滨海地区潮汐对地下水位变化影响的统计学分析

本文采用互相关分析、谱分析、Mallat分解重构算法等理论与方法,利用实测的潮汐资料和观测井水位资料,并结合实测的电导数据,从统计学上分析计算了广东省珠海市唐家镇附近,滨海含水层地下水水位波动的原因以及波动的位相、周期、振幅对海潮潮汐的响应。结果表明,微承压水和基岩裂隙水水位波动的原因均是含水层承受的质量负荷随潮汐的变化而变化;微承压水水位波动相对海潮潮汐的位相延迟时间约为7.0h,基岩裂隙水约为1.5h;微承压水水位波动的周期组成成份比海潮潮汐略少,基岩裂隙水水位波动的周期组成成份与海潮潮汐基本相同;微承压水水位波动的振幅约为海潮潮汐的1/100左右,基岩裂隙水为1/3左右;本研究区域海潮潮汐对浅层基岩裂隙水水位波动的水平影响范围在1 000m之内。     

滨海地区潮汐对地下水位变化影响的统计学分析—以中山大学珠海校区为例

摘要：本文采用互相关分析、谱分析、Mallat分解重构算法等理论与方法，利用实测的潮汐资料和观测井水位资料，并结合实测的电导数据，从统计学上分析计算了广东省珠海市唐家镇附近，滨海含水层地下水水位波动的原因以及波动的位相、周期、振幅对海潮潮汐的响应。结果表明，微承压水和基岩裂隙水水位波动的原因均是含水层承受的质量负荷随潮汐的变化而变化；微承压水水位波动相对海潮潮汐的位相延迟时间约为7.0h，基岩裂隙水约为1.5h；微承压水水位波动的周期组成成份比海潮潮汐略少，基岩裂隙水水位波动的周期组成成份与海潮潮汐基本相同；微承压水水位波动的振幅约为海潮潮汐的1/100左右，基岩裂隙水为1/3左右；本研究区域海潮潮汐对浅层基岩裂隙水水位波动的水平影响范围在1000m之内。     

潮汐波动对秦山三期核电工程场地裂隙含水层的影响

杭州湾潮汐的波动在临近的含水层中产生的压力波，由于压力波向内地传播，使地下水位和水力坡度连续不断地发生波动，并直接影响场地周围含水层中压力表的读数。为了掌握潮汐对场地地下水的影响，通过比较地下水和地表水平均水位标高计算地下水的平均水力坡度。压力波按正弦波传播，地下水相对于潮水有一时间滞后，本文中计算了不同观测地点的滞后时间，影响因子和波长，为核电站的建设提供了重要的依据。     

河流-承压含水层系统压力传导系数的谱分析

含水层对河水的响应程度与含水层的压力传导系数密切相关。借鉴多孔介质热运移的相关研究成果,推导得到了河流-承压含水层系统压力传导系数的功率谱解析表达式,进而提出了一种联合使用河水位和地下水位观测数据估算承压含水层压力传导系数的新方法。采用该方法,应用螺山水文站水位数据和洪湖地区承压地下水位数据,估算了长江洪湖地区承压含水层的压力传导系数,结果表明:该方法估算得到的压力传导系数为1.6×10~4～8.7×10~5 m~2/d,平均值为1.8×10~5 m~2/d,与非稳定抽水试验和数值模型反演得到的结果2.5×10~4～3.8×10~(5 )m~2/d具有较好的一致性,功率谱分析是估算承压含水层压力传导系数的有效方法。     

潮汐对地下水波动影响的数值模拟

本文从经典的Boussinesq方程出发，在考虑浸润面影响的基础上，建立了基于有限差分法的滨海地区一维地下水运动数值模型。通过将潮汐运动概化为正弦波，模拟了滨海地区地下水水位随潮汐波动的变化。结果显示，地下水水位的波动相对于潮汐波动来说具有不对称性、振幅衰减以及相位滞后等特征。通过比较受潮汐影响的地下水平均水位与不考虑潮汐影响的地下水水位发现，实际的地下水平均水位要高于未考虑潮汐影响的地下水水位。最后数值模拟了浸润面的形成和消失的过程。     

