河床地貌所引起的潜流交换研究
发布时间：2018-12-27 14:39
【摘要】：潜流带是河流和地下水进行物质和能量交换的区域。潜流交换对河流或地下水质及其生态都有重要影响。本论文以经典的EB模型为基础,通过解析解的方法研究了区域地下水流动,潜流带岩石各向异性,河水位变动以及沙丘移动等常见因素对由河床沙丘所引发的潜流交换的影响(由河床沙丘移动产生的潜流交换为冲淤交换)。研究表明:(一)、区域地下水补给和排泄流动影响潜流上升区和下降区的混合深度,模拟河流水质的瞬时储存模型的参数应该考虑区域地下水补给或排泄的影响;(二)、潜流带纵向渗透系数与横向渗透系数比值增大,潜流交换量也随之增加,平均停留时间趋于零的时间变短,溶质质量交换增加;(三)、对于由河床水位随时间波动引起的非稳定泵吸流,随着水位波动频率的增大对潜流带流场造成的扰动越大,潜流交换量增加,平均停留时间趋于零的时间变短,溶质质量交换变大;随着压力传导系数的减小,潜流交换先增大后减小,平均停留时间趋于零的时间变长,溶质质量交换先增大后减小;(四)、对于由河床沙丘移动引起的非稳定冲淤流,随着河床沙丘移动速度的增大对潜流带流场造成的扰动越大,平均停留时间趋于零的时间减小,溶质质量交换减小;随着压力传导系数的减小,潜流交换随之减小,最后趋于一个定值,平均停留时间在更短的时间内趋近于零,溶质质量交换减小。这两种情况下的非稳定潜流,当压力传导系数变的更大的时候,潜流带的流场都不再发生改变。
[Abstract]:The subsurface flow zone is the area where rivers and groundwater exchange matter and energy. Subsurface flow exchange plays an important role in river or underground water quality and ecology. Based on the classical EB model, the regional groundwater flow and rock anisotropy in the subsurface flow zone are studied by the analytical solution method in this paper. The influence of some common factors, such as river water level change and dune movement, on the subsurface flow exchange caused by the riverbed dune movement, which is called scour and silt exchange. The results show that: (1) regional groundwater recharge and discharge flow affect the mixing depth of subsurface flow rising and descending zone, and the parameters of instantaneous storage model for simulating river water quality should consider the influence of regional groundwater recharge or discharge; (2) with the increase of the ratio of longitudinal permeability coefficient to transverse permeability coefficient in the subsurface flow zone, the amount of subsurface flow exchange increases, the mean residence time tends to zero, and the mass exchange of solute increases. (3) for the unstable pump which is caused by the fluctuation of river bed water level with time, with the increase of the frequency of water level fluctuation, the greater the disturbance to the flow field of the subsurface flow zone, the more the exchange quantity of the subsurface flow increases, and the time of the average residence time tends to zero becomes shorter. Mass exchange of solute becomes larger; With the decrease of the pressure conduction coefficient, the subsurface flow exchange first increases and then decreases, the mean residence time becomes longer, and the solute mass exchange increases first and then decreases. (4) for the unstable scour and silt flow caused by the moving of the riverbed dune, the disturbance of the flow field in the subsurface flow zone is greater with the increase of the moving velocity of the riverbed dune, the mean residence time tends to zero, and the mass exchange of solute decreases; With the decrease of the pressure conduction coefficient, the subsurface flow exchange decreases, and finally tends to a fixed value, the mean residence time approaches to zero in a shorter time, and the mass exchange of solute decreases. In both cases, when the pressure conduction coefficient becomes larger, the flow field in the subsurface flow zone will not change.
【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;P339
，
本文编号：2393224
[Abstract]:The subsurface flow zone is the area where rivers and groundwater exchange matter and energy. Subsurface flow exchange plays an important role in river or underground water quality and ecology. Based on the classical EB model, the regional groundwater flow and rock anisotropy in the subsurface flow zone are studied by the analytical solution method in this paper. The influence of some common factors, such as river water level change and dune movement, on the subsurface flow exchange caused by the riverbed dune movement, which is called scour and silt exchange. The results show that: (1) regional groundwater recharge and discharge flow affect the mixing depth of subsurface flow rising and descending zone, and the parameters of instantaneous storage model for simulating river water quality should consider the influence of regional groundwater recharge or discharge; (2) with the increase of the ratio of longitudinal permeability coefficient to transverse permeability coefficient in the subsurface flow zone, the amount of subsurface flow exchange increases, the mean residence time tends to zero, and the mass exchange of solute increases. (3) for the unstable pump which is caused by the fluctuation of river bed water level with time, with the increase of the frequency of water level fluctuation, the greater the disturbance to the flow field of the subsurface flow zone, the more the exchange quantity of the subsurface flow increases, and the time of the average residence time tends to zero becomes shorter. Mass exchange of solute becomes larger; With the decrease of the pressure conduction coefficient, the subsurface flow exchange first increases and then decreases, the mean residence time becomes longer, and the solute mass exchange increases first and then decreases. (4) for the unstable scour and silt flow caused by the moving of the riverbed dune, the disturbance of the flow field in the subsurface flow zone is greater with the increase of the moving velocity of the riverbed dune, the mean residence time tends to zero, and the mass exchange of solute decreases; With the decrease of the pressure conduction coefficient, the subsurface flow exchange decreases, and finally tends to a fixed value, the mean residence time approaches to zero in a shorter time, and the mass exchange of solute decreases. In both cases, when the pressure conduction coefficient becomes larger, the flow field in the subsurface flow zone will not change.
【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;P339
，
本文编号：2393224
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