Water Table Depth (WTD) NIMS grid Atqasuk, Alaska 2012

Water table depth (WTD) measurements were taken along the Networked Info-mechanical Systems (NIMS) grid in Atqasuk, Alaska during the summer of 2012. The NIMS grid is situated about 50 meters to the south of the International Tundra Experiment (ITEX) dry site. If a uniform representation of the water table within each plot was visible, then a WTD tube was placed there to measure the change in water table throughout the season. For instance if the plot was half saturated and half dry, then that plot was skipped and no tube was placed there. The exact location of WTD tubes are as follows: Between meters 0-1, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20, 21-22, 23-24, 25-26, 32-33, 34-35, 36-37, 38-39, 40-41, 42-43, 44-45, 46-47 & 48-49. A total of 22 WTD tubes were installed into the NIMS grid in Atqasuk. Measurements were made every few days during the summer snow free period between mid June and mid August. WTD was calculated as the difference between the depth (cm) of the water table above or below the measuring tube (- Values = water above tube, + Values= water level below the height of the tube) and the height of the top of the measuring tube above the ground level. Measurements were not made (NA in data sheet) if there was persistent snow cover, interference or disturbance from other experimental infrastructure, or if water table depth tubes were dry to the upper surface of the permafrost.

2012年夏季，地下水位深度（Water Table Depth, WTD）测量于阿拉斯加阿特卡苏克（Atqasuk）的网络化信息机械系统（Networked Info-mechanical Systems, NIMS）网格沿线开展。该NIMS网格位于国际苔原实验（International Tundra Experiment, ITEX）干旱样地以南约50米处。若每个样地内的地下水位呈现均匀分布，则在该位置放置一根WTD管，以测量整个季节内地下水位的变化；例如，若某样地一半饱和、一半干燥，则跳过该样地，不放置测量管。WTD管的具体位置如下：0-1米、3-4米、5-6米、7-8米、9-10米、11-12米、13-14米、15-16米、17-18米、19-20米、21-22米、23-24米、25-26米、32-33米、34-35米、36-37米、38-39米、40-41米、42-43米、44-45米、46-47米及48-49米区间。阿特卡苏克的NIMS网格中共安装了22根WTD管。在6月中旬至8月中旬的夏季无雪期内，每隔数日进行一次测量。WTD的计算方式为：测量管内地下水位相对于管体的深度（单位：厘米，负值表示水位高于管体，正值表示水位低于管体高度）与测量管顶部距地面高度的差值。若存在持续积雪覆盖、其他实验设施的干扰或扰动，或WTD管内干燥至永久冻土层上表面，则不进行测量（数据表中标记为NA）。