Spatial Data Management and Numerical Modelling: Demonstrating the Application of the QGIS-Integrated FREEWAT Platform at 13 Case Studies for Tackling Groundwater Resource Management

Because of the spatial nature of groundwater-related data and their time component, effective groundwater management requires the application of methods pertaining to the Information and Communication Technologies sector, such as spatial data management and distributed numerical modelling. The objective of this paper is to demonstrate the effectiveness of the QGIS-integrated FREEWAT platform and an approach combining spatial data management and numerical models to target groundwater management issues. FREEWAT is a free and open source platform integrated in a Geographic Information System environment and embedding tools for pre- and post-processing of spatial data and integrating numerical codes for the simulation of the hydrological cycle, with a main focus on groundwater. To this aim, this paper briefly presents the FREEWAT platform, introduces the FREEWAT approach, and showcases 13 case studies in European and non-European countries where the FREEWAT platform was applied. Application of the FREEWAT platform to real-world case studies is presented for targeting management of coastal aquifers, ground- and surface-water interaction, climate change impacts, management of transboundary aquifers, rural water management and protection of groundwater-dependent ecosystems. In this sense, compared to other existing software suites, FREEWAT allows data analysis and visualization to accomplish each step of the modelling workflow, i.e., from data analytics, to conceptual model definition, to numerical modelling and reporting of results. The presented experiences demonstrate that improved access to data and the portability of models and models’ results can help to promote water sustainability from the local- to the basin-scale. Furthermore, FREEWAT may represent a valuable tool to target the objective of increasing the capabilities of public authorities and private companies to manage groundwater resources by means of up-to-date, robust, well-documented and reliable software, without entailing the need of costly licensing, nowadays seldom affordable by public water authorities. Based on the strengths highlighted, the FREEWAT platform is a powerful tool for groundwater resources management, and for data collection, sharing, implementation and comparison of scenarios, for supporting planning and decision-making

Management of groundwater resources of aquifers subjected to seawater intrusion regime: the case of western coastal plain of Rhodope prefecture

