盆地多级次地下水流系统识别方法研究

发布时间：2018-04-16 06:07

本文选题：多级次地下水流系统 + 自流状况　；参考：《中国地质大学(北京)》2015年博士论文

【摘要】：区域地下水流理论较好地刻画了盆地尺度的地下水循环与演化规律,是指导地下水生产、研究的有力工具。识别盆地内部不同级次地下水流系统的空间分布是应用该理论进行地下水资源勘查和解释一系列相关水文地质问题的前提和关键。本博士论文在深入分析多级次地下水流系统的自流状况、矿化度空间分布和滞留时间分布特征的基础上,提出了三种方法,有效识别盆地内部不同级次的地下水流系统。前人关于自流状况的研究多为定性描述。通过引入潜水面“相对起伏”因子建立地形起伏和潜水面分布的定量关系,并定义自流水头,推导得到了理想单元盆地和理想复杂盆地自流水头的解析解,定量分析了盆地自流状况及其影响因素。研究表明,理想单元盆地中,自流水头在河谷附近取值为正,在分水岭附近取值为负,垂向上近似呈负指数变化。自流水头取值为零的等值线为自流区和非自流区的分界线,对应自流井发育的临界深度。盆地自流状况受到盆地深宽比,潜水面“相对起伏”因子和渗透系数的各向异性比和衰减系数的显著影响。理想复杂盆地中,呈嵌套结构的多级次地下水流系统对盆地自流水头的空间分布具有显著影响。盆地内部可以发育多个自流区和非自流区。区域分水岭附近的局部河谷处(或区域河谷附近的局部分水岭处),自流水头随埋深变化的曲线中存在极值,所在深度附近发育内部驻点。在此基础上,盆地自流状况的理论研究成果被应用于鄂尔多斯高原的两个野外实例。理想单元盆地实例研究中,使用实测自流水头随埋深变化曲线的斜率估算了渗透系数的各向异性比和衰减系数；理想复杂盆地实例研究中,使用实测自流水头随埋深变化曲线中的极值识别了地下水流系统的多级次循环模式。地下水矿化度蕴含着地下水循环与演化过程中的重要信息。首先通过引入地下水矿化度的控制方程,使用COMSOL Multiphysics模拟得到了理想复杂盆地地下水矿化度的空间分布,发现存在两大突出特征：局部和区域水流系统在盆地下游存在地下水矿化度的垂向突变界面；两个相邻的局部水流系统之间存在“脊状”局部高矿化度异常带。这两大特征是后续地球物理勘探解译的理论基础。然后,尝试使用EH-4电导率成像系统获得了都思兔河流域中下游一条南北向跨河剖面的视电阻率空间分布,并根据相关水文地质钻孔资料和勘探点附近的民井水化学资料,验证了地球物理勘探结果的可靠性,建立了白垩系含水层视电阻率与地下水矿化度的经验关系,进而近似得到了白垩系含水层地下水矿化度的空间分布。最后,将地下水矿化度的实测分布与理论模拟分布相类比,综合考虑地形和蒸发浓缩作用,解译了地球物理勘探剖面白垩系含水层中的多级次地下水流系统。盆地地下水滞留时间分布从时间域的角度审视了盆地尺度地下水的循环与演化。依据不同级次地下水流系统滞留时间的离散特征,提出了适用于复杂三维地下水流场的“晚峰”法。“晚峰”法使用MODFLOW和MODPATH计算盆地地下水滞留时间分布密度函数和盆地地下水滞留时间场,将盆地地下水滞留时间分布密度函数中的“晚峰”作为临界滞留时间划分盆地地下水滞留时间场,进而识别局部、中间和区域地下水流系统。为了验证“晚峰”法的适用性,分别引入二维、三维理想复杂盆地模型作为算例。算例结果表明,“晚峰”法的识别结果与传统模型识别方法,驻点法(二维)和补给-排泄流线追踪法(三维),一致。最后,选择鄂尔多斯高原都思兔河流域开展综合研究。基于当地水文地质条件,使用MODFLOW建立了该流域的地下水流数值模型,并使用实测地下水位和自流井分布信息进行了模型校正。在水流模型的基础上,首先使用MODPATH定量研究了地下水的渗流路径和滞留时间,发现地下水径流长度、穿透深度和滞留时间两两近似服从幂次定律；然后使用“晚峰”法识别了都思兔河流域的局部和区域地下水流系统,定量研究发现局部水流系统具有径流长度短(l*0.53),穿透深度浅(d*0.2),滞留时间短(t*0.18),流域体积占有率低(约占22%),地下水循环量大(约占76%)的特点(区域水流系统具有相反特点)；最后通过与基于水文地球化学和地球物理勘探的识别结果进行比较,证明了“晚峰”法的有效性。本博士论文的相关研究成果不仅有助于深入认知鄂尔多斯高原地区地下水的循环与演化规律,促进当地地下水资源的合理开发利用,还是对区域地下水流理论的补充与完善。
[Abstract]:Regional groundwater flow theory which describes groundwater circulation and evolution of the basin scale, is a powerful tool to study the groundwater production and distribution within the basin. The identification of different levels of underground water space is the application of the theory of groundwater resources exploration and interpretation of the premise and key of a series of related hydrogeological problems. This thesis in depth analysis of multistage underground water artesian conditions, mineralization degree and spatial distribution of residence time distribution based on the feature of the proposed three methods, the groundwater flow system to effectively identify the different grades of the interior of the basin. The study on the status of the previous artesian for more qualitative description. Through the introduction of water table "fluctuation" factor of topography and the quantitative relationship between the distribution of the diving surface, and the definition of artesian head is derived, the ideal unit of basin and basin since the ideal complex flow The head of the analytical solution, the quantitative analysis of the factors of self status and its impact basin. The study shows that the ideal unit in the basin, in the valley near the artesian head value is positive, negative values in the watershed near, vertically in a negative exponential change. The value of artesian head contour is zero artesian area and non artesian area the dividing line, the corresponding critical depth of artesian well development. Basin artesian conditions have significantly affected the depth to width ratio, anisotropy of water table "relative fluctuation" factor and the permeability coefficient ratio and attenuation coefficient. The ideal complex basin, a multi-level groundwater flow system of nested structure has significant effect on the spatial distribution of basin artesian head the interior of the basin. Can the development of multiple self and non self. The local area near the river valley watershed (at the local watershed or region near the valley), artesian head changes with depth The existence of extremal curve, located near the depth of internal development stagnation. On this basis, the status of the theoretical research results of artesian basin was applied to two field examples Ordos plateau. The ideal research unit basin example, using the measured slope artesian head changes with depth curve to estimate the anisotropic permeability