长江口北支盐沼地典型剖面地下水流数值模拟
发布时间：2018-09-09 20:54
【摘要】：盐沼地排泄的来自内陆的地下水是营养物或者污染物的重要载体。分析地下水-地表水的相互作用机理对研究盐沼地潮间带的植物长势、分布及种类的研究具有重要实际意义。2013年夏季我们在崇明岛北岸选了一个长1km,在高潮时能全部淹没,并生长着不同植物的剖面,在剖面上埋设5口监测井,监测地下水水位、温度及电导率,监测频率为1小时1次,距离江水和内陆最近的两口井持续监测一年,其他三口井持续一个月。通过野外观测和监测数据的分析发现,土壤饱和程度与植物种类分布有很好的相关性：即芦苇生长在潮间带的上部,该处土壤都是非饱和的,而互花米草生长的区域的表层土壤几乎都是饱和的,说明植物分区生长与地下水有紧密联系。另外,长期数据表明地下水温度和电导率在年际变化上存在很好的正相关性。我们运用二维垂直剖面有限元数值模拟程序MARUN对野外一个月的数据进行模拟和拟合。通过野外实际观测和参考近期文献,将研究剖面分成两层,即垂向渗透系数(10-7m/s)极小的粘土表层(厚度为0-3m)和垂向渗透系数(10-Sm/s)较大的底层(厚约22m),上下层横向和纵向渗透系数的各向异性比分别为1和3,其中表层存在两个较大的地形转折点。数值模拟结果表明,通过剖面表层平均流速的计算,在大小潮期间地下水的排泄量为0.33 m3m-1d-1,其中来自内陆的淡水为0.21 m3m-1d-1。地下水的排泄区集中在离内陆400米到1000米的区域内,地下水的入渗区集中在离内陆180米到400米的地方,地下水的排泄区和江水入渗区分别是互花米草和芦苇生长的区域,两者的交换速率在地形突变点达到最大,表明地形对整个地下水的循环起着很重要的作用。在排泄区,垂直于表层的平均流速为4 mm/d,入渗区的平均流速为3 mm/d。最后,我们用图形的方式概化了盐沼地地下水-江水循环系统模式。
[Abstract]:Groundwater discharged from inland salt marshes is an important carrier of nutrients or pollutants. The analysis of the interaction mechanism between groundwater and surface water is of great practical significance for the study of plant growth, distribution and species in the intertidal zone of salt marshes. In summer 2013, we selected a 1km long one on the north shore of Chongming Island, which can be completely submerged at high tide. Five monitoring wells were planted in the profile to monitor the groundwater level, temperature and conductivity. The monitoring frequency was 1 hour, and the two wells closest to the river water and inland were monitored continuously for one year. The other three wells lasted for a month. Through the analysis of field observation and monitoring data, it is found that the soil saturation degree has a good correlation with the distribution of plant species: the Reed grows in the upper part of the intertidal zone, where the soil is unsaturated. However, the surface soil of Spartina alterniflora growing area is almost saturated, indicating that the growth of plant zoning is closely related to groundwater. In addition, long-term data show that there is a good positive correlation between groundwater temperature and conductivity. The data of one month in the field are simulated and fitted by the finite element simulation program MARUN. Based on field observations and recent references, the study profile is divided into two layers. That is, the surface layer (0-3m thickness) with minimal vertical permeability coefficient (10-7m/s) and the lower layer (about 22m thick) with larger vertical permeability coefficient (10-Sm/s) have anisotropy ratios of 1 and 3 respectively. A great turning point in the terrain. The numerical simulation results show that the groundwater discharge is 0.33 m ~ (-3) m ~ (-1) d ~ (-1) and 0.21 m ~ (-3) m ~ (-1) d ~ (-1) for fresh water from inland during the period of large and small tide. The drainage zone of groundwater is concentrated in the area of 400m to 1000 meters from the inland, and the infiltration zone of groundwater is concentrated in the area of 180-400m from the inland. The discharge zone of groundwater and the infiltration zone of river water are the growing areas of Spartina alterniflora and Reed, respectively. The exchange rate of the two is maximum at the abrupt point of topography, which indicates that topography plays an important role in the circulation of the whole groundwater. In the drainage zone, the average velocity perpendicular to the surface is 4 mm/d, the average velocity of infiltration is 3 mm/d.. At last, we generalize the model of groundwater-river circulation system in salt marsh.
【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】：P641.2
本文编号：2233540
[Abstract]:Groundwater discharged from inland salt marshes is an important carrier of nutrients or pollutants. The analysis of the interaction mechanism between groundwater and surface water is of great practical significance for the study of plant growth, distribution and species in the intertidal zone of salt marshes. In summer 2013, we selected a 1km long one on the north shore of Chongming Island, which can be completely submerged at high tide. Five monitoring wells were planted in the profile to monitor the groundwater level, temperature and conductivity. The monitoring frequency was 1 hour, and the two wells closest to the river water and inland were monitored continuously for one year. The other three wells lasted for a month. Through the analysis of field observation and monitoring data, it is found that the soil saturation degree has a good correlation with the distribution of plant species: the Reed grows in the upper part of the intertidal zone, where the soil is unsaturated. However, the surface soil of Spartina alterniflora growing area is almost saturated, indicating that the growth of plant zoning is closely related to groundwater. In addition, long-term data show that there is a good positive correlation between groundwater temperature and conductivity. The data of one month in the field are simulated and fitted by the finite element simulation program MARUN. Based on field observations and recent references, the study profile is divided into two layers. That is, the surface layer (0-3m thickness) with minimal vertical permeability coefficient (10-7m/s) and the lower layer (about 22m thick) with larger vertical permeability coefficient (10-Sm/s) have anisotropy ratios of 1 and 3 respectively. A great turning point in the terrain. The numerical simulation results show that the groundwater discharge is 0.33 m ~ (-3) m ~ (-1) d ~ (-1) and 0.21 m ~ (-3) m ~ (-1) d ~ (-1) for fresh water from inland during the period of large and small tide. The drainage zone of groundwater is concentrated in the area of 400m to 1000 meters from the inland, and the infiltration zone of groundwater is concentrated in the area of 180-400m from the inland. The discharge zone of groundwater and the infiltration zone of river water are the growing areas of Spartina alterniflora and Reed, respectively. The exchange rate of the two is maximum at the abrupt point of topography, which indicates that topography plays an important role in the circulation of the whole groundwater. In the drainage zone, the average velocity perpendicular to the surface is 4 mm/d, the average velocity of infiltration is 3 mm/d.. At last, we generalize the model of groundwater-river circulation system in salt marsh.
【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】：P641.2
【参考文献】
相关期刊论文 前1条
1 战庆;王张华;王昕;李晓;;长江口区晚新生代沉积物粒度特征和沉积地貌环境演变[J];沉积学报;2009年04期
，本文编号：2233540
本文链接：https://www.wllwen.com/kejilunwen/diqiudizhi/2233540.html
