Physical Sciences and Mathematics Commons^™

Monitoring Subsurface Drainage Flow At Remote Locations, Stephen R. Workman, Stephen F. Higgins, Scott A. Shearer

Biosystems and Agricultural Engineering Faculty Publications

Laboratory evaluations and field results are presented for a slotted weir used to measure discharge from subsurface drains. The head–discharge curve for the vertical slot is a simple power function with an exponent of 1.5. There was excellent agreement (r² > 0.99 and 1:1 slope) between predicted and observed discharge in laboratory testing of 12 test weirs representing five slot widths. The primary advantages of the vertical slot weir are its simplicity, ease of maintenance, and ability to measure small flow rates. Disadvantages include a tendency for the slot to close a small amount over time as a result of …

Evaporation Reduction Potential In An Undisturbed Soil Irrigated With Surface Drip And Sand Tube Irrigation, Masoud Meshkat, Richard C. Warner, Stephen R. Workman

Biosystems and Agricultural Engineering Faculty Publications

The efficiency of drip irrigation is highly dependent on evaporation losses occurring from the constantly saturated soil beneath emitters. Advent of subsurface drip irrigation is in part an approach to curb this inefficiency. An irrigation method, Sand Tube Irrigation (STI), is proposed to increase the efficiency of “Normal” surface applied drip Irrigation (NI method) on permanent tree crops without the need for burying the irrigation tubing. The sand tube consists of removing a soil core beneath the emitter and filling the void with coarse sand. A weighing lysimeter was constructed in the laboratory and instrumented to directly measure temporal evaporation …

Comparison Of Water And Temperature Distribution Profiles Under Sand Tube Irrigation, Masoud Meshkat, Richard C. Warner, Stephen R. Workman

Biosystems and Agricultural Engineering Faculty Publications

Drip irrigation is one of the most efficient systems in delivering water to the plant root zone. Research has shown that the saturated, or nearly saturated, surface beneath the emitter may increase evaporation thereby reducing the irrigation efficiency. To increase the efficiency of surface applied drip irrigation on permanent tree crops a sand tube irrigation (STI) method was developed and tested. The sand tube method consists of removing a soil core beneath the emitter and filling the void with coarse sand. A weighing lysimeter was designed and instrumented to directly measure temporal evaporation during irrigation and for a period of …

Comparison Of Daily Water Table Depth Prediction By Four Simulation Models, Eric D. Desmond, Andrew D. Ward, Norman R. Fausey, Stephen R. Workman

Biosystems and Agricultural Engineering Faculty Publications

The Agricultural Drainage And Pesticide Transport (ADAPT) model was compared to the water management simulation models DRAINMOD, SWATREN, and PREFLO. SWATREN and PREFLO are one-dimensional finite-difference models while ADAPT and DRAINMOD are one-dimensional mass balance models. ADAPT, an extension of the computer model GLEAMS, also provides chemical transport information. All four models were tested against field data from Aurora, North Carolina. Observed water table depth data were collected during 1973 through 1977 from a water table management field experiment with three subsurface drain spacing treatments of 7.5, 15, and 30 m.

Both the standard error of estimate and the average …

Vertical Drainage In Field Cores, Larry G. Wells, R. W. Skaggs

Biosystems and Agricultural Engineering Faculty Publications

No abstract provided.

Upward Water Movement In Field Cores, Larry G. Wells, R. W. Skaggs

Biosystems and Agricultural Engineering Faculty Publications

No abstract provided.