Snow cover, snowmelt timing and stream power in the Wind River Range, Wyoming
Snow cover, snowmelt timing and stream power in the Wind River Range, Wyoming
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DOI：
10.1016/j.geomorph.2010.11.011
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发表时间：
2012-01
期刊：
影响因子：
3.9
通讯作者：
D. Hall;J. Foster;N. DiGirolamo;G. Riggs
中科院分区：
文献类型：
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作者：
D. Hall;J. Foster;N. DiGirolamo;G. Riggs
至少在过去50年里，美国西部出现了更早的春季天气，包括更早的积雪融化。由于美国西部的大部分(70%)供水来自积雪融化，对春季积雪(和冰川缩小)的分析对径流管理具有重要意义。积雪中的水量影响水流流量，而水流流量也可以通过改变水流功率或水流做功的速率来影响侵蚀和泥沙输送，例如移动泥沙和侵蚀河床。这项工作的重点是怀俄明州中西部的风河山脉(WRR)。研究了中分辨率成像光谱仪(MODIS)10年积雪、云间隙填充(CGF)地图产品以及30年的流量和气象站资料。来自WRR流域河流的径流数据显示，21世纪头10年的年流量和融雪早于前30年，尽管在21世纪头10年没有观察到径流减少或融雪早的趋势。结果显示，在20世纪70年代的十年中，以及整个40年的研究期间，每周最高气温(研究的五个气象站中的三个)上升的95%置信度(或更高)有统计上的显著趋势。利用MODIS CGF积雪图从WRR最低海拔带(2500-3000米)得到的积雪范围(流域覆盖的百分比)与4月30日的最大月流量有很强的相关性，在2000年代的十年中，Spearman等级相关系数Rs=0.89。我们还调查了牛湖上方的牛湖溪的水流功率，发现从1970年到2009年有减少水流功率的趋势(在90%的置信度水平下非常显著)。观测到的河流流量和水流功率的变化可能与在40年研究期间测量的每周最高气温上升有关，这可能是导致积雪减少的原因之一。此外，流域被雪覆盖的百分比和月最大径流量之间的强烈关系表明，MODIS雪盖地图对于预测径流是有用的，可以用于改善美国西部干旱多发地区的水资源管理。
Earlier onset of springtime weather, including earlier snowmelt, has been documented in the western United States over at least the last 50years. Because the majority (>70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack (and shrinking glaciers) has important implications for the management of streamflow. The amount of water in a snowpack influences stream discharge which can also influence erosion and sediment transport by changing stream power, or the rate at which a stream can do work, such as move sediment and erode the stream bed. The focus of this work is the Wind River Range (WRR) in west-central Wyoming. Ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover, cloud-gap-filled (CGF) map products and 30years of discharge and meteorological station data are studied. Streamflow data from streams in WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades, though no trend of either lower streamflow or earlier snowmelt was observed within the decade of the 2000s. Results show a statistically-significant trend at the 95% confidence level (or higher) of increasing weekly maximum air temperature (for three out of the five meteorological stations studied) in the decade of the 1970s, and also for the 40-year study period as a whole. The extent of snow-cover (percent of basin covered) derived from the lowest elevation zone (2500–3000m) of the WRR, using MODIS CGF snow-cover maps, is strongly correlated with maximum monthly discharge on 30 April, where Spearman's Rank correlation, rs,=0.89 for the decade of the 2000s. We also investigated stream power for Bull Lake Creek above Bull Lake; and found a trend (significant at the 90% confidence level) toward reduced stream power from 1970 to 2009. Observed changes in streamflow and stream power may be related to increasing weekly maximum air temperature measured during the 40-year study period, possibly contributing to a reduction in snow cover. In addition, the strong relationship between percent of basin that was snow covered, and maximum monthly streamflow indicates that MODIS snow-cover maps are useful for predicting streamflow, and can be used to improve management of water resources in the drought-prone western United States.