前期土壤含水量对水文模拟不确定性影响分析

Effect of Antecedent Soil Water Content on the Uncertainty of Hydrological Simulation

前期土壤含水量是影响洪水形成的重要流域物理因素,在该次水文模拟中土壤初始含水量采用新安江日模型计算得出.研究中,通过改变日模型模拟的时间长度TP,来研究初始时刻土壤含水量的变化对洪水模拟精度的影响.结果表明:初始土壤含水量对于洪水模拟的精度有显著影响,不同日模型计算时间可以使次洪初始土壤蓄水量W的变化达到42%,而相应的洪峰偏差达到57.7%.土壤和降雨观测数据分析显示,土壤体积含水量与前期累积降雨量有一定地相关关系.为有效解决传统模型与流域真实物理属性数据的融合问题,初步建立了实测土壤体积含水量数据与模型中土壤湿度参数及前期降雨的经验关系.

Antecedent soil water content is an important physical factor for hydrological response at a watershed outlet. In hydrological modeling, initial soil water content is calculated by data. In this paper, uncertainty in hydrological simulation is studied by altering antecedent soil water content parameters of the distributed hydrology model. The initial soil water content has prominent influence on the accuracy of hydrological modeling results, especially for the hydrological processes with rare antecedentrainfall. The relationship between observed soil volume water content and antecedent rainfall is given. The correlation coefficient is high between soil volume water content and 15--day antecedent rainfall. The experiential relationship of the observed soil volume water content, antecedent precipitation and the soil moisture pa- rameters is researched in order to provide a way for combining volume water content with soil water parameters in a conceptual model. This relationship facilitates the combination between traditional model and physical features of the basin, which will improve the accuracy and reliability of hydrological simulation.