Drainage Network Structure and Hydrologic Behavior of Three Lake-Rich Watersheds on the Arctic Coastal Plain, Alaska
Drainage Network Structure and Hydrologic Behavior of Three Lake-Rich Watersheds on the Arctic Coastal Plain, Alaska
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DOI：
10.1657/1938-4246-44.4.385
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发表时间：
2012-11-01
影响因子：
2
通讯作者：
Urban, F. E.
中科院分区：
文献类型：
--
作者：
Arp, C. D.;Whitman, M. S.;Urban, F. E.
阿拉斯加北极海岸平原（ACP）的流域主要由永久冻土和融雪径流组成，这些径流以湖泊、湿地和珠状溪流的形式创造了丰富的地表蓄水。这些地表水要素构成了复杂的水系网络，影响着水生生态系统的连通性和水文行为。4676 km（2）的Fish Creek流域由三个流域组成，代表了ACP景观的梯度，具有不同程度的风成、湖泊和河流地貌。在每个流域，我们分析了2.5米分辨率的航空摄影，5米的数字高程模型，河流测量和气候记录，以更好地了解ACP流域的结构和过程。我们发现，连接的湖泊流域之间的排水密度占19至26%，大多数所有的渠道开始从湖泊盆地的形式珠流。在这些流域的2500多个湖泊中，33%具有常年径流连通性，占湖泊总面积的66%。更深的湖泊越冬栖息地更丰富的流域风成沙沉积物，而流域海洋淤泥沉积物包含了更大程度的串珠流和浅热岩溶湖泊，提供必要的夏季觅食栖息地。流域间水流状况的比较表明，湖泊面积越大、排水湖盆面积越小，融雪量越低，基流径流量越高。流域之间基流径流的变化是最明显的干旱条件下，在2007年与相应的减少融雪峰值流量的第二年。与其他北极流域的比较表明，湖泊面积的范围对应于缓慢衰退的融雪和基流径流。这些分析有助于我们更好地理解北极流域的结构和水文功能，强调湖泊盆地的重要作用，并提出未来湖泊变化可能如何影响水文过程。
Watersheds draining the Arctic Coastal Plain (ACP) of Alaska are dominated by permafrost and snowmelt runoff that create abundant surface storage in the form of lakes, wetlands, and beaded streams. These surface water elements compose complex drainage networks that affect aquatic ecosystem connectivity and hydrologic behavior. The 4676 km(2) Fish Creek drainage basin is composed of three watersheds that represent a gradient of the ACP landscape with varying extents of eolian, lacustrine, and fluvial landforms. In each watershed, we analyzed 2.5-m-resolution aerial photography, a 5-m digital elevation model, and river gauging and climate records to better understand ACP watershed structure and processes. We show that connected lakes accounted for 19 to 26% of drainage density among watersheds and most all channels initiate from lake basins in the form of beaded streams. Of the >2500 lakes in these watersheds, 33% have perennial streamflow connectivity, and these represent 66% of total lake area extent. Deeper lakes with over-wintering habitat were more abundant in the watershed with eolian sand deposits, while the watershed with marine silt deposits contained a greater extent of beaded streams and shallow thermokarst lakes that provide essential summer feeding habitat. Comparison of flow regimes among watersheds showed that higher lake extent and lower drained lake-basin extent corresponded with lower snowmelt and higher baseflow runoff. Variation in baseflow runoff among watersheds was most pronounced during drought conditions in 2007 with corresponding reduction in snowmelt peak flows the following year. Comparison with other Arctic watersheds indicates that lake area extent corresponds to slower recession of both snowmelt and baseflow runoff. These analyses help refine our understanding of how Arctic watersheds are structured and function hydrologically, emphasizing the important role of lake basins and suggesting how future lake change may impact hydrologic processes.