基于SWAT模型的基流估算及评价——以洛河流域为例

SWAT是一个具有很强物理机制的长时段的流域分布式水文模型,它能够利用GIS和RS提供的空间数据信息,模拟复杂大流域中的径流成分。本文应用SWAT模型对基流进行模拟,分别采用1992～1996年和1997～1998年洛河流域卢氏水文站逐年、月实测径流资料进行模型校准和验证,确定模型的敏感性参数:径流曲线数、地下水再蒸发系数、土壤蒸发补偿系数和植物蒸发补偿系数;并借助滤波技术对实测径流进行基流分割。将滤波分割的基流与SWAT模拟值进行对比,采用线性回归系数(R2)和Nash-Suttclife模拟系数(Ens)对SWAT模型进行评价,其结果月基流R2为0.76,Ens为0.75,模拟精度较高。

The Study on Baseflow Estimation and Assessment in SWAT --Luohe Basin as An Example

Baseflow, usually separated from total streamflow, is very important in many research fields. Two methods to analyze and calculate baseflow were introduced. The first method uses the water balance components from the soil and water assessment tool model (SWAT). The second method uses a digital recursive filter to separate baseflow from daily flow. The result was applied in Lushi basin located in the upper of Luohe to calibrate baseflow in SWAT model. Simulated flow was calibrated against calculated flow at Luohe (4 623km 2 ) from 1992～1996.To validate the model, calibrated and simulated monthly flow at Luohe from 1997～1998 was compared with a R 2 of 0.81 and an Ens of 0.84. Four sensitive factors, including CN_2 , RWVAPC, ESCO and EPCO, are determined after calibration and validation of the model. The rate of three-month (Aug. to Oct.) baseflow in annual total one is 46% because the floods usually took place in August and September in the study area. Comparing simulated monthly baseflow to the filtered one from 1992～1998, a good result can be gained with a R 2 of 0.76 and an E_ns of 0.75.The case study illuminates that SWAT model can simulate baseflow well, and the filter technique has the potential to provide realistic estimates of baseflow for input into regional groundwater models and a check for surface hydrologic models.