Abstarct: One of the most important issues when constructing and operating dams is the problem of water leakage from the supports and their supports, which are commonly used to prevent or reduce the injection curtain. Because calcareous laxyers contain relatively high solubility, it is possible that the previous or residual duct injection may develop over time. In dams built in karstic areas due to the presence of two conduit and matrix systems, the mechanism of groundwater movement and leakage is complex. Karun 4 Dam is built on Karun River in a karstic range. First, hydraulic parameters of aquifer matrix environment were determined in MODFLOW software. For this purpose, groundwater level data before and after dam construction, drilling logs, injection curtain results, aquifer geometry, and other information have been used to simulate groundwater flow. CAVE dual solubility porosity software was used to model. The model used is dual finite element porosity, which simulates the matrix flow baxsed on the Darcy relation and the flow in the conduit environment baxsed on the turbulent flow relationships. Calibration and validation taking into account the level of boreholes in steady state, unstable and during dam construction, carried out in the next step taking into account the hydrological conditions prevailing in the area and applying the conditions existing at the dam site for a period of time. 100 years of aquifer behavior was evaluated. Applying the existing and proposed conditions at the site of permeability barrier of the curtain has a great impact on the sealing and development of ducts. The duct development in aquifer is non-uniform and the ducts near the injection curtain are most developed, as well as the possibility of water escaping from the dam in future Karun 4 dam due to duct dissolution.