Changing characteristics of runoff and freshwater export from watersheds draining northern Alaska
Changing characteristics of runoff and freshwater export from watersheds draining northern Alaska
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DOI：
10.5194/tc-13-3337-2019
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
M. Rawlins;L. Cai;S. Stuefer;D. Nicolsky
中科院分区：
文献类型：
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作者：
M. Rawlins;L. Cai;S. Stuefer;D. Nicolsky
抽象的。北极地区的河流流量和质量受到许多过程的影响，包括气候、流域属性以及越来越多的水文循环强化和永久冻土融化。我们使用水文模型量化了基线条件，并调查了1981-2010年期间乌恰格维克(以前称为巴罗)和麦肯齐河以西之间的北极分水岭的水文要素的变化特征。测量和模型模拟的综合结果表明，该地区通过河流排放输出31.9km3yr−1的淡水，其中55.5%(17.7km3yr−1)来自科尔维尔河、库帕鲁克河和萨加瓦尼尔克托克河。模拟表明，北坡几条大型河流，包括科尔维尔河和库帕鲁克河，以及整个地区的冷季流量(CSD)显著(p<；0.05)增加(平均值的134%-212%)。该地区和42个研究流域中的24个流域的地下径流占总径流的比例显著增加，这种变化在布鲁克斯山脉的北麓最为普遍。模拟活动层厚度(ALT)相对较大的增加表明气候变暖、永久冻土退化和流向溪流和河流的地下流量增加之间存在物理联系。陆地水储量(TWS)的下降归因于土壤冰的损失超过了土壤液态水的储存收益。在30年的时间里，春季(淡水)流量高峰的时间提前了4.5d，尽管时间趋势只有轻微的显著(p=0.1)。北极河流的这些变化特征对沿海环境中的水、碳和养分循环具有重要影响。
Abstract. The quantity and quality of river discharge in Arctic regions is influenced by many processes including climate, watershed attributes and, increasingly, hydrological cycle intensification and permafrost thaw. We used a hydrological model to quantify baseline conditions and investigate the changing character of hydrological elements for Arctic watersheds between Utqiagvik (formerly known as Barrow)) and just west of Mackenzie River over the period 1981–2010. A synthesis of measurements and model simulations shows that the region exports 31.9 km3 yr−1 of freshwater via river discharge, with 55.5 % (17.7 km3 yr−1) coming collectively from the Colville, Kuparuk, and Sagavanirktok rivers. The simulations point to significant (p<0.05) increases (134 %–212 % of average) in cold season discharge (CSD) for several large North Slope rivers including the Colville and Kuparuk, and for the region as a whole. A significant increase in the proportion of subsurface runoff to total runoff is noted for the region and for 24 of the 42 study basins, with the change most prevalent across the northern foothills of the Brooks Range. Relatively large increases in simulated active-layer thickness (ALT) suggest a physical connection between warming climate, permafrost degradation, and increasing subsurface flow to streams and rivers. A decline in terrestrial water storage (TWS) is attributed to losses in soil ice that outweigh gains in soil liquid water storage. Over the 30-year period, the timing of peak spring (freshet) discharge shifts earlier by 4.5 d, though the time trend is only marginally (p=0.1) significant. These changing characteristics of Arctic rivers have important implications for water, carbon, and nutrient cycling in coastal environments.