Can an environment-friendly management policy improve the overall performance of an artificial lake? Analysis of a multipurpose dam in Greece

Taking as example a multipurpose dam in Greece, we wish to show that by following a rational operation policy, where the improvement of the broader environmental system becomes a high-priority target, it is possible to achieve a much more efficient allocation of its “traditional” water uses. In this context, we review the 50-year history of the Plastiras reservoir in central Greece, to highlight the multiple negative impacts from a non-systematic, abstraction-oriented, operation policy. This kind of management is contrasted to a hypothetical one, obtained through a multidisciplinary methodological framework that has been developed ten years ago, which aimed to compromise a number of conflicting water uses. This required establishing a minimum allowable level for agricultural abstractions and stabilising the annual releases for irrigation and drinking water supply. The criteria under study are, directly or indirectly, related to the water storage in the lake. Therefore, the key idea is to investigate the performance of each criterion with regard to the variability of the level, by examining alternative level vs. abstraction control rules. Thus, the quantity of water that would be yearly available is a function of the minimum level allowed and the desirable reliability. In fact, objective analysis indicates that the maintenance of the reservoir level as high as possible is necessary for the conservation of the quality of the lake’s landscape, for the development of tourist activity and also for providing drinking water of good quality. The advantages of the proposed framework are then exhibited through a back-analysis that focuses to the recent period. The implementation of this management policy not only would improve the water and landscape quality as well as the tourist perspectives, but also allow for a much more efficient planning of the agricultural and, under some premises, hydroelectric energy needs. Thus, the adoption of a constant annual release, irrespective of the recent sequence of inflows, may be beneficial for the long-term interests of all social groups and, therefore, conflicts among drinking water supply, tourism, landscape quality, irrigation and hydroelectric production would become less intense. Yet, the practice showed that a consensus between scientists, authorities and stakeholders for establishing the suggested policy is a considerably difficult task.