2004 Volume 48 Pages 31-36
A method of separately estimating daily rainfall-interception evaporation and transpiration in forested watersheds is proposed using available 365-daily data of temperature, relative humidity and sunshine duration, as well as rainfall-runoff. A non-linear interception model is developed, and restraints of transpiration under the conditions of low-flow and high pressure defict of saturation vapor are considered. In order to evaluate the storage depth of non-overland-flow separated from observed runoff depths, a runoff-tank model with separated overland-flow is used. The parameter identification of the runoff-tank model is made using storm hourly data of rainfall-runoff besides 365-daily data of temperature, relative humidity, estimated radiation and rainfall-runoff. The maximum storage depth of non-surface flow for a heavy storm with a daily rainfall depth of 391mm in the Okunoi experimental watershed is found to be 98mm, while interception and overland-flow depths are 71 and 208mm, respectively, that are 18 and 52% of the total rainfall depth.
