Implementation and evaluation of DROP, a model for the simulation of rainfall distribution below plants described in 3D

Rainfall interception by plants affects environmental processes such as water distribution, erosion and leaching of pollutants. In order to quantify the effect of plant cover for the management of water fluxes we developed the DROP model to simulate the water distribution through plants to the soil surface. It leaned on the discretization of the plant architecture provided by a computerized model or by the digitization of an actual plant. A spatially discrete rainfall table was modified until it reached the soil according to the interception and transmission properties of plant elementary surfaces. Below a maize plant, on sampling areas of 31.2 cm(2), the measured transmission ratio (rainfall at the soil surface to incident rainfall) reached 35 for stemflow and varied between 3.5 and 0.05 elsewhere. The DROP model reproduced that distribution fairly well and can be used below plants to map relative water distribution on a grid with a pixel size of 100 cm(2).