Rain gardens are increasing in use as the shift from gray to green infrastructure continues. Water that enters a rain garden is removed by three mechanisms: overflow to an outlet, percolation to the underlying soil, and evapotranspiration (ET) to the atmosphere. Despite the importance of ET in aiding a rain garden to recover void space during the time between storm events, it is not often measured or calculated because it is so difficult to do so. This paper explores the use of soil moisture sensors to estimate ET, since they are relatively inexpensive to purchase and install. Three rain garden weighing lysimeters in Villanova, PA, were used for this study. Over a 3‐yr study period daily ET was calculated each dry day and summed during the time in between storm events >25 mm. The cumulative changes of soil moisture readings during the interevent time at three depths were compared with the concurrent cumulative changes in the lysimeter weight readings. Cumulative soil moisture change was found to be strongly correlated to the cumulative ET for the different lysimeter media and drainage types. Using the two soil moisture sensors at the top and bottom of the soil column provided a similar result to using all soil moisture reading depths. The best single soil moisture reading depth was at the bottom of the lysimeter. The ET estimates via soil moisture tracking performed similar to uncalibrated potential ET estimates, but not as well as calibrated ET estimates.

中文翻译：

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利用土壤湿度传感器估算雨季的蒸散量

随着从灰色基础设施向绿色基础设施的转变，雨水花园的使用量正在增加。进入雨林的水可以通过三种机制去除：溢流到排水口，渗入下面的土壤以及蒸散（ET）到大气。尽管ET在协助暴风雨之间恢复雨水空间的重要性，但由于很难做到，ET并不经常测量或计算。本文探索了使用土壤湿度传感器来估算ET，因为它们的购买和安装相对便宜。这项研究使用了宾夕法尼亚州维拉诺瓦的三个雨量计称重计。在为期3年的研究期内，每天在每个干旱天都计算出ET，并在风暴事件> 25 mm之间的时间内求和。将三个深度的事件间隔时间内土壤水分读数的累积变化与溶渗仪重量读数的同时累积变化进行了比较。对于不同的渗漏介质和排水类型，累积的土壤水分变化与累积ET密切相关。使用土壤柱顶部和底部的两个土壤湿度传感器可提供与使用所有土壤湿度读数深度相似的结果。最佳的单一土壤湿度读数深度是在溶渗仪的底部。通过土壤水分跟踪进行的ET估算与未校准的潜在ET估算相似，但不如校准的ET估算好。对于不同的溶渗仪介质和排水类型，累积的土壤水分变化与累积ET密切相关。使用土壤柱顶部和底部的两个土壤湿度传感器可提供与使用所有土壤湿度读数深度相似的结果。最佳的单一土壤湿度读数深度是在溶渗仪的底部。通过土壤水分追踪进行的ET估算与未校准的潜在ET估算相似，但不如校准的ET估算好。对于不同的溶渗仪介质和排水类型，累积的土壤水分变化与累积ET密切相关。使用土壤柱顶部和底部的两个土壤湿度传感器提供的结果与使用所有土壤湿度读数深度的结果相似。最佳的单一土壤湿度读数深度是在溶渗仪的底部。通过土壤水分跟踪进行的ET估算与未校准的潜在ET估算相似，但不如校准的ET估算好。