Abstract：The concentrated leakage passage in fissured rock is studied with dummy heat source method. The temperature of reservoir water at the bottom is commonly low，whereas the temperature of bedrock increases with depth，so there will be reservoir water leakage around the temperature abnormal area at the dam site. There will be thermal exchange between the leakage and around strata. The leakage water with low temperature will absorb heat from strata；and on the other hand，the strata will discharge heat. According to the theory of energy conservation，these qualities of heat mentioned above are equal. The concentrated leakage passage can be regarded as a dummy heat source；moreover，the temperature distribution in stratum out of the passage is only influenced by the surface layer of passage and not relative to the inner temperature distribution of the passage，namely，the inner temperature distribution of passage is caused by water and the outside temperature distribution is shaped by heat conduction. Then，based on the theory of heat conduction and energy conservation，the temperature distribution in strata can be determined，which can be used to locate the leakage area. A dummy heat source model is proposed to calculate the quantity of leakage water. As an example，a reservoir leakage is analyzed quantitatively.
