Measurements and modeling of throughfall variability for five forest communities in the southeastern US

The temporal variability of interception losses was measured for contrasting forest communities in the southeastern United States. Throughfall was measured simultaneously at Fort Benning in western Georgia for the five forest communities that are characteristic of the region. The measured interception losses over the study period were 22.3, 18.6, 17.7, 17.6, and 17.4% of the total precipitation in the pine, mixed forest, lowland hardwood, pine plantation, and upland hardwood forests, respectively. The Gash model with a wet canopy Penman-Monteith evaporation, using annual average canopy cover values, predicted interception losses with an agreement of −8.1-10.5% on an annual basis. The model improved accuracy for all forest communities when seasonal changes in canopy cover were included. The Gash model's assumption of a constant canopy storage capacity was examined for pine and lowland hardwood plots with varying densities and found to have good agreement for mature pine forests having 64, 44, and 29% canopy cover. However, riparian wetland forest predictions required corrections for species composition and understory vegetation.