【作者】 牟丽琴；

【导师】 胡和平；

【作者基本信息】 清华大学 ， 水利工程， 2008， 博士

【摘要】 基于REW的流域热力学系统水文模型(THModel)直接在宏观尺度描述流域水文过程,克服了传统物理性水文模型固有的方程适用尺度和模型应用尺度不匹配的问题,为水文模拟提供了新思路。THModel对REW的重新定义,为描述不同下垫面的水文过程,探究水文过程与其他过程之间的耦合规律奠定了基础,尤其为冰川积雪区水文过程的的模拟提供了灵活的模型框架。流域是个以水分运动为主导、多过程耦合的、具有一定自组织性的复杂系统,其中水分运动与能量交换过程的耦合是寒区水文模拟的关键。论文在THModel的模型框架下,采用能量平衡、度日因子和最大未冻水含量模型等方法闭合了冰川子区、积雪子区以及考虑土壤冻融的非饱和子区的质量、能量守恒方程,建立了冰川积雪区流域热力学水文模型,以土壤水分特征曲线为例,探讨了在气象条件、土壤类型、地下水埋深不同组合的虚拟情景下宏观尺度土壤水分特征曲线的特性。模型分别应用于不同气候特点的我国乌鲁木齐河源区和美国Reynolds Creek实验流域。在乌鲁木齐河源区,对8年的夏季径流模拟取得了较好的效果,并发现能量输入的季节变化对径流形成有很大影响;在美国Reynolds Creek实验流域,各年径流过程的模拟效果不同,其中对年均流量小于0.2m3/s的年份模拟效果较差,这与研究区域流量较小,模型采用一套率定参数不能反映流域的空间变异性等因素有关,但模型对积雪面积、雪盖温度、雪盖密度变化的模拟基本反映了积雪消融过程的物理规律。结合实例应用对模型参数开展了不确定性分析。在乌鲁木齐河源区,分别采用扰动分析法和极大似然不确定性估计方法(GLUE)对模型的主要参数进行了敏感性分析,结果表明冰川辐射系数最为敏感,而增加模型输入数据在一定程度上将降低模型的不确定性;在美国Reynolds Creek实验流域应用时,针对积雪消融的空间变异性,分析了不同积雪消融曲线形式对径流过程的影响。更多还原

【Abstract】 Representative Elementary Watershed (REW) approach first proposed by Reggiani et al. (1998) presents a different perspetive for hydrological modeling via developing scale adaptable equations. Thermodynamic watershed Hydrological Model (THModel) developed by Tian et al. (2006) further extends the REW theory by explicitly incorpotating energy balance equations. In this extensible framework, the energy sensitive hydrological processes such as evaporation, transpiration, snow and glacier melting, soil freezing and thawing can be modeled in a physically reasonable way, which provides a flexbile modeling framework for cold regions.Catchment is a complex system with a certain degree of self-organization. The interaction of different processes plays an important role in evolution of this particular system. For cold regions, water movement is intensively coupled with energy processes which should be coped with in a simultaneously manner. In this thesis, a thermodynamic hydrological model for cold regions is developed based on the THModel framework. The energy balance equations for the glacier zone, snow zone and unsaturated zone are closed aided by energy balance method, degree-day approach and the maximum unfrozen-water content model. Also, the characteristics of constitutive relationships at the REW scale are analyzed by virtual experimental method, and the promising method to develop the general closure relations is proposed.The Thermodynamic Hydrological Model for Cold regions is applied to two catchments, the headwaters of the Urumqi River basin and Reynolds Creek Experiment Watershed with different climates. In both basins the model can simulate the streamflow reasonable well. In the application of the headwaters of the Urumqi River basin, the significant influences of seasonality of energy input on the runoff generation which presents the tight coupling of water and energy. In the Reynolds Creek Experiment Watershed, the model can not reproduce the annual daily discharge below 0.2m3/s very well, but the simulated snowcover area ratio, snow temperature and snow density follow the physical law of snow accumulation and depletion.The sensitivity analysis of model parameter is carried out by both“one-at-a-time”approach and Generalized Likelihood Uncertainty Estimation (GLUE) method. The results show the heterogeneity coefficient of radiation has significant influences on the watershed hydrological responses, and additional data can reduce the uncertainty to a certain extent. The prediction uncertainty relating to the form of snow delption curve is also estimated for Reynolds Creek Experimental Watershed.更多还原