Determining contemporary and historical sediment sources in a large drainage basin impacted by cumulative effects: the regulated Nechako River, British Columbia, Canada
Determining contemporary and historical sediment sources in a large drainage basin impacted by cumulative effects: the regulated Nechako River, British Columbia, Canada
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DOI：
10.1007/s11368-019-02299-2
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发表时间：
2019-09-01
影响因子：
3.6
通讯作者：
Dery, Stephen J.
中科院分区：
文献类型：
--
作者：
Gateuille, David;Owens, Philip N.;Dery, Stephen J.
研究目的大多数大型河流流域的沉积物动力学受到各种不同的自然和人为压力的影响，解开这些累积效应仍然是一个挑战。这项研究确定了一个大型受管制河流流域中细粒（< 63 μ m）沉积物的当代和历史来源，并将来源变化与流域活动联系起来。这条河的奇努克鲑鱼、红鲑和濒临灭绝的内查科白色鲟鱼数量有所下降，沉积物（细粒和沙子）的运输和沉积被认为是这些下降的潜在原因。材料和方法悬浮沉积物和潜在的源材料的样品，收集了分布在加拿大不列颠哥伦比亚省，整个上Nechako河流域的许多网站。还收集了河漫滩沉积物岩心，以重建沉积物来源，在过去类似的70年。在MixSIAR模型中使用了鉴别指纹特性，以在子流域和土地利用类型之间分配源。结果进行了比较记录的降水量和Nechako河流量的趋势，并在景观发展的变化。结果与讨论在大多数站点，来自河道河岸侵蚀的贡献占悬移质泥沙的主导地位。2015年田间季节沉积物来源的变化反映了Nechako水库的融雪和放水模式，影响了支流和Nechako河干流的泥沙承载能力。2015年的空间变化也反映了土地利用的分布（例如，森林或农业用地）以及地形（例如，斜率陡度）。在过去近70年的时间里，沉积物来源和沉积物特征（例如，有机物含量和粒度组成）与肯尼大坝（1954年运行）的建设以及林业和农业部门毁林的影响有关。加上野火和严重的山地松树甲虫侵扰，导致受影响地区的侵蚀率更高。结论沉积物来源指纹技术结合流域水文气象、土地利用和河流管理的历史信息，为了解Nechako河流域沉积物动态提供了有价值的信息。这种方法可以帮助解开大型河流系统如何应对自然和人为压力的组合。
Purpose Sediment dynamics in most large river basins are influenced by a variety of different natural and anthropogenic pressures, and disentangling these cumulative effects remains a challenge. This study determined the contemporary and historical sources of fine-grained (< 63-mu m) sediment in a large, regulated river basin and linked changes in sources to activities in the basin. The river has seen declines in chinook salmon, sockeye salmon, and the endangered Nechako white sturgeon populations, and sediment (both fine-grained and sands) transport and deposition have been identified as potential causes of these declines. Materials and methods Samples of suspended sediment and potential source materials were collected from numerous sites distributed throughout the upper Nechako River Basin in British Columbia, Canada. A floodplain sediment core was also collected in order to reconstruct sediment sources over the last similar to 70 years. Discriminating fingerprint properties were used within the MixSIAR model to apportion sources among sub-basins and land-use types. Results were compared to records of precipitation and Nechako River discharge trends, and to changes in landscape development. Results and discussion Contributions from the erosion of channel banks dominated the suspended sediment load at most sites. Changes in sediment sources during the 2015 field season reflected snowmelt and patterns of water release from the Nechako Reservoir that affected the sediment-carrying capacity of tributaries and the Nechako River main stem. Spatial variations in 2015 also reflected the distribution of land use (e.g., forested or agricultural land) as well as topography (e.g., slope steepness). Over the last similar to 70 years, variations in sediment sources and the characteristics of the sediment (e.g., organic matter content and particle size composition) were linked to the construction of the Kenney Dam (operational in 1954) and the impacts of deforestation by the forestry and agricultural industries. Superimposed on these have been wildfires and a major mountain pine beetle infestation leading to higher erosion rates in the affected areas. Conclusions The sediment source fingerprinting technique, in combination with historical information on the hydrometeorology and the land use and river management in the basin, has provided valuable information with which to understand sediment dynamics in the Nechako River Basin. Such an approach can help to disentangle how large river systems respond to a combination of natural and anthropogenic pressures.