A modeling system for the evaluation of water resources management strategies in Thessaly, Greece

A modeling system was developed to evaluate the sustainability of water resources management strategies in the two major basins of Thessaly Region in Greece, namely the Pinios River and the Lake Karla basins. The intense and extensive agriculture of water demanding crops, such as cotton, and the absence of reasonable water resources management have led to a remarkable water demand increase, which is usually fulfilled by the over-exploitation of groundwater resources. This unsustainable practice has deteriorated the already disturbed water balance and accelerated water resources degradation. The modeling system consists of a hydrological model, a reservoir operation model and methods for the estimation of water demands. The study area was sub-divided into sub-basins and water balance analyses were performed for each sub-basin and each control node of the system for a number of water resources management strategies. Four strategies of hydro-technical project development were coupled with two strategies of groundwater withdrawal and three water demand strategies. In total, more than 24 water management strategies were evaluated. The results showed that, under the existing water resources management, the water deficit of the Pinios River and Lake Karla basins is very large. However, the development of proposed hydro-technical projects in the Pinios River basin coupled with water demand management measures, like improvement of existing water distribution systems, change of irrigation methods, and changes of crop cultivation could alleviate the problem and lead to sustainable and ecological use of water resources in the study area.