基于GIS下的岷江干旱河谷地区泥石流发生域危险性评价

Risk Assessment of Debris Flow in Dry Valley Region of Minjiang River Basin Based on GIS

四川省汶川县地处岷江上游 ,是我国泥石流频发地区。泥石流的发生与分布受地质构造、地貌条件、岩石种类、降水和植被等多种因素影响。以汶川县为例 ,在GIS技术支持下 ,通过计算机对空间数据获取、处理和分析 ,建立该地区泥石流发生域危险性评价指标体系及评价模型。通过合理选取评价指标、确定指标权重、计算综合评价值 ,得出 :在该研究区域的 16条沟系中 ,依据综合指数值 ,最易发生泥石流的沟系为桃关沟 ,佛堂坝沟等沟系 ,有潜在泥石流发生的沟系为新桥沟 ,板子沟等 ,而炭里沟 ,板桥沟等沟系属于无泥石流发生沟系。该评价结果经与历史资料对比和专家认可 ,符合实际 ,客观可行 ,可为防灾减灾。

Wenchuan county in Sichuan is located on head of Minjiang, where debris flow takes place frequently. The eruption and distribution of debris flow in this area are influenced by many factors, such as geologic structure, physiognomy, rock kind, precipitation, vegetation, etc. Taking Wenchuan county for example, special data are collected, disposed and analyzed by computer, the risk assessment indexes system and models of debris flow are established based on GIS. After adopting proper appraisable indexes and confirming indexes weight, synthetical appraising value was computed. The results showed that based on synthetical appraising value, probability of debris flow in Taoguangou, Fotangbagou, etc. is great, probability of debris flow in Xinqiaogou, Banzigou, etc. is moderate, and probability in Tanligou, Banqiaogou, etc. is very small. Those accords with historical data can provide reference for preventing and reducing disaster and debris flow forecast.