基于改进的Vensim模型模拟岩溶泉水文过程

Modelling the hydrological process of the karst spring using a revised Vensim model

经典的Vensim模型采用2个平行线性水箱来模拟岩溶水文系统中的慢速流和快速流,很难模拟岩溶水文系统内的非线性水文过程。提出一种改进的R-Vensim模型,将Vensim中的一个水箱改为非线性水箱,同时进一步考虑不同水文条件下降雨分配系数的变化,用于模拟岩溶含水层中存在的非线性水文过程。2个模型被用于模拟丫吉试验场的S31岩溶泉,模拟结果表明R-Vensim能更好地模拟不同降雨条件下岩溶泉水文动态过程,而Vensim总是低估暴雨下的流量峰值和高估低强度降雨下的流量峰值。研究区岩溶水文系统中慢速流呈现强烈的非线性,而快速流更接近于线性过程,2个模拟时段内78.5%和68.4%的泉流量来源于非线性水箱。研究结果表明模型中考虑非线性水文过程对于岩溶泉流量尤其低流量过程的精准模拟十分重要。

The conventional Vensim model uses two parallel reservoirs to simulate the slow and fast flows in karst systems,which can hardly simulate the existing nonlinear hydrological process.This paper proposed a revised Vensim model(R-Vensim)to further enhance its ability to simulate the nonlinear hydrological process in karst systems.This revised version changed one linear reservoir in the Vensim model into a nonlinear reservoir and considered the variation in the distribution coefficient under different hydrological conditions.The two models were applied to simulate the discharge of karst spring S31 located at the Yaji experimental site.The simulation results indicated that the R-Vensim model can reasonably reproduce the discharge dynamics under different precipitation conditions,whereas the Vensim model underestimated the fast flow peaks and overestimated the slow flow peaks.In the study catchment,the fast flow was almost linear,whereas the slow flow was highly nonlinear.In the calibration period,78.5%of spring discharge came from the nonlinear reservoir.The results showed that,considering the nonlinear hydrological process was a key issue to accurately simulate the karst spring,particularly for the slow flow condition.