coefficient ratio and attenuation coefficient ideal; complex basin case study, using the observed extreme artesian head changes with depth curve of the identified multistage circulation mode of underground water. The mineralization degree of groundwater contains important information of groundwater circulation and evolution. Firstly, applied to the governing equation of groundwater salinity, the use of COMSOL Multiphysics simulation to obtain the ideal complex the distribution of groundwater salinity, it is found that there are two prominent features: local and regional water system in the basin You are the salinity of groundwater vertical mutation "ridge" interface; local high salinity anomaly zone between two adjacent local flow system. These two characteristics is the theoretical basis for subsequent geophysical interpretation. Then, try to use the EH-4 conductivity imaging system was lower in dusitu River Basin in a North and south to the spatial distribution of apparent resistivity profiles across the river, and the water chemistry data according to near borehole data and hydrogeological exploration point, verify the reliability of geophysical exploration results, experience the Cretaceous aquifer resistivity and groundwater salinity, then the approximate distribution of the Cretaceous aquifer groundwater salinity the space is obtained. Finally, the measured distribution and the theory of groundwater salinity distribution simulation analogy, considering the topography and evaporation, geophysical interpretation The exploration section of Cretaceous aquifers in multistage underground water. Groundwater residence time distribution from the time domain to the perspective of circulation and evolution of the basin scale groundwater. Based on the discrete characteristics of underground water system of different levels of retention time, was proposed for the complex three-dimensional flow field in the late evening peak "method." the peak method using MODFLOW and MODPATH to calculate the groundwater residence time distribution density function and the residence time of groundwater basin, the basin groundwater residence time distribution density function in the "late peak" as a critical time dividing basin groundwater residence time field, and then identify the local, intermediate and regional groundwater flow system. In order to verify the applicability of "the evening peak" method, were introduced into two-dimensional, three-dimensional model of ideal complex basin as an example. The numerical results show that the "late peak" method recognition results With the traditional model identification method, stationary point method (2D) and supplies - excretion (San Wei), streamline tracing method. Finally, choose dusitu River Basin Ordos plateau to carry out a comprehensive study. Based on the local hydrogeological conditions, groundwater flow in the basin of the numerical model is established using MODFLOW, and the use of underground water and artesian well measured distribution information the model calibration. Based on the flow model, firstly study the seepage path of groundwater and the residence time of the use of MODPATH quantitative analysis, found the groundwater runoff length, depth of penetration and retention time of 22 approximately obey the power law; then use the "late peak" method to identify the dusitu River Basin local and regional groundwater flow system. Quantitative study found that the local flow system with short length of runoff (l*0.53), shallow penetration depth (d*0.2), short retention time (t*0.18), watershed volume share is low (about 2 2%), groundwater circulation volume is large (about 76%) (the characteristics of regional flow system has the opposite characteristics); and finally the hydrogeochemical and identification of geophysical exploration based on the results of the comparison, proved the effectiveness of the late peak "method. The relevant research results of this dissertation not only circulation and evolution contribute to the in-depth understanding of Erdos plateau groundwater, promote the rational exploitation and utilization of local groundwater resources, or to supplement and perfection of the theory of regional groundwater flow.

【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P641

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