突发地质灾害气象预警统计模型与应用

Early Warning Statistical Model of Sudden Geological Hazards and Its Application

通过引入地质灾害潜势度,突发地质灾害气象预警统计模型解决了雨量判据法不能明确表达地质环境条件的问题,在此基础上,提出了潜势度计算、大气降雨变量设计、预警方程优化3方面的改进方法。为提高潜势度计算的准确性,增加了基于卡方检验的地质环境因子独立性判别步骤;对地质环境因子确信程度初始值和权值计算中确信程度变化量初始值设置进行了规定;并将预警模型中累计雨量修正为更为合理的有效累计雨量。在现有的预警方程的基础上提出了基于联合概率分析的预警方程,避免了其与基本地质认识和物理规律存在一定距离、方程系数的意义不明确的局限。以2009年7月2日发布的24 h雨量预报为例,计算结果表明:虽然预报区域面积从101 008 km^2减小到27 553 km^2,但是地质灾害点落入预报区的比例从44%增加到62%。这说明通过改进的预警模型理论上更加严密,空间准确率有所提高,空报率有所下降。

By adding geological hazard potential as a parameter, the statistical model of sudden geological hazards early warning has solved the problem caused by rainfall criterion method which could not express the geological environmental condition clearly. The calculation of potential, the design of variable parameters of rainfall and the optimization of early warning equation were a!so improved in this model. In order to increase the accuracy, an additional step for relatively independent geological environmental factor judging based on chi-square test was supplemented in this model. The initial value of the certainty level of the geological environmental factor and the set of initial value of the certainty level change in the weight calculation were also ruled. And valid cumulative rainfall was adopted in this model instead of cumulative rainfall, which makes this modle more reasonable. An early warning equation based on a joint probability analysis was proposed in this study, which avoids inconsistency with the basic geological cognition and the physics law, and a lack of the equation coefficients meaning. A 24 h forecast of July 2nd, 2009 was taken as a case study. The results showed that the geological hazard points within the forecast area ratio increased from 44% to 62%, although the forecast area decreased from 101 008 km2 to 27 553 km2. It indicates that the improved early warning model will be more rigorous theoretically, increase its spatial accuracy and decrease its invalid report rate.