Canopy Storage Implications on Interception Loss Modeling

A rainfall interception methodology was implemented in a deciduous Ficus benjamina (L.) tree to evaluate the interception loss, as well as the dynamics on canopy storage capacity (S) and free through fall (ρ). Measurements of gross precipitation (Pg), through fall and meteorological data were recorded every 5 minutes. Nineteen individual storms from summer to autumn 2005, and twenty one in spring to autumn, 2006 were analyzed. For the studied period, 151.59 mm and 203.35 mm of rainfall occurred on 2005 and 2006 respectively. Canopy interception was 59.46% and 70.98% of Pg for the first and second year. Throughfall data recorded during 2005 were 38.14% (of Pg) and 27.21% (of Pg) for 2006. The throughfall and gross precipitation relationship yielded S = 1.50 mm for the 2005 data. In 2006 storms were analyzed in detail, where ρ and S varied in a range from 0.10 to 0.64 and from 1.00 to 2.03 mm, respectively. Moreover, application of the Rutter and Gash models with two years of rainfall data (2005-2006) from the study area indicated an underestimation and overestimation of 69% and 88%, respectively. The slightly best prediction of the interception loss was obtained with the Gash model. Yet S and ρ change significantly due to wind speed, temperature, rainfall intensity and seasonal vegetation development.