Abstract. Understanding when and why groundwater recharge occurs is of fundamental importance for the sustainable use of this essential freshwater resource for humans and ecosystems. However, accurately capturing this component of the water balance is widely acknowledged to be a major challenge. Direct physical measurement identifying when groundwater recharge is occurring is possible by utilizing a sensor network of hydrological loggers deployed in underground spaces located in the vadose zone. Through measurements of water percolating into these spaces from above, we can record the potential groundwater recharge process in action. By using automated sensors, it is possible to precisely determine when recharge occurs (which event, month, or season, and for which climate condition). Combined with daily rainfall data, it is possible to quantify the ‘rainfall recharge threshold’, the amount of rainfall needed to generate groundwater recharge, and its temporal and spatial variability. Australia’s National Groundwater Recharge Observing System (NGROS) provides the first dedicated sensor network for observing groundwater recharge at an event-scale across a wide range of geologies, environments, and climate types representing a wide range of Australian hydroclimates. Utilizing tunnels, mines, caves, and other subsurface spaces located in the vadose zone, the sensors effectively record ‘deep drainage’, water that can move beyond the shallow subsurface and root zone to generate groundwater recharge. The NGROS has the temporal resolution to capture individual recharge events, with multiple sensors deployed at each site to constrain the heterogeneity of recharge between different flow paths, and to quantify (including uncertainty bounds) rainfall recharge thresholds. Established in 2022, the network is described here together with examples of data being generated.

中文翻译：

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地下滴水监测网络，用于表征澳大利亚不同地质、环境和气候下地下水的降雨补给

摘要。了解地下水补给的时间和原因对于人类和生态系统可持续利用这一重要淡水资源至关重要。然而，准确捕获水平衡的这一组成部分被广泛认为是一项重大挑战。通过利用部署在渗流区地下空间的水文记录仪传感器网络，可以直接进行物理测量来识别地下水何时发生补给。通过测量从上方渗入这些空间的水，我们可以记录潜在的地下水补给过程。通过使用自动传感器，可以精确确定何时进行补给（哪个事件、月份或季节以及哪种气候条件）。结合每日降雨量数据，可以量化“降雨补给阈值”、产生地下水补给所需的降雨量及其时间和空间变化。澳大利亚国家地下水补给观测系统 (NGROS) 提供了第一个专用传感器网络，用于在代表澳大利亚各种水文气候的各种地质​​、环境和气候类型的事件范围内观测地下水补给。利用位于包气带的隧道、矿井、洞穴和其他地下空间，传感器有效地记录“深层排水”，即可以移动到浅层地下和根部区域之外以产生地下水补给的水。NGROS 具有捕获单个充电事件的时间分辨率，在每个地点部署多个传感器，以限制不同流动路径之间补给的异质性，并量化（包括不确定性界限）降雨补给阈值。该网络成立于 2022 年，此处描述了该网络以及生成的数据示例。