Research On Flood Submergence Loss Analysis And Countermeasure Based On ArcGIS

Flood disaster is one of frequent occurrence natural disasters in our country, and serious threat to the lives of citizens and the development of social economic. According to statistics, an average of about 700 million hectares of farmland suffers from flood disasters each year. And the average annual economic losses caused by flood disasters are about thousands of billion Yuan, accounting for 1.2% of GNP, and showed a growing trend. Therefore, to enhance the loss analysis of flood disaster and the study of flood evacuation scheme for asylum, to transfer of the affected people safely and efficiently, and to reduce property loss of life caused by flooding put as the focus of widespread concern. With the development of information technology and geographic information systems, the GIS technologies are widely used in study and analyze on the flood area, evacuation plan and flood damage assessment.In this paper, the depth and range of flood inundation are calculated by meanings of secondary development in ArcGIS using VBA. And then, the asylum unit, refuge settlements and the best evacuation road are studied based on the spatial analysis and network analysis functions in ArcGIS. And the economic losses of farmland in the submerged region are assessed based on the flood risk maps,that provides a theoretical basis to leaders for flood control, making correct decisions.Its main contents are as follows:(1) the calculation method and program for water depth and range of flood submergence area are given out based on equal volume theory using ArcGIS VBA environment, supported by the digital elevation model (DEM); Combined with the ArcGIS spatial analysis function,the steps of computing and mapping flood inundation map is also presented.(2) According to the water depth and scope of the flood zone, the assessments of economic losses of crops are carried out. The curve of the vulnerability under different water depth and duration of time are also drawn out, based on the mathematical model of crop vulnerability, and providing a scientific basis for studying the evaluation of flood.(3) The Dijkstra algorithm for shortest path and the road right computational algorithms are analyzed and the corresponding calculation process is presented based on the calculated results of water depth and scope of the flood zone. The same time, the specific process of calculating the shortest path are given out combined with ArcGIS network topology analysis.(4) According to the principle of asylum and the principle of selection and construction resettlement unit, the affected areas are evacuated and resettlement points are selected; And then the comprehensive evaluation of asylum are assessed by means of the variable fuzzy sets theory, providing a theoretical basis for selecting the best refuge.(5) Taking a vulnerable spot of Liaohe River for example, the water depth and scope are calculated using ArcGIS VBA based on the date of Liaohe River flood in 100 years. And then specific values of agricultural economic losses are obtained according to the loss rate curves of Rice and maize. Finally, according to the flood range in the affected areas, the appropriate settlements and the best migration path is obtained.