汉江中下游消落区及水域面积时空变化分析

基于1987～2017年Landsat时序数据,提取汉江中下游河流消落区及水域面积和淹没频率逐年变化信息,分析消落区及水域时空变化过程及阶段性特征。结果表明:汉江消落区呈上游宽下游窄的特征分布,消落区面积最为集中的区域位于中游的宜城-钟山口段,相对较少的区域位于下游的仙桃-汉川段。在过去30年间,汉江中下游消落区平均面积在76到256 km~2之间波动,水域面积在183～550 km~2之间变化,水域及消落区面积均呈波动特征并存在较大时空差异。汉江中下游总体淹没频率在1987～2001年间呈减小特征,2002～2017年存在增加趋势。汉江中下游大型水利枢纽工程库区的水域面积、淹没频率在水库建成后大幅度增加,消落区面积波动幅度减小;而非水库地区的水域及消落区面积无明显增减趋势。

Spatio-temporal Changes of the Water-Level Fluctuation Zone and Inundation Areas in Middle and Lower Reaches of the Hanjiang River

Based on timeseries of the Landsat images from 1987 to 2017, the information of water-level fluctuation zone and inundation frequency in middle and lower reaches of the Hanjiang River was extracted, and the spatial and temporal changes and phase characteristics of the water-level fluctuation zone and water area were analyzed. The results show that in the past 30 years, the average area of fluctuation zone ranges from 76 to 256 km2, and water areas ranges from 183 to 550 km2, but it differs among different regions. In general, the fluctuation zone is characterized by a wide upstream and a narrow downstream. The area with the largest area of the water-level fluctuation zone is located in the Yicheng-Zhongshankou section of the middle reaches, and the smallest area is located in the Xiantao-Hanchuan section of the lower reaches. The overall inundation frequency of middle and lower reaches of Hanjiang River decreased in 1987-2001 and increased in 2002-2017, indicating the change of the temporal rhythm of the water-level fluctuation zone. The characteristics of the water area, fluctuation zone and the inundation frequency differ between in the large reservoir regions and in others. The water area and the inundation frequency of the reservoir regions increase greatly after the completion of the reservoir, and the fluctuation zone range decreases. But in other regions, the water and fluctuation area change little, and the inundation frequency increases first and then decreases.