Identifying spatial and temporal dynamics of proglacial groundwater–surface-water exchange using combined temperature-tracing methods

AbstractThe effect of proglacial groundwater systems on surface hydrology and ecology in cold regions often is neglected when assessing the ecohydrological implications of climate change. We present a novel approach in which we combined 2 temperature-tracing techniques to assess the spatial patterns and short-term temporal dynamics of groundwater–surface-water exchange in the proglacial zone of Skaftafellsjökull, a retreating glacier in southeastern Iceland. Our study focuses on localized groundwater discharge to a surface-water environment, where high temporal- and spatial-resolution mapping of sediment surface and subsurface temperatures (10–15 cm depth) were obtained by Fiber-Optic Distributed Temperature Sensing (FO-DTS). The FO-DTS survey identified temporally consistent locations of temperature anomalies at the sediment–water interface, indicating distinct zones of cooler groundwater upwelling. The high-resolution FO-DTS surveys were combined with calculations of 1-dimensional groundwater seepage fluxes based on 3 vertical sediment temperature profiles, covering depths of 10, 25, and 40 cm below the lake bed. The calculated groundwater seepage rates ranged between 1.02 to 6.10 m/d. We used the combined techniques successfully to identify substantial temporal and spatial heterogeneities in groundwater–surface exchange fluxes that have relevance for the ecohydrological functioning of the investigated system and its potential resilience to environmental change.

Raw project data is available by contacting [e-mail]

摘要：在评估气候变化对生态水文学影响时，冷地区冰川前地下水系统对地表水文学和生态的影响往往被忽视。本研究提出了一种新颖的方法，将两种温度追踪技术相结合，以评估冰岛东南部退缩冰川斯卡法塔菲尔斯约库尔冰川前区地下水与地表水交换的空间格局和短期时间动态。研究聚焦于地下水向地表水环境的局部排放，通过光纤分布式温度传感（FO-DTS）获得了沉积物表面和地下（10-15厘米深度）的高时空分辨率温度映射。FO-DTS调查确定了沉积物-水界面处温度异常的时空一致位置，表明存在独特的较冷地下水上升区。高分辨率FO-DTS调查与基于三个垂直沉积温度剖面（10、25和40厘米深度）的一维地下水渗透通量计算相结合。计算得到的地下水渗透速率介于1.02至6.10米/日之间。我们成功地将这些技术相结合，识别出地下水-地表交换通量在时空上的显著异质性，这对所研究系统的生态水文学功能和应对环境变化的潜在适应性具有重要意义。

原始项目数据可通过联系[e-mail]获取。