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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Residence time of alluvium in an aggrading fluvial system
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Residence time of alluvium in an aggrading fluvial system

机译：冲积物在不断积聚的河流系统中的停留时间

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Relationships between the surface area and age of alluvial deposits were used to estimate the residence time of alluvium in the 2205 km(2) Waipaoa River basin, New Zealand. The contemporary Waipaoa River is an efficient transporter of sediment to the continental shelf, but the basin has been characterized by rapid channel and valley aggradation in the historic period, and by extensive mid- to late Holocene alluvial storage in the lower reaches. The areaweighted mean age of alluvial deposits in the lower part of the river basin is similar to 4400 yr. These deposits comprise terrace remnants isolated by downcutting, and Holocene to Recent sediments that are potentially remobilizable by the modern river. Even though the amount of storage is small relative to downstream transport, the majority of the potentially remobilizable alluvium is likely to remain in storage for > 100 yr, and its half-life (time for 50 per cent removal) is > 2000 yr. Within the confines of the floodplain, the apparent 'loss' of older deposits is due primarily to burial, but losses of the most recent deposits are due almost entirely to remobilization (30-40 per cent), with the remainder preserved in the alluvial record for at least 104 yr. Most of this sediment is likely to remain in storage until there is a shift to a degradational state. Copyright (c) 2006 John Wiley & Sons, Ltd.
机译：冲积物的表面积与年龄之间的关系被用来估算冲积物在新西兰2205 km（2）Waipaoa流域的停留时间。当代的怀波阿河是将沉积物有效输送到大陆架的方法，但该流域的特点是在历史时期内快速的河道和山谷积聚，并在下游有中新世末期广泛的冲积物。流域下部的冲积物的面积加权平均年龄约为4400年。这些沉积物包括通过切屑隔离的阶地残余物，以及全新世至可能由现代河流带走的最近沉积物。即使相对于下游运输而言，其存储量很小，但大多数可迁移的冲积层仍可能在存储中保留> 100年，并且其半衰期（清除时间为50％）> 2000年。在洪泛区范围内，较旧的沉积物明显的“损失”主要是由于埋葬，但最新沉积物的损失几乎完全是由于迁移（30-40％），其余的保留在冲积记录中至少104年。这些沉积物中的大部分可能会保留下来，直到转变为降解状态为止。版权所有（c）2006 John Wiley＆Sons，Ltd.

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