| Huangjinping hydropower station is one of the large-scale step hydropower projects to be developed on Daduhe River recently. On the right side of dam site region of Huangjinping hydropower station around the tail water outlet , there stands a rather large-scale debris flow gulley—Longda gulley, which ever generated large-scale debris flow in history. So investing Longda gulley debris flow's nature, characteristic and formation conditions, predicting its breaking out scale, analyzing the influence on the hydropower station and putting forward corresponding prevention countermeasure are necessary.The thesis introduces the development geological environment of the debris flow firstly, then analyses the formation condition from aspects of landform, precipitation confluence and solid matter supply; formulates the debris flow's development characteristics, including gulch characteristic, valley subzone characteristic, development history and activity discrimination; according to its character, selecting the latest research results at present, calculates the debris flow's the moving, dynamical characteristics and the scale, such as, the velocity of flow, the wallop, the peak value flux, and the total flux; adopting two grades fuzzy synthesis appraisal and improved risk factor calculation formula for single debris flow gulley to make risk appraisal, in two grades fuzzy synthesis appraisal, fifteen factors are selected according to the gulley's characteristic, and in the improved formula, effects of rainfall intensity is enhanced, and the results by two means are unanimous; according to calculation model for primary deposit extent, referring to the gulley's landform characteristic, generalizes deposit modes and calculates the primary deposit extent to design frequency; according to primary deposit extent results, evaluates the risk degree to the hydropower engineering pivots by Longda gulley debris flow, and according to the...
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