基于GCT模型的洞庭湖一般垸划分

General Polder Division of Dongting Lake Based on GCT Model

一般垸是洞庭湖特有的堤垸形式,但随着社会经济发展,各个一般垸的防洪保护对象已存在较大差异,急需进一步确定洞庭湖一般垸在防洪划区时所归属的类别,以制定相应的防洪措施。通过GCT图形几何变换,结合人口密度、每千米堤防保护人数、堤防等级、蓄洪损失、耕地面积、重要性参数,建立一般垸的防洪保护区、蓄滞洪区形状相似性判定模型,完成洞庭湖区230个一般垸划分。防洪保护区参考值6维雷达图的各项参数依次为900人/km2,0.46人/km,2级堤防,32元/m^(3),666.67 hm^(2)耕地,重要性2分;蓄滞洪区参考值6维雷达图的各项参数依次为600人/km2,0.18人/km,4级堤防,32元/m^(3),66.67 hm^(2)耕地,重要性1分。运用Matlab对数据进行归一化处理,将每一个一般垸的6项参数划为范围在1~5以内的无量纲,并绘制成6维雷达图,同时完成与防洪保护区参考值6维雷达图的相似性判定,判定结果为不相似的一般垸,继续与蓄滞洪区参考值6维雷达图进行相似性判定,仍然不相似的,判定为洪泛区。划分结果表明,防洪保护区67个、蓄滞洪区53个、洪泛区110个。通过对结果进行进一步分析,提出了模型修改意见与后续一般垸规划建议,为洞庭湖区一般垸拟开展的防洪保护区、蓄滞洪区、洪泛区划分工作提供了参考。

The general polder is a unique polder form of Dongting Lake.However,with the development of social economy,the flood control protection objects of various general polders are quite different.It is urgent to further determine the classification of general polders in Dongting Lake during the flood control zoning,so as to formulate appropriate flood control measures.Using the geometric transformation of GCT graph,combined with population density,number of people protected by levees per kilometer,levee grade,flood storage loss,cultivated land area and importance parameters,Establish a model for judging the shape similarity of flood protection areas and flood storage and detention areas of general polders,230 general polders in Dongting Lake area were divided.The parameters of the 6-dimensional radar map of the reference value of the flood protection area are 900 people/km2,0.46 people/km,Grade 2 embankment,32 yuan/m^(3),666.67 hectares of arable land,2 points for importance.The parameters of the 6-dimensional radar map of the reference value of the flood storage and detention area are 600 people/km2,0.18 people/km,Grade 4 embankment,32 yuan/m^(3),66.67 hectares of arable land,1 point for importance.Use Matlab to normalize the data,divide the 6 parameters of each general polders into dimensionless ones within the range of 1~5,and draw a 6-dimensional radar map.At the same time,the similarity judgment of the 6-dimensional radar map with the reference value of the flood protection area is completed,and the judgment result is general polder that is not similar,continuing to determine the similarity with the 6-dimensional radar map of the reference value of the flood storage and detention area.If it is still not similar,it will be determined as a flood area.The results show that there are 67 flood protection areas,53 flood storage and detention areas and 110 flood areas.Through a further analysis of the results,suggestions on model modification and subsequent general polders planning are put forward.It serves as a reference for the division of flood protection area,flood storage and detention area and flood plain to be carried out in the general polders of Dongting Lake Area.