Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya
Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya
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DOI：
10.5194/hess-16-2193-2012
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发表时间：
2012-07
影响因子：
6.3
通讯作者：
Hendrik Wulf;B. Bookhagen;D. Scherler
中科院分区：
文献类型：
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作者：
Hendrik Wulf;B. Bookhagen;D. Scherler
流经喜马拉雅河流的沉积物流量直接影响水质，对维持农业以及维持饮用水和水力发电十分重要。尽管最近对这些资源的需求有所增加，但人们对极端沉积物通量事件的触发因素和来源知之甚少，这些事件降低了水质，并造成了大量的水电水库蓄水和涡轮机磨损。在这里，我们提出了一个全面的时空变化趋势的悬浮泥沙通量的基础上，在过去的十年（2001 - 2009年）的日常数据从四个站点沿着Sutlej河及其四个主要支流。结合卫星数据描绘的降雨和积雪，气温和地震记录，和实地观测，我们推断的气候和地质控制的峰值悬浮泥沙浓度（SSC）事件。我们的研究确定了三个关键的发现：第一，峰值SSC事件（≥ 99th SSC百分位数）经常（57 - 80%）与暴雨重合，并占半干旱到干旱造山带内部悬浮泥沙通量的30%左右。其次，我们观察到的悬浮泥沙通量增加，从青藏高原到喜马拉雅山前的平均年时间尺度。这种沉积通量梯度表明，平均，现代的侵蚀在喜马拉雅西部是最明显的锋面地区，其特点是高季风降雨量和厚的土壤覆盖。第三，在七个集水区，我们发现一个anticoncular滞后回线的年泥沙通量变化相对于河流流量，这似乎是有关的增强冰川沉积物疏散在夏末。我们的分析强调了高海拔地区松散沉积物的重要性，这些沉积物很容易被水文气象事件和更高的冰川融水贡献所调动。在未来的气候变化情景中，包括持续的冰川退缩和喜马拉雅地区更频繁的季风暴雨，我们预计SSC峰值事件会增加，这将降低水质并影响水力发电。
The sediment flux through Himalayan rivers directly impacts water quality and is important for sustaining agriculture as well as maintaining drinking-water and hydropower generation. Despite the recent increase in demand for these resources, little is known about the triggers and sources of extreme sediment flux events, which lower water quality and account for extensive hydropower reservoir filling and turbine abrasion. Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001–2009) from four sites along the Sutlej River and from four of its main tributaries. In conjunction with satellite data depicting rainfall and snow cover, air temperature and earthquake records, and field observations, we infer climatic and geologic controls of peak suspended sediment concentration (SSC) events. Our study identifies three key findings: First, peak SSC events (≥ 99th SSC percentile) coincide frequently (57–80%) with heavy rainstorms and account for about 30% of the suspended sediment flux in the semi-arid to arid interior of the orogen. Second, we observe an increase of suspended sediment flux from the Tibetan Plateau to the Himalayan Front at mean annual timescales. This sediment-flux gradient suggests that averaged, modern erosion in the western Himalaya is most pronounced at frontal regions, which are characterized by high monsoonal rainfall and thick soil cover. Third, in seven of eight catchments, we find an anticlockwise hysteresis loop of annual sediment flux variations with respect to river discharge, which appears to be related to enhanced glacial sediment evacuation during late summer. Our analysis emphasizes the importance of unconsolidated sediments in the high-elevation sector that can easily be mobilized by hydrometeorological events and higher glacial-meltwater contributions. In future climate change scenarios, including continuous glacial retreat and more frequent monsoonal rainstorms across the Himalaya, we expect an increase in peak SSC events, which will decrease the water quality and impact hydropower generation.