Alternative TitleStochastic Simulation of Soil Moisture and Salinity Dynamics in an Oasis-Desert System of Sangong River Watershed
Thesis Advisor李彦
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline理学硕士
Keyword绿洲-荒漠复合系统 灌溉方式 土壤水分 土壤盐分 随机模拟 Oasis-Desert System Irrigation Method Soil Salinity Soil Moisture Stochastic Simulation
Abstract土壤水盐动态是干旱区生态水文学研究的关键变量, 具有强烈的非线性和不确定性。 理解和掌握干旱生态系统土壤水盐的动态特征及时空分布, 是区域水资源合理利用、 生态水文过程模拟和植被生态保育的核心与基础。 为揭示荒漠绿洲区较大尺度复合景观土壤水盐时空演变规律及其生态水文效应, 本研究以新疆三工河流域绿洲-荒漠复合系统为研究对象, 利用野外定位试验、 区域随机采样和不同年代遥感资料, 基于概率统计思想, 采用水量平衡原理、 质量守恒原理、 微积分理论和地理信息技术, 优化并构建绿洲-荒漠复合系统点尺度和区域尺度土壤水分、 盐分动态随机模型, 量化绿洲-荒漠复合系统传统灌溉时期(1999—2007年) 和节水灌溉时期(2011—2018 年) 水文气象因子、 土壤水分、 盐分动态特征与分布规律, 探讨影响土壤水、 盐动态的关键因素。 主要结论如下:(1) 研究区绿洲-荒漠复合系统年内和年际尺度水文气象因子动态特征与分布规律: 降水量年内和年际均呈不明显的增加趋势, 降水事件以小雨(<10 mm)为主, 降水间隔以 0~5 d 为主, 降雨序列以 2~5 年为主周期, 服从正态分布。 气温呈明显上升趋势, 蒸发呈明显下降趋势; 年均气温和蒸发分别以 8 年和 21 年为主周期, 均不服从正态分布。 地下水位年内和年际均呈下降趋势, 其中绿洲区呈明显下降趋势, 荒漠区呈不明显下降趋势; 地下水位和水质突变均发生在传统灌溉与节水灌溉的过渡时期。 传统和节水灌溉时期水文气象因子动态特征与分布规律均满足土壤水盐动态随机模型的应用条件。(2) 研究区绿洲-荒漠复合系统不同灌溉时期土壤水分随机特征及其影响因素: 荒漠区传统与节水灌溉时期根系层土壤水分均服从正态分布, 绿洲区均不服从正态分布, 土壤水分概率密度函数 p(s)曲线均呈单峰状(除绿洲区传统灌溉时期全年外) 。 荒漠区平面和坡面尺度、 绿洲区考虑潜水蒸发的土壤水分动态随机模型有效性均较好, 模拟精度均较理想。 平均降水量α、 日降水频率λ、 日潜在蒸散量 Emax、 降水径流系数 C、 水分胁迫点 s*、 地下水位 Z 为影响绿洲-荒漠复合系统土壤水分动态模拟的关键参数。 灌溉方式的转变是造成三工河流域绿洲-荒漠复合系统土壤水分动态特征变化的重要原因。(3) 研究区绿洲-荒漠复合系统不同灌溉时期土壤盐分随机特征及其影响因素: 荒漠区和绿洲区传统与节水灌溉时期根系层土壤盐分均服从正态分布, 土壤盐分概率密度函数 p(C)曲线均呈单峰状。荒漠区土壤盐分动态随机模型有效性较好, 绿洲区考虑潜水蒸发的土壤盐分动态随机模型有效性较好, 且可将灌溉作为单次降雨事件来处理; 各灌溉时期荒漠区和绿洲区点尺度 p(C)曲线特征、 绿洲-荒漠复合系统土壤相对盐浓度 C 模拟精度均满足要求。 地下水盐浓度 CZ、 盐分渗漏系数 b´、 标准化降水量γ、 Emax、 Z、 λ为影响绿洲-荒漠复合系统土壤盐分动态模拟的关键参数。 灌溉方式的转变是造成三工河流域绿洲-荒漠复合系统土壤盐分动态特征变化的重要原因。
Other AbstractAs indispensable parts of the research on the interactions and feedbacks betweenhydrological processes and terrestrial ecosystem processes in arid areas, soil moistureand salinity dynamics manifest strong nonlinearity and uncertainty. Identifying thetemporal and spatial dynamic and distribution characteristics of soil moisture andsalinity in arid ecosystem is of great significance in regional water resourcesutilization and management, hydrological and ecological processes modeling andvegetation conservation. To understand the landscape-scale spatial-temporal evolutionpatterns and eco-hydrological effects of soil moisture and salinity in differentlandscapes of oasis-desert region, this study carried out a case study in an oasis-desertsystem of the Sangong River watershed in arid northwest China. Data sets werecollected from field location experiments, macro scale investigations and remotesensing images. Stochastic modelling of soil moisture and salinity dynamics at pointand regional scales were optimized and developed by using water balance and massconservation principle, probability statistics, calculus theory, and geographicinformation technology. Distribution patterns and dynamic characteristics ofhydrometeorological factors and soil moisture and salinity of oasis-desert system indifferent irrigation methods period (i.e., traditional irrigation period during 1999-2007and microirrigation period during 2011-2018) were quantitative research. Meanwhile,the key factors affecting the dynamic of soil moisture and salinity were discussed. Themain results are outlined as follow: (1) The annual and seasonal precipitation had noobvious increase or decrease trend, the precipitation events, interval and periodic weredominated by <10 mm, <10 d and 2~5 years, respectively, the precipitation mutationoccurred in 1982 and 2010, and the precipitation followed a normal distribution. Themean annual temperature and annual evaporation were 7.05 ℃ (had an obviousincrease trend) and 1748.91 mm (had an obvious decrease trend), respectively, thetemperature and evaporation had the periodic variations of 8 years (mutation occurredin 1988) and 21 years (contained multiple mutation points), respectively, and which followed a non-normal distribution. The annual and seasonal groundwater levels hadbeen declining continuously, and