SWAT模型基于不同坡度林地径流调节作用的实现与应用

Application of SWAT model and realization of hydrological adjusting function of forests on different slopes

在国内外许多地区,SWAT模型广泛应用于表征土地利用变化的水文效应。但鲜有学者考虑模型对土地利用模拟方法的改进。SWAT模型概化了土地利用类型的坡度和空间差异,降低了结果的精确性。文章以提高SWAT模型对土地利用(尤其是林地)改变的敏感性和径流模拟能力为目标,考虑土地利用类型CN值随不同坡度变化以及林地对径流汇流的调节作用,对SWAT模型进行改进。研究以老灌河上游流域为实验区,将流域划分为4个坡度带,以子流域为单位分别计算各土地利用类型的CN值,提高模型对土地利用空间变化的敏感性;在此基础上改进模型汇流模块,实现各坡度带下林地对汇入径流的调节功能,并与原始模型进行比较。结果表明,改进后的SWAT模型在月、日径流模拟高于原SWAT模型精度,尤其对汛期产汇流过程的模拟效果有明显提高。考虑了不同坡度林地径流调节作用的模型可以更为准确地刻画研究区的水文特征,为模型模拟水文过程以及因气候变化和土地利用变化引起的水文响应提供更为准确、有效的工具。

SWAT model has been widely used in simulating the effects of land use change on hydrology, but its application to assessment of the impacts of major shifts in land use needs further enhancement. The accuracy of this model is reduced by homogenizing the slope and spatial difference of land use. SWAT model has been modified in this study considering the CN value of land use type （especially the forest） to different slopes and the forest hydrological adjusting function, to improve its sensitivity to changes in land use and its runoff simulation. The area of Lao Guanhe watershed was selected in a case study by dividing each of its sub-basins into four slope grades, and the CN value was calculated for each land use type in different slope grades; and the SWAT model was modified to achieve the forest hydrological adjusting function in each slope grade through improving the methods for estimation of surface runoff. The results show that a significant improvement was achieved in monthly and daily hydrological simulations in comparison to the original SWAT simulations for both model calibration and validation periods, especially in rainy season. The modified SWAT model considering the forest hydrological adjusting function can provide better response to climate change and land use change.