基于SWAT模型的拉萨河流域水文模拟研究

发布时间：2019-04-11 06:53

【摘要】：拉萨是西藏的政治、经济、文化和宗教的中心,掌握拉萨河流域在不同降水频率和不同土地利用条件下的径流变化过程等规律对该流域的水资源合理开发利用、防汛抗旱、水库调度及西藏地区经济和社会发展繁荣具有重要意义。因此拉萨河流域用分布式水文模型SWAT(Soil and Water Assessment Tool)建立水文模拟系统,在改变气象资料、土地利用数据等输入条件,模拟拉萨河流域在不同条件变化下径流变化情况,进而找出影响拉萨河流域径流变化的主要因子,为拉萨河的水资源综合开发利用和规划管理提供科学依据。本文首先主要采用线性回归等长序列趋势分析方法对拉萨河流域1963~2008年近46年间的气温、降水以及拉萨水文站点流量数据进行趋势变化分析,并对其显著性进行研究;随后,在拉萨河流域构建SWAT分布式水文模型,用于模拟拉萨河流域地表径流过程;最后,通过改变气温、降水等气候条件,使用不同年代背景下土地利用数据及假拟土地利用条件,对拉萨河流域多个不同情境下的的河流流量变化进行对比研究,得出了以下结论:(1)通过线性回归的方法对拉萨河流域近50年来的历史气温、降水以及流量数据变化进行趋势分析。拉萨河流域在1963~2008年间,流域内主要气象站平均、最高和最低气温及降水均呈上升趋势,且总体上变化趋势显著;径流一定程度上有所增加,但是变化趋势不显著。(2)构建拉萨河流域水文模型,模拟了流域地表径流过程。结果表明,模型率定期和两个验证期Nash-Sutcliffe效率系数Ens分别为0.83、0.72和0.62,相对误差Re分别为18%、31%和33%,相关系数R2分别为0.88、0.85和0.84;1995~2008年整个模拟期Nash-Sutcliffe效率系数Ens为0.75,相对误差Re为0.27,相关系数R2为0.87。模型结果总体较好,说明SWAT模型适用于拉萨河流域。(3)在上述研究成果基础上,对1980年、1995年和2014年的不同年代土地利用类型下的模拟结果,以及假设拉萨河流域未利用土地全部转化为草地、全部转化为林地两种土地利用情景下模型结果进行比较,结果发现,土地利用变化对拉萨河流径流变化影响不大。随后,利用假定气候情景法设定8种单气候因子和4种复杂气候因子变化情境下,对拉萨河流域径流进行模拟,结果发现,年径流变化与降水量呈正比关系,气温变化对径流亦有扰动作用,气温升高可减少径流,但影响较为微弱。
[Abstract]:Lhasa is the political, economic, cultural and religious center of Tibet. It is necessary to master the laws of runoff change in the Lhasa River basin under different precipitation frequencies and different land use conditions, and so on, to rationally exploit and utilize water resources in the Lhasa River basin, and to prevent and fight floods and drought relief. Reservoir operation and economic and social development and prosperity in Tibet are of great significance. Therefore, the distributed hydrological model SWAT (Soil and Water Assessment Tool) is used to establish the hydrological simulation system in the Lhasa River basin. In order to change the input conditions of meteorological data and land use data, the runoff changes in the Lhasa River basin are simulated under different conditions. The main factors affecting the runoff change of the Lhasa River basin are found out, which provides scientific basis for the comprehensive development and utilization of water resources and planning and management of the Lhasa River. In this paper, the linear regression isometric trend analysis method is mainly used to analyze the temperature, precipitation and flow data of Lhasa hydrological station in the recent 46 years in 1963 / 2008, and the significance of it is also studied. Subsequently, the SWAT distributed hydrological model is built in the Lhasa River basin to simulate the surface runoff process in the Lhasa River basin. Finally, by changing climate conditions such as air temperature and precipitation, using land-use data and pseudo-land-use conditions in different ages, this paper makes a comparative study on the variation of river flow in Lhasa River basin under many different circumstances. The conclusions are as follows: (1) the trend of temperature, precipitation and discharge data in Lhasa River basin in recent 50 years is analyzed by linear regression. In the Lhasa River basin during 1963 / 2008, the mean, maximum and lowest temperature and precipitation of the main meteorological stations in the basin showed an upward trend, and the overall change trend was remarkable. Runoff increased to a certain extent, but the trend of change was not significant. (2) the hydrological model of Lhasa River basin was constructed and the surface runoff process of Lhasa River basin was simulated. The results show that the Nash-Sutcliffe efficiency coefficient Ens is 0.83, 0.72 and 0.62 respectively, the relative error Re is 18%, 31% and 33%, and the correlation coefficient R2 is 0.88,0.85 and 0.84, respectively. From 1995 to 2008, the Nash-Sutcliffe efficiency coefficient (Ens), relative error (Re), and correlation coefficient (R ~ 2) were 0.75, 0.27 and 0.87, respectively. The results of the model are generally good, indicating that the SWAT model is suitable for the Lhasa River basin. (3) on the basis of the above research results, the simulation results of land use types in different years in 1980, 1995 and 2014 are given. It is assumed that all unused land in Lhasa River basin is transformed into grassland and forest land. The results show that land use change has little effect on runoff change of Lhasa River. Then, the runoff of the Lhasa River basin was simulated with 8 single climate factors and 4 complex climate factors by using the hypothetical climate scenario method. The results showed that the annual runoff variation was proportional to the precipitation, and that the annual runoff was in direct proportion to the precipitation in the Lhasa River basin. The change of air temperature also has disturbance effect on runoff. The increase of temperature can reduce runoff, but the influence is relatively weak.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P333

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