胶州湾西岸某泥质潮滩地下水—海水相互交换及营养盐迁移研究

发布时间：2018-01-16 16:17

本文关键词：胶州湾西岸某泥质潮滩地下水—海水相互交换及营养盐迁移研究　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：泥质潮滩对于增加土地资源、海岸防护和保持生物多样性等具有重要作用。潮间带是地下水-海水作用剧烈的区域,也是营养盐和污染物的重要载体。分析地下水-海水相互作用机理对于研究淤泥质潮滩的营养盐和污染物迁移、生物特性具有重要的现实意义。本文研究区位于胶州湾西岸红石崖镇的一个长约3000米坡度约为0.1%的泥质潮滩。沿剖面均匀布设8组垂向上固定距离的“对井”来监测地下水水位、电导率和温度,监测时间持续约20天,每小时记录一次数据。原位降水头实验测得典型井的垂向渗透系数变化范围为4.37×10-8~1.12×10-6m/s,盐度变化范围为26.23~31.52g/L。基于广义达西定律估算出剖面100小时中平均海底地下水排泄(SGD)和海水入渗量(Inflow)分别为2.24和1.77m2/d。以本研究区所属多层含水系统为研究对象,结合野外监测数据和实际情况建立了一个二维垂直剖面模型,利用数值模拟软件MARUN进行了地下水-海水相互交换量的数值模拟。定量探究了渗透系数、渗出面和海潮爬高效应等因素对地下水流的影响,对模型表、中层的渗透系数和爬高效应进行敏感性分析。通过试错法首次将各组井观测水头值和地下水-海水交换量进行同时拟合,评估了各模型参数对模拟结果的影响,并对该研究区的地下水流进行了分析,得出以下主要结论:(1)潮滩发育了大范围的渗出面,最大长度达2266m,并随潮汐波动呈周期性变化。(2)相比于中层渗透系数的变化,水头值和地下水流速模拟结果对表层渗透系数更敏感,海潮爬高效应对大尺度泥质潮滩水陆边界附近有显著影响。(3)地形转折点(波折点)对地下水流有显著影响,最大流速(流入:17.08mm/d,流出:5.50mm/d)均发生在波折点附近区域,显示波折点在地下水补给和排泄过程中起重要作用。数值模拟结果表明,在该剖面上100小时中SGD和Inflow平均值分别为2.16和1.60m2/d,与对井法直接观测计算的结果差别不大。渗出面排泄SGD占总SGD的85.6%。通过该剖面上营养盐数据分析得出以下结论:常规离子分析显示研究区受到了海水和地下水的共同影响,各井中地下水的亚硝酸盐氮和硝酸盐氮远大于海水中对应的浓度,很可能是因为化工厂排放以及反硝化作用共同作用的结果,各井中地下水DIN/DIP比值远大于Redfield比值,很可能是由于生活污水和工业废水排放。
[Abstract]:Muddy tidal flat plays an important role in increasing land resources, coastal protection and maintaining biodiversity. It is also an important carrier of nutrients and pollutants. The mechanism of groundwater-seawater interaction is used to study the transport of nutrients and pollutants in muddy tidal flat. Biological characteristics are of great practical significance. This study area is located in Hongshiya town, west coast of Jiaozhou bay, a muddy tidal flat with a slope of about 3, 000m and a slope of about 0.1%. Eight groups of vertical fixed distances are arranged evenly along the section. " To monitor the groundwater level. Electrical conductivity and temperature were monitored for about 20 days. The vertical permeability coefficient of a typical well measured by in-situ precipitation head experiment is 4.37 脳 10 ~ (-8) m / s, 1.12 脳 10 ~ (-6) m / s. The variation range of salinity is 26.23 ~ 31.52g / L. based on the generalized Darcy's law, the average undersea groundwater discharge (SGD) and seawater infiltration (Inflow) are estimated in 100 hours. 2.24 and 1.77 m2 / d, respectively. The multi-layer water cut system in this study area was taken as the research object. Based on the field monitoring data and the actual situation, a two-dimensional vertical profile model is established. The numerical simulation of the groundwater / seawater exchange is carried out by using the numerical simulation software MARUN, and the permeability coefficient is quantitatively explored. The influence of seepage surface and tide climbing effect on groundwater flow, and on the model table. The sensitivity analysis of permeability coefficient and climbing effect in the middle layer was carried out. The observed water head value and groundwater sea water exchange amount were fitted simultaneously by trial and error method for the first time, and the effects of model parameters on the simulation results were evaluated. Based on the analysis of the groundwater flow in the study area, the following main conclusions are drawn: (1) the tidal flat has developed a large scale exudation surface, the maximum length of which is 2266m. The water head value and groundwater velocity simulation results are more sensitive to the surface permeability coefficient than the change of the middle permeability coefficient. The effect of sea tide climbing has a significant effect on the land and water boundary near the large scale muddy tidal flat.) the topographic turning point (zigzag point) has a significant effect on the groundwater flow, and the maximum velocity (the flow velocity is 17.08 mm / d). The outflow: 5.50mm / d) occurs in the region near the breakout point, which shows that the corrugated point plays an important role in the process of groundwater recharge and discharge. The numerical simulation results show that the corrugated point plays an important role in the groundwater recharge and discharge process. The average values of SGD and Inflow were 2.16 and 1.60 m2 / d in the 100h section, respectively. There is little difference between the results of direct observation and calculation of the well method. The exudation surface excretion SGD accounts for 85.6% of the total SGD. Through the analysis of the nutrient data on the profile, the following conclusions are obtained:. Conventional ion analysis showed that the study area was affected by both seawater and groundwater. The concentration of nitrite nitrogen and nitrate nitrogen in groundwater in each well is much higher than the corresponding concentration in seawater, which is probably due to the combined effect of chemical plant discharge and denitrification. The DIN/DIP ratio of groundwater in each well is much higher than that of Redfield, which is probably due to the discharge of domestic sewage and industrial wastewater.
【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】：2017
【分类号】：P641.2;P731.2;X143

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