鄱阳湖水文特征动态变化遥感监测

鄱阳湖是中国第一大淡水湖,对鄱阳湖的水文变化进行持续监测可以为流域内生态环境变化提供基础数据,有利于研究其与长江和流域内河流的交互关系,更好地服务于陆面过程模式和水资源管理。本文利用卫星测高数据反演的鄱阳湖水位数据与MODIS数据结合,对鄱阳湖2000—2015年的水位、水域面积和水量变化进行研究,并通过水量平衡模型,推导出了同期长江—鄱阳湖的水量交互。研究发现,2000—2015年鄱阳湖面积呈现波动性变化,最大水域面积为3600 km ²,是最小水域面积482 km ²的7.5倍。2004年、2007年、2009年和2011年水域面积比较低,2012年后形势好转。每年1月、2月、12月份是鄱阳湖干季,水域面积低至500 km ²,湖口处水位可低至4.71 m,湖面从南往北倾斜,南北水位差异达2.59 m。相对于2000—2015年最低水量,干季时湖泊水量平均增加量为3 km ³。每年6—9月份是鄱阳湖的湿季,水域面积一般大于2670 km ²,水位高于15 m,南北水位差异不大,相对于2000—2015年最低水量,湿季时湖泊水量平均增加量为12 km ³。2000—2015年鄱阳湖流入长江的水量范围为-7~40.66 km ³,每年有93.33%的时间水流从鄱阳湖流入长江。流入长江的水量多少具有明显的季节性,通常5月、6月流入长江的水量高于7月、8月,主要因为7月、8月长江中上游降水增加,长江干流来水增多,对鄱阳湖湖水倒灌有一定的顶托作用。

Hydrologic changes of Poyang Lake based on radar altimeter and optical sensor

Poyang Lake is the largest freshwater in China. Continual monitoring on its hydrologic changes can supply basic data for ecological environment researches and is favorable for studying the exchange between the Poyang Lake and the Yangtze River or other rivers in the watershed. Hydrologic changes of Poyang Lake are essential to land-surface process studies and water resources management. Altimeter data and high-frequency MODIS images were used in this paper to obtain water levels, inundation extents and lake storage changes of Poyang Lake during 2000-2015. Then water exchange between Poyang Lake and Yangtze River was estimated based on water balance equation. The results showed that lake inundation presented a large fluctuation and an obvious seasonality. The maximum area was 3600 km^2, approximately 7.5 times of the minimum(482 km^2). Areas in the years 2004, 2007, 2009 and 2011 were smaller and the situation improved after 2012. The extent shrunk to less than 500 km^2 in dry season(January, February and December) when water level at Hukou Station was only 4.71 m.At that time, the water surface inclined from south to north, and the water level difference between south and north could reach 2.59 m. The increase of lake storage in dry season was 3 km^3 relative to the minimum during the study period. Surface extent was usually greater than2670 km^2 in wet season(June-September) when water level was higher than 15 m and the surface was almost flat. The increase of lake storage in wet season was 12 km^3 relative to the minimum during 2000-2015. Water exchange between Poyang Lake and Yangtze River was from 7 km^3 to 40.66 km^3 during the research period and water from the lake to the river occurred in 93.33% time of the year. The flow water volume had obvious seasonality. Usually,the exchanged volume in May and June was more than that of July and August when precipitation increased in the upper-middle reaches of Yangtze River, thus more volume of the main stream and water was hindered to flow from Poyang Lake to Yangtze River.