Performance of Revised Gash Model for Estimating Rainfall Interception in a Robinia pseudoacacia plantation during the leafed and leafless periods

Therefore, this study aimed to evaluate the revised Gash model in estimating interception by a Robinia pseudoacacia (L.) stand during the leafed and leafless periods in Chitgar Forest Park.

A circular plot with an area of 0.5 ha in Chitgar Forest Park was selected and rainfall, throughfall, and stemflow were measured for two years (from 22 December 2013 to 21 December 2015). Then, the amounts of canopy and trunks ecohydrological parameters were calculated, and finally, the efficiency of the revised Gash model for estimating interception was evaluated.

In this study, the mean amount of rainfall interception in the leafed period (12.7%) was significantly higher than the leafless period (9.7%). The determination coefficient (R2) value between the estimated interception values and the measured in the leafless period was higher than in the leafed period. Based on all model evaluation metrics, the performance of the revised Gash model in estimating interception in the leafless period was better than in the leafed period.

Based on the findings of this study, the Revised Gash model showed good ability in estimating interception during the leafless period, and a probable reason for the high estimation error of the model in the leafed period is the lack of direct measurement of the canopy percentage parameter. Accurately determining the amount of interception, as a canopy water loss, contributes significantly to the planning and decision-making process of forest managers and water resources managers for selecting the appropriate species for plantations.