The negative relief of large river floodplains
The negative relief of large river floodplains
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DOI：
10.1016/j.earscirev.2013.10.014
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发表时间：
2014-02
影响因子：
12.1
通讯作者：
J. Lewin;P. Ashworth
中科院分区：
文献类型：
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作者：
J. Lewin;P. Ashworth
大型洪泛平原有多个复杂的负起伏组合，其中洼地以各种尺度落在局部或一般洪泛平原表面以下。描述和比较了沿主要冲积廊道的负起伏沿着的产生和动态。这些洼地对于地表沃茨的储存和通行、形成一系列河岸、湿地、湖泊和流水生境以及有机物质的长期积累都具有重要意义。河流作用于主河道遗迹、淹没河谷和沉降盆地，通过差异侵蚀和沉积作用改变洪泛平原的负地形。实际上，这发生在三个遗传区：流变，过渡和周流。我们发现，过渡区边缘活跃的渠道显着多样化的形式复杂，我们展示了穿时性的地带性过程和复杂的性质和步伐的抑郁症的修改和填充。评估了四组不太清楚的耦合现象：（i）与不连续河岸相关的洪泛平原，（ii）滚动条生成的规模和类型，（iii）曲流和辫状平原表面起伏之间的对比的潜在因素，（iv）大洪泛平原湿地和湖泊的生成和功能。这针对每个流变区、过渡区和围流区进行了描述。当代水生系统管理的影响进行了讨论。理解和管理大型河流洪泛区及其相关生态和沉积的负起伏的关键是量化沉积学和水文学的河流洪泛区连通性。
Large floodplains have multiple and complex negative relief assemblages in which depressions fall below local or general floodplain surfaces at a variety of scales. The generation and dynamics of negative relief along major alluvial corridors are described and compared. Such depressions are significant for the storage and passage of surface waters, the creation of a range of riparian, wetland, lacustrine and flowing-water habitats, and the long-term accumulation of organic materials.Working on trunk channel remnants, drowned valleys and subsidence basins, fluvial processes modify floodplain negative relief through differential erosion and sedimentation. Effectively this takes place in three genetic zones: rheic, transitional and perirheic. We show that transitional zones marginal to active channels significantly diversify form complexes, and we demonstrate the diachronous nature of zonal processes and the complex nature and pace of depression modification and infilling. Four less well-understood sets of coupled phenomena are assessed: (i) floodplains associated with discontinuous river banks, (ii) the scales and types of scroll bar generation, (iii) factors underlying the contrasts between meander and braidplain surface relief, and (iv) the generation and function of large floodplain wetlands and lakes.The survival likelihood of surface negative relief relates to geomorphological connectivity; this is described for each of the rheic, transitional and perirheic zones. The implications for contemporary aquatic system management are discussed. A key to understanding and managing negative relief on large river floodplains, and their associated ecologies and sedimentation, is to quantifybothsedimentological and hydrological river-floodplain connectivity.