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Infiltration from a surface point source and drip irrigation: 1. The midpoint soil water pressure
Author(s) -
Revol P.,
Vauclin M.,
Vachaud G.,
Clothier B. E.
Publication year - 1997
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/97wr01006
Subject(s) - midpoint , hydraulic conductivity , infiltration (hvac) , drip irrigation , low flow irrigation systems , hydrology (agriculture) , soil science , infiltrometer , irrigation , environmental science , mathematics , geotechnical engineering , soil water , geology , geometry , agronomy , physics , meteorology , biology
Bresler [1978] proposed a procedure for drip irrigation design which is focused on the midpoint soil water pressure h c . We present a practical field test of this approach in order to evaluate the validity of the underlying assumptions. The simulated h c values were obtained from Raats ' [1971] steady state theory for 32 points in the field where the hydraulic conductivity parameters K s and αwere measured. The h c values were measured at the same locations during microirrigation of a maize crop. Measured h c 's appear to be lower than the simulated ones, especially late in the season. The measured spatial variability in h c appeared to be higher than the simulated ones. This could well have been caused by root uptake activity, which is not considered in the analysis, as well as by the large but typical drippers spacing of d = 1.00 m. Thus the tensiometers could have been beyond the practical limit of wetting. Consequences for design and management are important. For design, even if a high h c value is chosen, there is no real guarantee that the wetting would be effective at the midpoint. For irrigation management, tensiometer placement too far from the dripper would lead to overirrigation, so for a large dripper spacing d , the midpoint placement is not judicious.