Parameter calibration is essential for establishing and using a hydrological model. In multi-objectives hydrological calibra -tion, different weights of objective functions directly affect the calibration results, and how to determine the weights of different ob -jective functions is a key step of hydrological calibration. The HSPF (Hydrological Simulation Program-Fortran) model that is a typ -ical semi-distributed hydrological model was taken to study the effect of objective weights for different calibration functions on hy -drological simulation. The upstream watershed of the Niulanjiang River was selected as a case study to simulate runoff by the PEST-HSPF model, and the study was supposed to be a guide for parameter optimization of HSPF by automatic calibration ap -proach. Through altering the objective function weights, the goodness of fit of the model was recorded to determine the impact of different weights on the performance of PEST-HSPF simulation. The results indicate that: (1) when the weight of single objective function (daily flow, month flow, hypercritical flow days) of PEST-HSPF rises, Nash coefficient of the model and the relative devia -tion present nonlinear variation response with a vast and unstable variation in value; (2) Higher prediction ability and less error can be obtained when the three weights of the objective functions are set within 1-10 orders of magnitude. The Nash coefficient can reach over 0.8 and the relative error is lower than 10%; (3)The weight of hypercritical flow days has a greater influence on the a -bility to prediction while the weight of daily flow has a greater influence on the fluctuation of relative deviation. When the weight of hypercritical flow days varies between 1 and 1000, the corresponding Nash coefficient is between 0.02 and 0.86; the relative er -ror will change greatly when the weight of daily flow exceeds 30.%参数率定是水文模型构建与应用的重要基础.在多目标水文校准中,不同目标函数的权重设置直接影响校准的结果,如何确定不同目标函数的权重是水文校准的关键问题.选择典型半分布式水文模型HSPF(Hydrological Simulation Program-Fortran),基于PEST多目标校准模型,以牛栏江上游流域为研究对象,研究目标函数权重对HSPF水文模拟拟合优度的影响,为HSPF模型参数自动率定提供指导与借鉴.结果表明:(1)当PEST-HSPF水文校准的单目标函数权重(日流量、月流量、超流天数)上升时,模型的纳什系数和相对偏差呈现非线性变化特征,不规则波动幅度较大;(2)3个目标函数的权重在1~10量级内模型能够获得较高的预测能力和较低的误差,模型的纳什系数平均可达到0.8以上,相对偏差在10%以内;(3)超流量天数权重设置对模型的预测能力变化影响较大,日流量天数权重对相对偏差的波动影响较大,当超流天数的相对权重在1~1000范围内变化时,模型纳什系数在0.02~0.86之间波动剧烈,当日流量相对权重值超过30时,相对偏差变化明显.
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