Synergistic remote sensing of Lake Chad: Variability of basin inundation
Synergistic remote sensing of Lake Chad: Variability of basin inundation
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DOI：
10.1016/s0034-4257(99)00105-4
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发表时间：
2000-05-01
影响因子：
13.5
通讯作者：
Birkett, CM
中科院分区：
文献类型：
--
作者：
Birkett, CM
近几十年来，干旱和人为影响导致乍得湖缩小，对粮食和水资源产生不利影响。当地居民已学会适应湖盆季节性泛滥减少的情况，但容易受到干旱和过多流入的影响。在这里，协同卫星雷达测高和近红外图像，以获得目前的洪水模式的知识。利用TOPEX/POSEIDON卫星的数据，得出了20世纪90年代流入河流和永久性和季节性湖泊沃茨的地表水位变化。美国国家海洋和大气管理局的高级甚高分辨率辐射计图像提供了从1995年到1998年流域淹没的其他变化，使用一个简单的像素直方图技术。在精度大于或等于10 cm rms的情况下，测高显示了0.5-6 m数量级的季节性水位变化，湖盆内的最低水位显著上升，每年15-35 cm（-1）。在沙里河/洛贡河的源头和西部湖泊沼泽地之间也观察到4至5个月的峰值相位滞后。图像结果显示，永久湖泊面积约为1.385 km（2），并且以近似5%的精度，周围地区已额外遭受洪水，最多可达3，600 km（2）年（-1）。尽管目前盆地的复杂性，协同面积/水平测量证实了已知的水力关系在低水位。这两套测量数据反映了1993/1994年和1997/1998年洪水泛滥年份的情况，尽管有迹象表明区域降水量、洪水泛滥程度和地表水水位普遍恢复，但这两套测量数据为这些遥感技术提供了一种额外的工具，用于洪水/干旱预测和提供未来的快速交付数据，这是一种近实时监测机制。(C)Elsevier Science Inc.，2000.
During recent decades, drought and anthropogenic influences have led to the diminishment of Lake Chad with adverse effects on both food and water resources. The local population has learned to adapt to the reduced seasonal inundation of the lake basin but are vulnerable to both droughts and excessive inflows. Here synergistic satellite radar altimetry and near-infrared imagery are employed to gain knowledge of the current flooding patterns. Variations in surface level for the inflowing rivers and the permanent and seasonal lake waters are derived for the 1990s using data from the TOPEX/POSEIDON satellite. National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer images provide additional variations of basin inundation from 1995 to 1998, using a simple pixel histogram technique. With accuracy greater than or equal to 10cm rms, the altimetry reveals seasonal water-level variations of the order 0.5-6 m and there is a notable rise in minimum levels, 15-35 cm year(-1) within the lake basin. Peak-level phase lags of 4 to 5 months are also observed between the headwaters of the Chari/Logone rivers and the western lake marshes. Image results reveal that the permanent lake area is similar to 1.385 km(2), and that with an accuracy of similar to 5% the surrounding regions have been additionally flooding by up to similar to 3,600 km(2) year (-1). Despite current basin complexities, the synergistic area/level measurements corroborate the know hydraulic relationship at low water levels. Both measurement sets reflect the poor inundation years of 1993/1994 and 1997/1998, despite the indication of a general recovery in regional precipitation, inundation extent, and surface water level offers these remote sensing techniques as an additional tool for flood/drought forecasting and the availability of future fast delivery data, a mechanism for near-real time monitoring. (C) Elsevier Science Inc., 2000.