Estimating runoff curve number for irrigated paddy fields

摘要

The runoff curve number (CN) for irrigated, level-terraced paddy fields was estimated from measured rainfall and runoff data. The CN values were determined from the maximum retention storages at probabilities of 10, 50, and 90 percent, from a fittedlognormal distribution. The CN values at the antecedent moisture condition (AMC) I, II, and III were found to be 67, 82, and 91, respectively. Flooding depths and the heights of check gates were also monitored to work out the hydrologic characteristics for paddy fields. The field data showed flooding depth seem to be a major factor affecting retention storage. Thus, flooding depth in paddy fields corresponding 10, 50 and 90 percent probabilities were consider to be equivalent to AMC I, II, and AMC III,respectively.