Interpretation of conceptual hydrologic model parameters with watershed characteristics. Exploration using the model Zygos

Watershed runoff depends on many factors such as: geology (rock permeability), morphology (slopes, geometry of river net, human interferences) and rainfall (intensity, duration and distribution on catchment area). The current thesis investigates the hydrological and hydrogeological parameters of lumped conceptual water balanced model ZYGOS which has been planned and constructed by research team of ITIA of National Technical University of Athens. Although ZYGOS model, like most models of this category, constitute an incorporated algorithm for the optimization of its parameters, the results are not always representative or even close to their true values. The parameters of the model have been calibrated after many experiments and there has been an effort to be interpreted and explained firstly according to the hydrogeological characteristics of 10 Greek river basins and particularly according to the types of rocks, their proportion of participation in the basin and according to the percentage of the basic water streams that flow on the geological formations. Secondly, information has been taken into account about altitude, morphologic slopes of basins, the appearance of springs, sea water intrusion in fresh aquifers, land usages, the tectonic status of the studied area and the construction and operation of technical works (reservoirs, net irrigation etc). Most of the above mentioned information has been taken into account in an indirect way for the interpretation of the results of the model. At the end of each basin analysis it is given a description of Nash coefficient sensitivity in variations of the parameters of the model and a justification for its fluctuations and its optimum values that have been defined. Finally in the chapter of conclusions the optimum values of Nash coefficient and the parameters of the model are presented in total in a table for all 10 basins.