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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Scale variation of post-glacial sediment yield in Chilliwack Valley, British Columbia
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Scale variation of post-glacial sediment yield in Chilliwack Valley, British Columbia

机译：不列颠哥伦比亚省奇利瓦克谷冰川后沉积物产量的尺度变化

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The Holocene volumetric sediment budget is estimated for coarse textured sediments (sand and gravel) in a large, formerly glaciated valley in southwest British Columbia. Erosion is estimated by compiling volumetric loss estimated in digital elevation models (DEMs) of gullied topography and by applying a non-linear diffusion model on planar, undissected hillslopes. Estimates of steepland yield are based on estimates of post-glacial deposition volumes in fans, cones and deltas at the outlets of low-order tributary catchments. Erosion of post-glacial fans and tributary valley fills is estimated by reconstructing formerly continuous surfaces. Results are classed by catchment order and compared across scales of contributing area, revealing declining specific sediment yield (in m3km-2a-1) with catchment area for the smaller tributaries (<10km2) and increasing specific sediment yield for larger tributaries and Chilliwack Valley itself. Approximately 60% of mobilized sediment is redeposited in first- to third-order catchments, with lesser proportions stored at the outlets of higher order catchments. A simple network routing model emphasizes the significant sediment flux contributions from colluvium, drift blankets and gullies in steeper terrain. As this material is deposited at junctions within the lower drainage network, an increasing proportion of material is derived from remnant valley fills and para-glacial fans in the major valleys. Yield from lower-order, steepland catchments tends to remain in storage, indefinitely sequestered on footslopes. These observations have implications for modelling the post-glacial sediment balance amongst catchments of varying size. After 104 years, the system remains in disequilibrium. The critical linkage lies between low-order, hillslope catchments (
机译：估计全新世体积沉积物的预算是不列颠哥伦比亚省西南部一个大的，以前为冰河谷的粗纹理沉积物（沙和砾石）的总和。通过编辑在沟状地形的数字高程模型（DEM）中估计的体积损失并在平面的，未解剖的山坡上应用非线性扩散模型来估计侵蚀。陡坡产量的估算是基于低阶支流集水口出口扇形，圆锥形和三角洲冰川后沉积量的估算。通过重建以前连续的表面来估算冰川后扇和支流谷填充物的侵蚀。结果按集水顺序分类，并在各个贡献区域进行比较，发现较小的支流（<10km2）的特定沉积物产量（以m3km-2a-1为单位）随着集水面积的减少而较大的支流和奇利瓦克河谷本身的特定沉积物产量增加。大约60％的动员沉积物被重新沉积到一到三级流域中，而较少的比例则存储在较高级流域的出口处。一个简单的网络路由模型强调了在较陡峭的地形中来自崩积层，漂流层和沟壑的显着泥沙通量贡献。由于这种物质沉积在下部排水管网的交界处，越来越多的物质来自主要山谷中的残余山谷填充物和准冰川扇。低阶陡坡集水区的产量往往会无限期地被封存在山坡上。这些观察结果对模拟大小不同的集水区的冰川后沉积物平衡具有重要意义。 104年后，该系统仍然处于不平衡状态。关键的联系在于低阶的山坡流域（<第四阶）与较大的河谷和较复杂的河流系统之间。

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