基于Landset TM/ETM 和HJ 1A/B影像的丹江口水库水域变化监测研究

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10 a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10 a整体来看，水库水域面积基本维持在300 km2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10 a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

WATER SURFACE MONITORING OF THE DANJIANGKOU RESERVOIR USING REMOTELY SENSED LANDSAT TM/ETM AND HJ 1A/B IMAGERY

The Danjiangkou Reservoir located at the junction of Hubei and Henan province, is the water source area of the Middle Route of China's South to North Water Transfer Project. Monitoring of the water resource in the reservoir is critical for the inter basin water transfer project. In this study, we collected 47 Landsat TM/ETM and HJ 1A/B remotely sensed imageries for monitoring changes of water surface using Normalized Different Water Index(NDWI) based on the threshold segmentation method in the reservoir from 2002 to 2011. The results indicated that water surface decreased from December to March of the next year, increased from March to December, and the minimal and maximal water area appeared in February and December respectively. Water area had larger variations in the wet season than that in the dry season due to the seasonality of precipitation in the upper Han river and reservoir management, and the water area standard deviation was 66.8 and 44.2, respectively. The inundation area ranged between 316.4 km2 on September 25, 2002 and 562.3 km2 on December 13, 2011 in the wet season because of the anomalous weather, but fluctuated between 291.5 km2 on April 18, 2011 and 483.2 km2 on June 24, 2009 in the dry season. Significant seasonality variability was also found during the past ten years. The water surface area was relatively stable in spring (water area ratio and standard deviation were 1.55 and 44.11) and summer (water area ratio and standard deviation were 1.40 and 44.56 ), but fluctuated dramatically in autumn(water area ratio and standard deviation were 1.67 and 73.16 ) and winter(water surface area ratio and standard deviation were 1.63 and 70.87 respectively). In order to ensure water storage in the dry season, the management department should strengthen monitoring and increase storage reasonably so that there are enough water to supply to the North China after the project finished. Water surface area of the Danjiangkou Reservoir was almost kept larger than 300 km2, and presented a growth trend in May, in which the water area was most stable. The same growth trend was also found in wet season, dry season and the whole past 10 years. The increased water area was mostly located in the east and north of the reservoir, where soil erosion and non point source pollution should be concerned