Remotely Sensed Agroclimatic Classification and Zoning in Water-Limited Mediterranean Areas towards Sustainable Agriculture

Agroclimatic classification identifies zones for efficient use of natural resources leading to optimal and non-optimal crop production. The aim of this paper is the development of a methodology to determine sustainable agricultural zones in three Mediterranean study areas, namely, “La Mancha Oriental” in Spain, “Sidi Bouzid” in Tunisia, and “Bekaa” valley in Lebanon. To achieve this, time series analysis with advanced geoinformatic techniques is applied. The agroclimatic classification methodology is based on three-stages: first, the microclimate features of the region are considered using aridity and vegetation health indices leading to water-limited growth environment (WLGE) zones based on water availability; second, landform features and soil types are associated with WLGE zones to identify non-crop-specific agroclimatic zones (NCSAZ); finally, specific restricted crop parameters are combined with NCSAZ to create the suitability zones. The results are promising as compared with the current crop production systems of the three areas under investigation. Due to climate change, the results indicate that these arid or semi-arid regions are also faced with insufficient amounts of precipitation for supporting rainfed annual crops. Finally, the proposed methodology reveals that the employment and use of remote sensing data and methods could be a significant tool for quickly creating detailed, and up to date agroclimatic zones

Remotely Sensed Comparative Spatiotemporal Analysis of Drought and Wet Periods in Distinct Mediterranean Agroecosystems

Drought is a widespread natural hazard resulting from an extended period of reduced rainfall, with significant socioeconomic and ecological consequences. Drought severity can impact food security globally due to its high spatial and temporal coverage. The primary objective of this paper consists of a comparative spatiotemporal analysis of environmental extremes (drought/wetness) through the estimation of a twelve-month Standardized Precipitation Index (SPI12) between three distinct vulnerable agricultural regions in the Mediterranean basin (i.e., Spain, Lebanon and Tunisia), under a climate change environment in the last 38 years (1982–2020). The added value of this paper lies in the simultaneous estimation of temporal and spatial variability of drought and wetness periodic events, paying special attention to the geographical patterns of these extremes both in annual and interannual (seasonal) time scales. The results indicated that Spain and Tunisia (western Mediterranean) exhibit similar patterns over the studied period, while Lebanon demonstrates contrasting trends. Comparing the two extreme dry hydrological years, the Spanish study area faced the highest drought intensity, areal extent and duration (SPI12 = −1.18; −1.84; 28–78%; 9–12 months), followed by the Lebanese (SPI12 = −1.28; −1.39; 37–50%; 7–12 months) and the Tunisian ones (SPI12 = −1.05; −1.08; 10–34%; 8 months). Concerning the wettest hydrological years, the Lebanese study domain has recorded the highest SPI12 values, areal extent and duration (SPI12 = 1.58; 2.28; 66–83%; 8–11 months), followed by the Tunisian (SPI12 = 1.55; 1.79; 49–73%; 7–10 months) and Spanish one (SPI12 = 1.07; 1.99; 21–73%; 4–11 months). The periodicity of drought/wetness episodes is about 20 years in Spanish area and 10 years in the Lebanese area (for drought events), whereas there seems no periodicity in the Tunisian one. Understanding the spatial distribution of drought is crucial for targeted mitigation strategies in high-risk areas, potentially avoiding broad, resource-intensive measures across entire regions

Groundwater Pollution: Sources, Mechanisms, and Prevention

Groundwater resources are vital for ecosystems and human health and prosperity [...

Groundwater resources management under conditions of uncerainty: the value of information in environmentally degraded aquifers

