基于修正的Gash模型模拟中亚热带常绿阔叶林降雨截留过程

Simulation of Canopy Rainfall Interception of the Evergreen Broad-leaved Forest in Mid Subtropical Zone Using the Modified Gash Model

于2016年和2017年的5—9月期间收集研究区磨盘山国家森林常绿阔叶林的26场降雨数据,并对其林冠截留和降雨分配过程进行分析,结合研究期间的气象数据和林地调查资料,运用修正的Gash模型对其降雨截留过程进行模拟。结果表明:研究期间大部分为低雨强、低历时、中雨级的降雨;大气降雨量、穿透雨量、树干茎流量、林冠截留量分别为994.07,562.90,16.90,406.40mm。根据修正的Gash模型得出穿透雨量、树干茎流量、林冠截留量相对应的模拟值为548.63,21.75,403.28mm,与实测值相比,三者的相对误差分别为2.60%,22.29%,3.34%。总体来说,修正的Gash模型适用于拟合中亚热带地区常绿阔叶林降雨截留过程。对模型中出现的相关参数(c、P_t、S、S_t、、)进行敏感性分析,得出6个参数对林冠截留量模拟结果的影响顺序为c>>S>>S_t>P_t。

Evergreen broad-leaved forest is well-preserved,and is playing an irreplaceable role in water conservation and ecological regulation in forest areas in Mid subtropical zone.In order to investigate the canopy interception and allocation and evaluate forest hydrological function and benefit of the evergreen broad-leaved forest in mid subtropical area quantitatively,positioning experiments were implemented during two rainy seasons of from 2016 to 2017 in Mopan Mountain national nature reserve.The amount of throughfall,stemflow and precipitation were measured and interception loss was subsequently calculated.Based on the observations of 26 rainfall events,canopy interception process of evergreen broad-leaved forest was simulated using the modified Gash model.The results showed that most of the observed rainfall had the low intensity,low duration and moderate rain.The amount of rainfall,throughfall,trunk flow and canopy interception were 994.07 mm,562.90 mm,16.90 mm and 406.40 mm,respectively,during the study period.According to the modified Gash model,the simulated amounts of throughfall,stemflow and canopy interception were 548.63 mm,21.75 mm,403.28 mm,respectively,and their relative error were 2.60%,22.29% and 3.34% respectively compared to the measured.The results of sensitivity analysis showed that the sequence of simulated results of canopy interception from large to small was c,,S,,S_t,P_t.