赣江三角洲地下水与地表水交互关系及其生态效应

发布时间：2018-10-25 18:52

【摘要】：鄱阳湖是我国最大的淡水湖,也是世界重要的湿地与候鸟保护区。由于人口增长和兴修水利工程、植树造林等各种人类活动,使得鄱阳湖生态环境受到了一定的影响。尤其是2003年以来长江三峡水库蓄水对鄱阳湖枯水位影响,以及拟建鄱阳湖水利枢纽可能对鄱阳湖生态环境的影响引发了广泛的社会舆论和学术争鸣。研究长江三峡水库蓄水前后鄱阳湖水文情势变化特征,揭示三峡工程对鄱阳湖水文情势的影响势在必行。赣江三角洲是鄱阳湖水系入湖处发育规模最大、最完整的三角洲,研究其地下水与地表水交互关系对掌握鄱阳湖地区的水文及生态过程具有重要意义,并依此分析拟建枢纽对鄱阳湖地下水及环境的影响,为评判枢纽建设的可行性提供科学依据。本文综合采用数值模拟、智能计算、统计分析等方法对上述问题进行了系统研究。采用小波分析法寻找降水量相近的水文系列,分析三峡水库建设前后鄱阳湖水文情势变化特点,结果是枯水期提前并延长,枯水期初期水位降低,但枯水期末期水位略有增高。基于水均衡理论建立研究区三维地下水运动模型,探讨地下水补给与排泄各要素间的关系,结合区域地下水与地表水动态特征,分析地下水与地表水交互关系,结果表明研究区主要为地下水补给地表水,在丰水期河水位较高时为地表水补给地下水；研究区地下水与地表水交互作用较弱,地下水径流滞缓。运用水量平衡及支持向量机计算枢纽调控后鄱阳湖各测站水位,结合地下水运动模型模拟枢纽运行对地下水的影响,总的结果是调控期距河岸3 km范围内的地下水上升0-3 m,研究区地下水径流强度减弱。从模型均衡结果看枯水期地下水排泄量减少21.55%,丰水期补给量减少21.54%,地下水流场进入一种新的均衡状态。统计分析鄱阳湖水位与草滩范围、地下水埋深与植被带分布,结果显示出露草洲表现出明显的“水落滩出、水进草退”现象,且不同植被带内地下水埋深差异显著,地下水对地表水具有一定的补偿作用,地下水主要通过水埋深与总溶解固体影响土壤含水量与盐分,从而影响地表植被的分布与生长。本文将研究区地下水数值模拟技术与人工智能算法相结合,进行湿润地区关于地下水生态环境效应研究,解决了鄱阳湖地表水与地下水交互关系、拟建设鄱阳湖枢纽工程对地下水及生态环境影响、三峡水库蓄水对鄱阳湖水文情势的影响等科学问题,取得了一定成果与独特见解。
[Abstract]:Poyang Lake is the largest freshwater lake in China and also an important wetland and migratory bird reserve in the world. The ecological environment of Poyang Lake has been affected by various human activities, such as population growth, construction of water conservancy projects, afforestation and so on. Especially since 2003, the influence of the three Gorges Reservoir water storage on the dry water level of Poyang Lake and the possible impact of the proposed Poyang Lake Water Conservancy Project on the ecological environment of the Poyang Lake have caused widespread public opinion and academic controversy. It is imperative to study the variation characteristics of the hydrological situation of Poyang Lake before and after the three Gorges Reservoir impounding, and to reveal the influence of the three Gorges Project on the hydrological situation of the Poyang Lake. Ganjiang Delta is the largest and most complete delta in Poyang Lake. It is of great significance to understand the hydrological and ecological processes of Poyang Lake area by studying the interaction between groundwater and surface water. The influence of the proposed hub on the groundwater and environment of Poyang Lake is analyzed, which provides a scientific basis for judging the feasibility of the construction of the hub. In this paper, numerical simulation, intelligent calculation and statistical analysis are used to study the above problems. Wavelet analysis is used to find the hydrological series with similar precipitation, and the variation characteristics of the hydrological situation of Poyang Lake before and after the construction of the three Gorges Reservoir are analyzed. The results show that the low water period is advanced and prolonged, and the initial water level of the low water period decreases, but the water level slightly increases at the end of the dry season. Based on the theory of water equilibrium, a three-dimensional model of groundwater movement in the study area is established. The relationship between groundwater recharge and discharge elements is discussed, and the interaction between groundwater and surface water is analyzed in combination with the dynamic characteristics of regional groundwater and surface water. The results show that the main groundwater recharge in the study area is surface water, when the water level is high in the high water period, the surface water recharge groundwater. The interaction between groundwater and surface water is weak, and groundwater runoff is slow. Water balance and support vector machine are used to calculate the water level of Poyang Lake station after the control of the hub, and combined with the groundwater movement model to simulate the influence of the hub operation on the groundwater. The total result is that the groundwater in the range of 3 km from the river bank rises 0-3 m, and the intensity of groundwater runoff weakens in the study area. According to the results of model equilibrium, the groundwater discharge is reduced by 21.55 in dry season and the recharge in high water is reduced by 21.54. The groundwater flow field has entered a new equilibrium state. The water level and grass beach range, groundwater depth and vegetation distribution in Poyang Lake were statistically analyzed. The results showed that there were obvious phenomena of "water falling out, water entering and grass retreating", and the depth of groundwater buried in different vegetation zones was significantly different. Groundwater has a certain compensatory effect on surface water. Groundwater affects soil water content and salt mainly through water depth and total dissolved solids, thus affecting the distribution and growth of surface vegetation. In this paper, the numerical simulation technology of groundwater in the study area is combined with artificial intelligence algorithm to study the ecological environment effect of groundwater in humid area, which solves the interaction between surface water and groundwater in Poyang Lake. Some scientific problems, such as the influence of the construction of Poyang Lake hub project on groundwater and ecological environment, and the influence of the three Gorges Reservoir water storage on the hydrological situation of Poyang Lake, have obtained some achievements and unique opinions.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P339

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