摘要:
本文基于1979~2013年官厅水库动水位的变化特征，利用同时间序列中等分辨率的MSS/TM/ETM+遥感影像，采用主成分分析法，分析动水位条件下官厅水库边岸的变化特征。结合水库边岸宽度差与水位差，对边岸的类型及其空间分布进行了定量的分析，并通过质心变化分析了动水位条件下不同边岸类型的时空变化特征。研究表明：1) 基于官厅水库长时间水位变化速率以及水位涨落的反复性特征，将近35年来的水位变化分成三个阶段：1979~1996年水位间歇性涨落、1996~2007年水位持续下落和2007~2013年水位的频繁涨落阶段。2) 在3个水位波动时间段中，官厅水库侵蚀型边岸的空间分布变化不大，主要分布在官厅水库狭长带两侧，面积依次为0.834 km2、4.50 km2和0.54 km2。淤积型边岸分布呈现内缩趋势，主要分布在康西草原、永定河河口以及妫水河河口一带，面积分别为26.024 km2、31.65 km2和10.11 km2。稳定型边岸在空间分布上变化较大：1979~1996年主要分布于妫水河库区西北弧形岸带、康西草原弧形岸带，面积为10.50 km2；随后在两个弧形岸带向内变化，面积为31.54 km2；而2007~2013年官厅水库边岸主要以淤积为主，仅有少许稳定型边岸零星分布，面积为0.24 km2。3) 35年来不同水库边岸的质心发生了不同程度的偏移，淤积型边岸有明显的向内扩张的趋势，其质心在东偏北16.19˚方向上移动2.82 km后往东偏南4.97˚方向上移动1.97 km。侵蚀型边岸质心在东南方向偏移后转向东北方向，稳定型区域发生变化，其趋势和格局分布变化原因与淤积型一致。
Abstract:
Using moderate resolution remote sensing images MSS/TM/ETM+, the paper detected the changes of Guanting Reservoir shore in conditions of different water levels using the principal components analysis method (PCA), based on the variation water levels during 1979 and 2013. According to the ratio of reservoir bank width and water head, we confirmed the distribution of the silted bank, the stable bank and the eroded bank, and combined with the changes in centroids of three types of banks to analyze characteristics of temporal and spatial variation of each bank type during three periods. The results showed that: 1) in the three periods, the distribution of erosion coast changed little, mainly located in both sides of the narrow zone and the southwestern coast of Yongding River, with 0.834 km2, 4.50 km2 and 0.54 km2 respectively; 2) the silted bank showed an inward trend, mainly distributed in the Kang Xi prairie, the Yongding River estuary and the Guishui River estuary. The areas of each region are 26.024 km2, 31.65 km2 and 10.11 km2; 3) the distribution of stable coast varied: mainly distributed in the northwest Guishui River and Kang Xi prairie arc-shaped coast, with area of 10.50 km2 in 1979-1996; then expanded to the two arc-shaped coast inward, with area of 31.54 km2; during 2007 and 2013, only a little stable coast distributed sporadically, and the area is 0.24 km2; 4) in 35 years, each type of reservoir bank shifted to different extents; the centroid in silted bank moved 2.82 km towards east-north direction in 16.19˚, then moved 1.97 km towards east-north direction in 4.97˚. The centroid of erosion coast had the same tendency with the silted bank, moving 3.79 km on the direction of east-north in 27.18˚ and 1.87 km of east-north in 56.31˚. Compared with 1996-2007, the centroid of stable bank moved 0.52 km to the northeast of 9.46 in 1979-1996, then moved 1.84 km towards west-north direction in 51.34˚.