Uso combinado de análisis multicriterio y simulación de aguas subterráneas dentro de un marco espacial de toma de decisiones para la asignación óptima del agua de riego

In arid and semiarid areas in the world, including the Mediterranean region, groundwater has been widely and intensively used for irrigation over the last few decades. Practical as well as economic reasons make its use much more preferable, as compared to surface water, especially to individual farmers. Yet, this rapid and largely uncontrolled expansion in groundwater exploitation, which stimulated the socioeconomic development of numerous rural communities, has produced many negative impacts on aquifer degradation and environmental deterioration. The most common remedy to such problems is the application of specific groundwater management policies that can simultaneously meet socioeconomic and environmental protection goals. In this sense, the paper introduces a methodology for an optimal management of irrigation water, by specifically exploring the socioeconomic and environmental impacts of spatially allocated water conservation measures at the watershed level. The analysis is conducted by developing a multi-criteria decision-making framework, consisting of three distinct models: a hydrogeological, an optimization, and a multi-criteria one, which appraises the results of the other two. The proposed methodology is presented through a case study at a rural Greek watershed, in which groundwater is the sole water source for an intensively practiced agriculture. A system of water use quotas is the resource conservation policy instrument that is examined under a decision-making approach. Results show that some specifically designed and spatially non-uniform quota allocation schemes can meet in an optimum way the relevant criteria.Las aguas subterráneas se han usado intensivamente en las regiones áridas y semiáridas del planeta, incluyendo el Mediterráneo. Hay razones económicas y prácticas que las hacen preferibles a las aguas superficiales, especialmente para agricultores individuales. Sin embargo esto ha conducido a una expansión incontrolada del uso de aguas subterráneas que ha estimulado el desarrollo de muchas comunidades rurales, pero que ha producido impactos negativos como degradación en acuíferos y deterioro ambiental. El remedio más común para estos problemas es la aplicación de políticas de gestión de aguas subterráneas que busque satisfacer simultáneamente los objetivos ambientales y socioeconómicos. Este trabajo introduce una metodología explorando los impactos ambientales y socioeconómicos de una asignación de recursos a nivel de acuífero. El análisis se hace desarrollando un esquema multicriterio consistente en tres modelos: hidrogeológico, optimización, y función multicriterio, que evalúa los resultados de los otros dos. La propuesta se aplica a un estudio del caso de un acuífero rural en Grecia, en el cual el agua subterránea es el único recurso disponible para una agricultura intensiva. El instrumento utilizado para la política de conservación es la asignación de cuotas. Los resultados muestran que unas cuotas diseñadas específicamente y repartidas espacialmente de manera no-uniforme pueden servir para alcanzar los objetivos diseñados

Combined use of groundwater simulation and multi-criteria analysis within a spatial decision-making framework for optimal allocation of irrigation water

In arid and semiarid areas in the world, including the Mediterranean region, groundwater has been widely and intensively used for irrigation over the last few decades. Practical as well as economic reasons make its use much more preferable, as compared to surface water, especially to individual farmers. Yet, this rapid and largely uncontrolled expansion in groundwater exploitation, which stimulated the socioeconomic development of numerous rural communities, has produced many negative impacts on aquifer degradation and environmental deterioration. The most common remedy to such problems is the application of specific groundwater management policies that can simultaneously meet socioeconomic and environmental protection goals. In this sense, the paper introduces a methodology for an optimal management of irrigation water, by specifically exploring the socioeconomic and environmental impacts of spatially allocated water conservation measures at the watershed level. The analysis is conducted by developing a multi-criteria decision-making framework, consisting of three distinct models: a hydrogeological, an optimization, and a multi-criteria one, which appraises the results of the other two. The proposed methodology is presented through a case study at a rural Greek watershed, in which groundwater is the sole water source for an intensively practiced agriculture. A system of water use quotas is the resource conservation policy instrument that is examined under a decision-making approach. Results show that some specifically designed and spatially non-uniform quota allocation schemes can meet in an optimum way the relevant criteria

ECONOMIC VALUATION OF IRRIGATION WATER BY THE CONTINGENT VALUATION METHOD

Η οικονομική αποτίμηση των περιβαλλοντικών αγαθών και υπηρεσιών αποτελεί έναν από τους κύριους τρόπους αντιμετώπισης των αυξανόμενων απειλών προς τη βιώσιμη ανάπτυξη και την προστασία του περιβάλλοντος. Στην εργασία αυτή εφαρμόζεται η μέθοδος της εξαρτημένης αξιολόγησης - μία τεχνική που βασίζεται σε έρευνα ερωτηματολογίου - με στόχο την αποτίμηση της αξίας του αρδευτικού νερού σε δύο περιοχές της Βόρειας Ελλάδας. Τα αποτελέσματα δείχνουν ότι η μεθοδολογία αυτή αποτελεί μια ευέλικτη και αποτελεσματική τεχνική αποτίμησης που μπορεί να οδηγήσει σε αξιόπιστες εκτιμήσεις, υπό την προϋπόθεση ότι τόσο η υποθετική αγορά όσο και η οικονομετρική ανάλυση που την ακολουθεί έχουν σχεδιασθεί και εφαριιοσθεί με ορθό τρόποThe economic valuation of environmental goods and services is one of  prevailing approaches to confront the increasing threats to sustainable development and protection of the environment‘ In the present paper the contingent valuation method - a survey-based technique - is applied to valuate the irrigation water in two legions of Northern Greece. Results show that this methodology is a flexible and powerful technique and can lead to reliable estimates. Provided that both the hypothetical market and the subsequent econometric analysis have been carefully designed and implemented

A DECISION MODEL FOR THE ENGINEERING DESIGN OF A GROUNDWATER DECONTAMINATION SYSTEM

Στην εργασία αναπτύσσεται και επιλύεται ένα μοντέλο απόφασης για τον σχεδιασμό έργων απορρύπανσης σε έναν υδροφορέα που έχει υποβαθμισθεί ποιοτικά. Η λήψη των αποφάσεων γίνεται σε συνθήκες επικινδυνότητας, καθώς η αβεβαιότητα για τις τιμές του πεδίου της μεταφορικότητας θέτει σε αμφιβολία την αποτελεσματικότητα των σχεδιαζόμενων έργων. Οι πιθανότητες αστοχίας των έργων υπολογίζονται μετά από επίλυση του στοχαστικού μοντέλου της προσομοίωσης και στο μοντέλο της απόφασης ενσωματώνεται το κόστος από το ενδεχόμενο δυσμενών επιπτώσεων. Εξετάζονται και αξιολογούνται έξι σενάρια διαχείρισης του υδροφορέα και επιλέγεται τελικά εκείνο για το οποίο η επίλυση του μοντέλου της απόφασης δίνει τον καλύτερο συνδυασμό αποτελεσματικότητας και οικονομίας.A decision model for the engineering design of a groundwater decontamination system is developed and solved. The uncertainty of the transmissivity field is the cause for the risk conditions under which decisions should be taken. The risk of failing to meet design objectives is taken into account and the probabilities of failure are computed after the solution of the stochastic simulation model. The concequenses of failure are quantified and their probabilistic costs are taken into account for the development of the decision model. Six alternative scenarios with different design schemes are evaluated and the best of them is selected