| Flood disaster is one of the most serious natural disasters in today's world. It destroys farmlands,drowns crops and results in serious threat to the national economy,people's lives and property. In our country, about 50% of the population and 70% of the property are distributed in the flood region, which leads to great damages and losses each year. and has a clear upward trend. Huaihe River Basin is one of the four major drainage areas in Henan Province. Due to special geography and complicated climate, flood disaster hits Huaihe River Basin frequently. So effective and scientific risk analysis ,monitoring and evaluation of the flood in this area have becoming an urgent problem. In this paper, based on pioneer works in the literature,combining with the concrete facts of the study area, then, determined the evaluation indicators, at last, a comprehensive study of main techniques for flood disaster risk analysis and assessment was made. This study used the experimental data of flooded crops and flood monitoring and survey data,At the same time, utilized remote sensing data, the technology of geographic information spatial analysis and mathematical models are also employed in this research work.The main contribution includes three aspects:(1) Analyzing context of climate, geographical features, causes and variation patterns of flood disasters in the Huaihe River Basin. Then from the danger of flooding, socio-economic vulnerability as well as carrying body disasters, utilizing GIS spatial analysis, we made a comprehensive analysis and assessment from natural factors and socio-economic factors for 39 sites in the Huaihe River Basin. The natural factors includes storm intensity, ground elevation and water system etc, while the socio-economic factors includes population density, arable land, per capita GDP and the forest coverage rate etc. And eventually, we established a flood disaster risk assessment model and the assessment zoning map of flood risk for Huaihe River Basin, which provides a scientific basis for flood control and disaster reduction.(2) Experiments on the effects of flood for agricultural crops were done in Zhumadian. corn was selected as the experimental material, and choosing 3 days, 5 days and 7 days submerged days and the jointing stage, tasselling stage for artificial irrigation respectively. The field was given conventional management. After harvest, we recorded various characters and production data, and then compared them with the controlled areas. Then analysis and assessment of the impact of main flood factors on the crops were built. The results show that :the number of days flooded to the crop yield was significantly affected, The impact of flooding during the jointing stage than tasselling stage.This could provide the basis for linear relationship analysis between flooded days and Traits and production of various crops. It can also provide reference data for quick assessment of flood disasters based on the number of flooded days, so to minimize the losses and improve the flood disaster mitigation capabilities.(3) Studied the evaluation method for the losses of crops caused by the floods, This research was based on the flood data occurred in the Huaihe River basin in July, 2007.we take advantage of EOS / MODIS remote sensing data for the flood hazard monitored, and then determined the extent of damage of affected crops through NDVI vegetation index and the field survey data. Then using GIS software, according to the actual size of each pixel estimated the different affected extent crops. This resulted in a quick assessment of the flood disaster, which could provide a scientific basis for the relief and reconstruction work.
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