This paper takes flood disaster risk assessment in Songyuan as an example, introducing the application of remote sensing technology in natural disaster assessment.
This paper analyzes indicators from four aspects of hazard causing factors, hazard-formative environments, hazard-bearing body status, and hazard prevention and mitigation ability.
Hazard causing factors
Hazard causing factors refers to the dynamic factor causing flood and waterlogging. For rainstorm and flood, the leading triggering factor is rainstorm. In this paper, rainfall factors are used to construct disaster causing factors.
Disaster causing factor index
It can be seen from the figure, two counties in the northeast and southwest of Songyuan city -- less rainfall Changling county and Fuyu county, followed by Qianan county and Ningjiang district, the highest rainfall in Qian Gorlos Mongolian Autonomous County.
Hazard-formative environments refers to the underlying surface in natural conditions, they can redistribute the flood, has relative stability, such that terrain can control the regional convergence and drainage conditions, and vegetation can play water keeper, the function of soil and water conservation. In this paper, the indicators of hazard-formative environments are selected to build terrain, water system and vegetation coverage data.
Index of hazard-formative environments factor
It can be seen from the figure, affected by topography, vegetation cover, the northern city of Songyuan, especially the environmental disaster index of Qian''''an county and Ningjiang district is the highest, in addition, the index Hazard-formative environments is also showed high in Songhua River area.
Hazard-bearing body status and hazard prevention and mitigation ability
The situation of disaster body, usually refers to the regional social and economic status, all personnel and property such as possible disaster threats, a region of population and property more concentrated, potential losses may suffer greater risk of flood disaster is also larger;
Disaster prevention and mitigation capacity refers to the affected areas in the face of flood disaster, the measures, such as hospital care, and these measures require local government economic support and the level of local economic development support.
In this paper, the index of carrying capacity is selected to build the average population, land average GDP, the proportion of cultivated land; the ability index of disaster prevention and mitigation is selected per capita GDP and the number of shelters is constructed. The comprehensive effects of disaster and disaster prevention and reduction factors are shown in the following picture.
Indicators of disaster bearing and disaster prevention and reduction
It can be seen from the figure, factors in the role of social economic construction, within the scope of Songyuan city Changling County, Fuyu county and Qian Gorlos Mongolian Autonomous County of the disaster and disaster prevention and reduction factor is higher, Qian''''an weaker, and the lowest in Ningjiang district.
Three important factors in flood risk assessment are analyzed, and the weights of the three factors are also different. For example, in some places, although there is a large amount of precipitation, the environmental risk index is low and the disaster bearing body is good, so the risk assessment is very low. Therefore, it is necessary to consider various factors comprehensively. Finally, the weight of each index is determined by analytic hierarchy process (AHP), and the risk distribution map of rainstorm and flood disaster in Songyuan is calculated.
Risk distribution map of rainstorm and flood disasters in Songyuan
It can be seen from the figure: after comprehensive consideration, the high risk areas of flood disasters in Songyuan city are mainly in Qian''''an County, Ningjiang District and along the Songhua River in the East; the north of Qian Gorlos Mongol Autonomous county and the east of Changling County small area belong to middle and high risk area; and Fuyu County and Changling County are mainly lower risk region and low risk region.