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1.
地下水动态趋势和短临异常 总被引：3，自引：0，他引：3
在无其他因素引起水量增、减条件下,地下水动态大于一年的趋势变化是地下水动态的异常变化。识别地下水动态异常变化的条件是调查观测井的水文地质环境、水动力条件及水量有无变化。在趋势异常发展背景下地下水动态趋势的转折与地震活动有关。列举了河间等三口井近年来的水位观测结果,表明短临异常在震前均有趋势变化背景,因此短临异常的判别要以趋势变化分析为基础。地下水动态趋势异常和短临异常随时间的分布是有序的,用序列异常方法分析异常与地震活动形势,研究序列异常发生、发展、演变的规律与地震活动的关系,对地震发生的时间和强度有较好的预报意义。 相似文献
2.
滇21井水位微动态特征研究 总被引：1，自引：1，他引：0
本文通过对滇２１井的地质构造部位、水文地质条件、井孔结构等方面的论述,应用该井水位观测结果,以地下水微动态理论为指导,分析了气压、固体潮、降雨等干扰因素对水位的影响,归纳出该井水位正常动态特征,探讨了识别震兆异常的方法,为综合分析多井水位异常打下了基础。 相似文献
3.
对北京地区超采引起的地下水位动态特征与成因作了详细分析,并对超采背景下如何提取地震前兆异常信息的问题作了探讨．北京地区地下水位年动态的主要影响因素是地下水开采和降雨,而地下水位动态的趋势变化则与区域地下水超采量有直接关系．本文用相关分析的方法,分析了北京平原区超采量与水位变化之间的关系,为评价超采区观测井的干扰影响程度、识别地震前兆信息提供依据．研究结果表明,在区域超采不严重的地区引起的水位趋势性变化中,也包含着地震前兆信息;采用消除趋势及年变化影响的数学处理方法,可提取出地震的趋势异常变化． 相似文献
4.
分析华北地区 2 0余年地下水动态与强地震活动的关系 ,发现部分井水位动态在几次强地震前短期阶段出现形态相似的下降变化 .其特征表现为水位以突变下降或加速下降开始 ,转折后变为速率较缓慢的上升 ,其幅度比下降幅度小得多 ;地震发生在水位缓慢上升过程 ,震时或震前水位大幅度上升 .这种下降形态的异常在华北地区上百口观测井中记录虽然不多 ,但是在几次强地震前不同的井记录了形态相同的水位变化过程 .表明地下水的地震前兆异常具有一定的重现性 ,在不同的强地震前可重复出现 .因此 ,有必要研究这类异常的成因及其与强地震活动的关系 . 相似文献
5.
分析华北地区20余年地下水动态与强地震活动的关系，发现部分井水位动态在几次强地震前短期阶段出现形态相似的下降变化. 其特征表现为水位以突变下降或加速下降开始，转折后变为速率较缓慢的上升，其幅度比下降幅度小得多；地震发生在水位缓慢上升过程，震时或震前水位大幅度上升. 这种下降形态的异常在华北地区上百口观测井中记录虽然不多，但是在几次强地震前不同的井记录了形态相同的水位变化过程. 表明地下水的地震前兆异常具有一定的重现性，在不同的强地震前可重复出现. 因此, 有必要研究这类异常的成因及其与强地震活动的关系. 相似文献
6.
识别地下水动态地震前兆异常,必须根据观测井地质及水文地质条件,分析地下水的多年动态特征,影响水位的干扰因素及异常变化与地震活动的关系。本文通过上述分析,认为大同6.1级地震前,河北省地下水网中万全、雄县、完县三口井存在水位异常变化。 相似文献
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重点分析了新疆及边邻地区1980年以来6次7级以上地震前后北天山地下流体动态异常资料，其中3次地震前地下水有短期前兆异常变化，震时同震地震波效应普遍存在，震后异常十分突出且幅度大；以水位为主的水动力学效应反映了大区域应力调整过程具有不可逆特征。水文地球化学参数的变化不敏感。讨论了地下水远程效应与井震距离的关系以及阶跃异常的幅度等问题。 相似文献
9.
地下水动态受水文因素影响较大,对地震和构造活动具有较灵敏的响应。判别并排除各种水文干扰,确认地下水在地震前的异常变化,对提高地震分析预报能力,具有重要作用。马家沟矿井水位动态观测层与地下水开采层为同一含水层,井水位于2010年出现破年变异常,加速持续上升,截至2015年,最大上升幅度约30 m。依据该井水文地质环境特征,根据唐山市区2001-2015年地下水位、降雨量、地下水开采量实测资料,建立合理多元回归模型和三维地下水流动模型,发现地下水开采量减少应为影响马家沟矿井水位动态的可能因素。文中采取的异常识别与分析方法,可为其他类似井孔的地下水动态异常识别及判定提供一定借鉴。 相似文献
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地下水动态的异常变化既有可能是地震前兆异常信息,也有可能是某种环境干扰所引起的,如何及时识别并排除环境干扰,对于成功判定地震前兆异常至关重要。马鞍山皖27井水位自2012年10月以来反复出现下降型异常,下降程度超正常年份最低值,最大降幅达70cm。为了准确客观地判定该异常的成因,本文利用水化学和物理相结合的方法对皖27井地下水动态变化成因及开采干扰进行分析,研究表明:大气降水在皖27井水补给源中占了一定的份额,除此之外,还存在深部补给来源;深井抽水活动影响着皖27井水位的变化,但不能将皖27井本次异常变化完全归因于深井抽水,区域构造活动是引起本次水位异常的主要原因。本文所采取的异常识别与分析方法,为今后地下水动态异常识别及前兆判定工作提供重要依据。 相似文献
11.
Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water‐level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water‐level stresses simultaneously during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water‐level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three‐dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping‐induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period. 相似文献
12.
水位变化对河流、湖泊湿地植被的影响 总被引：12，自引：6，他引：6
水位是湿地生态水文过程的关键因素之一,其改变将影响湿地植被覆盖度和物种组成,最终产生群落演替.从水位梯度,水位波动和人工控湖、控河工程3方面论述水位变化对湿地植被的影响:由于对水位选择的不同及彼此竞争力的差异,湿地植物种沿水位具有梯度分布现象,同时形态可塑性能对其分布范围产生一定影响;水位波动的频率和淹没持续时间对于植被演替具有基础性的作用,水位波动幅度的影响则相对较小,周期性波动能维持以草本植物为主的湿地植被的物种多样性和稳定性,非周期性波动以洪水、干旱为主,易促进湿地植被向固定的水生或陆生方向演替;人工控湖、控河的影响在机理上并无特殊之处,但保证物种多样性和生态系统稳定性的各种缓解措施具有较高的参考价值.基于机理的量化模型,自然、人为因素驱动下水位变化对湿地植被影响的差别研究,模拟水位波动实验以及人工控湖、控河工程的跟踪观测将是今后该领域研究的热点. 相似文献
13.
A two‐dimensional semi‐analytical solution to analyse stream–aquifer interactions in a coastal aquifer where groundwater level responds to tidal effects is presented. The conceptual model considered is a two‐dimensional subsurface system with stream and coastline boundaries at right angles. The dimensional and non‐dimensional boundary value problems were solved for water level in the aquifer by successive application of Laplace and Fourier transform techniques, and the results were obtained by numerical inversion of the transformed solution. The solution was then verified by reducing the solutions to one‐dimensional known problems and comparing the results with those from previous studies. Hypothetical examples were used to examine the characteristics of water‐level variations due to the variations in stream stage and the fluctuations in tide level. Sensitivity analysis indicated that streambed leakance has no influence over the amplitude of groundwater fluctuations, but that the effect of stream stage increases with increasing leakance. Little difference was observed in the water level for different aquifer penetration ratios with narrow stream width. Increases in streambed leakance caused increases in the effect of aquifer penetration by the stream on the water level. An increased specific yield value resulted in decreased amplitude of water fluctuations and mean water level, and showed that water‐level variations due to stream and tidal boundaries are sensitive to specific yield. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
14.
中国大陆井水位与水温动态对汶川M_S 8.0地震的同震响应特征分析 总被引：6，自引：0，他引：6
分析了汶川MS8.0地震在中国大陆引起的水位、水温同震变化特征,对比研究了2007年9月12日印尼苏门答腊MS8.5远震和汶川MS8.0近震在四川及其附近地区引起的水位、水温同震变化差异,结果表明:汶川地震在中国大陆引起的水位同震变化以上升为主,同时水位上升与下降的井点空间分布表现出一定的分区性;水位、水温同方向阶变的井点数比例高于两者反方向阶变井点数比例,当水位同震变化为振荡型时,水温以下降型为主;相对于远震,近震引起的水位、水温同震变化井点数量增加,无变化井点数量减少;所有井水位和大多数井水温同震阶变的方向都不因地震的远近、大小、震源机制或地震方位的变化而改变,个别发生水温同震升降方向变化的井点是由于水的自流状态和水位同震阶变由振荡转为阶变的改变所引起;水位同震升降性质受控于当地的地质构造环境和水文地质条件,而水温同震变化还与地震波引起的井孔中水的运动方式、水温探头放置的位置等因素有关,其机理更为复杂 相似文献
15.
An investigation of groundwater table fluctuations induced by rainfall should consider interactions between the liquid and gas phases in soils. In this study, a water‐air two‐phase flow model was initially verified by simulating an infiltration experiment. It was then employed to model the interactions between liquid and gas phases regarding actions of airflow on the groundwater table and the fluctuations of the phreatic level and water level in the well induced by rainfall. The effects of airflo7w caused by rainfall on phreatic level fluctuations were also studied quantitatively by comparing the results obtained using the proposed model with those obtained from a water single‐phase flow model. The simulation results show that in addition to actual recharge, compressed airflow in unsaturated zones causes the phreatic level to increase, but the rise in the phreatic level is lower than that in the pore‐air pressure head in unsaturated zones due to the mitigation of capillary fringe. The existence of airflow enhances the phreatic level rise during and after rainfall. In addition, the water level in the well, pushed by the phreatic level fluctuations, varies similarly to the phreatic level, but it experiences somewhat delayed and slightly attenuated. The Lisse effect precisely reflects the phreatic level fluctuations before actual recharge. Furthermore, the fluctuations in the phreatic level and water level in the well and the contributions of airflow to phreatic level fluctuations are affected by many factors: rain intensity, initial moisture, overlying aquitard, groundwater table depths, and screen depths of the well. 相似文献
16.