滨海深部含水层地下水排泄量评估

为了进一步计算评估滨海深部含水层地下水排泄量,以一个海底深部承压含水层系统为例,包括承压含水层及上覆弱透水含水层(海底),在内陆补给上考虑了与时间无关的年平均补给(常数)和由季节性降雨引起的周期性补给两种情况,从而建立了一个描述承压含水层中海底地下水排泄的数学模型,并得到其解析解。继而利用解析解分析了位于美国南大西洋Onslow海湾的SGD。结果显示,SGD排泄宽度变化范围为0.5~3.0 km,在承压含水层中海岸线处高于平均海平面1.0 m的水头值,其所产生的SGD速率为1.1~10.0 m2/d。     

受潮浪和径流影响滨海承压层抽水数学模型及其解析解

为研究滨海承压含水层地下水在潮浪、抽水井流扰动及径流和越流补给综合影响下的渗流和水位变化,建立了滨海承压水抽水不稳定流的数学模型,并得到其解析解。通过实例计算和分析可知：潮浪的波动作用与抽水的井流作用将相互影响,潮位升高时承压水水位上升,减缓了抽水引起的水位下降量,而潮位降低时承压水水位下降,将加剧抽水引起的水位下降;越流和径流作用可以减缓承压水水位下降;当承压水径流朝向海洋时,径流作用使水位降“漏斗中心”逆着水流而朝远离海岸线方向移动,并且承压水径流补给对减缓地下水水位下降的作用随时间越来越明显,因此径流作用可以减轻井水受潮浪和海水入侵的影响程度;如井设置在距海岸较远处,潮浪对抽水水位降“漏斗”形状改变不明显;受潮浪和抽水共同作用时的地下水水位-时间曲线围绕仅受抽水作用时的地下水水位-时间曲线上下波动。     

受潮浪、径流和越流影响滨海承压层抽水数学模型及解析解

为研究滨海承压含水层地下水在潮浪、抽水井流扰动及径流和越流补给综合影响下的渗流和水位变化，建立了滨海承压水抽水不稳定流的数学模型，并得到其解析解。通过实例计算和分析可知：潮浪的波动作用与抽水的井流作用将相互影响，潮位升高时承压水水位上升，减缓了抽水引起的水位下降量，而潮位降低时承压水水位下降，将加剧抽水引起的水位下降；越流和径流作用可以减缓承压水水位下降；当承压水径流朝向海洋时，径流作用使水位降“漏斗中心”逆着水流而朝远离海岸线方向移动，并且承压水径流补给对减缓地下水水位下降的作用随时间越来越明显，因此径流作用可以减轻井水受潮浪和海水入侵的影响程度；如井设置在距海岸较远处，潮浪对抽水水位降“漏斗”形状改变不明显；受潮浪和抽水共同作用时的地下水水位-时间曲线围绕仅受抽水作用时的地下水水位-时间曲线上下波动。     

露天煤矿开采后地下水疏干范围研究

将梁家碛露天煤矿开采后对地下水的影响概化为奥陶系中统灰岩岩溶裂隙含水层,石炭—二叠系碎屑岩裂隙含水层,第三系、第四系松散孔隙含水层,研究梁家碛露天煤矿开采后地下水疏干范围。其中,首采区、二采区奥陶系岩溶水突水系数小于受构造破坏地段突水系数的临界值(0.06 MPa/m),不会造成突水事故,也不会破坏该层含水层。采用塞罗瓦特科公式和无观测孔完整井抽水状态下的影响半径公式分别讨论了煤炭开采后对第三系、第四系松散孔隙含水层,石炭—二叠系碎屑岩裂隙含水层地下水的疏干范围,结果表明,其影响半径分别为5 864.12、4 895.50 m。     

变化环境下玛纳斯河流域绿洲区地下水位变化特征及影响因素分析

地下水作为水循环的重要环节,变化环境下其补给、径流和排泄条件发生改变,影响着干旱区水安全和生态环境维系。以西北典型内陆河玛纳斯河流域为研究区,采用衬度系数方差分析法分析了绿洲区地下水位空间分布及变幅特征,阐明了变化环境下玛纳斯河流域地下水位变化主要影响因素。研究结果表明：(1)2012—2019年地下水水位呈先下降后上升而后再趋于逐年波动、小幅下降的趋势,下降趋势逐渐变缓;(2)地下水位年内变化为3、4月到8、9月波动下降,8、9月到来年3、4月水位有所回升,年内变幅0.29～19.05 m;(3)人为因素对地下水水位具有显著的影响,主要表现在流域土地利用变化和用水量变化。研究结果可以为玛纳斯河流域地下水资源合理开发与管理提供科学依据。     

