Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain

Teresa Palacios-Cabrera¹, Antonio Jodar-Abellan², Ryan T. Bailey³, Dámaris Núñez-Gómez², Derdour Abdessamed⁴, Seyed Babak Haji Seyed Asadollah⁵, Pablo Melgarejo²

¹Faculty of Geology, Mines, Petroleum and Environmental Engineering. Central University of Ecuador. teresaalejandrap3@gmail.com

²Centro 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.

How to cite: Palacios Cabrera, T. A., Jodar Abellan, A., Núñez Gómez, D., Melgarejo, P., Abdessamed, D., Bailey, R., and Haiji Seyed, S. B.: Assessing urban water supply from karstic groundwater reservoirs through two hydrological models and the Exploitation Index in the southeast of Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3584, https://doi.org/10.5194/egusphere-egu23-3584, 2023.

How to cite: Guisiano, P.-A., Santoni, S., Huneau, F., Garel, É., and Mattei, A.: Importance of baseflow contribution in mountainous Mediterranean watersheds highlighted by geochemical and isotope tracers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6734, https://doi.org/10.5194/egusphere-egu23-6734, 2023.

The Tensift basin is prone to drought and, with the increasing frequency of extreme events, their forecasting and monitoring are becoming more complex. The present work aims to shed light on the interactions between meteorological and agricultural droughts while using multiple drought indices, and analyzing its temporal and spatial patterns over the Tensift basin in Morocco. To this purpose, we initially performed a trend analysis of the main parameters used in this study namely precipitation, temperature, NDVI, and soil moisture using the Mann-Kendall test. Moreover, a data-driven approach was adopted here to reveal the impact of lack of precipitation on the soil and vegetation cycles. Remote sensing data of precipitation from ERA5Land and soil moisture data from ESA-CCI as well as land surface temperature and NDVI from MODIS are used to calculate the standardized precipitation index (SPI), the vegetation condition index (VCI), the temperature condition index (TCI), and the soil moisture condition index (SMCI) for the period 2001–2021. A comparison analysis was conducted to test the performance and concordance of the indices. Then, to analyze the propagation of meteorological drought to the other components we conducted a cross-correlation study between drought indices.  The results reveal an upward trend of NDVI which is noticeable from the first decade (2009) and is attributed to the development of irrigated areas in this period. In contrast, the basin has shown a significant decline in monthly soil moisture for the period extending from 2001 to 2021, which could be explained by the way how soil moisture is retrieved in the ESA CCI product, and the trend in vegetation. On the other hand, the monthly precipitation and land surface temperature time series show no significant trend. The comparison between the indices showed moderate to low agreement. Correlations between TCI and SPI were eventually negative and significant at small time scales. A moderate correlation was observed between SPI1, SPI3, and TCI (0.45). The strongest correlations between SMCI and SPI were found at the 3 and 6-month time scales. Furthermore, the concordance between VCI and SPI is stronger at larger SPI time scales, the best correlation was observed between the indices VCI and SPI at 12 months with a correlation coefficient of 0.44. The correlations in the Tensift basin reflect spatial heterogeneities where some indices are more prevailing than others. Lag analysis results demonstrate valuable insights into the leading and preceding behavior of different variables regarding SPI. Relevant responses were identified at short, mid, and long-term influence of precipitation deficits on soil moisture, vegetation, and temperature. The results of this study highlight the interest in analyzing drought with different indices dedicated to each type of drought in order to improve early warning systems and risk management strategies for semi-arid areas.

How to cite: oukaddour, K., Fakir, Y., and Le Page, M.: Interactions between meteorological and agricultural droughts at different temporal and spatial scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7926, https://doi.org/10.5194/egusphere-egu23-7926, 2023.

