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Water markets are considered an effective groundwater management instrument. However, the emergence of market power during their operation, i.e., price manipulation, cannot be excluded. In this paper, a simple water market between two groups of farmers is modeled and an attempt is made firstly to quantify the loss of aggregate total benefits during a given planning period from the occurrence of market power in this market using a "structural model" to describe the market conditions and solving an optimal control problem and secondly to determine the initial allocation of water rights that limits the loss of benefits due to market power. The results of simulations based on hydro-economic data of a region in Northern Greece lead to two conclusions. The first conclusion is that the loss of aggregate total benefit is likely to reach even 10 % compared to perfect competition when there is a full monopoly or monopsony in the water market. The second conclusion is that an initial allocation close to the quantities consumed by each group under perfect competition leads to a limitation of the impact of market power on the aggregate total benefit gained by the two groups of farmers during the planning period. [ABSTRACT FROM AUTHOR]

In this paper the main results from the implementation and interpretation of a geophysical survey carried out in Chalkidiki (Northern Greece) are presented. The objective of the geophysical survey was to study the general geological conditions of the area (stratigraphy and tectonism) and to focus on the hydrogeological behaviour of the geological formations in the area. The ultimate target was to point out the most promising locations for the successful construction of hydro wells. Since direct hydrogeological information was not available, three different geophysical techniques were applied in order to follow a step by step approach to the exploration of the study area. Firstly, the Very Low Frequency (VLF) electromagnetic method was applied since the majority of the area was dominated by the formation of ophiolites and water flow was possibly expected only in fractured zones at a relatively small depth. Secondly, at the locations of the conductive zones detected by the VLF survey additional Electrical Resistivity Tomography (ERT) sections at different scales were measured to provide more detailed information about the geometrical characteristics of them. Finally, Self-Potential (SP) measurements along the same profiles were conducted in order to provide supplementary information concerning the nature of the conductive zones such as the possible relation with electrokinetic sources. The combined interpretation of the geophysical data proved very efficient for deciding the most promising locations for the construction of hydro wells. [ABSTRACT FROM AUTHOR]

Conventionally, irrigation development planning has been based on cropping pattern selection aiming at maximizing the revenue from irrigation activities. In the real world however, several complexities make the cropping pattern selection a more complicated mathematical problem. Of great interest is the case of water supply from multiple sources (e.g. surface and groundwater) in which a multi-criteria approach is most appropriate. Goal programming has been used in the past to solve cropping pattern selection problems, with criteria of a similar nature, the net benefit being included as a constraint. This paper presents a methodology, based on the fuzzy set theory, for enhancing the goal programming approach to solve similar problems under various sets of criteria of a different nature. In the proposed methodology the net benefit maximization is considered together with all other criteria. The methodology is illustrated using data from the Thessaly Plain in Greece. [ABSTRACT FROM AUTHOR]