Abstract: The paper studies the canal seepage between Zhengyixia Valley and Langxin Mountain of Heihe River. Synthetically water supply conditions and seepage capacity were concerned and a natural channel flow evolution model was established under the strong seepage condition by using the average water surface breadth and product of leakage rate calculated the seepage amount per unit length, and with the change of water surface breadth reflect the seepage surface along with the change of the water fluctuation. The results show that:(1) model reflected the real situation well and its errors did not go beyond 5%. (2) Through the model and the parameters, daily seepage were calculated by using the method of classification summary working out seepage of 2005 to 2013, we found that the leakage of the model simulation is basically consistent with the calculation by using the water balance method,for instance, the multi-yaer mean leakage of the model simulation was 2.69×10⁸ m³ and the calculation by using the water balance method was 2.84×10⁸ m³, absolute error was only 0.15×10⁸ m³, (3) Based on the measured flow and the calculation of the leakage loss, a exponential model was established to model the relationship between the flow rate and the leakage of the Zhengyixia Vallye under the conditions of before over water and without water. We can use the mode analyze the possible leakage and prediction of downstream runoff process in the actual water diversion work.

Key words: canal seepage, stream routing model, water balance, Heihe River