In this study an innovative decision framework is presented for the optimum and sustainable management of an over-exploited aquifer, under uncertain conditions. This framework is a modelling system of specifically designed and combined models and which use information from the stochastic analysis, the water resources simulation and the groundwater management. The models that are incorporated and combined – through their data exchange – are six, with four of them being simulation models. Initially, the modeling system was used for the simulation of Lake Karla watershed aquifer’s present situation. Historical data series were used and the results confirm the over-exploitation status of the aquifer and the impressive drop of the water table. The heterogeinity of hydraulic conductivity though and the lack of data, create an uncertain hydrogeological environment. The K parameter uncertainty is assessed through the use of stochastic simulation and more specifically through geostatistical methods. Since the quantitative status of aquifer and the hydraulic conductivity uncertainty are assessed, a conceptual framework of reservoir restoration is developed. Lake Karla recreation project, which is the most important environmental project in Balkans, plays critical role to this restoration. The management plan of this project involves the supply of a great part of irrigation water needs from the surface water of the new reservoir, making the proposed strategy absolutely realistic and applicable. Other simulation models of the watershed water resources are incorporated in the system, fulfilling the European legislation terms for the integrated water management at the watershed scale. Aquifer’s restoration is based on the optimal management of its renewal resources, under uncertainty. Thus, all possible and alternative management strategies can be presented properly, including the relevant risks. The strategy that will be selected eventually will generate the optimum results taking into account all the parameters of the complex problem. In the present study, the goal of the groundwater management problem is not only the aquifer’s water table restoration, but also the optimal allowable groundwater volume that will be extracted for irrigation need. Since, in a first place, the environmental requirement of future aquifer’s restoration is satisfied, then the optimal use of the remaining renewable resources can be assessed. Nevertheless, to confirm the parametric uncertainty, which leads to an important financial uncertainty, a new methodology is employed. The methodology results to the definition of the optimal hydraulic conductivity sample values, which will lead to the parameter uncertainty decrease and finally to the financial cost decrease, one, creating a more clear picture for the administrator.Στην παρούσα διατριβή προτείνεται και εφαρμόζεται επιτυχώς ένα καινοτόμο εργαλείο απόφασης για τη βέλτιστη και ταυτόχρονα βιώσιμη διαχείριση ενός υπόγειου υδροφορέα που βρίσκεται σε κατάσταση εντατικής εκμετάλλευσης, σε συνθήκες υδρογεωλογικής αβεβαιότητας. Απαρτίζεται από ειδικά συνδυασμένα μοντέλα. Για τη λειτουργία του συστήματος αυτού χρησιμοποιούνται και συνδυάζονται στοιχεία από την στοχαστική ανάλυση, την προσομοίωση των υδατικών συστημάτων και τη διαχείριση των υπόγειων υδατικών πόρων. Το υπόψη σύστημα χρησιμοποιείται αρχικά για την αποτύπωση της υφιστάμενης κατάστασης του υπόγειου κοκκώδη υδροφορέα της λεκάνης απορροής της λίμνης Κάρλας, από ποσοτικής πλευράς. Εξαιτίας, όμως, της χωρικής μεταβλητότητας της υδραυλικής αγωγιμότητας και της έλλειψης επαρκών δειγματοληπτικών τιμών της, η εκτίμηση της ποσοτικής κατάστασης του υπόγειου υδροφορέα εμπεριέχει αβεβαιότητα. Η αβεβαιότητα αυτή αποτιμάται με τη χρήση της στοχαστικής προσομοίωσης και ειδικότερα με τη χρήση γεωστατιστικών μεθόδων. Αφού λοιπόν εκτιμηθούν η κατάσταση του υδατικού δυναμικού του υπόγειου υδροφορέα ποσοτικά και αποτιμηθεί η αβεβαιότητα της υδραυλικής αγωγιμότητας, τίθεται σε εφαρμογή ένα μεθοδολογικό πλαίσιο αποκατάστασης του υπόγειου υδροφορέα, σε μελλοντική περίοδο.. Η ποσοτική αποκατάσταση του υπόγειου υδροφορέα βασίζεται στη βέλτιστη διαχείριση των ανανεώσιμων αποθεμάτων του, πάλι όμως σε συνθήκες αβεβαιότητας μιας και για τη λήψη της ορθής απόφασης θα πρέπει να απεικονίζονται ξεκάθαρα όλες οι πιθανές λύσεις, αλλά και η επικινδυνότητα (ρίσκο) που η καθεμία από αυτές εμπεριέχει. Με τον τρόπο αυτό η στρατηγική διαχείρισης, που τελικά θα επιλεγεί, θα αποφέρει τα βέλτιστα αποτελέσματα έχοντας συμπεριλάβει όλες τις παραμέτρους του πολύπλοκου προβλήματος. Η διαχείριση του υδροφορέα στοχεύει όχι μόνο στην ανύψωση του υδροφόρου ορίζοντα και την αποκατάστασή του, αλλά και στον υπολογισμό ταυτόχρονα του βέλτιστου επιτρεπόμενου αντλούμενου υδατικού όγκου για άρδευση. Αφού λοιπόν, σε πρώτη φάση εξασφαλιστεί η περιβαλλοντική απαίτηση της αποκατάστασης του υπόγειου υδροφορέα σε βάθος δεδομένου χρόνου, δεσμεύοντας ένα σημαντικό ποσοστό των ανανεώσιμων αποθεμάτων του, στη συνέχεια εκτιμάται η βέλτιστη χρήση των υπόλοιπων υδατικών διαθέσιμων για την κάλυψη των αρδευτικών αναγκών, με στόχο τη μεγιστοποίηση του κέρδους του διαχειριστή. Η παραμετρική αβεβαιότητα οδηγεί σε σημαντική οικονομική αβεβαιότητα στα αποτελέσματα της διαχείρισης, δημιουργώντας συνθήκες επικινδυνότητας στη λήψη οποιασδήποτε στρατηγικής αποκατάστασης. Προτείνεται μία νέα μεθοδολογία για τον υπολογισμό του βέλτιστου πλήθους των μετρήσεων της παραμέτρου στο πεδίο, που θα οδηγήσει στη μείωση της παραμετρικής αβεβαιότητας και εν τέλει και της οικονομικής, δίνοντας στον διαχειριστή μία πιο ξεκάθαρη εικόνα για τη λήψη της διαχειριστικής στρατηγικής που θα ακολουθήσει

