This study adopts an improved method of the rough set.In view of the typical moraine-dammed lakes in Tibet

China

it is proposed that the moraine lakes prone to outburst often have the five characteristics of steep glacial relief of moraine lake area

frequent glacial activities

large scale of moraine lakes

poor stability of moraine dam

and wet-hot climate condition.Based on the characteristics

evaluation factors are selected in the hazard assessment of moraine-dammed lake outburst.Then

weights are determined for the factors in consideration of practical survey result and verified by fuzzy comprehensive evaluation.By the weights

it can be concluded that the most important factor on outburst is the stability of moraine dam(weight value 0.42)

the second is the climate condition(weight value 0.18)

and the other three are closely equal(each weight value about 0.13).Width of moraine dam and warm-humid combination are the important influencing factors;lake-glacial distance

lake area

and altitude height are the secondarily important influencing factors;moraine distal flank steepness and average particle size of moraine dam are the ordinary factors.The result of fuzzy comprehensive evaluation is consistent with that of practical survey

so the weights of the high accuracy can be of great reference value to the hazard assessment of moraine-dammed lake outburst in China.