Global compilations of river sediment loads show that mountainous areas produce a high proportion of the sediment transported to the oceans. However, because of the effort involved in measuring sediment fluxes in mountain river systems, the loads of these rivers are generally unknown. Here, we present estimates of contemporary sediment loads of 16 gravel bed rivers draining the Ecrins-Pelvoux Massif in southeast France. Sediment production in this part of the Alps is relatively high and many river segments are either wandering or braided. We model sediment fluxes and annual sediment yields by coupling hydraulic-based relations for sediment transport with hydrologic-based relations for flow frequency. Bed load fluxes are modeled for a range of discharges using a function that relates transport rates to excess shear stress. Fluxes are then weighted by the frequency of individual discharges and summed to get the annual bed load for each site. The suspended load is estimated empirically as a fraction of the bed load. Results suggest that bed load fluxes at channel-forming flows scale almost linearly with downstream increases in discharge. In addition, it appears that annual sediment loads (bed load + suspended load) scale linearly with drainage area. A complementary relation for specific sediment yield suggests that the load per unit drainage area is constant across the range of basins studied. The modeled sediment yields are comparable to previous field-based estimates of modern sediment yields, and generally lower than estimates developed from analyses of cosmogenic radionuclides.

中文翻译：

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法国高山河流的沉积物生产

全球河流泥沙负荷的汇编表明，山区产生了大部分输送到海洋的泥沙。然而，由于测量山区河流系统中的泥沙通量所付出的努力，这些河流的负荷通常是未知的。在这里，我们提供了对法国东南部 Ecrins-Pelvoux 地块排水的 16 条砾石床河流的当代沉积物负荷的估计。阿尔卑斯山的这一部分沉积物产量相对较高，许多河段要么是蜿蜒的，要么是辫状的。我们通过将基于水力的泥沙输送关系与基于水文的流量频率关系耦合来模拟泥沙通量和年泥沙产量。使用将传输速率与过度剪切应力相关联的函数，针对一系列排放对床负载通量进行建模。然后，通量按个别排放的频率加权并求和，以获得每个地点的年度河床负荷。悬浮载荷根据经验估计为床载荷的一部分。结果表明，河道形成流中的床负荷通量随着下游流量的增加几乎成线性比例。此外，似乎年泥沙荷载（河床荷载+悬浮荷载）与流域面积呈线性关系。特定沉积物产量的互补关系表明，在研究的盆地范围内，每单位流域面积的负荷是恒定的。模拟的沉积物产量与以前基于实地的现代沉积物产量估计值相当，并且通常低于从宇宙放射性核素分析得出的估计值。