Seawater intrusion phenomenon is one of most important environmental problems of coastal areas, especially at those where there is a significant amount of anthropogenic activities related to the exploitation of the groundwater resources. In such cases, the groundwater salinisation takes serious economic as well as social dimensions, apart from the direct environmental ones. The majority of the costal aquifers in Greece, appear to be quantitatively degraded due to the overpumping conditions in which they are subjected, practice which results in qualitative degradation due to the intrusion of seawater. The present doctoral dissertation investigates the phenomenon of seawater intrusion, as it evolves and develops, at the western coastal plain area of the Prefecture of Rhodope, under the prism of an integrated groundwater resources management of the examined aquifer system. The area of investigation extends between Lake Vistonida inlet and Lake Ismarida (from west to east) as well as between Aspropotamos River and the coastline (from north to south). The period of investigation, including the bibliographic research, the main investigation period with the relevant field works and finally the authoring of the dissertation in question, is limited between 2002 and 2006. Firstly it presents a bibliographic approach, regarding the phenomenon of seawater intrusion -the hydraulics of the coastal aquifers and the formation of the salt and fresh water interface- as well as the general managerial principles which are associated with the groundwater resources of coastal aquifers. It also includes an assessment of different case studies of coastal aquifers which are subjected to seawater conditions in Greece and aboard, as published in international scientific journals and conference proceedings. The area of investigation extends up to 165.1 km2, which is almost exclusively used for agricultural activities, apart from a small part which refers to built-up areas. The morphological relief of the study area is mainly semi-hilly to hilly, containing a significant hydrographic network which contributes to the recharge conditions of the study aquifer system. Regarding the hydrogeological characteristics of the study area, the upper geological layer (providing the confined conditions to the aquifer system), which overlies the main aquifer is composed of mudstones, sandstones and clays, while the aquifer layer is mainly composed of alluvial deposits, sands, gravels and conglomerates. The bottom of the aquifer system is composed of a grey-green clay layer, which extends up to the whole area of investigation. The investigation of the present doctoral dissertation was carried out under a both quantitative as wellΤο φαινόμενο της θαλάσσιας διείσδυσης αποτελεί ένα από τα σημαντικότερα περιβαλλοντικά προβλήματα των παράκτιων περιοχών, ειδικότερα εκεί όπου καταγράφεται ένας σημαντικός αριθμός ανθρώπινων δραστηριοτήτων που σχετίζονται με την εκμετάλλευση του υπόγειου υδατικού δυναμικού των παράκτιων υδροφόρων. Σε αυτές τις περιπτώσεις, η υφαλμύριση των υπόγειων νερών λαμβάνει εκτός από περιβαλλοντικές, και οικονομικές καθώς και κοινωνικές διαστάσεις. Η πλειοψηφία των παράκτιων υδροφόρων στην ελληνική επικράτεια εμφανίζουν ποσοτική υποβάθμιση, εξαιτίας της υπαράντλησης των περιεχόμενων υπόγειων υδατικών πόρων τους, πρακτική η οποία επιφέρει και ποιοτική υποβάθμιση λόγω της διείσδυσης της θάλασσας και της επερχόμενης υφαλμύρισης. Η παρούσα διδακτορική διατριβή εξετάζει το φαινόμενο της θαλάσσιας διείσδυσης, όπως αυτό εμφανίζεται και εξελίσσεται στο δυτικό πεδινό και παράκτιο τμήμα του Νομού Ροδόπης, υπό το πρίσμα μιας ολοκληρωμένης διαχείρισης των υπόγειων υδατικών πόρων του υπόγειου υδροφόρου συστήματος. Η περιοχή έρευνας οριοθετείται γεωγραφικά από τον όρμο της λίμνης Βιστωνίδας έως τη λίμνη Ισμαρίδα (από δυτικά προς ανατολικά) καθώς και από τον Ασπροπόταμο έως την ακτογραμμή (από βόρεια προς νότια). Η χρονική περίοδος εκπόνησης της παρούσας διατριβής, συμπεριλαμβανομένης της βιβλιογραφικής αναζήτησης, των εργασιών υπαίθρου και της συγγραφής, αφορά στο διάστημα μεταξύ 2002 έως 2006. Κατ’ αρχάς παρουσιάζεται και προσεγγίζεται βιβλιογραφικά το φαινόμενο της θαλάσσιας διείσδυσης -η υδραυλική των υπόγειων νερών των παράκτιων υδροφόρων και ο σχηματισμός και η ανάπτυξη της διεπιφάνειας μεταξύ του αλμυρού και του γλυκού νερού- αλλά και γενικότερα οι διαχειριστικές παράμετροι που διέπουν τη διαχείριση των υπόγειων υδατικών πόρων των παράκτιων υδροφόρων. Επίσης παρατίθεται και αναλύεται ένας σημαντικός αριθμός περιπτώσεων εμφάνισης του φαινομένου της θαλάσσιας διείσδυσης σε παράκτιους υδροφόρους στην Ελλάδα και στο εξωτερικό, όπως καταγράφεται σε επίπεδο τρέχουσας γνώσης από διεθνή επιστημονικά περιοδικά και συνέδρια. Η έκταση της περιοχής μελέτης ανέρχεται στα 165,1 km2, συμπεριλαμβανομένων και των δομημένων εκτάσεων οι οποίες καταλαμβάνουν ένα μικρό τμήμα της, ενώ με εξαίρεση αυτές τις δομημένες εκτάσεις, όλο το υπόλοιπο τμήμα της χρησιμοποιείται αποκλειστικά για γεωργικές δραστηριότητες. Το μορφολογικό ανάγλυφο της περιοχής έρευνας χαρακτηρίζεται ημι-λοφώδες έως λοφώδες ενώ περιέχει ένα αξιόλογο υδρογραφικό δίκτυο μικρών χειμάρρων και ποταμών στα όριά της. Σχετικά με τα υδρογεωλογικά χαρακτηριστικά της περιοχής έρευνας, αναφέρεται το ανώτερο γεωλογικό στρώμα, υπερκείμενο του κυρίως υδροφόρου στρώματος, το οποίο περιλαμβάνει σχετικά στεγανά για την περιοχή υλικά όπως ιλυόλιθους, ψαμμίτες, μικροκροκαλοπαγή και αργίλους, υπεύθυνα για τη δημιουργία υπό πίεση συνθηκών. Το άμεσα υποκείμενο στρώμα περιέχει αλλουβιακές αποθέσεις που αποτελούνται από χονδρόκοκκα υλικά (άμμους, χαλίκια και κροκάλες), αποτελώντας το υδροφόρο στρώμα της περιοχής. Τα υδρογεωλογικά όρια ως προς το βάθος του υπό εξέταση υδροφόρου συστήματος, καθορίζονται από την εμφάνιση της γκριζοπράσινης αργίλου σε όλη την έκταση της περιοχής έρευνας. Η έρευνα της παρούσας διατριβής επεκτάθηκε τόσο στα ποσοτικά χαρακτηριστικά του υπόγειου υδροφόρου συστήματος όσο και στα ποιοτικά χαρακτηριστικά των υπόγειων υδατικών πόρων του υδροφόρου συστήματος