groundwater levels and quality mutation occurred inthe transition period of the transformation of irrigation method. The dynamiccharacteristics and distribution patterns of hydrometeorological factors of this studyarea satisfied the basic application conditions of stochastic modelling of soil moistureand salinity. (2) There was no significant difference of the soil moisture in the desertregion between traditional irrigation period and microirrigation period, and the soilmoisture in the root zone followed a normal distribution. The soil moisture in thecotton field of the oasis region in traditional irrigation period was higher than that inmicroirrigation period, and the soil moisture in the root zone followed a non-normaldistribution. The soil moisture in oasis-desert system had great temporal and spatialvariability in different irrigation methods period. The probability distribution shown asingle peak-shape in different irrigation methods period except for the annual scale ofthe traditional irrigation period in the oasis area. The curve characteristics of the soilmoisture probabilistic density function (PDF) and the relative soil moisture contentsimulated by the developed model had a good consistence with observed values.Indicating the stochastic modelling of soil moisture dynamics at point and regionalscales are effective for estimating the soil moisture PDF in this study area. Meanwhile,the mean rainfall depth (α), arrival rate of rainfall events (λ), runoff coefficient (C),maximum evapotranspiration rate (Emax), critical point of plant undergoes water stress(s*), and groundwater level (Z) are the key parameters affecting stochastic simulationof soil moisture dynamics in the oasis-desert system. The change of irrigation methodis an important reason for the change of soil moisture dynamic characteristics in theoasis-desert system of Sangong River watershed. (3) The soil salinity of each soillayer in the interdune was significantly higher than that in the top of the dune in thedesert region during different irrigation methods period. The soil salinity in the cottonfield of the oasis region in microirrigation period (0.522 dS/m) was higher than that intraditional irrigation period (0.409 dS/m), and the salt discharge effect of traditionalirrigation is obviously better than that of microirrigation. The soil salinity in the rootzone in oasis-desert system increased from south to north, and the accumulation of soil salinity in the root zone of agricultural land was obvious in this study area. Thesoil salinity in the root zone in the desert and oasis region followed a normaldistribution, and the probability distribution shown a single peak-shape in differentirrigation methods period. The curve characteristics of the soil salinity PDF and therelative soil salt concentration simulated by the developed model had a goodconsistence with observed values. Indicating the stochastic modelling of soil salinitydynamics at point and regional scales are effective for estimating the soil salinity PDFin this study area, and the irrigation could be considered a random event. Meanwhile,the salt concentration of the groundwater at depth Z (CZ), soil salinity leakagecoefficient (b´), root zone normalized average precipitation per event (γ), Emax, Z, andλ are the key parameters affecting stochastic simulation of soil salinity dynamics inthe oasis-desert system. The change of irrigation method is an important reason forthe change of soil salinity dynamic characteristics in the oasis-desert system ofSangong River watershed. In conclusion, this study could provide scientific methodsand theoretical basis for the ecological conservation of desert vegetation and precisionirrigation of oasis agriculture in arid ecosystems.
Subject Area生态学
Document Type学位论文
First Author Affilication中国科学院新疆生态与地理研究所
Recommended Citation
GB/T 7714
尹鑫卫. 三工河流域绿洲-荒漠复合系统土壤水盐动态随机模拟[D]. 北京. 中国科学院大学,2019.
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