涪江上游泥石流灾损土地特征及典型流域淤积危险性研究

CHARACTERISTICS OF DEBRIS FLOW DEPOSITION LAND AND THE RESEARCH OF THE RISK EVALUATION ON THE FUJIANG RIVER UPSTREAM

涪江上游以高山峡谷为主,人地矛盾突出,泥石流灾损土地是山区居民选择的主要生产生活场所。通过野外调查,初步查明目前涪江上游泥石流灾损土地以淤高的发展趋势为主,灾损土地扇形完整性程度达58%,以中等易发为主;大部分灾损土地距离主河距离为100~350 m,距离适中,水热条件良好。基于不同降雨频率条件下泥石流主沟内泥深、流量差异性,建立泥石流灾损土地的淤积危险范围确定方法;快速得到南坝窖子沟20 a一遇、50 a一遇、100 a一遇3种降雨频率条件下泥石流淤积危险范围,分别为0.167 km^2、0.292 km^2、0.420 km^2。为下一步建立基于土地潜力和灾害风险两个指标的灾损土地资源化潜力评估方法,探索泥石流灾损土地资源化利用模式,提供基础条件,并为山区居民进行土地利用提供快速指导。

Fujiang River upstream is typical of high ridge and narrow valley physiography,which results in its contradictory between people and land. Therefore,the land after debris flow disasteris the main living place for local residents. Through field survey,we found the current development tendency of the debris flow disaster landis mainly depositing. The extent of deposition fan reached 58 percent and the distance from debris flow disaster land to the river ranges from 100 to 350 meters. The debris flow disaster land has good hydrothermal condition. Based on the difference of debris flow depth and the discharge under designed rainfall frequencies,we set up a method to determine the deposition hazard range of debris flow disaster landin Fujiang River upstream. The deposition scopes under different rainfall frequencies with 20 years return period,50 years return period and 100 years return period were calculate as 0. 167 km^2,0. 292 km^2 and 0. 420 km^2,respectively. It will be benefitfor building debris flow disaster evaluation method based on land utilization and disaster risk in advance.