Multi-Variable SWAT Model Calibration Using Satellite-Based Evapotranspiration Data and Streamflow

In this study, monthly streamflow and satellite-based actual evapotranspiration data (AET) were used to evaluate the Soil and Water Assessment Tool (SWAT) model for the calibration of an experimental sub-basin with mixed land-use characteristics in Athens, Greece. Three calibration scenarios were performed using streamflow (i.e., single variable), AET (i.e., single variable), and streamflow–AET data together (i.e., multi-variable) to provide insights into how different calibration scenarios affect the hydrological processes of a catchment with complex land use characteristics. The actual evapotranspiration data were obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS). The calibration was achieved with the use of the SUFI-2 algorithm in the SWAT-CUP program. The results suggested that the single variable calibrations showed moderately better performance than the multi-variable calibration. However, the multi-variable calibration scenario displayed acceptable outcomes for both streamflow and actual evapotranspiration and indicated reasonably good streamflow estimations (NSE = 0.70; R2 = 0.86; PBIAS = 6.1%). The model under-predicted AET in all calibration scenarios during the dry season compared to MODIS satellite-based AET. Overall, this study demonstrated that satellite-based AET data, together with streamflow data, can enhance model performance and be a good choice for watersheds lacking sufficient spatial data and observations

Identification of Patterns and Influential Factors on Civil Protection Personnel Opinions and Views on Different Aspects of Flood Risk Management: The Case of Greece

The views and perceptions of the civil protection community have a central position in any risk management process or initiative, and are crucial to its success. However, knowledge of the views and perceptions of officials, and what affects them remains limited in the current literature. This work uses questionnaires to explore the views of civil protection personnel in Greece on different elements of flood risk management and identify factors that influence them. Results provide a basic understanding of officials’ views, indicating certain shortcomings in various sectors and dissatisfaction in several aspects of everyday practice. Interestingly, responses of participants to perception- and knowledge-related questions show a pattern, relating to respondents’ attributes and characteristics, such as experience, age, qualifications, and others. On the contrary, their views on everyday practice issues of flood risk management are associated with the type of position they have in the civil protection community. The findings contribute to the overall effort to improve the understanding of the characteristics of civil protection organizations across Europe, as a means to enhance cooperation

Conceptual and Mathematical Modeling of a Coastal Aquifer in Eastern Delta of R. Nestos (N. Greece)

In this paper, the development of the conceptual and groundwater flow model for the coastal aquifer system of the alluvial plain of River Nestos (N. Greece), that suffers from seawater intrusion due to over-pumping for irrigation, is analyzed. The study area is a typical semi-arid hydrogeologic environment, composed of a multi-layer granular aquifers that covers the eastern coastal delta system of R. Nestos. This study demonstrates the results of a series of field measurements (such as geophysical surveys, hydrochemical and isotopical measurements, hydro-meteorological data, land use, irrigation schemes) that were conducted during the period 2009 to 2014. The synthesis of the above resulted in the development of the conceptual model for this aquifer system, that formed the basis for the application of the mathematical model for simulating groundwater flow. The mathematical modeling was achieved using the finite difference method after the application of the USGS code MODFLOW-2005

Preliminary Results from Unsaturated Zone Studies in Unconfined Unconsolidated Coastal Aquifers

Chloride concentration and salinity tend to vary spatially in depth within the unsaturated zone, according to the local hydrologic conditions; and therefore are widely used as naturally occurring environmental tracers. In this study, undisturbed material from the unsaturated zone was collected at regular intervals of 50 cm down to a maximum depth of 300 cm in 17 different locations. Vacuum filtration has been used for extraction of soil water from 75 soil samples, and chemical analyses showed that the chloride concentrations in soils range from 0.4 to 79 meq/L indicating the existence of soluble salts, also verified by elevated electrical conductivity values