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Title: STATISTICAL APPROACH TO INCORPORATING THE INFLUENCE OF LAND-GRADING PRECISION ON LEVEL-BASIN PERFORMANCE

Author
item Clemmens, Albert
item EL-HADDAD, ZAKARIA - ZAGAZIG UNIV, EGYPT
item FANGMEIER, DELMAR - UNIV OF ARIZONA, TUCSON
item OSMAN, HASSAN - AG ENG RES INST, EGYPT

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Historically, the performance of surface irrigation systems has been low, particularly in areas with a long history of surface irrigation like the Nile Delta of Egypt. This poor performance often leads to problems with soil salinity management, reduced yields, and in some cases, water lost to further reuse. Improving the performance of surface irrigation systems is often limited by the precision of land grading. In this paper a simple method is presented for estimating the effect of poor land grading on the resulting uniformity of infiltrated irrigation water within a level basin. This paper shows that traditional land grading practices have a serious negative affect on level basin performance. Leveling precision with laser-controlled grading equipment has a very small effect on performance except when high levels of irrigation uniformity are attempted. This information should be of use to action agencies, agricultural consultants and irrigation extension specialists in the United States, Egypt and other countries where level-basin irrigation is practiced.

Technical Abstract: Monte-Carlo simulation was used to determine the suitability of statistical equations for estimating the influence of soil surface elevations on the low-quarter distribution uniformity, DUlq, of level-basin irrigation systems. It was shown that these equations give reasonable estimates of DUlq, provided that the advance curve is known. The Monte-Carlo simulations salso provided an estimate of the variation in DUlq for different fields with the same standard deviation of elevations. The statistical equations demonstrate that irrigation uniformity is influenced by the ratio of soil surface elevation standard deviation to average depth infiltrated. For conditions that would be typical of laser leveled basins within the U.S., the influence of elevation variations on DUlq is small. However, these elevation variations can significantly reduce DUlq, thus limiting potential efficiencies for poorly leveled fields, which frequently occurs in Egypt. These simple equations can be used to adjust level-basin designs to accoun for the variation in surface elevations without the need for extensive simulation studies.