Budyko框架下黄土高原流域蒸散时空变化及其归因分析

发布时间：2018-01-15 13:36

本文关键词：Budyko框架下黄土高原流域蒸散时空变化及其归因分析　出处：《中国科学院教育部水土保持与生态环境研究中心》2017年博士论文　论文类型：学位论文

【摘要】：受气候和下垫面变化的双重影响,流域水文循环过程也随之发生变化,其中蒸散过程作为联接水文过程与生态过程的纽带,更受学界关注。Budyko框架具有坚实的理论基础和明确的物理含义,籍此开展的流域生态水文研究已成为水文学研究的前沿和热点之一。黄土高原生态环境脆弱,近几十年来包括以退耕还林还草为主要内容的生态建设、煤田油气能源基地建设以及新城镇建设等在内的大规模、高强度的人类活动又使得下垫面发生了显著变化,在这种背景下该区域蒸散发生了怎样的变化,气候和下垫面变化对其贡献影响如何需要深入研究。为此,本论文在分析黄土高原水热条件时空变化的基础上,首先基于全微分方程对本区域潜在蒸散时空变化进行了定量归因;然后在年际尺度上研究Budyko框架下水热耦合控制参数与下垫面变化(以植被为代表)和气候季节变化之间的关系,并探讨了影响水热耦合控制参数的各因子间关联性及时间尺度效应;最后估算了气候和下垫面变化对流域实际蒸散的贡献,得到的主要结论有:(1)近几十年来黄土高原气温显著升高,而基于FAO 56 Penman-Monteith公式计算的潜在蒸散整体上则有轻微减小的表现,说明该区域存在“蒸发悖论”现象;降水的年内变异和波动较之于潜在蒸散的更大,气候季节性指数S呈微弱降低趋势,意味着近几十年来降水和潜在蒸散差值的季节波动趋于减小。(2)基于全微分方程对潜在蒸散时空过程上所发生的实际变化进行归因分析表明:在时程变化上,多年来潜在蒸散对实际水汽压最敏感,对太阳辐射和平均气温的敏感性次之,而对风速的敏感性最小。但同时受各气象因子实际变化幅度的影响,多年来对该区域潜在蒸散变异贡献最大的因子却是平均气温,其次为风速和太阳辐射,而实际水汽压的贡献最小。造成潜在蒸散在空间上从鄂托克旗向东和向南递减的主导因子分别是这两方向上逐渐下降的太阳辐射和逐渐增加的实际水汽压;而从鄂托克旗至西南方向,下降的风速对该方向上潜在蒸散的变化贡献最大。(3)在水文年尺度上分析了13个典型流域水热耦合控制参数ω与植被盖度M和气候季节性指数S的关系后发现,在年际变化过程中,所有流域ω都呈现出了上升的趋势,这种上升趋势在80年代以后变得更加明显;参数ω与M在所有流域都表现出正相关关系,而与S则为负相关关系;在考虑参数ω与M和S的关系和边界条件后,构建了参数ω的半经验公式,交叉验证的结果说明该公式用于估算黄土高原流域年实际蒸散结果较可靠。(4)分析了不同时间尺度上影响参数ω的主要因子间的关联性后发现,Budyko框架下多年尺度上,流域植被与地形和气候季节性显著相关,逐步回归的结果也证明地形和气候季节性与植被间存在多重共线性问题,因此植被作为关键因子,可单独拟合控制参数;年际尺度上,植被和气候季节性的相关性在多数流域都不显著,在构建控制参数的经验公式时可同时考虑二个因子;在流域地形因子的表征指标方面,发现采用地形起伏度要优于前人用到的坡度和地形湿润指数,实施多年的退耕还林还草工程使得植被覆盖度随着地形起伏度的增大愈趋增强。(5)在Budyko框架下对流域实际蒸散变化进行归因的全微分法、外推法、互补法和分解法进行比较后发现,互补法最具优越性;1981-2012年,多年尺度上各流域实际蒸散对降水的变化最敏感,对参数ω的敏感性次之,对潜在蒸散的敏感性最差;年际尺度上,各流域实际蒸散对ω和潜在蒸散的敏感性呈显著降低趋势,而对降水的敏感性却呈显著上升趋势。在大多数流域,改善的植被条件对实际蒸散起到正贡献的作用,而流域水热匹配性的减弱对实际蒸散变异都是负贡献;如果不考虑气候的季节性变化,那么在估算下垫面变化对流域实际蒸散的贡献时将存在较大的误差,误差的大小等于气候季节性变化对实际蒸散的贡献值。本论文基于Budyko假设,分析和探讨了黄土高原蒸散的时空变化及气候和下垫面变化对其的影响,深化和扩展了不同时间尺度上水热耦合控制参数的影响因子及其之间耦合关系的认识,有助于黄土高原以有限水资源可持续利用为基础的农业生产和生态建设的发展。
[Abstract]:Affected by climate and underlying surface change, hydrological processes are changed, the evapotranspiration process as the link of hydrological processes and ecological processes, more by academia.Budyko framework has solid theoretical basis and clear physical meaning, which carry out the watershed eco hydrological research has become one of the frontier and focus of hydrology research. The fragile ecological environment of the Loess Plateau in recent decades, including the ecological construction of returning farmland to forest and grassland as the main content of the construction of the energy base of oil and gas in the construction of new towns, large scale, high intensity of human activities and the underlying surface changed significantly, in this context of the what happens to the regional evapotranspiration, how to influence the climate and underlying surface change on the contributions need to be deeply studied. Therefore, based on the analysis of heat and water in Loess Plateau a time The change on the basis of the first differential equation for quantitative attribution of potential evapotranspiration temporal and spatial variation of the region based on the research of Budyko framework; and then the water and heat coupling control parameters and the underlying surface changes in interannual scale (with vegetation represented) and the relationship between climate and seasonal variation, and discusses the influence of the association and the time scale effect each factor of water heat coupling control parameters; the contribution of climate and underlying surface change of the actual evapotranspiration basin the final estimates, the main conclusions are: (1) in recent decades the Loess Plateau significantly increased temperature, and based on the FAO 56 Penman-Monteith formula to calculate potential evapotranspiration overall slightly reduced performance, indicating the existence of "evaporation paradox in the region; of precipitation variation and fluctuation in potential evapotranspiration more seasonal climatic index S showed a slight decreasing trend in recent decades, means The seasonal fluctuations of precipitation and potential evapotranspiration value decreases. (2) the differential equation of the actual change of the potential evapotranspiration temporal process attribution analysis showed that: in the process of change based on potential evapotranspiration over the years, the most sensitive to the actual