Groundwater-surface water interaction model: A case study in Silifke-Goksu deltaic plane

The interaction between groundwater and surface water is quite complex and it is a difficult process to simulate this interaction, particularly simultaneously. Therefore until recently, the two systems have been studied separately and hydrological models have been developed usually focusing on only one of the surface water or groundwater resources. In this study, the interaction between groundwater and surface water was investigated in the Göksu Deltaic Plain which has various surface waters such as river, drainage channels, wetland and coastal lagoon. To this end, the GSFLOW integrated flow model, which can simulate groundwater and surface waters simultaneously, is used. GSFLOW was created by combining surface water model PRMS and groundwater flow model MODLFOW-2005. Before integration, PRMS and MODFLOW-2005 models were established and calibrated, then GSFLOW calibrated. The calibration of MODFLOW-2005 was made under steady state flow conditions, compared with modeled and measured groundwater levels. For this, static water depths were measured for one year in the 18 wells determined in the field. As a result of modeling, it was concluded that there is a continuous and dynamic interaction between groundwater and surface water in the research area. It has been proposed to improve the study by measuring in a larger number of wells to better represent the area, determination of the geological cross section, creating of detailed topographic maps and including the new irrigation project which has been in operation yet.