南方水土流失区马尾松林降雨截留再分配特征与修正的Gash模型模拟

以我国南方典型水土流失区福建省长汀县河田镇马尾松林为研究对象，观测2018年5-11月降雨情况，分析马尾松林降雨截留再分配特征，以修正的Gash模型模拟林冠截留、树干茎流、穿透雨。结果表明，观测期间研究区共发生90次降雨，累计林外降雨量1 191.0 mm、穿透雨1 017.7 mm、树干茎流15.4 mm、林冠截留156.9 mm，且以低强度、小雨级降雨事件为主。林外降雨量与穿透雨、树干茎流呈线性正相关，与林冠截留呈对数关系。以修正的Gash模型模拟林冠截留量、树干茎流量、穿透雨量的均方根误差（RMSE）分别为1.38、0.15、1.34 mm，估测精度（RM）分别为84.53%、78.46%、98.04%。在-50%~50%变化范围内分析修正的Gash模型参数敏感性，模型参数敏感性顺序为平均降雨强度（R）>郁闭度（c）>林冠饱和下平均蒸发速率（E）>树干持水能力（S_t）>树干茎流系数（P_t）>林冠持水能力（S）。

Redistribution Characteristics of Rainfall Interception and the Modified Gash Model Based Simulation of Pinus massoniana in Southern Soil Erosion Area

Taking Pinus massoniana forest occurring in Hetian Township,Changting County,Fujian Province,where is a typical soil erosion area as the study object,we observed the rainfall events from May to November 2018 and analyzed the rainfall redistribution characteristics of P.massoniana,then the modified Gash model was used to simulate canopy interception,stemflow,and throughfall.The results showed that there were 90 times of rainfall in the study area during the observation period,including 1 191.0 mm of accumulated rainfall outside the forest,1 017.7 mm of accumulated throughfall,15.4 mm of accumulated stemflow,156.9 mm of accumulated canopy interception.The rainfall events were mainly low-intensity and light rain events.The rainfall outside the forest had a linear positive relationship with throughfall and stemflow,and a logarithmic relationship with forest canopy interception.The root mean square error (RMSE) of canopy interception,stemflow,and rainfall derived from the modified Gash model were 1.38,0.15,and 1.34 mm,respectively with the values of estimation accuracy (RM) of 84.53%,78.46% and 98.04%,respectively.The parameter sensitivity of the modified Gash model was analyzed in the range of -50%-50%.The order of the sensitivity of the model parameters was average rainfall intensity (R)>canopy closure (c)>average evaporation rate under canopy saturation (E)>tree trunk water holding capacity (S_t)>stemflow coefficient (P_t)>canopy water holding capacity (S).