ANALYTICAL SOLUTION OF GROUNDWATER FLUCTUATIONS IN ESTUARINE AQUIFER

1.INTRODUCTIONTide-induced head fluctuations are a naturalphenomenon in a coastal aquifer[1-3].For an un-confined aquifer,groundwater level changes corre-sponding to the tidal waves.As the tidal propagateinland,their amplitude is attenuated and phase-shifts occur.A typical damping distance for tidalwater table fluctuation in an unconfined aquifer isseveral hundred meters whereas the tidal influenceon a confined aquifer can extended landward byseveral thousand meters[2,4].According to thef…     

On the Estimation of Phreatic Aquifer Parameters by the Tidal Response Technique

This paper focuses on the effects of tidal fluctuations on groundwater in the Konan groundwater basin of Japan and the methodology for estimating aquifer parameters by the tidal response technique. The field investigation revealed that the twowells (H-5 and I-2) near the coastline are significantly affectedby seawater intrusion, and the water quality is not suitable for most beneficial uses. The tidal cycle further aggravates the groundwater contamination by seawater intrusion into the basin. Using the tidal response model, the aquifer hydraulic conductivity(K) at these two sites is estimated to be 4.5 × 10^-3 and 5.1 × 10^-3 m s^-1, respectively. It was also indicated by the inverse modeling that the tidal fluctuations affect the study area up to about 1 km from the coastline. Further, the tidal efficiency was determined in the range of 20 to 21% at Site I-2 and 38 to 41% at Site H-5. The estimates of the storage coefficient (S) based on the time lag equation were not found reliable for the phreatic aquifer. However, the tidal efficiency-factor equation yielded reliable S estimates in this study. Finally, it is concluded that the tidal response techniqueis effective and reliable for estimating aquifer parameters in the coastal region, and that the Konan basin must be managed judiciously to ensure sustainable utilization of its vital groundwater resources.     

Hydraulic Parameters of Coastal Aquifer Systems by Direct Methods and an Extended Tide–Aquifer Interaction Technique

Adequate and reliable parameters are key to the sustainable management of vital groundwater resources. Present study focuses on the evaluation of direct methods (tidal efficiency and time lag methods) and an extended tide–aquifer interaction technique for determining the hydraulic parameter of coastal unconfined and confined aquifer systems. The hydraulic diffusivities of unconfined and confined aquifer systems were estimated using the tidal efficiency and time lag methods as well as they were optimized using the tide–aquifer interaction model and the Levenberg–Marquardt optimization technique. The hydraulic diffusivities were optimized by the Levenberg–Marquardt technique following two approaches: lumped tidal component approach and multi-tidal component approach. The effect of spring and neap tidal data on parameter estimates was also analyzed. The tide–aquifer interaction data for two unconfined sites and three confined sites were used in this study. For all the five sites under study, the aquifer hydraulic diffusivities based on the time lag method were found to be much larger (2 to 14 fold for the unconfined sites and 5 to 8 fold for the confined sites) than those based on the tidal efficiency method. The analysis of the optimization results indicated that the hydraulic diffusivities following “multi-tidal component approach” are more reliable and accurate for both unconfined and confined aquifers than those obtained following “lumped tidal component approach”. Consequently, the use of “multi-tidal component approach” is strongly recommended for the determination of aquifer parameters by the tide–aquifer interaction technique. Furthermore, the tide–interaction data corresponding to spring and neap tidal events were found to significantly affect the aquifer diffusivities yielded by the tide–aquifer interaction technique. It is concluded that a judicious use of tide–aquifer interaction technique is indispensable for the reliable estimates of hydraulic parameters of coastal aquifer systems.     

Influences of coastal underground reservoir construction and utilization on saltwater and freshwater transport law in aquifersEI北大核心CSCD

In order to reveal the impact of underground reservoir construction and extraction methods on the saltwater and freshwater transport law in coastal aquifers, a 300m × 900m × 30m conceptual numerical model was established. The variable density current simulation method of unconfined aquifer was used to analyze the saltwater and freshwater transport law in coastal aquifer under different extraction scenarios before and after the construction of underground dam. The results show that the construction of underground dam can significantly reduce the scope and degree of seawater intrusion. Groundwater extraction can accelerate the intrusion and diffusion of residual saltwater in underground reservoirs within a certain time range. The coefficient of saltwater intrusion is exponentially related to extraction scale and the distance between extraction wells and underground dams. Reasonable layout of the location and scale of extraction wells can effectively reduce the negative impact of groundwater extraction on water salinity in the reservoir area. © 2023, Editorial Board of Water Resources Protection. All rights reserved.     

