【作者】 张荔；

【导师】 王晓昌；

【作者基本信息】 西安建筑科技大学 ， 市政工程， 2010， 博士

【摘要】 水文循环是联系地球系统中地圈—生物圈一大气圈的纽带,水文循环决定着水资源形成与演变规律,也决定着流域的水环境特性。因此,开展水文循环系统的研究对流域水环境的可持续发展具有重要的意义。由于水文循环过程十分复杂,流域水文模型逐渐成为研究水文循环规律、进行流域水文系统模拟的必然结果,同时也是全面把握水文过程的作用机理、系统评价流域水资源演变规律、客观发现人与水及生态之间存在的不和谐问题等的有效工具。分布式水文模型(distributed hydrological model)以水文科学的理论知识为基础,针对流域水文系统的空间分布性和非线性特点,从流域水文循环的物理机制入手,充分考虑流域各处的地形、地貌、土壤、植被、土地利用和降水等基础信息的空间分布特征及变化,通过模拟水文循环的各个环节,全方位获悉流域各水文要素的状态及变化规律。渭河是黄河的第一大支流,流经甘肃、宁夏、陕西三省(自治区),自西至东横贯富饶的关中平原。渭河流域不仅在黄河的治理和合理开发中占有重要地位,在区域经济发展和西部大开发中也具有重要的战略意义。随着经济社会的快速发展和人口的增长,受自然变化和人类活动的影响,渭河流域尤其是中下游地区出现了河流流量减小、水资源短缺、水污染加剧和水环境恶化等问题,人与自然的冲突加剧,损伤了流域及社会的可持续发展。因此,迫切需要充分熟谙渭河流域的水文循环规律和水资源信息,并正确认识自然变化和人类活动所引起的流域水文效应,以保护和改善流域水环境,促进人与自然和谐相处。论文在已有水文循环系统的作用机制及分布式水文模型研究成果的基础上,基于GBHM (Geography-Based Hydrological Model)模型的方法,引入“山坡”单元对流域进行离散化,构建了基于单元地貌的分布式水文模型。模型以地理信息系统(GIS)和遥感(RS)为技术支持,在流域数字高程模型(DEM)的基础上,利用计算机充分提取流域的地形、地貌特征等水文参数信息。通过对流域进行空间离散,逐级划分流域为若干子流域,子流域沿汇流长度再依次划分为一系列汇流区间,每个汇流区间内又包含若干几何相似的“山坡”单元,最终作为流域水文模拟的基本计算单元。在每一个水文计算单元上,利用模型推求降雨产流及地面径流,再进行河道汇流模拟,求出每个子流域的出口断面流量,以实现对整个流域的坡面产流、地面径流、河道汇流等水文过程的模拟。论文面向渭河流域的自然状况、径流特性及水环境现状,将已构建的基于单元地貌的分布式水文模型应用于渭河流域,系统分析了渭河流域陕西片的水文循环规律、径流分布及水资源变化等特性。对流域内的每个“山坡”单元,根据多种土地利用和土壤类型进行组合,可将每个“山坡”单元概化为对称坡面上沿河道方向平行排列的一系列矩形,每个矩形代表一种土地利用和土壤类型的组合,每个矩形所产生的径流均直接汇入子流域的主河道。在“山坡”单元的坡度、坡长、土地利用和土壤类型等水文要素已知的情况下,对每个水文计算单元进行水文过程模拟,并通过模型输出。通过对渭河干流主要断面的流量模拟结果与实测值的比对,二者吻合较好,说明借助基于单元地貌的分布式水文模型对渭河流域复杂的水文循环过程进行模拟是可行的,能够充分反映流域下垫面的空间特性对水文过程的影响。认识气候和流域下垫面等变化条件下的水文响应特征,有效预测流域径流和水资源的变化,是“维持健康渭河、实现人水和谐”的科学基础。为了鉴别降雨及土地利用对流域径流的影响,定量描述流域水环境的不确定性变化,本文接着建立了运用分布式水文模型预测流域径流变化规律的情景分析方法。结合渭河流域陕西片的降雨变化趋势,在现状自然条件以及人类活动的基础上,随机设定了一系列降雨和土地利用情景,通过构建的基于单元地貌的分布式水文模型,有效揭示了降雨及土地利用对流域径流及水文循环的影响效应,探讨了渭河流域陕西片的水环境不确定性问题。研究结果表明,对于不同的降雨情景,年降雨总量对年径流总量影响显著,说明渭河流域陕西片的地表水资源主要取决于降雨资源。但是,由于渭河流域陕西片地处干旱半干旱地区,降雨量较少而蒸发量较大,伴随着可能的土地利用方式改变,流域片的径流及水文循环的响应并不显著。论文针对渭河干流陕西段水量及水质的变化趋势与波动性,以基于单元地貌的分布式水文模型为框架,关联河流水质模型,构建了分布式水文水质耦合模型,同步模拟了渭河干流陕西段的流量和主要水质的变化趋势与波动性,以及主要污染物的空间分布,对渭河流域陕西片的水环境安全进行了评价和预测。结果表明,渭河流域陕西片水环境安全的未来趋势依然严峻,河流生态健康受到严重威胁,有必要对渭河流域的水环境污染进行修复,以保障流域水环境安全,实现可持续发展和构建和谐社会。更多还原

