Using isotopes to understand landscape‐scale connectivity in a groundwater‐dominated, lowland catchment under drought conditions
Using isotopes to understand landscape‐scale connectivity in a groundwater‐dominated, lowland catchment under drought conditions
复制标题
使用同位素了解干旱条件下以地下水为主的低地流域的景观尺度连通性
DOI：
10.1002/hyp.14197
复制
发表时间：
2021-04
影响因子：
3.2
通讯作者：
L. Kleine;D. Tetzlaff;A. Smith;T. Goldhammer;C. Soulsby
中科院分区：
文献类型：
--
作者：
L. Kleine;D. Tetzlaff;A. Smith;T. Goldhammer;C. Soulsby
Demnitzer米尔克里克集水区（DMC）是一个66平方公里的长期实验集水区，位于柏林东南50公里处。过去30年的监测重点是与农业集约化程度降低和以雨养农业和林业为主的低洼景观中的河岸恢复相关的水文和地球化学变化。然而，流域的水文功能，这是密切相关的养分通量和高度敏感的气候变化，仍然知之甚少。在过去的三年里，长期干旱，降雨量低于平均水平，气温高于平均水平，导致水文变化显著。这导致生长季节土壤水分储存量低，农业产量损失，地下水补给减少，以及部分日益断开的渠道网络中的间歇性径流。本文重点介绍了一项为期两年的同位素研究，旨在了解干旱条件下流域的不同部分如何影响生态水文分区，水文连通性和径流生成。这项工作表明，地下水储存在维持水流、基本的河流生态系统服务以及植被对地下水补给的主导影响方面至关重要。与草地相比，森林下的冬季补给量要低得多，而且发生在较短的时间窗口内。相反，通过恢复河岸湿地和从溪流到地下的依赖储存的水损失，局部地增强了地下水补给。同位素变异性显示出复杂的新兴时空格局的流连接和流动持续时间在干旱期间，可能有影响流溶质运移和未来的生态水文景观和河流景观之间的相互作用。鉴于气候预测干燥和温暖的夏天，减少和越来越多的间歇性溪流很可能不仅在研究区域，但在欧洲各地的类似低地地区。土地和水的综合管理战略对于今后维持这种集水系统的集水生态系统服务至关重要。
The Demnitzer Millcreek catchment (DMC), is a 66 km2 long‐term experimental catchment located 50 km SE of Berlin. Monitoring over the past 30 years has focused on hydrological and biogeochemical changes associated with de‐intensification of farming and riparian restoration in the low‐lying landscape dominated by rain‐fed farming and forestry. However, the hydrological function of the catchment, which is closely linked to nutrient fluxes and highly sensitive to climatic variability, is still poorly understood. In the last 3 years, a prolonged drought period with below‐average rainfall and above‐average temperatures has resulted in marked hydrological change. This caused low soil moisture storage in the growing season, agricultural yield losses, reduced groundwater recharge, and intermittent streamflows in parts of an increasingly disconnected channel network. This paper focuses on a two‐year long isotope study that sought to understand how different parts of the catchment affect ecohydrological partitioning, hydrological connectivity and streamflow generation during drought conditions. The work has shown the critical importance of groundwater storage in sustaining flows, basic in‐stream ecosystem services and the dominant influence of vegetation on groundwater recharge. Recharge was much lower and occurred during a shorter window of time in winter under forests compared to grasslands. Conversely, groundwater recharge was locally enhanced by the restoration of riparian wetlands and storage‐dependent water losses from the stream to the subsurface. The isotopic variability displayed complex emerging spatio‐temporal patterns of stream connectivity and flow duration during droughts that may have implications for in‐stream solute transport and future ecohydrological interactions between landscapes and riverscapes. Given climate projections for drier and warmer summers, reduced and increasingly intermittent streamflows are very likely not just in the study region, but in similar lowland areas across Europe. An integrated land and water management strategy will be essential to sustaining catchment ecosystem services in such catchment systems in future.