water vapor pressure, time sensitive to solar radiation and average temperature, and sensitivity to wind speed minimum. But at the same time affected by various meteorological factors the actual variation, over the years of the regional potential evapotranspiration variation is the largest contribution factors of average temperature, followed by wind and solar radiation, and the actual water vapor pressure. The minimum contribution caused by the dominant factor decrease from Etuokeqi to the East and to the south in the space of potential evapotranspiration are solar radiation decreased gradually in the two direction and increasing the actual water vapor pressure; and from the ertok banner to southwest direction, the direction of the wind speed on the decline of potential evapotranspiration Bulk changes the largest contribution. (3) in the annual scale hydrological analysis 13 typical basin water heat coupling control parameter W and vegetation coverage M and seasonal climate index S relationship found in the interannual change process, all in Omega are showing a rising trend, this trend becomes more obvious since 80s; parameter W and M in all basin showed positive correlation with S is negative correlation; considering the parameter W and M and S and the relationship between the boundary conditions, constructing the semi empirical formula parameter W, cross validation results show that the formula for estimating the Loess Plateau Basin the actual evapotranspiration results are more reliable. (4) to analyze the association of the main factor parameter w between different time scales on that scale for many years under the framework of Budyko, the vegetation and topography and climate seasonal significant correlation, stepwise regression results To prove the existence of multicollinearity problem of terrain and climate and seasonal vegetation, the vegetation as a key factor, can separate the control of fitting parameters; interannual scale, correlations between vegetation and climate in most seasonal watershed are not significant, in the empirical formula construction control parameters when considering the two factors in the index of River Basin; the topographic factors, the topography is better than the previous use of slope and terrain wetness index, the Reafforestation project makes the vegetation coverage increases with relief is increasingly enhanced. (5) were attributed to differential method, actual evapotranspiration change of basin under the framework of Budyko extrapolation complementary method and decomposition method, compared the complementary method most superiority; 1981-2012 years, years of scale change of actual evapotranspiration in each basin of precipitation is the most sensitive, sensitive parameters of Omega The perceptual sensitivity of the potential evapotranspiration, the actual evapotranspiration; interannual time scale, the sensitivity of the Omega basin and potential evapotranspiration was significantly decreased, and the sensitivity of precipitation has increased significantly. In most watershed, vegetation conditions to improve the positive contribution effect on actual evapotranspiration, and the water basin thermal matching weakened are negative contribution to the actual evapotranspiration variation; if you do not consider the seasonal climate changes, so in the estimation of underlying surface change on actual evapotranspiration basin contribution will there is a big error, error is equal to the magnitude of the climate change on seasonal actual evapotranspiration contribution value. This paper based on the Budyko assumption. The analysis and discussion of the temporal and spatial change of climate in Loess Plateau and the evapotranspiration of underlaying surface changes to its influence, deepen and expand the influence factor of different time scale hydrothermal coupling control parameters and between The understanding of the coupling relationship will help the development of agricultural production and ecological construction on the Loess Plateau Based on the sustainable utilization of limited water resources.

【学位授予单位】：中国科学院教育部水土保持与生态环境研究中心
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P426.2

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