EXPERIMENTAL INVESTIGATION OF EFFECT OF TIDE ON COASTAL GROUNDWATER TABLE

In this article,a tide simulation system based on a two-way water pump technique is developed.Using this system and numerical simulations,the groundwater table fluctuation characteristics,relative over height of groundwater table,and influencing factors of over height are investigated.The experimental and numerical results indicate that the groundwater table fluctuation is of periodic,and of asymmetric.The amplitude of groundwater table fluctuations decreases with the increase of the onshore distances.There...     

An Analytical Solution of Groundwater Flow in Wedge-shaped Aquifers with Estuarine Boundary Conditions

The issue of the groundwater fluctuation due to tidal effect in a two-dimensional coastal leaky aquifer system has attracted much attention in recent years. The predictions of head fluctuation play an important role in dealing with groundwater managements and contaminant remediation problems in costal aquifers. This article presents a two-dimensional analytical model describing the groundwater flow in a coastal leaky aquifer of wedge shape affected by the tides and bounded by two estuarine rivers with an arbitrary included angle. The solution of the model is derived in the Polar coordinates by the Hankel transform and finite sine transform. The head fluctuation predicted by this new solution is compared with that by an existing solution for groundwater flow in a non-L shaped tidal aquifer. The groundwater fluctuation due to the joint effect of estuarine tides is explored based on the present solution. Moreover, the influences of the parameters such as diffusion (D_i), included angle (Ф), and tidal river coefficients (K₁, K₂) on the head fluctuation in the aquifer are also assessed and discussed. The results demonstrate that those parameters have significant effects on the head fluctuation in the leaky confined aquifer system. Moreover, the effect of D_i increases with Ф, and the effects of K₁ and K₂ on the normalized amplitude and phase lag of the groundwater fluctuation are significant when both parameter values are larger than 10^?5.     

洪水过程对河岸带地下水水位波动的影响

为揭示洪水作用下河岸带地下水的响应过程,利用室内物理模型试验和数值模拟,研究了不同洪峰及洪峰持续时间对地下水水位波动的影响。结果表明:河岸带地下水水位的波动具有不对称性,水位上升快下降慢,沿程地下水水位的波动呈指数形式衰减,并表现出明显的滞后性;随着洪水洪峰增大,地下水水位波动增大,河水和地下水的交换量增大,而地下水水位的滞后变化不明显;洪峰持续时间变长,地下水水位的滞后性显著,内陆地下水水位波动的幅度增大,恢复至初始状态的时间变长。     

用于大规模区域供冷的地下含水层输运海洋冷量技术模拟

利用沿海地下含水层结构输运冷媒水,传递来自海洋的冷量,以构筑大中型城市地区性节能的建筑空调系统,从而实现大规模区域的廉价空调供冷。应用控制容积法和交替方向隐式求解方法,对含水层中的热量运移进行数值模拟,研究分析热弥散系数、岩层比热容及水力传导系数对热量运移过程的影响。研究证明,该方案有效降低了含水层中的地下水温度;借助大流量、大扬程的抽水井将冷媒水过量注入地下,能够有效控制地面沉降,促成已沉降地面的微量回升。此技术是一项符合可持续发展原则的地区性空调技术,具有节约能源、保护环境的积极意义。     

Groundwater Response to Tidal Fluctuation in an Inhomogeneous Coastal Aquifer-Aquitard System

This paper investigates tide-induced groundwater fluctuation and submarine groundwater discharge (SGD) in a leaky inhomogeneous coastal aquifer system with an upper unconfined aquifer, a lower confined aquifer, and an aquitard between them. The upper left aquifer is formed due to land reclamation. The SGD defined as the groundwater flow from land into the sea is controlled mainly by the hydraulic gradient between land and sea. An analytical expression is developed to discuss and assess the effect of inhomogeneity on the groundwater head fluctuation in the leaky aquifer system. Joint effects of aquifers’ parameters such as leakage and hydraulic diffusivity on the groundwater head fluctuation and SGD are investigated. The predicted results from the analytical expression indicate that the groundwater head fluctuation in both unconfined and confined aquifers is dependent on dimensionless leakages and increases with dimensionless hydraulic diffusivity.