ESTABLISHING A HYDROLOGIC OBSERVATORY TO SUPPORT THE DETERMINATION OF THE LONG-TERM AVAILABLE (GROUND-) WATER RESOURCES IN THESSALY BASIN (CENTRAL GREECE)

Abstract

In order to maintain agriculture as a key economic sector in Thessaly basin it is mandatory to adapt the regional (ground-)water management to the renewable (ground-)water resources. The obstacles impeding the implementation of regionally adapted and efficient (ground-)water management strategies are manifold. Due to lack of reliable time series from meteorological and runoff monitoring networks the available renewable groundwater resources cannot be quantified with high accuracy. The lack of vegetation specific parameters additionally impedes the model-based determination of actual evapotranspiration rates. Thus, even the possibilities to determine the total available renewable water resources (total runoff) is limited. Against the background that in situ groundwater recharge generation contributes only to a small extent to the available groundwater resources in Thessaly basin, it is also part of the overall research strategy of a Greek – German cooperation project to determine the lateral groundwater inflow from adjacent mountainous aquifers into the Thessaly basin. For this purpose state-of-the-art devices to quantify hydrologic fluxes in detail have been installed in a test site located in the transition zone of the basin and adjacent mountains (Agia observatory): (a) 2 fully equipped precipitation and climate stations, (b) A wireless sensor network for measuring spatial soil water content variability as a data basis for determining vegetation specific evapotranspiration parameters, and (c) A groundwater observation network and pumping wells for determining hydraulic parameters and seasonal patterns of groundwater velocity in the transition zone. The derived parameters and lateral groundwater flow rates will then additionally be used to support the implementation and adaptation of the water balance model mGROWA (Herrmann et al. 2015) in the entire Thessaly basin, especially with regard to the model-based assessment of the sustainably available groundwater resources