The Study On Relativity Of Debris Flow Regular Pattern And Precipitation Variation In Southern Liaoning

The debris flow disaster in the south of Liaoning is relatively serious.This paper confirmed that debris flow in southern Liaoning is a typical rainfall-typedebris flow by making a comparative analysis of the inducing factors. Rainfall is the primaryfactor of the formation of debris flow. Precipitation feature is the main content of the questingof the regularity of debris flow in southern Liaoning.According to21meteorological stations’ daily precipitation data from1958to2008inLiaoning province, using the Z-index method, this paper make an EOF analysis of temporaland spatial characteristics of precipitation in Liaoning Province in recent51years by usingMorlet wavelet and Kriging spatial interpolation.From time variation perspective,there is a fluctuating downward trend in the type ofprecipitation,the annual amplitude of precipitation oscillated sharply,which has a decreasingtrend of1.96mm/a and appearing cyclical variation, of which the mainly period for9yearsand the secondary period for24years and3years；Monthly precipitation is mainly distributedin July and August, which rainfall in July is more concentrated; the debris flow behave as noobvious interannual cycle, but opposite of that, seasonal rainfall is more conspicuous andconcentrated, which is distributed in July and August, especially in August. The debris flow’sactive period is slightly lags behind the rainy season, and be synchronized with the rainyseason.From the spatial variation perspective, basis of EOF-analysis method, the spatialdistribution of precipitation has showed as the modle of The Whole Region,Southeast-Northwest opposite phase,Middle-Both Side opposite phase. The mainly changesare the average annual precipitation decreasing warp-wise progressively from the southeastcoast of Liaoning to the northwest inland. The distribution of Debris flow disaster areconcentrated in the gully of the numerous large and medium-sized rivers in the southernregion, which activity areas are relatively dispersed, and the pattern is inconsistent with the gradient change trends of precipitation. It’s obviously subject to steep topography conditions.The debris flow in the south of Liaoning is a typical rainfall-type debris flow, forecast of debris flow should be more concerned about the prediction of rainfall. Theprediction of rainfall can be obtained according to experience curve of power functionfor10days cumulative value, in addition, the15days cumulative value and the30dayscumulative value is a useful reference.