Management of Groundwater Resources in Karstic Aquifer using Visual MODFLOW flex, Case Study of Altinova Antalya Turkey

This study was carried out over the karstic area of Altınova region in Antalya-Turkey. The aim of this study is to simulate groundwater in the karst region of Altınova using Visual MODFLOW Flex. The study also aims at assessing the current condition of groundwater in Altınova and formulate scenarios to foresee the future groundwater table elevation. The model girds were designed in such a way that the spatial resolution has a dimension of 25600 m2 over an area of approximately 75 km2. The model domain was divided into two recharge and hydraulic conductivity zones based on the geological formation. The model was run as two dimensional in steady-state. Hydraulic conductivity in the lateral direction was handled as the only calibration parameter. The computed groundwater table elevations were calibrated by comparing with average observed groundwater table elevations data collected in Nov 2015, Feb 2016 and May 2016. The calibration results in the Kurşunlu non- karstic area tend to be more satisfactory with lower residual values than in the travertine karstic area. Overall the correlation coefficient between measured and simulated groundwater table elevation was reasonable with the value of 0.99. The calibrated values of hydraulic conductivity in both karst and non-karst area ranged from 0.01 to 266 m/day. Overall, the calibrated values of hydraulic conductivity in both karst and non-karst areas of Altınova were within the literature ranges. The water budget in the period of the simulation shows a good balance between inflow and outflow. Recharge was the highest component of inflow in the water budget for the entire study area and was sensitive in the model. Following the model calibration, three management scenarios were developed. The groundwater table elevation imperiled to decline under different three hydrological scenarios. A groundwater flow direction map was produced based on modeling outputs. Overall, the groundwater flows from north to southwest then to south in the karstic travertine, while in the non-karst Kurşunlu formation the groundwater flows from north to the south. KEYWORDS: Altınova, Groundwater table elevation, Karstic aquifer, Modeling, Visual MODFLOW Flex.