Infiltration and Water Table Effects of Soil Air Pressure Under Border Irrigation1
- D. R. Linden and
- R. M. Dixon2
Field studies investigated infiltration and water table responses to soil air pressure under border irrigation. The water table was depressed in the center and elevated near the edge of a border strip in response to differences in soil air pressure during an irrigation. Also, water table elevations indicated that infiltration and subsequent groundwater recharge rates were greater in the vicinity of a border dike than at the center of the border. An infiltration response was measured by: (i) venting soil air during an actual irrigation and (ii) pumping air into the soil during simulated irrigations. An actual border irrigation experiment indicated that displaced soil air pressure ha (expressed as equivalent heads of water) rising to values of 13 to 24 cm of H2O reduced infiltration over a 70-min period from 14.3 to 10.3 cm. Simulated border irrigation experiments indicated that displaced soil air pressure ha must exceed surface head hs to have significant influence on infiltration and that the first few minutes of infiltration may determine the ha-to-hs relationship and subsequent infiltration effects. In the simulated irrigations with hs = 6.3 cm, total infiltration in 1 hour was 6.0 and 1.5 cm when ha was 0 and 10 cm of H2O, respectively. Infiltration was only slightly reduced during the first 5 min when ha was 5 cm of H2O.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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