ABSTRACT

The U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) maintains seven in situ soil moisture networks throughout the continental United States, some since 2002. These networks are crucial for understanding the spatial and temporal extent of droughts in their historical context, parameterization of hydrologic models, and local agricultural decision support. However, the estimates from these networks are dependent upon their ability to provide reliable soil moisture information at a large scale. It is also not known how many network stations are sufficient to monitor watershed scale dynamics. Therefore, the objectives of this research were to: (1) determine how temporally stable these networks are, including the relationships between various sensors on a year-to-year and seasonal basis, and (2) attempt to determine how many sensors are required, within a network, to approximate the full network average. Using data from seven in situ, it is concluded that approximately 12 soil moisture sensors are sufficient in most environments, presuming their locations are distributed to capture the hydrologic heterogeneity of the watershed. It is possible to install a temporary network containing a suitable number of sensors for an appropriate length of time, glean stable relationships between locations, and retain these insights moving forward with fewer sensor resources.

摘要

美国农业部的农业研究服务 (USDA-ARS) 在整个美国大陆维护着七个原位土壤水分网络，其中一些是自 2002 年以来的。这些网络对于了解干旱在其历史背景下的时空范围、参数化至关重要水文模型和当地农业决策支持。然而，这些网络的估计取决于它们大规模提供可靠土壤水分信息的能力。也不知道有多少网络站足以监测流域尺度动态。因此，本研究的目标是：（1）确定这些网络的时间稳定性，包括各种传感器之间的逐年和季节性关系，(2) 尝试确定一个网络中需要多少个传感器来近似整个网络的平均值。使用来自七个原位的数据，可以得出结论，在大多数环境中，大约 12 个土壤湿度传感器就足够了，假设它们的位置分布在捕捉流域的水文异质性。可以在适当的时间长度内安装一个包含适当数量传感器的临时网络，收集位置之间的稳定关系，并保留这些见解，以更少的传感器资源向前推进。假设它们的位置分布以捕捉流域的水文异质性。可以在适当的时间长度内安装一个包含适当数量传感器的临时网络，收集位置之间的稳定关系，并保留这些见解，以更少的传感器资源向前推进。假设它们的位置分布以捕捉流域的水文异质性。可以在适当的时间长度内安装一个包含适当数量传感器的临时网络，收集位置之间的稳定关系，并保留这些见解，以更少的传感器资源向前推进。