Location: Hydrology and Remote Sensing Laboratory
Title: Long-term agro-hydrological research in upper Washita river experimental watersheds: Inter-annual persistence of soil water content profiles Authors
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2013
Publication Date: N/A
Interpretive Summary: Long term soil water content data is useful for climate and agricultural monitoring. Ground stations are able to provide long term records on a small scale, but a significant number of stations are necessary to provide an accurate large scale estimate. This is both expensive and difficult to maintain for long periods of time. It is shown in a study of two long term networks, just a few stations are able to provide a large scale estimate by taking advantage of persistent spatial patterns of soil water content. This method will help to fill in gaps in station data when equipment malfunction occurs. This type of analysis will also inform network managers who must often optimize and improve efficiencies when stations must be removed.
Technical Abstract: Scaling in situ soil water content time series data to a large spatial domain is a key element of watershed environmental monitoring and modeling. The primary method of estimating and monitoring large-scale soil water content distributions is via in situ networks. It is critical to establish the stability of in situ networks when deploying them to study long hydrologic systems. Two watersheds in Oklahoma, the Little Washita River Experimental Watershed and the Fort Cobb Experimental Watershed, are two prime examples of long-term in situ networks providing valuable surface and profile soil moisture data. The Little Washita Experimental Watershed has been in operation since 2002, with twenty soil water content stations available for investigating soil water dynamics at the watershed scale. Temporal stability analysis of the network is complicated by the changing configuration of the network, but it is possible to determine a singular long-term average for the network. The Fort Cobb Experimental Watershed consists of fifteen soil water content station and began operation in 2007, providing detailed information across a mixed agricultural domain and was determined to be stable and representative of the region. This study reinforces the applicability of temporal stability analysis to very long time scales, which are now becoming available for soil moisture monitoring. Each of these networks is temporally stable with respect to soil water content at each depth, on a spatial basis, but not through the profile, which is likely the result of variation in the installation of the sensors and differences in soil texture through the soil column.