ain Sefra y el impacto del cambio climático, se varios índices de sequía y datos de teledetección. Al analizar los registros de precipitación desde 1965 hasta 2021, a través de varios índices de sequía, se identificaron las sequías como un fenómeno recurrente. Además, la frecuencia de años secos sucesivos es relativamente alta. Hubo tres períodos secos continuos más prolongados. La primera fase duró siete años, de 1980 a 1987, la segunda doce años, de 1994 a 2006, y la tercera nueve años, de 2012 a 2021. El cálculo del Índice de Vegetación Ajustado al Suelo Modificado (MSAVI) para cinco imágenes satelitales multifecha nos permitió seguir la evolución de los elementos de uso del suelo en esta región desde 1977 hasta 2017. De hecho, el estudio de estas imágenes multitemporales revela un crecimiento considerable de arenas, moviéndose hacia el norte y noreste de la zona durante las últimas décadas. La combinación de índices de sequía y sensores remotos parece ser muy prometedores, pues sus resultados son valiosas herramientas de orientación y apoyo a la decisión de los entes locales y regionales. Financial support to perform this study was provided partially by the University Center Salhi Ahmed Naama (Argelia). Antonio Jodar-Abellan acknowledges financial support received form the XTREME Spanish National Project (Ref: PID2019-109381RB-I00/AEI/10.13039/501100011033).

The phenomenon of aeolian sand deposit constitutes a major problem in the region of Ksour Mountains in Algeria, which causes serious social and economic problems. To assess the textural properties of sands, and to investigate the origin of aeolian sand deposit in the study area, eleven (11) samples were collected from the sands of Ain Sefra. Then the granulometry, calcimetry and morphoscopy of the samples were studied. Granulometric testing of samples from 11 locations showed that sand size was very fine to fine grained, with a mean grain value of 226.5 μm. It sort ranged from 1.22 to 1.90, indicating well sorting the sands and skewness values ranging from-0.4 to 0.66, being mainly negative with an average of -0.06, indicating symmetrical to fine skewed values. The values of kurtosis ranges from 0.79 to 1.5, with an average of 0.93, where 64 percent of samples are Mesokurtotic and 36 percent of samples are Platikurtotic. Calcimetric results show a very low percentage of carbonate, which ranges from 1.85 % to 7.4 % and illustrate a very low content of fine fraction and organic matter. The preliminary examinations of the sands in our study area by morphoscopy showed that 73 percent of sand are in RM category, 19 percent in the rounded and shiny (EL) category. In comparison, 08 percent are represented by the fresh and angular (NU) category. The outcome of various experimentation led to the conclusion that the aeolian sand deposit in the study area, are linked to the wind transport from the Moroccan territory such as Chott Tigri, Oued Maader, the corridor between Figuig, Bouarfa and Massa Daraa, which are the dominant sources of sands in the region of the study area. Therefore, the study better understands the origin of sands and their characteristics in this part of the Ksour Mountains.

This research was funded partially by the Central University of Ecuador and by the projects RESERVOIR (PRIMA programme supported by the European Union under grant agreement no. 1924) and BBVA2021-Leonardo2 along with local companies (projects Comunidad Regantes 220-I and Comunidad Regantes 1-20T). Antonio Jodar-Abellan acknowledges financial support received from the project BBVA2021-Leonardo2. In the same way, this work has been conducted within the Catedra del Agua of the University of Alicante (catedradelaguaua.org). Moreover, authors acknowledge the reviewers of the manuscript whose comments contributed greatly to improve this paper., Non-planned agricultural land abandonment is affecting natural hydrological processes. This is especially relevant in vulnerable arid karstic watersheds, where water resources are scarce but vital for sustaining natural ecosystems and human settlements.However, studies assessing the spatiotemporal evolution of the hydrological responses considering land-use changes and precipitation cycles for long periods are rare in karstic environments. In this research, we selected a representative karstic watershed in a Mediterranean semiarid domain, since in this belt, karst environments are prone to land degradation processes due to human impacts. Geographic Information Systems-based tools and hydrological modeling considering daily time steps were combined with temporal analysis of climate variables (wavelet analysis) to demonstrate possible interactions and vulnerable responses. Observed daily flow data were used to calibrate/ validate these hydrological models by applying statistic indicators such as the NSE efficiency and a selfdeveloped index (the ANSE index). This new index could enhance goodness-of-fit measurements obtained with traditional statistics during the model optimization. We hypothesize that this is key to adding new inputs to this research line. Our results revealed that: i) changes in the type of sclerophyllous vegetation (Quercus calliprinos, ilex, rotundifolia, suber, etc.) from 81.5% during the initial stage (1990) to natural grasslands by 81.6% (2018); and, ii) decreases in agricultural areas (crops) by approximately 60% and their transformation into coniferous forests, rock outcrops, sparsely natural grasslands, etc. in the same period. Consequently, increases in the curve number (CN) rateswere identified as a result of land abandonment. As a result, an increase in peak flow events jointlywith a relevant decrease of the average flow rates (water scarcity) in the watershed was predicted by the HEC-HMS model and verified through the observed data. This research provides useful information about the effects of anthropogenic changes in the hydrodynamic behaviour of karstic watersheds andwater resource impacts, especially key in water-scarce areas that depict important hazards for the water supply of related populations and natural ecosystems., Central University of Ecuador, European Commission 1924, Comunidad de Madrid 220-I, Catedra del Agua of the University of Alicante