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位于湖北和河南两省交界的丹江口水库是南水北调中线工程的水源地,水库的水域变化监测与评估,对保障水库调水能力具有重要意义。收集了2002~2011年47幅Landsat TM/ETM和HJ-1A/B卫星遥感影像,采用基于阈值分割的归一化水体指数法(NDWI)提取了过去10a的水库水域动态信息。结果表明:水库各月份平均水域面积从12月至次年3月,呈现下降趋势,而从3月到12月,呈现波动上升的趋势,最小水域面积出现在3月份,最大水域面积出现在12月份;由于受上游明显季节性降雨及水库运行管理的影响,丹江口水库丰水期(7月~次年1月)水域面积较枯水期(2月~6月)波动更为明显。而四季之中,春夏季节水库水域面积相对稳定,秋冬季节水域面积波动较大。针对枯水季节水库水量少的情况,管理部门应该加强监测力度,合理调蓄,保证水库的供水能力。从过去10a整体来看,水库水域面积基本维持在300km2以上,通过分析水库水域面积波动较小、影像积累最多的5月份遥感影像,发现水库水域面积呈现增长趋势,并且在枯水期、丰水期和过去10a整体上都呈现了不同程度的增长趋势;此外,水库蓄水新增的水域面积主要集中在水库东、北部地区,应加强对这部分地区的生态恢复和环境监测。
Danjiangkou Reservoir, located at the border between Hubei and Henan provinces, is a water source for the mid-route of the South-to-North Water Diversion Project. Monitoring and assessing changes in the water area of reservoirs is of great significance for ensuring reservoir water diversion capability. Forty-seven Landsat TM / ETM and HJ-1A / B satellite remote sensing images were collected from 2002 to 2011, and the past 10 years of reservoir water dynamic information were extracted by the normalized water index based on threshold segmentation (NDWI). The results show that the average water area in each month of the reservoir shows a downward trend from December to March of next year, while the trend of fluctuation shows a rising trend from March to December. The minimum water area appears in March and the maximum water area appears in 12 Month. Due to the obvious seasonal rainfall in the upper reaches and the operation and management of reservoirs, the water area of the Danjiangkou Reservoir in the wet season (July to January) is more obvious than that in the dry season (February to June). Among the four seasons, the water area of reservoirs in spring and summer is relatively stable, and the water area fluctuates greatly in autumn and winter. For the dry season, less water reservoir situation, management should strengthen the monitoring efforts, reasonable storage, to ensure that the reservoir’s water supply capacity. From the past 10 years as a whole, the reservoir water area basically maintained at 300km2 above, by analyzing the reservoir area less volatile, the most accumulated image of May remote sensing images and found that the reservoir water area showed an upward trend, and in dry season, wet season and In the past ten years, all of them showed different degrees of growth trend. In addition, newly added water area of the reservoir was mainly concentrated in the east and the north of the reservoir, and ecological restoration and environmental monitoring should be strengthened in this area.