Abstract:

Our aim is to verify the applicability of the revised Gash analytical model to canopy interception loss of typical evergreen broadleaved forests in the Jinyun Mountains in Three Gorges Reservoir Area.The rainfall，throughfall and stemflow data were observed and collected by the rain gauges and data loggers，and the canopy interception loss was simulated with the revised Gash analytical model.A comparison in hourly cumulative rainfall and a rainfall event interception was conducted between the simulated and measured values based on meteorological data and forest survey data during AprilJuly of 2012.In addition,the effects of the model parameter on interception was analyzed with a sensitivity analysis method.The results indicated that the cumulative gross rainfall of 34 sampled events was 5221 mm and the mean rainfall intensity was 13 mm/h.The measured throughfall，stemflow and canopy interception were 450.9 mm，9.6 mm and 61.6 mm,respectively.Most of the rainfalls had a low rainfall intensity,low rainfall levels,and long duration.Throughfall,stemflow and canopy interception were simulated by the revised Gash model were 446.1 mm,77 mm and 682 mm,respectively.The simulated interception loss was lower by 108% than the measured ones.It was indicated that the revised Gash analytic model could be used for estimating canopy interception of single field rainfall in the evergreen broadleaved forest in the Jinyun Mountains in Three Gorges Reservoir Area.The simulation with the revised Gash model was affected in the highest level by canopy density,in the middle level by mean rainfall intensity R,in the low level by canopy storage capacity,mean evaporation rate during rainfall E,but the simulation was not sensitive to trunk storage capacity   and proportion of stemflow   in rainfall since these two parameters only had a small effect on total interception