SCS-CN模型中土壤参数的作用机制研究

土壤参数是地表径流模型中的关键参数,对径流过程模拟有重要影响,因此有必要明确土壤参数的作用机制。论文结合SWAT (Soil and Water Assessment Tool) 模型,以广泛应用的径流曲线数模型(SCS-CN) 为例,对土壤参数在SCS-CN模型中的作用进行了理论推导、分析和实例研究。分析表明,土壤饱和含水量参数与田间持水量参数的比值,是影响不同土壤湿度下地表产流能力的重要因素,两者比值越大,土壤含水量对地表产流能力的调节越弱,导致基于不同土壤模拟的地表径流量随土壤湿度的波动而上下反转。以实际流域为例,发现不同土壤数据模拟地表径流间差别的显著季节性特征;阐明该差别季节性变化的内在机制,验证了理论分析结论。为深入理解产流过程、合理选择土壤数据、模型参数优化及模拟结果解释提供了参考。

Effects of Soil Parameters in SCS-CN Runoff Model

Soil data is one of the major input datasets for surface runoff simulation and has large impact on variation of the calculated results. It's important and helpful to understand seasonal variations of the impacts of soil data on calculated surface runoff. This study theoretically analyzed the effects of soil data on daily SCS-Curve Number (CN) runoff model in SWAT model (Soil and Water Assessment Tool), and a case study was also conducted to verify the analysis. Results show that the daily adjusted curve number is largely affected by ratio of two soil hydrologic parameters, saturated soil water content (SAT) to field capacity (FC). Large ratio of SAT/FC leads to smaller variation magnitude of curve number according to a given variation of soil water content, and differences of simulated runoff between soils with different SAT/FC change seasonally as adjusted by soil water content. A case study adopted two different soil datasets for runoff simulation was conducted in Brewery Creek watershed (about 19.5 km²), and the experimental results matched that of the theoretical analysis well.