林冠截持降雨模型的初步研究

通过对林冠截持过程的研究，将单场降雨划分成很多个小的时段，顺序计算各小时段内降雨在林冠内的分配，建立了一个林冠降雨截持模型.模型考虑了冠层和树干干燥度对冠层雨期蒸发的影响，并在计算雨期蒸发时引入冠层叶面积指数、单位林地面积上树干表面积.运用模型对华北落叶松林的降雨截持进行模拟，结果表明，模拟穿透雨与实测穿透雨基本吻合，误差在±1 mm范围内，但在小降雨(＜6 mm)时模拟值偏低；树干茎流量模拟值偏低，茎流模拟相对误差随着降雨量增大而减小.同时模拟了穿透降雨的过程，结果与林内自动气象站实测穿透降雨的过程基本吻合，模拟效果较好.

Rainfall interception model of forest canopy:A preliminary study

Canopy interception is an important hydrological process in forest ecosystem, and its modelling is of significance to understand and estimate the rainfall interception by the canopy. In this paper, a canopy rainfall interception model was established by dividing a rain incident into a set of short period, calculating the rainfall distribution intercepted by the canopy, and educing the process of the rain incident. This model considered the effects of the dryness of canopy and trunk on the evaporation from wet canopy and trunk during one rain incident, and introduced two factors, leaf area index (LAI) and surface area of trunk per unit area of ground (SAI), when computing the evaporation. The application of the model to simulate the rainfall interception process in a Larix principis-rupprechtii plantation in Guyuan, south Ningxia Hui autonomous region of China showed that the simulated and measured throughfall were identical, and the absolute deviation between simulated and measured results was within +/- 1 mm. But, when the precipitation was smaller than 6 mm, the simulated throughfall was lower than the measured one. The values of simulated stemflow were lower than the measured values, and the relative deviation between simulated and measured values was smaller when the precipitation was larger. The process of throughfall in the forest was also simulated, with the results fitted well to the measured one.