Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 2005
Publication Date: May 23, 2005
Citation: Guber, A., Pachepsky, Y.A., Van Genuchten, M.T., Jacques, D., Cady, R.E., Nicholson, T.J. 2005. Using temporal persistence to improve monitoring and upscale soil moisture contents [abstract]. Joint Assembly of the American Geophysical Union. 86(18):H43C-06.
When a field or a small watershed is repeatedly surveyed for soil water content, sites often can be spotted where soil is consistently wetter or consistently dryer than average across the study area. The phenomenon has been called time stability, temporal stability, or temporal persistence in spatial patterns of soil water contents. It was shown that such persistence can be used to optimize monitoring and upscaling of soil moisture. Relatively less is known about the temporal persistence of water content at various depths in vadose zone. The objectives of this work are to demonstrate the temporal persistence in soil water contents measured on a vertical two-dimensional grid, and to propose a technique to utilize this persistence to monitor and upscale soil water content. Sixty TDR probes were installed along the trench in loamy soil at 12 locations with 50-cm horizontal spacing at 5 depths. Some probes at a given depth consistently showed water contents below average whereas others show water contents above the average. To quantify the persistence, we computed relative water contents as ratios of individual-probe water contents to average water contents from the same depth. The number of probes could be decreased and the soil water content could be upscaled efficiently because the variability ranges of relative water contents were narrow. A numerical experiment showed the efficiency of the proposed technique. Corrections for temporal persistence can be useful to improve estimates of layer-averaged water contents and their uncertainty.