The Mediterranean Basin is classified as one of the hot-spots for climate change, where a significant decrease of precipitation and an increase of temperature are expected. This will most likely lead to a redistribution of water within Mediterranean catchments. However, the scale and magnitude and spatial differences of the impact of climate change on water security across the Mediterranean is still uncertain. Here we present the preliminary results of a systematic review on the impact of climate change on water security in the Mediterranean Basin. In this systematic review we focused on studies performed in the Mediterranean Basin that apply a hydrological model forced by climate model output and report changes in blue and/or green water, i.e. water stored in rivers and reservoirs (e.g. runoff or reservoir storage) and water stored in soils (e.g. groundwater recharge). The variables obtained from the studies include variables related to study area, climate and hydrological models, and model output. Our preliminary results show that the general tendency is a decrease of precipitation and an increase of temperature, which will cause a decrease of projected blue and green water. This will have serious consequences for the potential of irrigated agriculture, industry and household water use in the Mediterranean Basin, which heavily rely on the availability of blue water. But also for rainfed agriculture, where a decrease of green water may force farmers to abandon their land or transform to irrigated agriculture.

We acknowledge funding from the Spanish Ministry of Science and Innovation (AEI) (PID2019-109381RB-I00/AEI/10.13039/501100011033).

How to cite: Eekhout, J. and de Vente, J.: The impacts of future climate change on water security in the Mediterranean Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13882, https://doi.org/10.5194/egusphere-egu23-13882, 2023.

The Po valley (northern Italy) hosts important economic activities and contributes to a significant fraction of the national agricultural production. On its coastal region (the Po Delta) reclaimed agricultural lands coexist, largely below the mean sea level, with natural areas of outstanding environmental relevance. Besides affecting the socio-economic and ecological dynamics within its basin, the modulation of the hydrological regime of the Po river also plays a major role in controlling the oceanographic processes occurring in the northern Adriatic Sea, from coastal circulation to deep ventilation and thermohaline circulation at the Mediterranean scale. In this framework, the severe drought that affected large areas of Europe in Spring and Summer 2022 hit the Po river system with particular intensity, with heavy impacts on productive activities and extensive saltwater intrusion in the coastal areas.

By means of observed discharge records and precipitation data from reanalysis and climate models, this contribution presents an analysis of the 2022 drought event, investigating its exceptionality in the recent past climate and exploring its possible recurrence in future conditions. Ensemble projections of rainfall regimes on the Po River basin in two climate change scenarios (RCP4.5 and RCP8.5) show that persistent negative rainfall anomalies like the one that characterised the 2022 event will unlikely become typical features of the future climate, but could remarkably increase their frequency. Furthermore, the impacts of these events will be magnified by rising temperatures, enhancing evapotranspiration rates in agriculture and water demand. Particularly in severe climate change scenarios, heavier and more frequent episodes of water shortage, combined with a rising sea level, are expected to intensify the pressure of saltwater intrusion in the coastal areas of the Po Delta, increasing the risk for environmental impoverishment and for loss of agricultural lands.

Besides investigating in a climate change perspective a recent severe event that struck an important economic and ecological region, the present contribution aims at stimulating the development of advanced climate change adaptation strategies in riverine, deltaic and estuarine systems, emphasizing the importance of an integrated source-to-sea approach to this process. 

How to cite: Bonaldo, D., Bellafiore, D., Ferrarin, C., Ferretti, R., Ricchi, A., Sangelantoni, L., and Vitelletti, M. L.: The summer 2022 drought in the Po valley (Italy): a glimpse of the future climate?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15504, https://doi.org/10.5194/egusphere-egu23-15504, 2023.

This research aims at establishing an integrated modelling framework to assess the impact of climate change on water supply and demand across an arid area in the western Haouz plain in Morocco. Five General Circulation Models (GCM) are used to evaluate future water resources availability under Representative Concentration Pathways (RCP4.5 and RCP8.5 emission scenarios). The projected crop water demand and irrigation water demand were analysed using Aquacrop software, taking into account the impact of climate change on both reference evapotranspiration and crop cycle lengths. The future water balance is simulated by means of Water Evaluation And Planning (WEAP) Tool, including several socioeconomic and land use scenarios under RCP4.5 and RCP8.5. The results reveal an important decrease in net precipitation with an average of -36.2% and -50.5% under RCP4.5 and RCP8.5, respectively. In terms of water balance, the “business as usual” scenario would lead to an increasing of unmet water demand of about +22% in the 2050 horizon and to an increased depletion of the water table that could reach 2m/year. Changing water management and use practices remains the only solution to ensure sustainable water use and deal with the projected water scarcity.