This study employed a coupled water-air two-phase flow and salt water transport model to analyze the behaviors of generated airflow in unsaturated zones and the fluctuations of salinity at the salt–fresh water interface in a two-layered unconfined aquifer with a sloping beach surface subjected to tidal oscillations. The simulation results show that as the new dynamic steady state including effects of tidal fluctuations is reached through multiple tidal cycles, the dispersion zone in the lower salt water wedge is broadened because fresh water/salt water therein flows continuously landward or seaward during tidal cycles. The upper salt–fresh water interface exhibits more vulnerable to the tidal fluctuations, and the variation of salinity therein is periodic, which is irrelevant to the hydraulic head but is influenced by the direction and velocity of surrounding water-flow. With the tidal level fluctuating, airflow is mainly concentrated in the lower permeable layer due to the restraint of the upper semi-permeable layer, and the time-lag between the pore-air pressure and the tidal level increases with distance from the coastline. The effect of airflow in unsaturated zones can be transmitted downward, causing both the magnitude of salinity and its amplitude in the upper salt–fresh water interface to be smaller for the case with airflow than without airflow due to the resistance of airflow to water-flow. Sensitivity analysis reveal that distributions of airflow in unsaturated zones are affected by the permeability of the upper/lower layer and the van Genuchten parameter of the lower layer, not by the van Genuchten parameter of the upper layer, whereas the salinity fluctuations in the salt–fresh water interface are affected only by soil parameters of the lower layer. 相似文献
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A detailed investigation was carried out to evaluate long-term groundwater level fluctuation in regular monitoring wells constructed by the Ministry of Water Resources in Barka, Sultanate of Oman. For this study, groundwater level data for 71 wells and rainfall data from six stations were collected from 1984 to 2003 and analysed. Based on long-term water level fluctuation, groundwater wells are classified into three groups. In group 1, water level shows a long-term cyclic trend without yearly fluctuation whereas in group 2 the water level declined continuously until 1995 followed by a constant water level. In group 3, water level decreases continuously throughout the study periods with rapid annual cyclic variation. Group 1 wells show high water-level fluctuations (5 to 10 m) and seem to be regulated by discharge (lateral flow) from this aquifer and recharge from the adjacent Jabal Akhdar mountainous region. Constant trend in water level after 1995 in group 2 wells illustrates the advancement of saline–fresh water interface to the inland due to heavy pumping which is justified by higher electrical conductivity and Cl/HCO3 ratio. In group 3 wells, the water level dropped continuously due to overabstraction by agricultural farms and human settlements. In addition, wells existing near the recharge dams express the influences of recharge dams and rainfall, and exhibit high water-level fluctuations during heavy rainfall periods. The long-term regional variation indicates that water level drops continuously in the coastal and central parts of the study region. Linear regression analysis revealed that the decline in water level is 0·3–0·4 m year−1 near the coastal and central parts of the study area and is almost constant in the remaining area. We conclude that the contribution of man-made activities on groundwater level is well compared with natural factors. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
19.
2016—2019年高邮车逻井水位出现多次大幅波动变化。结合周边自然环境和农业活动的调查工作,对异常成因和影响水位变化的因素进行了跟踪分析。研究认为,该井水位出现的大幅波动变化异常是高邮湖水位短期大幅波动产生的荷载影响所致,与水利部门对高邮湖水位调控间关系密切,而非地震地球物理异常。 相似文献
20.
In this work, we study groundwater system temporal scaling in relation to plant water use and near‐river‐stage fluctuations in riparian zones where phreatophytes exist. Using detrended fluctuation analysis (DFA), we investigate the influence of regular diurnal fluctuations due to phreatophyte water use on temporal scaling properties of groundwater level variations. We found that groundwater use by phreatophytes, at the field site on the Colorado River, USA, results in distinctive crossovers (slope changes when the plots are fitted with straight lines) in the logarithm plots of root‐mean‐square fluctuations of the detrended water level time series versus time scales of groundwater level dynamics. For groundwater levels monitored at wells close to the river, we identified one crossover at ～1 day in the scaling characteristics of groundwater level variations. When time scale exceeds 1 day, the scaling properties decrease from persistent to close to 1/f noise, where f is the frequency. For groundwater levels recorded at wells further away from the river, the slope of the straight line fit (i.e. scaling exponent) is smallest when the time scale is between 1 and 3 days. When the time scale is < 1 day, groundwater variations become persistent. When the time scale is between 1 and 3 days, the variations are close to white noise, but return to persistent when the time scale is > 3 days. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献