KARST IS A DRY LANDSCAPE SITUATED ON SOLUBLE CARBONATE ROCKS. LIMESTONES AND DOLOMITES WITH UNDERGROUND FLOW OF WATER. ALTHOUGH KARST TERRAINS OF THE WORLD MAKE A RELATIVELY MINOR PERCENTAGE AROUND 10% OF THE EARTH SURFACE BUT THEY PRESENT THE MOST RISK PRODUCING CONDITIONS FOR A FULFILLING IN PROJECT OBJECTIVES AMONG THE OTHER GEOLOGICAL FORMATIONS. IN THIS RESEARCH WE ARE AFTER TO FIGURE OUT THE KARST MAIN PROBLEM, SEEPAGE, IN DAMS AND RESERVOIRS AND STUDY THIS PHENOMENON NUMERICALLY. THE COMPLEXITY OF THE KARST SYSTEM PROBLEMS IN SALMAN FARSI DAM SITE IS SO SERIOUS THAT A VARIETY OF REMEDIAL MEASURES HAS BEEN PRESENTED. AMONG THOSE FIVE MAIN SUGGESTIONS ARE CHOSEN TO BE MODELED. CHOOSING THE BEST NUMERICAL METHOD TO ANALYZE THE KARST PROBLEM NEEDS A COMPLETE STUDY OF ALL POSSIBLE WAYS. AFTER A FULL INTRODUCTION ON DIFFERENT MODELING METHODS WE HAVE A FULL INVESTIGATION ABOUT SALMAN FARSI DAM GEOLOGY AND HYDROGEOLOGY CONDITIONS. COMPLICATED KARST CAVES AND CAVERNS SYSTEMS AND THE DAM RIGHT ABUTMENT FRACTURED FORMATION HAD ENCOUNTERED A LOT OF PROBLEMS FOR THE DAM WATER PROOFING. FINDING THE BEST WATER PROOFING METHOD WAS AN AIM. THE NUMERICAL METHOD CHOSE FOR THIS RESEARCH IS DOUBLE CONTINUUM POROSITY EQUIVALENT (DCPE). OUR MOST IMPORTANT OBJECTIVE IS TO MODEL THE SEEPAGE FLOW FROM SALMAN FARSI KARSTIC FORMATION. THE VISUAL MODFLOW PROGRAM HAS BEEN USED TO GRID THE AREA AND THE DAM CHARACTERISTICS INPUTTING DATA. THE DIFFERENT SUGGESTED TECHNICAL METHODS FOR WATER PROOFING ARE MODELED WITH DCPE AND THE RESULTS ARE COMPARED, ANALYZED AND TABLED. THE DCPE METHOD HAS THREE KINDS OF OUTPUT WHICH ARE THE BASE OF JUDGMENT. "CONSTANT HEAD OUT", "OTHER POROSITY" AND "TOTAL IN_OUT" ARE THE PROGRAM RESULTS WHICH THE LAST ONE HAS BEEN CHOSEN AS THE CRITERIA OF CHOOSING THE BEST SEEPAGE CONTROL METHOD PRESENTED ACCORDING TO THE MINIMUM AMOUNT OF SEEPAGE DOWNSTREAM. THE PROCEDURE, FLOWCHART, ANALYSIS, RESULTS AND CONCLUSION AND SUGGESTIONS ARE PRESENTED IN THIS PAPER.