EVALUATION OF TIME-RATED INFILTRATION FAMILIES FOR NONCRACKING SOILS

The time-rated infiltration families proposed by Merriam and Clemmens were further developed and evaluated using infiltration data far noncr acking soils. infiltration experiments were monitored, using a double- ring infiltrometer, at 10 field sites in New South Wales (NSW), Austra lia. Published infiltration data for soils in Botswana were also inclu ded to extend the range of soil types and field conditions in the stud y. A methodology was developed for identifying the infiltration family of soil at a given field. The time-rated infiltration family concept along with the methodology developed was evaluated under a range of he ld conditions. For 80% of field situations, the error introduced in in filtration characteristics due to the use of the family concept is <35 % with an average value of the error about 20%. The infiltration chara cteristics of soil at. a given site in this study exhibited a high var iability although the measurements were made only a few meters apart. This observation reinforces potential benefits of using infiltration f amily concepts in the design and management of irrigation systems.