城陵矶至螺山河段槽蓄量及冲淤变化计算

介绍了利用GIS建立河道地形三维表面,计算分析河段槽蓄量以及冲淤变化的主要步骤和具体方法.该方法具有计算精度高、河道形态显示直观、冲淤部位空间分析能力突出等优点.以长江干流城陵矶至螺山河段为例,选用6个测次的河道地形图,计算分析了近30 a来该河段的槽蓄量变化和冲淤时空分布.分析结果表明城陵矶至螺山河段20世纪70年代河道淤积较为严重,1981～1998年冲淤变化不大,1998～2001年平滩河槽有所淤积,近期冲淤基本处于平衡状态.由于在河道形态的显示、冲淤部位的空间分析方面的突出能力,若进一步和河流水沙数学模型以及其他相关分析相结合,基于GIS的河道冲淤变化分析更能有利于发现河道泥沙淤积的规律,为洪灾成因和防洪减灾对策研究提供决策支持.

Computation of channel storage capacity and scouring and silting variation of the Yangtze river from Chenglingji to Luoshan

The main procedure and concrete method for establishment of 3-D surface of channel topography by using GIS and for calculation and analysis of channel storage and changes in scouring and siltation are presented. The method has obvious advantages of higher calculation accuracy, visualized channel morphology and distinct capability of spatial analysis of scouring and siltation locations. Taking the Yangtze river's stem stream reach from Chenglingji to Luoshan as an example, the channel storage changes and the time and spatial distributions of scouring and siltation in recent 30 years in this channel reach are calculated and analysed by using the channel reach's topographic maps obtained from 6 times of surveys. The analysis results show that in 1970s, the siltation in this channel reach was rather serious; in 1981-1998, the changes in scouring and siltation were not great; in 1998-2001, slight siltation took place in the beach-level channel; and in recent period, the scouring and siltation were basically balanced. If it is combined with a mathematical model of channel flow-sediment and with other correlation analysis, the scouring and siltation analysis method based on GIS will be advantageous to finding the rule of channel sedimentation, providing decision support for researches on contributing factors of flood disaster and on flood control and disaster mitigation.