Multi-decadal erosion rates from glacierized watersheds on Mount Baker, Washington, USA, reveal topographic, climatic, and lithologic controls on sediment yields
Multi-decadal erosion rates from glacierized watersheds on Mount Baker, Washington, USA, reveal topographic, climatic, and lithologic controls on sediment yields
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DOI：
10.1016/j.geomorph.2023.108805
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发表时间：
2023-10
期刊：
影响因子：
3.9
通讯作者：
Eli Schwat;E. Istanbulluoglu;A. Horner‐Devine;Scott Anderson;F. Knuth;D. Shean
中科院分区：
文献类型：
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作者：
Eli Schwat;E. Istanbulluoglu;A. Horner‐Devine;Scott Anderson;F. Knuth;D. Shean
了解陆面变化和沉积物输出的冰前景观是了解地质灾害和洪水风险的工程时间尺度和地貌时间尺度的景观演变特征的关键。我们使用自动化的Structure from Motion软件处理历史航空照片，并使用现代激光雷达数据，生成了1947年至2015年期间覆盖美国华盛顿贝克山10个冰川流域的高分辨率DEM时间序列。我们测量了流域范围内的产沙量和山坡上和河道中的沉积物再分配。大多数测得的侵蚀点内的坡度高于理论和观测到的泥石流阈值。我们观察到山坡出现严重的侵蚀，山坡和河道的沉积量有限。在净侵蚀期间的泥沙输移比平均为0.73。我们确定，与以前的实地观察一致，泥石流起源于冰碛是一个主要的侵蚀机制，在冰川前区贝克山。时间序列测量表明，侵蚀率的时间变化与气候振荡有关，在凉爽多雨的时期，侵蚀率较高。全流域产沙量与岩性（r2= 0.54）、坡度（r2= 0.52）、流域面积（r2= 0.82）呈正相关，与河道坡度（r2= 0.67）呈负相关。高产和低产盆地之间的地形差异表明，贝克山侵蚀的空间变异对更新世和全新世冰川和火山活动敏感。在六个流域的具体泥沙产量平均为4600吨/平方公里/年，与全球冰川流域的测量结果一致。比产沙量随着流域面积的增加而减少，下游主要干Nooksack河的总负荷估计在480吨/平方公里/年至820吨/平方公里/年之间。冰前产沙量占Nooksack河干流总输沙量的18%至32%，超过了海崖和阶地侵蚀的贡献，后者占总输沙量的8%至13%。我们的研究结果表明，在冰川流域的侵蚀是敏感的年代际气候振荡和高的冰前沉积物产量下游河流系统提供了重要的贡献，特别是在集水区的高地地形和岩性是有利的。
Understanding land surface change in and sediment export out of proglacial landscapes is critical for understanding geohazard and flood risks over engineering timescales and characterizing landscape evolution over geomorphic timescales. We used automated Structure from Motion software to process historical aerial photographs and, with modern lidar data, generated a high-resolution DEM time series with coverage over 10 glacierized watersheds on Mount Baker, Washington, USA for the time period between 1947 and 2015. We measured basin-wide sediment yields and sediment redistribution on hillslopes and in stream channels. Slopes within most measured erosion sites are above theoretical and observed debris-flow thresholds. We observed significant erosion of hillslopes and limited deposition on hillslopes and in stream channels. Sediment delivery ratios during time periods with net erosion averaged 0.73. We determined, consistent with previous field observations, that debris flows originating from moraines are a primary erosion mechanism in proglacial zones on Mount Baker. Time series measurements indicate that temporal variability in erosion rates is associated with climate oscillations, with higher erosion rates during cooler-wetter periods. Basin-wide sediment yield is positively correlated with lithology (r2= 0.54), hillslope angle (r2= 0.52), drainage area (r2= 0.82), and negatively correlated with stream channel slope (r2= 0.67). Topographic differences between high and low yielding basins indicate that spatial variability in erosion on Mount Baker is sensitive to Pleistocene and Holocene glacial and volcanic activity. Specific sediment yields in six basins averaged 4600 ton/km2/yr, consistent with global measurements in glacierized catchments. Specific sediment yield decreased with increasing basin area, with total loads in the downstream main stem Nooksack River estimated between 480 and 820 ton/km2/yr. Proglacial sediment yields account for between 18 and 32 % of total sediment load in the main stem Nooksack River and exceed contributions by bluff and terrace erosion, which account for between 8 and 13 % of total load. Our findings indicate that erosion in glacierized basins is sensitive to decadal climate oscillations and that high proglacial sediment yields provide an important contribution to river systems downstream, particularly in catchments where upland topography and lithology is favorable.