| The law of distribution of disaster-affected bodies in time and space is not only limited by the natural environment but also related to human activities,and is often the result of the interaction between humans and the nature.The massive reconstruction of buildings in the Wenchuan earthquake area was affected by geological disasters,and the buildings were damaged and discarded,which shows that the risk of regional geological disasters after the earthquake was seriously underestimated,and there were certain problems and difficulties in the regional reconstruction planning and disaster reduction work.The research of positive and negative responses on important disasters-affected bodies in time and space are weak aspects of the reconstruction planning in the earthquake area.Through the analysis and summary of the disaster-affected body's spatial-temporal evolution,the experience and lessons learned can also be useful to the formulation and adjustment of related planning.It is often scientific,reasonable and feasible for post-earthquake regional planning,reconstruction,and disaster mitigation.The reasonable advancement of such work has great practical and scientific significance.However,at this stage,few researchers have considered the reasons and laws of the evolution of the disaster-affected body in a smaller scale and constructed a database of multi-temporal disaster-affected bodies for geological disasters in strong earthquake regions,and the research of its evolution is still rare.The Longchi zone in Dujiangyan City,an extremely-stricken area,was selected as a case.Based on GIS and RS technology,the multi-inventory of high-resolution remote sensing,relevant literature review,field investigation and household interview,a multi-phase database of disaster-affected body in strong earthquake zone was constructed,and all aspects of attributes in the disaster-affected body database were extracted by Arcmap,and the quantitative statistical analysis of the change of regional disaster-bearing bodies was conducted to achieve scientific and accurate quantification of the temporal and spatial changes of disaster-affected bodies in strong earthquake regions.The result has practical significance not only for the advancement of disaster prevention and reduction work in disaster areas,but also provides scientific reference for other types of natural disaster risk assessment research.The main ideas,conclusions and innovations of the paper are as follow:(1)An effective method for multi-temporal and high-precision disaster-affected bodies database is established.Based on the detailed interpretation of remote sensing images of multi-temporal disaster-affected bodies,relevant academic data,detailed flied investigation and household review,the results were corrected to establish effective multi-stage database of disaster-affected bodies.In order to ensure that the database construction method of multi-temporal disaster-affected body in strong earthquake area has good portability,and the process and method of database construction are described in detail so that other researchers can study the database based on this method more quickly.(2)It is pointed out that the strong effect of the combined effect of discharge and damage amplification between the mountain flood and the debris flow should be paid attention to in the strong earthquake area,and the importance and seriousness of the river bed uplift should be recognized.According to the database analysis,there are 140 buildings affected by geological disasters in remote sensing images in 2011,the buildings affected by debris flows accounting for 67.14%.The road directly damaged by debris flow accounted for 55.02% of the total length,and the roads damaged by debris flow erosion were 1.93 km,accounting for 24.52% of the total road length.Floods and debris flow are important and long-term composite disasters in strong earthquake regions,and they have the combined effect of superposition and amplification and should be taken into account in the planning of earthquake reconstruction and related risk evaluation.(3)A quantitative study of the dynamic evolution of multi-temporal disaster-affected bodies was achieved.Through a multi-temporal quantitative study on the structure,function,value,disappearance,and growth of important buildings,the results show that the number and value of residents' self-built buildings respectively accounted for 56.79% and 27.58% of the total damage of ?8.13? debris flow event.The government-built houses have a more comprehensive and professional risk awareness and reconstruction plan.The number and value of damaged buildings accounted for only 2.12% and 3.21% of the total,but with the high value of government-built houses,and the total value of losses is still close to the loss of residents' self-built houses.At the same time,the buildings in the study area are abandoned,and the number of vacant buildings is large and the value is concentrated,the rate of disposal and vacancy can reach 13.5%,and the total value of abandoned and vacant buildings accounts for.18.04% of the total value of construction,and a large number of vacant and abandoned resources have restricted the sustainable development of the region.(4)Summing up the experiences and lessons from the positive and negative responses of the evolution of the disaster-affected body in the study area.The massive reconstruction of buildings were affected by geological disasters,damaged and abandoned,and it shows that the risk of regional geological disasters after the earthquake is seriously underestimated,there are certain problems and difficulties in the regional reconstruction planning and disaster reduction work,and the reconstruction and planning of scattered households and residential sites are pending.On the basis of scientific and comprehensive regional risk assessments,reconstruction planning,disaster prevention and disaster reduction work will be carried out.In the strong earthquake zone,we should consider the construction of tourism-related buildings(such as agritainments,commercial buildings,etc.)during the period from 3 to 5 years after the earthquake;we should temporarily stop the construction of dams and drainage channels in the debris flow channels with large drainage area.Before the scientific and comprehensive site investigation and risk assessment,buildings should be forbidden to be built near the channels;when constructing buildings in the low elevation areas along the river,the influence of various geological disasters should be strictly considered,and it is necessary to take into account the materials transported by debris flow.With the hazard amplification effect caused by the amplification effect of debris flow and flood,The site should be carefully selected under the guidance of and comprehensive geological disaster risk assessment,and it is necessary to find a ?safety island? such as the Longchi town weakly affected as soon as possible.We will use limited resources on "safe islands" where the threat of disasters is relatively weak or non-threatening,which minimizes unnecessary property losses and casualties,and enhance the sustainability of regional development.With the limitations of research level and data,the multi-temporal disaster-affected database and the analysis system constructed in the paper may have some errors in the process of statistical analysis.Even so,the results of the study can provide reference for the formulation and adjustment of regional reconstruction planning and disaster reduction work after the earthquake. |
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