Development of integrated hydro-biogeochemical model in a forest catchment

在对一个温带森林小流域进行深入观测的基础上，建立了一个描述和预测森林小流域生态地球化学响应的综合水化学模型。以流域尺度饱和-非饱和入渗土壤化学过程的水化学模拟为原型，提出了SiO_2浓度生成的数值模型。建立了面向过程的一维pH模拟模型和氮碳动力学模型。流域尺度模型具有多个子单元，每个子单元的土壤深度由实际土壤深度分布决定。利用实测降雨量和降雨质量资料，对各子单元进行了饱和-非饱和入渗和对流-扩散耦合计算。利用适当估算的化学风化速率，该模型可以再现暴雨和基流期间观测到的河流和地下水SiO_2浓度的时间序列变化。一维pH模拟模型是基于实际土层中缓冲系统的观测信息。该模型模拟了土壤溶液的CO_2浓度和碱度。它可以成功地再现地下水和河水pH值的季节性变化。

An integrated hydrochemical model for description and forecast of biogeochemical responses in a forest catchment has been developed based on intensive observation in a temperate forest catchment. As the prototype of the basin-scale hydrochemical modeling taking the saturated-unsaturated infiltrated into the soil chemical process, a numerical model for SiO_2 concentration generation was proposed. The process oriented 1-D pH simulation model and nitrogen/carbon dynamics model were also proposed. The basin-scale model has multiple subunits with each soil depth that is determined by actual soil depth distribution. A coupling calculation of saturated-unsaturated infiltration and convection-diffusion process is conducted for each subunit using observed rainfall quantity and quality data set. Using the properly estimated chemical weathering rate, the model can reproduce the observed timesequential change of the SiO_2 concentration of stream and subsurface groundwater for the duration of both storm event and base flow periods. The 1-D pH simulation model is based on the observed information of buffering systems in actual soil layr. The model simulates the CO_2 gas profile and alkalinity of soil solution. It can successfully reproduce the seasonal changes in pH of groundwater and streamwater.