Study on debris flow rainfall threshold of Baihetan Hydropower Station near-zone area

Baihetan Hydropower Station near-zone area is threatened by a number of debris flow gullies, critical rainfall warning system is an effective way to mitigate debris flow disaster. Firstly, history debris flow activities and corresponding rainfall data were collected, then the rainfall threshold of 24hours, critical rainfall scope of 10 minutes and 1 hour were calculated respectively by means of investigation and frequency analysis method. Comprehensively considering debris flow activity specialty, rainfall characteristics and results of in situ experiment, the rainfall threshold of 24 hours, the precaution rainfall and warning index (rainfall threshold) of 10 minutes and 1hour are ascertained, the corresponding rainfall threshold of 24 hours are 10 mm (under antecedent rainfall) and 38.14 mm (without antecedent rainfall) respectively. 10 minutes rainfall between 6.41 to 8.84 mm and 1 hour rainfall between 13.63 to 18.78 mm are taken as precaution rainfall. Taking 8.84 mm/10 min and 18.78 mm/1 h as warning index, which is rainfall threshold for debris flow. Finally, on the basis of debris flow activity, debris flow complexity and the importance of Baihetan Hydropower Station, some suggestions are put forward for debris flow disaster mitigation, hopefully to provide some references for debris flow forecast, disaster prevention and mitigation. ©, 2015, China Water Power Press. All right reserved.