将泥石流危险性的评价问题从环境评价问题中独立出来，直接以泥石流源物质的重力势能来评估其潜在危害能力，也就定量确定了泥石流的危险度，即D＝a+blgU这个关系是普遍适用的，可以在不同地域环境下进行对比。也可以用其他可能的特征函数代替势能对泥石流活动进行评估，从而发现在相似的危险评价结果下，不同函数之间的数量关系。如果考虑泥石流的分布特征，在势函数中引入分布参数。这个定义也适用于区域危险度的评价和区划。

Separting assessment problem of debris from that of environment and assessing the dangerous potential of the debris flow with gravity potential energy of its source material directly, the dangerous degree of debris flow is determinded quantitatively as D＝a+blgU which is applicable unviversally and can be compared under different regional environments. The activity of debris flow can also be asesessed with other characteristic functions instead of potential energy and as a result the quantitative relationship between different functions can be recovered under same assessmet result. With consideration of distribution features of debris flow and introduction of distribution parameters in potential function the fefinition will be applicable to assessment and zonation of region dangerous degree.