Specific yield - laboratory experiments showing the effect of time on column drainage

Abstract

_____________________________________________________ Bl Introduction._ ____________________________________________________ 2 Scope of research._____________________________________________ 2 Purpose and scope of this report______________________________ 3 Acknowledgments. ____________________________________________ 3 Review of previous work-______________________________________ 3 Theory........______________________________________________ 8 Techniques._______________________________________________________ 12 Materials____________________________________________________ 12 Apparatus and controls_.._______-_____________________________-12 Procedure.____________________________________________________ 15 Discussion of test results___-_-_______-___-___-_______-_-_-_______-18 Drainage of 0.120-millimeter glass beads________________________ 19 Drainage of Fresno medium sand_._..____________________________ 26 Drainage of 20-mesh Del Monte sand.......________-_________.___ 34 Drainage of layered 20-mesh Del Monte sand and Fresno medium sand _______________________________________________________ 42 Summary______________________________________________________ 51 References_ _____________________________________________________ 54 36 19. Tension distribution during drainage of 20-mesh Del Monte sand (column 1).______________________ 37 20. Tension distribution during drainage of 20-mesh Del Monte sand (column 2)___._____________________ 38 21. Distribution of dry unit weight and porosity after draining columns of 20-mesh Del Monte sand_____ 39 22. Moisture retained after drainage of 20-mesh Del Monte sand...-.__________________________ 40 23. Relation of moisture content to tension for 20-mesh Del Monte sand_-.___-_______-____-__-________ 41 24. Moisture distribution during drainage of 20-mesh Del Monte sand (column l)__-_-_-_-__-_______ 43 25. Moisture distribution during drainage of 20-mesh Del Monte sand (column 2)___- .-_-._-_______-__ 44 26. Quantity of water drained from columns of 20-mesh Del Monte sand as related to time of drainage.-44 27. Tension distribution during drainage of a layered column of 20-mesh Del Monte sand and Fresno medium sand_________________-_-__- .-____-_-__ 45 28. Distribution of dry unit weight and porosity after draining a layered column of 20-mesh Del Monte sand and Fresno medium sand-_________________ 48 29. Moisture retained after drainage of a layered column of 20-mesh Del Monte sand and Fresno medium sand__- ....-_______-______-_________-_-_-49 30. Moisture distribution during drainage of a layered column of 20-mesh Del Monte sand and Fresno medium sand_________________________________ 50 31. Quantity of water drained from a layered column of 20-mesh Del Monte sand and Fresno medium sand__ 51

Quantifying Ephemeral Streambed Infiltration from Downhole Temperature Measurements Collected Before and After Streamflow

“…The base case saturated hydraulic conductivity was based on previously reported values for well‐sorted sand (Jury et al, 1991; Hillel, 1998; Stephens, 1996). The porosity, specific storage, residual water content, longitudinal dispersivity, transverse dispersivity, and the van Genuchten parameters (α and n ) were default values defined using a database within VS2DI for a medium sand (Lappala et al, 1987; Prill et al, 1965).…”

Ground Water

“…The average specific yield of saturated sediments, multiplied by the total volume of those sediments, gives the volume of water contained in those sediments that can be recovered by gravity drainage (Johnson, 1967). No time factor is included in the definition of specific yield, but many experiments have shown that draining is initially most rapid, decreases with time, and may continue for months or even years (Prill et al, 1965). Fine-grained materials have a lower specific yield than coarser materials, even though their porosity may be greater, and the drainage process is likely to continue for a much longer period of time than for coarse materials.…”

A method for estimating pore water drainage from marsh soils using rainfall and well records

“…A problem with this method is that the measurement of specific yield typically is made on a time scale (e.g., 5 to 13 days; Roukamen and Klove, 2005) that is considerably longer than the duration of drainage during tidal exposure in regularly flooded marshes. Indeed Prill et al (1965) claim that even with sand-size sediment months of drainage are required to reach exhaustion of the drainable pore water. Thus drainage estimates based on yields measured on cores are likely to overestimate the actual drainage unless the intervals between tidal inundation are on the order of ten or more tidal cycles.…”