Spatial and Temporal Evolution of an Avulsion on the Taquari River Distributive Fluvial System from Satellite Image Analysis
Spatial and Temporal Evolution of an Avulsion on the Taquari River Distributive Fluvial System from Satellite Image Analysis
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卫星图像分析塔夸里河分布式河流系统撕脱的时空演化
DOI：
10.2110/jsr.2011.040
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发表时间：
2011
影响因子：
2
通讯作者：
A. Hartley
中科院分区：
文献类型：
--
作者：
H. Buehler;G. Weissmann;L. Scuderi;A. Hartley
已经使用基于实地的研究观察和分析了剥离过程，然而，很少通过使用卫星图像进行分析，即使这样的方法可以记录所产生的沉积物的空间和时间变化。为了记录巴西塔夸里里河Caronal撕脱带发生的变化，汇编了1985年至今（2010年）的陆地卫星图像时间序列。截至2010年7月，图像显示，撕脱尚未完成，流量被引导到洪水流域的主河道和撕脱河道。当水流通过两个小裂缝从主河道转向洪泛流域时，撕裂开始了，这使得展曲得以发展和演变，只有一个展曲自1999年以来才稳定下来。撕脱区的特点是新的扇体的生长、撕脱带的形成以及撕脱沉积物向洪泛盆地的扩散。随着时间的推移，撕脱现场下游的主河道宽度逐渐减小，这与撕脱河道捕获的水和沉积物体积较大有关。由于这种撕脱尚未完成，我们预计随着撕脱带演变成主河道，会发生更多的形态变化。由这种撕脱作用引起的快速沉积和捕获这种变化的24年时间序列的图像使我们能够构建一个3D块，代表与撕脱作用相关的沉积环境的演变，使用垂直维度的时间。因此，我们可以代表地貌模式的演变，包括洪泛盆地，近堤，远堤，河道沉积物，并预测其随时间的分布。这一不断演变的沉积背景块可以作为未来沉积学研究的指导，提供有关沉积体系跟踪撕脱引发的变化的方式的视觉线索。
Avulsion processes have been observed and analyzed using field based studies, however, they have rarely been analyzed through use of satellite imagery even though such an approach allows documentation of spatial and temporal variations of the resulting deposits. In order to document changes that are occurring at the Caronal avulsion on the Taquari River, Brazil, a time series of LANDSAT imagery from 1985 to present (2010) was compiled. As of July 2010, the imagery shows that the avulsion is not yet complete, with discharge being routed to both the parent channel and the avulsion channel in the floodbasin. The avulsion was initiated as flow was diverted from the parent channel to the floodbasin through two small crevasses, allowing the development and evolution of splays, with a single splay stabilizing only since 1999. The avulsion area is marked by the growth of new splays, the formation of an avulsion belt, and progradation of avulsion deposits into the floodbasin. The parent channel downstream of the avulsion site has experienced decreasing width through time, associated with the higher volumes of water and sediment being captured by the avulsion channel. Because this avulsion is not yet complete, we expect more morphological changes to occur as the avulsion belt evolves into the primary channel. Rapid sedimentation caused by this avulsion and the 24-year time series of imagery that captured this change allowed us to construct a 3D block representing the evolution of depositional environments associated with avulsion, using time in the vertical dimension. Thus we could represent the evolution of geomorphological patterns, including floodbasin, proximal levee, distal levee, and channel deposits, and project their distributions through time. This block of evolving sedimentary settings can be used as a guide for future sedimentologic studies by offering visual clues regarding the way which depositional systems track avulsion-initiated changes.