How to cite: Abdessamad, H., Elmehdi Saidi, M., El Khalki, E. M., Aachrine, B., Saouabe, T., and Ait Elmaki, A.: Water demand versus supply in a Mediterranean Arid Region : current and future challenges, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17188, https://doi.org/10.5194/egusphere-egu23-17188, 2023.

Mountain areas constitute the headwaters of river basins, biodiversity hot-spots, and have a high value as ecosystem resources provision zones. Within the context of climate change, their meteorological trends and projections of future climate scenarios show a high resource vulnerability, highlighting the need to reduce the uncertainty associated with the dynamics of ecological-hydrological-meteorological processes. In these semiarid regions, there is a generalised increase in temperature, especially in summer, a decrease in average annual precipitation with an increase in torrentiality, and a decrease in snow's frequency and persistence. These can change the vegetation's phenological cycle, behaviour, and distribution. In addition, the socio-economic activities linked to these rural Mediterranean systems would be affected.

This study aims to establish a bridge between the different sources of available ecological-hydrological-meteorological information  and the local information that the final user needs, defining eco-hydrological indicators. Our long-term goal is to improve the management and conservation of Mediterranean mountains in the framework of climate change adaptation. 

For this purpose, we carried out a spatiotemporal analysis of precipitation and temperature historical trends (1960-2022, with nonparametric Mann-Kendall (MK) statistical test) as basic eco-hydrological indicators in the pilot area of the Sierras Subbéticas Natural Park (1570 m.a.s.l.) a  representative Mediterranean Mountain Range (Southern, Spain). This analysis constitutes the basis for the definition of targeted eco-hydrological management indicators. Among the different management challenges identified (e.g., sustainable olive tree production, preservation of autochthonous forest formations, water availability in groundwater reservoirs), we focus on the conservation of natural holm oak forest. Therefore, we selected as a targeted eco-hydrological indicator the occurrence of extreme drought periods in spring (3-months SPI in June), which is considered a primary meteorological factor influencing leaf development.

The trends analysis’ results reflect a significant increase in average annual mean temperatures, especially in the central and lowest areas of the mountain range. Regarding annual precipitation, there is great variability between dry and wet years, with a decreasing trend (-0,821 mm/year) without statistical significance. In the same way, the selected eco-hydrological indicator shows a non statistically significant trend.  This index directly influences the maintenance and regeneration of the Natural Park forest masses, which are of particular interest for managing its ecosystem services. In addition, this indicator constitutes an example of how these specific indicators allow us to use climatic-hydrological data sources in a practical application, with the future goal of integrating meteorological forecasts into the pipeline.

Acknowledgment: This work has been funded by project MONADA - "Hydrometeorological trends in mountainous protected areas in Andalusia: examples of co-development of climatic services for strategies of adaptation to climatic change", with the economic collaboration of the European Funding for Rural Development (FEDER) and the Andalusian Office of Economic Transformation, Industry, Knowledge and Universities. R+D+i project 2020.

How to cite: Calbet, A., Andreu, A., Aparicio, J., Polo, M. J., Torralbo, P., and PImentel, R.: Trend analysis on eco-hydrological indicators as management tools in Mediterranean Environmental Protected Areas: The case study of Sierras Subbéticas Natural Park (Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6360, https://doi.org/10.5194/egusphere-egu23-6360, 2023.