Gap Analysis Targeting WFD Monitoring and Pressure Mapping: Lessons Learned from “EcoSUSTAIN”, Interreg-MED Project

According to WFD, European countries shall establish monitoring programmes for water quality overview. In EcoSUSTAIN, an Interreg–MED project, Gap analysis, an approach that reveals the difference between current and desired level, was carried out, targeting five Mediterranean hydro-ecosystems covering “Monitoring Practices” and “Water Quality and Pressures”. Our goal is to investigate practicing deficiencies, as long as information lack and distance from desirable status, supporting water uses and WFD goals. Data was collected by literature research supported by questionnaires. The findings on both fields, revealed problematic areas dealing with the compliance with the WFD and several deficiencies in tackling pressures

Climatic Modeling of Seawater Intrusion in Coastal Aquifers: Understanding the Climate Change Impacts

The study examines the impacts of climate change and sea level rise on coastal aquifers, focusing on the influence of the components of the water cycle on seawater intrusion, and the evolution of the phenomenon in the future. The simulation of coastal water resources was performed using an integrated modeling system (IMS), designed for agricultural coastal watersheds, which consists of inter-connected models of surface hydrology (UTHBAL), groundwater hydrology (MODFLOW), and seawater intrusion (SEAWAT). Climatic models for the adverse impact scenario (RCP8.5) and the medium impact scenario (RCP4.5) of climate change were used. Transient boundary head conditions were set to the coastal boundary, to dynamically represent the rise in sea level due to climate change. The response of groundwater in the coastal Almyros Basin, located in central Greece, was simulated from 1991 to 2100. The findings indicate that seawater intrusion will be advanced in the future, in both climate change scenarios. The models show varying patterns in groundwater recharge, with varying uncertainty projected into the future, and sensitivity to time in the fluctuation of the components of the water cycle

Nutrient Concentrations in Seven Irrigation Reservoirs (Lake Karla Watershed Thessaly Greece)

The construction of irrigation reservoirs is a technical global solution for enhancing the agricultural production especially in arid and semi-arid areas. These water bodies are treated as technical projects and not as freshwater ecosystems. Eutrophication in new reservoirs becomes a hot issue in the world. The aim of the present study is to present the assessment of the key-eutrophication parameters in seven reservoirs located in the catchment area of Lake Karla. We suggest that the studied artificial ecosystems are sensitive in nutrients concentrations especially in the warm-dry period, influenced mainly by agricultural activities in the watershed

Groundwater Nitrate Contamination Integrated Modeling for Climate and Water Resources Scenarios: The Case of Lake Karla Over-Exploited Aquifer

Groundwater quantity and quality degradation by agricultural practices is recorded as one of the most critical issues worldwide. This is explained by the fact that groundwater is an important component of the hydrological cycle, since it is a source of natural enrichment for rivers, lakes, and wetlands and constitutes the main source of potable water. The need of aquifers simulation, taking into account water resources components at watershed level, is imperative for the choice of appropriate restoration management practices. An integrated water resources modeling approach, using hydrological modeling tools, is presented for assessing the nitrate fate and transport on an over-exploited aquifer with intensive and extensive agricultural activity under various operational strategies and future climate change scenarios. The results indicate that climate change affects nitrates concentration in groundwater, which is likely to be increased due to the depletion of the groundwater table and the decrease of groundwater enrichment in the future water balance. Application of operational agricultural management practices with the construction and use of water storage infrastructure tend to compensate the groundwater resources degradation due to climate change impacts

Integrated Modeling of Agronomic and Water Resources Management Scenarios in a Degraded Coastal Watershed (Almyros Basin, Magnesia, Greece)

The scope of this study is to assess the effects of agronomic and water resources management scenarios on groundwater balance, seawater intrusion, and nitrate pollution and the comparison of the developed scenarios relative to the current crop production and water management regime in the coastal agricultural Almyros basin in the Thessaly region, Greece. Agronomic and water resources scenarios have been simulated and analyzed for a period of 28 years, from 1991 to 2018. The analysis has been conducted with the use of an Integrated Modeling System for agricultural coastal watersheds, which consists of coupled and interlinked simulation models of surface water hydrology (UTHBAL), reservoir operation (UTHRL), agronomic/nitrate leaching model (REPIC), and groundwater models for the simulation of groundwater flow (MODFLOW) and contaminant transport of nitrates (MT3DMS) and chlorides (SEAWAT). The pressure on water resources has been estimated with the Water Exploitation Index (WEI+) and the reservoirs’ operation with the Reliability index to cover the water demands. The indices of Crop Water Productivity, Nitrogen Use Efficiency, and Economic Water Productivity have been used to quantify the benefits and the feasibility of the alternative scenarios. The best results for the sustainability of water resources are achieved under the deficit irrigation and rain-fed scenario, while the best results for water resources and the local economy are achieved under deficit irrigation and reduced fertilization scenario