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ALTERNATIVE INDICES OF THE OVERLOAD FREQUENCY IN AN EFFLUENT RE‐USE SYSTEM
Author(s) -
MURTAGH G. J.
Publication year - 1996
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/(sici)1099-1085(199609)10:9<1139::aid-hyp365>3.0.co;2-q
Subject(s) - decile , environmental science , effluent , irrigation , water storage , hydrology (agriculture) , environmental engineering , statistics , mathematics , engineering , ecology , mechanical engineering , geotechnical engineering , inlet , biology
An effluent re‐use system is examined in which all effluent was stored until it could be used for the irrigation of crops, the storage having sufficient capacity to limit overloading to one in ten years. Three methods for estimating the required storage capacity were compared using climate data from four locations in New South Wales, Australia. A daily soil water budget identified the irrigation opportunities, and a storage subroutine in the budget calculated the peak storage requirement in each year The first method used the ninth decile in the cumulative probability distribution of the annual peak storage requirements as a direct estimate of the storage capacity with a 10% frequency of overloading. The other methods used the peak storage requirement in selected design years. These represented years with either the tenth smallest annual irrigation potential or the tenth largest annual rainfall. Methods which used design years tended to underestimate the storage requirements because the indices did not assess the daily distribution of rainfall within a month or year. Although the overload frequency was set at 10%, the overload was less than 2% of the total volume of effluent because overloading did not occur throughout the year.