北川震后重构聚落的地质灾害灾情分析

北川羌族自治县是2008年"5·12"地震的极重灾区,地震给其境内的各类城乡建筑造成了严重的损失,经过3a多的灾后重建,该县聚落空间得到快速的重构。2013年的7·9洪灾之后,北川境内的地质灾害事件全面爆发,给重构聚落空间的安全造成了严重的威胁。以2013年7·9洪灾之后的灾情普查数据和北川的土地利用图为基础数据,利用GIS技术,使用最邻近法及主成份分析法分析评价了北川境内聚落空间的地质灾害灾情特征,并根据各个聚落斑块的灾情指数值的大小将其划分为灾情轻微、较重、严重和极严重的4个等级。评价的结果表明:北川县境内共有1 016个聚落斑块受到地质灾害点的威胁,占聚落斑块总数的5.702%;其中,灾情极重的聚落有45个、灾情严重的聚落有64个、灾情较重的聚落有775个、灾情较轻的聚落有132个。该评价结果可以为地方政府根据各受灾聚落灾情的轻重缓急而制定出科学的防灾减灾决策提供基本依据。

ANALYSIS ON GEOLOGICAL DISASTERS OCCURRED IN THE RECONSTRUCTED SETTLEMENTS SPACE AFTER THE EARTHQUAKE IN BEICHUAN

Beichuan Qiang Autonomous County was the very seriously destroyed area during the 2008's earthquake, with all kinds of urban and rural buildings greatly damaged because of the earthquake. The region's settlement space has been rapidly reconstructed during the post-disaster reconstruction of three years. However, the natural environment is not yet stable, coupled with the frequency of extreme weather events in recent years, a number of potential threats gradually were exposed, causing a number of catastrophic events in the settlement space of reconstruction after the earthquake. Particularly, the geological disasters broke out in Beichuan after the 7.9 flood disaster in 2013, causeing serious security threat to the settlement space of reconstruction. In this paper, the census data of disaster after the 7.9 flood disaster in 2013 and land use data of Beichuan were selected to analyze and evaluate the characteristics of geological hazard of the settlement space in Beichuan based on GIS technology, the nearest neighbor method and the principal component analysis method. Eventually, we calculated the disaster index of various settlement plaques, and divided them into four grades based on the size of the disaster index value as follows: mild, heavy, serious and very serious. The evaluation results showed that a total 1016 settlement patches are threatened by geological disasters points in the Territory of Beichuan County, accounting for 5.7 percent of the total settlement plaques. Among them, there are 45 settlements are very seriously destroyed by geological disasters and 64 settlements are seriously destroyed by geological disasters, 775 settlements are heavily destroyed by geological disasters, and 132 settlements are slightly destroyed by geological disasters. The evaluation results can provide a fundamental basis for local government to develop a scientific decision to disaster prevention and mitigation according to the disaster priorities of each affected settlements.