Assessment Of Farmland Flood Damage Degree Based On Normal Cloud Model

China's monsoon climate has a large area,high flood disaster rate and a wide area of disaster,which have affected people's production and life,aggravated the contradiction between human and land,and damaged the ecological environment seriously.In order to implement the strictest farmland protection system in China,observe the red line of farmland strictly and guarantee regional food security,it is urgent to assess the degree of damage of farmland destroyed by flood,analyse the main elements of farmland destroyed by flood,judge the degree of farmland damaged condition and formulate corresponding measures to restore and improve land capacity as soon as possible.Flood damage is a common form of farmland damage,which can involve all the damage types.Most assessment methods based on one damage type are not suitable,so it is necessary to introduce new methods and ideas.On the basis of summarizing the researcher on cultivated land damage and flood disaster,combining the theories of land fertility,arable land security,sustainable utilization,restoration ecology and disaster science,the key factors and weights of the assessment of the damaged farmland are determined by means of grey correlation analysis and the analytic hierarchy process and the entropy method.Then the assessment index membership for cloud model is generated,and the comprehensive membership degree is determined according to the established assessment criteria.Finally,the damage degree of the five typical damaged area are assessed by normal cloud model.The main conclusions are as follows:(1)Soil organic matter content,soil bulk density,gravel content,effective soil layer thickness,soil pH value,soil surface pressure ratio,irrigation and drainage conditions,road condition are the main factors that affect the quality of farmland after flood.(2)The damage level of Chaoyang village,Dongluo village,Nanmen village and area1 of Jinglan villagein Nan 'an township are moderate,while that of the farmland in area 2of Jinglan village is mild.The damage to farmland by flood is the reducing of soil nutrition by flood and the accumulation of gravel on the farmland which caused by secondary disasters.These affected crop growth and damaged field infrastructure,reducing crop yields.(3)The study also tested the evaluation results with the angle of the qualitative and quantitative analysis,and the results show that:Normal cloud model can make the evaluation results more intuitive.Normal cloud model can consider multiple evaluation indexes synthetically,so it avoid the inaccurate assessment due to the over-emphasis on some evaluation factors.And it can reduce the randomness and uncertainty of subjective human factors and help the evaluation result have an extensive use.The normal cloud model combines the uncertain features such as complexity,randomness and fuzziness in the evaluation of flood damaged farmland,reducing the impacts on the overall evaluation results caused by the fuzziness of a single evaluationindex,improving the relative stability of the assessment results,providing a new way of thinking for the assessment of flood damaged farmland.This study can be used as a reference for scientific assessment to the degree of flood damaged farmland by taking scientific reclamation measures.(4)Due to the complexity of the influencing mechanism of flood destroyed farmland,the research on it is not deep enough at present.The reclamation of flood destroyed farmland started late in China,so there are still many problems in the reclamation of farmland,including institutional weaknesses and difficulties in practical operation.In view of the problems existing in the reclamation of flood-destroyed farmland in the research area,combined with the current situation of flood-destroyed farmland in the research area,measures should be taken according to local conditions in the reclamation of water-destroyed farmland,and the principles of farmland reclamation should be clarified.Adopting scientific fertilizing technology to improve the quality of cultivated land in damaged areas.We should encourage different departments to participate in the reclamation work;establish the management and supervision mechanism;We should also actively guide local people to participate in reclamation work.