【Abstract】 The hydrological cycle is the connection of the earth circle-biocycle-atmosphere system. So, the hydrological cycle decides the formation and evolution pattern of water resources, and the water environment characteristic in a specific basin.Therefore, the research about hydrological cycle has an important implication to keep a basin with sustainable development. Because of the very complicated hydrology process, the hydrological model has inevitable becomes a power tool for studying hydrological cycle and simulating hydrology system. At the same time, the hydrological model is gradually becoming a power tool for overall grasping the laws of the hydrology process mechanism, scientific evaluating the water resources and its evolution pattern, and objective discovering the disharmony problem among human, water and ecosystem.The aim of the distributed hydrological model is to simulate each aspect during hydrological cycle with taking the basic knowledge of hydrology science as its foundation. Due to the spacial and non-linear characteristics of the hydrological system in a basin, the model starts with physical mechanism of the hydrological cycle, with adequately considering landform, geography, soil type, vegetation, land use and rainfall overall the basin, in order to comprehensively grasping the status and change of the main hydrological factor in a basin.The Weihe River is the biggest distributary of the Yellow River, flowing from west to east through three provinces (autonomous region) in Gansu, Ningxia and Shaanxi.The Weihe River basin not only significantly contributes to the management in the Yellow River, and occupies an important role in Shaanxi economy development, but also has an important strategic meaning in the west development. With the development of productive forces and the population growth, the conflict of the human and nature is increasingly severe, more and more problems appeared in the Weihe River basin such as the stream flow is decrease, the water pollution is serious, the hydrological disaster is severe, resulting in the deterioration of water environment, and the ecological enviroment in the watershed is damaged. All these issuses will prevent the sustainable development of the watershed and the community. Therefore, the research of the hydrological circle and the water environment in the Weihe river basin is of great significance. For promoting the harmony between human and nature, we need know well the theory of the hydrological cycle and the chang of water resources, and understand correctly the hydrology effect on the nature chang and the human activity in the Weihe river basin. On the basis of above scientific research, the protection and improvement for the water environment in Weihe river basin will be carried out accordingly.First, on the foundation of the water recycle mechanism and the research achievement on the distributed hydrological model, according to "hillslope" method, a geography based hydrological model was constructed in this paper. The model takes geography information system(GIS) and remote sensing(RS) as its technique supports, and withdraws the hydrology parameter informations such as geography and geography characteristic on the foundation of the digital elevation model (DEM). Accordingly, the whole basn is divided into some sub-basin, fter these Carrying on space through a convection area is long-lost, pursue class demarcation river valley is some sub-river valleys, sub-river valley along with remit to flow length again one by one in order divide the line to remit to flow zone for a series, each one remits to flow inside the zone again include some several what likeness of unit in"hillside" is finally the basic calculation unit that the river valley hydrology imitates.On each hydrology calculation unit, make use of model to reason rain to produce to flow and the ground path flow, again carry on course of river to remit to flow emulation, beg the exit cross section of an each statures river valley discharge, produce to flow to the whole ascent noodles of river valley by realization, the ground path flow, the course of river remit the emulation of flowing the etc. hydrology process.Secondly, for the natural state of the runoff and water quality characteristics in Weihe River basin, the constructed geography based hydrological model is applied to analyzing the main problem of the water environment in Weihe River basin. The hydrological components, including runoff generation from the hillslopes and the flow routing in the river network are modeled using physically-based approaches. The hydrological characteristics, the change of the flow and water quality, and the law of formation and transformation of water resources in Weihe River basin is also studied. The whole basin is divided into a number of sub-basins firstly, each sub-basin along the convergence of the length of interval is then divided into a series of convergence, and each convergence zone contains a number of geometric similarity of the hillslope unit as the basic calculation of hydrological modeling unit. Using the hillslope unit, the net rain of each hydrological unit is calculated firstly, then, the convergence of river network each sub-basin is calculated, and the whole export flow of each sub-basin is finally obtained. According to this simplified calculation method, the basin-wide hydrological processes is generalized and implemented. The results of this paper showed that the construction of the integrated hydrological and quality model can give a better simulation and forecast with less number of mesh and high-precision process, and has been satisfied with the analytical results of the water environment in the Weihe River basin. Through applying the model in the Weihe River basin to simulate natural water circle, the features and the applicability was well verified. The using of Basic Hydrology Unit could not only reflect the human activities impacting the rainfall-runoff process wit h physics-based parameters, but also greatly reduce the computation time.Roundly grasping the hydrology respond to the change of climate and characteristic in a basin, and effectively predicting the future trend of runoff, hydrological cycle and water resources in Weihe River basin are the science foundation to "maintaining healthy Weihe River, and achieveing human and water harmony". in order to explore climate change and human activities on water environment in response to the Weihe River basin, a quantitative description of the uncertainty change in water environment is discussed. The different rainfall and land-use scenarios are set to simulate the change and trend in the future of hydrology, water quality, water resources and water environment in the Weihe River basin, also using the integrated hydrological and quality model as the technical support. Finally, an objective assessment of the influence of natural changes and human activity on the uncertainty of the water environment changes in Weihe River basin is given. At the same time, the water quality under the different rate of flow in the main stream of the Weihe River in Shaanxi Province is evaluated and predicted.Finally, a distributed coupling model based on the geography based hydrological model and the river quality model was established in this paper, and the discharge and the quality of the main section on the Weihe River in Shaanxi piece was simulated simultaneously in order to reflect the trends of the amount of water and water quality changes. Accordingly, the spatial distribution of the main pollutants and the safety evaluation of water environment in Weihe River basin are also made. The results showed that water environment situation of Weihe River basin is still grave and serious, and it threats to the ecological health of river. On this basis, the proposal to restoring the water quality of Weihe River is proposed in order to protecting the water environment security, achieving sustainable development and building a harmonious society.更多还原