缺资料地区泥石流预警雨量阈值研究

Study of rainfall threshold of debris flow forewarning in data lack areas

合理的雨量阈值指标是保障泥石流预警报准确性的关键,对于研究泥石流形成机制、分析预测未来活动特点以及指导防治工程设计等方面均具有重要意义。由于国内山区大多数泥石流沟均无降雨和灾害资料,目前国内外通行的实证法和频率计算法不能满足其泥石流预警报的需要。通过分析泥石流预警区的降雨条件、水文特征及下垫面条件,提出了基于水力类泥石流起动机制来计算泥石流预警雨量阈值的方法。主要根据流域地形及松散固体物质等特征,计算该流域泥石流起动的临界水深,并结合流域产汇流机制、特征降雨量随海拔变化规律、暴雨雨型特征,进而计算该流域泥石流预警雨量阈值。研究成果在四川省凉山州宁南县城后山史家沟流域进行了应用和验证,结果表明该方法具有合理性和可行性。该方法解决了缺资料地区泥石流预警报的难题,为山区泥石流预警报提供了一种新的思路。

Reasonable rainfall threshold index is the key to ensure accuracy of debris flow forewarning.It is significant for the study of the formation mechanism of debris flow,the prediction of the future activities characteristics and the guidance of the prevention and controlling engineering.Most of the mountain areas have few rainfall and hazards data;therefore,both the traditional demonstration method and frequency calculated method can’t satisfied the debris flow forewarning.Through studying the characteristics of the forewarning regions,including the rainfall characteristics,hydrological characteristics,and underlying conditions,a method to calculate the rainfall threshold is put forward based on the initiation mechanism of hydraulic debris flow.Firstly,the critical water depth for the initiation of debris flows is calculated according to the topography conditions and physical characteristics of the loose solid materials.Then,the rainfall threshold is calculated combined with the mechanism of runoff yield and confluence,the change laws of rainfall with altitude,and the rainfall pattern.The results have been used in Shijia Gully in Ningnan city,Sichuan province;and it is shown that this method is reasonable and feasible.This method resolves the problem of debris flow forewarning in the data lack areas and provides a new thread for the debris flow forewarning in the mountain areas.