海潮引起的水平海底地下水与海水交换量的解析研究

发布时间：2018-07-18 10:29

【摘要】：海水—地下水的相互作用会明显地影响滨海地区的地下水流动,同时会引起各种水文地质、工程地质问题。例如地下水资源枯竭、泉水消失、海水(咸水)入侵、地面沉降、地面(岩溶)塌陷、土地沙漠化、地下水污染造成的水质恶化,甚至引起生态环境的退化等。海潮引起的地下水水位波动以及地下水与海水交换量的研究,对于了解滨海地区水环境演变和地下水开发利用均具有重要的意义。本文考查了一个海底含水层,该含水层表层直接与海水接触并在水平方向无限延伸,在模型的概化过程中,还用到了一些假设条件,如忽略咸淡水的密度差效应,沉积物含水层中水流为垂直一维流且服从达西定律等。在此基础上建立了描述该系统中地下水水头随潮汐波动的数学模型,推导得出了含水层水头以及地下水与海水交换量的解析解,分析得到了渗透系数、贮水率、沉积物厚度以及等水文地质参数对地下水头波动以及海水与地下水交换量的影响规律。在推导出解析解的基础上,讨论了含水层底部水头以及不同深度处的水头波幅和相位差随各水文地质参数的变化情况。研究结果表明,随着Te和渗透系数的减小,深度和贮水系数以及沉积物厚度的增大,会加强水头波幅的衰减,增加水头波动的滞后。基于本文的含水层系统模型和解析解,我们对山东省莱州湾海庙地区的海潮波动和地下水头动态观测资料进行了应用研究。本文利用最小二乘法确定了实际海潮周期主要分量的波幅和相位,得到多分量情况下的水头波动以及交换量的解析解,并将多分量情况下的水头解析解与观测值进行了拟合对比。结果表明,交换量与海潮荷载系数呈负相关关系,与渗透系数、贮水率以及沉积物厚度呈正相关关系。最后,利用观测数据和解析解拟合值分别计算了一个月时间内地下水与海水交换量的值,并进行了分析比较。
[Abstract]:The interaction between seawater and groundwater will obviously affect the groundwater flow in coastal areas and cause various hydrogeological and engineering geological problems. For example, the groundwater resource is exhausted, the spring water disappears, the sea water (salt water) invades, the land subsidence, the land (karst) collapses, the land desertification, the groundwater pollution causes the water quality deterioration, even causes the ecological environment degradation and so on. The study of the fluctuation of groundwater level and the amount of exchange between groundwater and sea water caused by sea tide is of great significance for understanding the evolution of water environment and the exploitation and utilization of groundwater in coastal areas. In this paper, a submarine aquifer is examined. The surface layer of the aquifer is directly in contact with the seawater and extends infinitely in the horizontal direction. In the process of generalization of the model, some hypothetical conditions are also used, such as neglecting the density difference effect of salty fresh water. The flow in the sediment aquifer is vertical one-dimensional flow and obeys Darcy's law and so on. On this basis, a mathematical model describing the fluctuation of groundwater head with tide in the system is established, and the analytical solutions of aquifer head and groundwater and sea water exchange amount are derived, and the permeability coefficient and water storage rate are obtained. The influence of sediment thickness and hydrogeological parameters on the fluctuation of groundwater head and the exchange between seawater and groundwater. Based on the analytical solution, the variation of the wave amplitude and phase difference of the water head at the bottom of the aquifer and at different depths with the hydrogeological parameters is discussed. The results show that with the decrease of Te and permeability coefficient, the increase of depth, water storage coefficient and sediment thickness, the attenuation of water head amplitude will be enhanced and the lag of water head fluctuation will be increased. Based on the aquifer system model and analytical solution in this paper, the tidal wave and the dynamic observation data of groundwater head in Haimiao area, Laizhou Bay, Shandong Province, are studied. In this paper, the amplitude and phase of the main components of the actual tidal period are determined by using the least square method, and the analytical solutions of the water head wave and the exchange amount are obtained in the case of multiple components. The analytical solution of water head in the case of multiple components is fitted and compared with the observed value. The results show that the exchange volume is negatively correlated with the tidal load coefficient, and positively correlated with the permeability coefficient, water storage rate and sediment thickness. Finally, the values of groundwater and sea water exchange in one month are calculated by using the observed data and the fitting value of the analytical solution, and the results are analyzed and compared.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P731.2;P641

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