Estimating crop evapotranspiration (ETc) is of primary importance for irrigation management. The model commonly used for this purpose is the FAO-56 approach which consists of accurately estimating the basal crop coefficient K_cb. Historically, K_cb is derived from optical indices such as NDVI giving its sensitivity to vegetation cover fraction and to the Leaf Area Index. Nevertheless, optical data are disturbed by the presence of clouds. In this context, the objective of this work is to investigate the potential use of all-weather radar data as a substitute of NDVI to derive K_cb. The study is conducted over two winter wheat fields (Field 1 and Field 2) in Morocco, monitored during two agricultural seasons 2016-2017 and 2017-2018. Each field is equipped with an eddy covariance station allowing the estimation of ETc every 30 minutes. In addition, a weather station was installed over an alfalfa plot near the study fields. First, the backscattering coefficient and the interferometric coherence ( ρ at VV polarization) are derived from Sentinel-1 data with a 6-day revisit time and a spatial resolution of 10 m. Second, empirical relationships have between established between K_cb, on one hand, and the interferometric coherence and the polarization ratio, on the other hand and the results are also compared to the classical K_cb-NDVI (derived from Sentinel-2) method. The results show that good statistical metrics are obtained between K_cb and NDVI (R=0.77 and RMSE=0.14 for Field 1). Similar results are obtained also using ρ (R=0.76, RMSE=0.18). Finally, the K_cb is estimated from the calibrated relationships on one season and then used to estimate ET_c. The results demonstrate reasonable estimates of ET_c on Field 1 (R=0.70, RMSE=0.75 mm/day and bias=-0.18 mm/days) using K_cb-ρ. By contrast, a significant overestimations is highlighted both with  (bias=0.73 mm/day) and NDVI (bias=1.46 mm/day) over Field 2. Interestingly, the K_cb-ρ relationship is more consistent in the estimation of ET_c when changing from one field to another. These outcomes open new perspectives for the estimation of ET_c from radar data as a potential substitute of NDVI in case of persistent cloud cover.

How to cite: Ouaadi, N., Jarlan, L., Khabba, S., Le Page, M., Chakir, A., Er-Raki, S., and Frison, P.-L.: C-band Sentinel-1 data for estimating the basal crop coefficient and evapotranspiration of winter wheat , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14819, https://doi.org/10.5194/egusphere-egu23-14819, 2023.

In recent decades, climate change has led to a sharp increase in water demand. Particularly in agriculture, this has put a great strain on already scarce water resources, increased the need for irrigation water, and led to overuse of groundwater. Therefore, sustainable management of water resources while maintaining good agricultural yield by monitoring crop water status is necessary for sustainable and rational management of these resources, especially in arid and semi-arid regions. For this purpose, a detailed knowledge of the different processes describing the diurnal water cycle of plants in a large area is essential. However, micrometeorological or physiological experimental measurements and their partitioning are laborious to perform and not very representative of large areas.

In this regard, remote sensing is a particularly suitable tool for monitoring agricultural areas because of its global and repeated observation. Several studies have highlighted the sensitivity of radar data to vegetation water content especially over the rainforest with spatial scatterometers that observe differences between morning and evening acquisitions. On the other hand, in situ radar experiments with high temporal frequency have made it possible to analyze radar responses over tropical and boreal forests.

This study relates to a similar experiment conducted on an olive orchard located in the semi-arid Mediterranean region of Chichaoua in central Morocco. It allows the acquisition of in situ C-band radar measurements in crop fields, which are acquired continuously, from a tower-based radar system, with a time step of 15 minutes.

The temporal evolution of the interferometric coherence r is analyzed on different baselines Dt, ranging from 15 minutes to 30 days, for the main physiological stages of the olive tree. Four different two-month periods, from December 2020 to November 2022, are chosen as the main physiological stages based on field observations.

The obtained results of r, especially at 15-min min-steps, show a global behavior similar to that observed in tropical and boreal forests: high values (r ≈1) are observed during the night (weak wind, vegetation resting), then a decrease/increase during the day mainly anti-symetric to the wind cycle. As over boreal and tropical forest, a decrease in r is observed before the wind picks up, with is time coincident with sap flows and ETR variations, traducing its sensitivity to water plant content.

Results show that over olive orchard, the r diurnal cycle is less marked than over boreal and tropical forests, due to lower ETR rates and certainly due to a significant soil contribution over this less dense vegetation layer. Furthermore, r values decrease when temporal baselines increase, but values are still meaningful for Dt = 6 days (r = 0.3 compared to 0.6 for Dt = 15 min. for the summer period), available with Sentinel-1 missions.

The present study provides particularly interesting results confirming the sensitivity of C-band coherence to vegetation water status, especially in the early morning. Further work needs to be pursued to verify if we are able to detect the water stress of these plants in semi-arid areas such as Chichaoua through coherence.

How to cite: Chakir, A., Frison, P., Khabba, S., Villard, L., Le-dantec, V., Ouaadi, N., Fanise, P., and Jarlan, L.: Analysis of the radar temporal coherence at C band over an olive orchard in semi-arid region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16445, https://doi.org/10.5194/egusphere-egu23-16445, 2023.