基于修正的Gash模型模拟缙云山毛竹林降雨截留

Simulation of Canopy Rainfall Interception of the Phyllostachys edulis Forest with the Revised Gash Model in the Jinyun Mountains of Chongqing

为了验证修正的Gash模型对缙云山毛竹林林冠截留模拟的适用性,基于2009年4—7月的气象和林分特征资料以及实测的穿透雨和树干茎流等资料,分析缙云山毛竹林林外降雨、穿透雨和树干茎流特征,并应用修正的Gash模型对林冠截留量进行模拟,对比分析周降雨累计截留量和单次降雨截留量的模拟值和实测值,采用敏感性分析法分析模型参数对截留量的影响程度。结果表明:研究期间共29次降雨,总降雨量为531.1mm,平均降雨强度为2.11mm·h-1,大部分为低雨强、低雨量级、长历时的降雨;穿透雨量、茎流量和林冠截留量的实测值分别为463.2,6.5和61.4mm,模拟值分别为461.1,6.1和63.9mm,模拟的截留量约高出实测值4.07%,模型计算的周累积截留量和单次降雨截留量与实测值相比的相对标准差分别为5.02%和7.13%,模拟效果较好,模型适用于缙云山毛竹林;以林冠郁闭度(c)对模拟结果影响最大,其次为平均降雨强度()、林冠持水能力(S)和林冠平均蒸发速率(),树干茎流系数(Pt)和树干持水能力(St)这2个参数对林冠截留总量影响很小。

In order to verify applicability of the revised Gash analytical model in simulating canopy interception of the Phyllostachys edulis forest in the Jinyun Mountains,the rainfall,throughfall and stemflow characteristics and their heterogeneity was measured,and the canopy interception was simulated with the revised Gash analytical model.A comparison in week cumulative rainfall and a rainfall event interception was conducted between the simulated and actual values basing on meteorological data,forest survey data during April～July of 2009.In addition,effects of the model parameter on interception was analyzed with a sensitivity analysis method.The results indicated that the cumulative gross rainfall of 29 sampled events was 531.1 mm and the mean rainfall intensity was 2.11 mm·h-1.The measured throughfall,stemflow and canopy interception were 463.2,6.5,and 61.4 mm,respectively.Most of the rainfalls had a low rainfall intensity,low rainfall levels,and long duration.Throughfall,stemflow and canopy interception simulated by the revise Gash model were 461.1,6.1,and 63.9 mm,respectively.The revised Gash analytical model of rainfall interception was employed and the simulated interception values were close to the measured ones with an underestimation of 4.07%.The comparison between the simulated and the measured canopy interception per week and per rain event during the study period showed that the relative standard error in the two interceptions between the simulated and the measured ones was 5.02% and 7.13%,respectively,indicating that the Gash analytic model could be used for estimating canopy interception in the P.edulis forest in Jinyun Mountains.The simulation with the revised Gash model was impacted most by canopy cover（c）,followed by mean rainfall intensity（）,canopy storage capacity（S）,mean evaporation rate during rainfall（）.But the simulation was not sensitive to trunk storage capacity（St） and proportion of rain diverted to stemflow（pt） since these two parameters only had a small effect on total interception.