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首页> 外文期刊>River Research and Applictions >TOLEDO BEND RESERVOIR AND GEOMORPHIC RESPONSE IN THE LOWER SABINE RIVER
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TOLEDO BEND RESERVOIR AND GEOMORPHIC RESPONSE IN THE LOWER SABINE RIVER

机译：下萨比恩河的托莱多弯曲储层和地貌响应

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摘要

Downstream geomorphic responses of stream channels to dams are complex, variable, and difficult to predict, apparently because the effects of local geological, hydrological, and operational details confound and complicate efforts to apply models and generalizations to individual streams. This sort of complex geomorphic response characterizes the Sabine River, along the Texas and Louisiana border, downstream of the Toledo Bend dam and reservoir. Toledo Bend controls the flow of water and essentially prevents the flux of sediment from three-quarters of the drainage basin to the lower Sabine River. Although the channel is scoured immediately downstream of the dam, further downstream there is little evidence of major changes in sediment transport or deposition, sand supply, or channel morphology attributable to the impoundment. Channels are actively shifting, banks are eroding, and sandbars are migrating, but not in any discernibly different way than before the dam was constructed. The Sabine River continues to transport sand downstream, and alluvial floodplains continue to accrete. The relatively small geomorphic response can be attributed to several factors. While dam releases are unnaturally flashy and abrupt on a day-to-day basis, the long-term pattern of releases combined with some downstream smoothing creates a flow regime in the lower basin which mimics the pre-dam regime, at least at monthly and annual time scales. Sediment production within the lower Sabine basin is sufficient to satisfy the river's sediment transport capacity and maintain pre-dam alluvial sedimentation regimes. Toledo Bend reservoir has a capacity: annual inflow ratio of 1.2 and impounds 74% of the Sabine drainage basin, yet there has been minimal geomorphic response in the lower river, which may seem counterintuitive. However, the complex linked geomorphic processes of discharge, sediment transport and loads, tributary inputs, and channel erosion include interactions which might increase as well as decrease sediment loads. Furthermore, if a stream is transport-limited before impoundment, the reduced sediment supply after damming may have limited impact.
机译：河道对大坝的下游地貌响应是复杂，易变且难以预测的，这显然是因为当地地质，水文和运营细节的影响使将模型和归纳应用于单个河道的努力变得复杂和复杂。这种复杂的地貌响应是托莱多本德大坝和水库下游沿德克萨斯和路易斯安那州边界的萨宾河的特征。托莱多弯道控制着水流，从根本上防止了沉积物从四分之三的流域流入萨宾河下游。尽管河道是在大坝的下游直接冲刷的，但在更下游的地方，几乎没有证据表明由于蓄水造成的沉积物运输或沉积，砂的供应或河道形态发生重大变化。渠道正在积极转移，堤坝正在侵蚀，沙洲正在迁移，但与修建大坝之前没有任何明显的不同。萨宾河继续向下游输送沙子，冲积洪泛区继续增加。相对较小的地貌响应可以归因于几个因素。虽然大坝的释放每天都异常地闪闪发光和突然，但长期的释放模式与下游的平滑作用相结合，在下流域形成了一种类似于大坝前状态的流态，至少在每月和每月一次。年度时间尺度。萨宾河下游盆地的泥沙产生足以满足河流的泥沙输送能力并维持大坝前的冲积作用。托莱多本德水库的容量为：年流入比为1.2，占萨宾河流域的74％，但下游河流的地貌响应最小，这似乎与直觉相反。然而，排放，泥沙输送和负荷，支流输入和河道侵蚀等复杂的链接地貌过程包括相互作用，这些相互作用可能会增加和减少泥沙的负荷。此外，如果在蓄水之前限制了河流的流量，则在筑坝后减少的泥沙供应可能会产生有限的影响。

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