Ecological Risk Assessment Within The Condition Forced By Mountain Disasters

Recently, with the changing of natural environment,being disturbed by the activities from human beings and other factors, the rate of incidents happened severely is rising gradually. It puts more influence on the safety of lives and assets from the locals after the incident happened. Therefore, making a forecast and an assessment on the incidents risk, which has been a vital part during making a decision about choosing the strategy of dealing with incidents. With the study about risk assessment being deeper increasingly and more important, people growingly focus on it. The way of studying Ecological Risk Assessment(ERA) has been changed from the small-scale to big-scale just like landscape and area. At the same time, the scope of the source and receptor of risk respectly varied from simplification to diversity. However, there is no a complete method system to study Ecological Risk Assessment all over the world. Based on the progress in Ecological Risk Assessment researching of home and abroad, and this paper thoroughly inquire into the theory and methods of Ecological Risk Assessment, combing the realities and the dates collected in the wild, which aims to enrich and supply the ways and case of studying Ecological Risk Assessment within the condition forced by mountain disasters in the mountainous area.After the earthquake in Wenchuan, the works of restoring are still being threatened by the secondary disaster in the earthquake-stricken area. This paper takes the Longmen Mountain Town in Sichuan Province as the study area and chooses and confirms the risk receptor, based on the dates being collected for 5 years in the wild. Taking the remote sensing image in high resolution, with ArcGIS, the number, area and circumference can be worked out. The ideology of Analytic hierarchy process(AHP) and conceptual frame of ERA were used to count out weight and establish index system. And then, the model of assessment can be established by the methods of Fuzzy Synthetic Evaluation. The value of ERA can be ranged, and the chart of ecological risk degree also can be exported. Finally, make an assessment. Main conclusions are list as follows:1. Establish index system. Based on the practicability of the dates available, statistical method and occurrence regularity and influence degree through of different risk sources, taking into account the geological disaster characteristics and geological condition in Longmen Mountain Town. Ecological evaluation index system of this paper is divided as target layer, criterion layer, index layer. The risk receptors are chosen as woodland, grassland, tillable field, bare land, water area and residential area. Eight indexes are chosen as quantitative method to reflect the relationship between landscape pattern and ecological loss index.2. Ecological risk source distribution. The main risk sources are mud-rock flow, landslide, torrential flood, collapse. Mud-rock flows are happened in all the area in Longmen Mountain Town, which are along both sides of Jianjiang River and the valley area. These area is steep terrain, the shape likes U or V. Landslides are distributed alone both sides of Jianjiang River, and the risk sources on the northern side are more than southern side. Collapses happen in the upper reaches and northern side of lower reach of Jianjiang River. Torrential flood mainly happen in the Yinchang gully scenic spot from lower spot in Dahaizi to Haihui Bridge.3. Ecological risk assessment. Ecological disasters in studying area are ranged 5 areas including extremely high risk, second high risk, third high risk, medium risk and lower risk. And the risk sources are ranked. It is obvious for regional distribution characteristics of ecological risk level in Longmen Mountian Town, eastern and southern areas mainly are in lower risk level, but in western and northern area existing second high risk. The extremely high risk areas are along the upper reaches of Jianjiang River in Longmen Mountain Town.4. The countermeasures to prevent and control ecological disasters. Establish monitoring network and early warning system, implementing a comprehensive disasters and focus hidden damage points. Strengthen ecological environment management, and make prevention and control plan about relative ecological disasters, which is for scientific and reasonable control. Make prevention and control measures by stages to different level risk area, strengthening the campaign of disaster mitigation and prevention, availably adjust the resident activities and establish disaster management financial system.