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1.
Black box identification techniques are very useful tools to study the relationship between rainfall and the discharge of karst aquifers. Autocorrelation, cross-correlation, cross-spectral, impulse response identification (Wiener–Hopf and error minimization methods) and parametric identification of transfer functions techniques have been used by different authors. A review of these techniques has been realized to assess the possibilities and limitations. The reviewed techniques are applied to a time rainfall–discharge series of Fuenmayor karst spring, (southern central Pyrenees, Spain) to establish the relative quality of the obtained models. The quality is evaluated with the Nash–Sutcliffe model efficiency coefficient. In addition, effective rainfall has been used to improve the performance of every model. The whitening technique has been used in the cross-correlation technique with good results. The studied spring shows a Fontestorbes type behavior. The linearity of the system has been analyzed by the coherence function. Fuenmayor has an acceptable linear response, except for high frequency events. The parametric identification provides the best efficiency value E = 0.8164 and provides a proper transfer function, with five parameters (one zero, two poles, the gain and the delay). The prediction power of this transfer function is validated with another time series, with an efficiency value of E = 0.7904.  相似文献   

2.
In order to study the function, hydrodynamic behavior, and hydraulic properties of the karst aquifers in Izeh, southwest Iran, time series analysis was applied to the precipitation, spring discharge, and piezometric head data of two representative karst systems of Zagros (Ilam-Sarvak and Asmari Formations). Time series analysis was applied to two karst aquifers, those of Asmari and Ilam-Sarvak Formations. The daily precipitations of anticlines were estimated based on the precipitation–elevation function which was applied on digital elevation model (DEM) of the area. The mean estimated daily precipitations were considered in bivariate time series analysis as input data of each karst system. The total length of time series was about 2.7 years, extending from May 2007 to December 2009. During the research, several one-parameter probe data loggers were installed, which daily measure the water surfaces in karst aquifers. Time series analysis was applied for describing Izeh karst aquifers with a focus on both univariate (autocorrelation and spectral analysis) and bivariate (cross-correlation, gain function, and coherency function) methods. The results show that Asmari karst aquifer in Kamarderaz Anticline has a large storage capacity. Because of lacking a well-organized karst network, in the Asmari karst aquifer, baseflow dominates with low contribution of quick-flow. In the Ilam-Sarvak karst aquifer (Shavish and Tanush Anticlines), the karstification occurred in fractures and small diameter conduits, which caused to quick-flow between dense limestone. The Ilam-Sarvak karst aquifer could be regarded as a transition between two extreme types of karst, e.g., highly karstified system and in the opposite, extremely diffused one. The analysis of well hydrograph in Ilam-Sarvak karst aquifer shows that the karst aquifer has a low storage capacity. Unlike Asmari karst aquifer, the fractures and small diameter conduits in Ilam-Sarvak karst aquifer are more enhanced, producing a better developed karst network. Contrary to the typical karst systems, however, diffuse flow and conduit flow coexist in the Asmari Formation.  相似文献   

3.
Karst aquifers are characterized by high heterogeneity and spatial variability of hydrogeological parameters. Time-series analysis of rainfall and discharge (as input and output functions), including correlation, cross-amplitude, phase and coherency, was applied to the Houzhai karstic water system in Guizhou Province, southwest China, in order to study the function, hydrodynamic behavior and hydraulic properties of the aquifer system. Autocorrelation and cross-correlation of the variables showed that the degree of sensitivity of the system to the rainfall input signal decreased gradually from the upstream to the downstream sections, but the memorizing action increased gradually. Analysis of the phase function showed that there is a lag in the discharge response to the rainfall input signal. The lag time increased gradually from the upstream to the downstream sections, and the degree of the linearity upstream is higher than downstream. The quick-flow and slow-flow components were also divided in the cross-amplitude analysis. The results showed that about 60% of spring discharge in the upstream section was quick flow. The quick-flow component downstream reduced to only 5%. The main control factors of the karst-system response are the karst geomorphology and the inner origination structure of the karstic multi-medium.  相似文献   

4.
The quantification of submarine and intertidal groundwater discharge (SiGD) or purely submarine groundwater discharge (SGD) from coastal karst aquifers presents a major challenge, as neither is directly measurable. In addition, the expected heterogeneity and intrinsic structure of such karst aquifers must be considered when quantifying SGD or SiGD. This study applies a set of methods for the coastal karst aquifer of Bell Harbour in western Ireland, using long-term onshore and offshore time series from a high-resolution monitoring network, to link catchment groundwater flow dynamics to groundwater discharge as SiGD. The SiGD is estimated using the “pollution flushing model”, i.e. a mass-balance approach, while catchment dynamics are quantified using borehole hydrograph analysis, single-borehole dilution tests, a water balance calculation, and cross-correlation analysis. The results of these analyses are then synthesised, describing a multi-level conduit-dominated coastal aquifer with a highly fluctuating overflow regime draining as SiGD, which is in part highly correlated with the overall piezometric level in the aquifer. This concept was simulated using a hydraulic pipe network model built in InfoWorks ICM [Integrated Catchment Modeling]® version 7.0 software (Innovyze). The model is capable of representing the overall highly variable discharge dynamics, predicting SiGD from the catchment to range from almost 0 to 4.3 m3/s. The study emphasises the need for long-term monitoring as the basis for any discharge studies of coastal karst aquifers. It further highlights the fact that multiple discharge locations may drain the aquifer, and therefore must be taken into consideration in the assessment of coastal karst aquifers.  相似文献   

5.
岩溶含水层具有高度的非均质性和各向异性,为定量识别济南泉域岩溶含水层发育状况,通过选取泉域岩溶水补给区和排泄区的地下水位动态数据,采用相关分析和频谱分析,研究其对降雨补给的响应特征.地下水位-降雨量的自相关和互相关分析表明,系统对降雨输入信号的敏感程度自补给区至排泄区逐渐降低,但记忆作用逐渐增强.相位分析结果表明泉域地下水位对降雨信号的响应存在滞后现象,自补给区至排泄区滞后时间逐渐延长,补给区地下水位与降雨具有更好的线性相关性.交叉振幅分析结果表明补给区地下水流中快速流约占20%~30%,而在排泄区快速流占比减少至2.5%~10.0%.岩溶含水系统地下水动力条件主要受岩溶发育程度等介质内部结构影响,济南泉域岩溶含水层岩溶发育程度较低,含水介质和水流通道以岩溶裂隙为主,地下水运动以基质流为主.   相似文献   

6.
The karst hydrological processes are the response of karst groundwater system to precipitation. The precipitation penetrates through the vadose zone, the subsequent groundwater pressure wave propagates to a spring outlet, and then, the spring discharge changes. This paper proposes a grey auto-incidence analysis for studying the karst hydrological processes. The method can detect the periodicity of a time series, for example, precipitation and spring discharge. Then the approach is applied to Liulin Springs Basin, China. The results show that the auto-incidence degree of precipitation reaches to the maximum (i.e., 0.816) when time delay equals to 8 years. The auto-incidence degree of spring discharge reaches to the maximum (i.e., 0.865) when time delay equals to 3 years. These results show that the periodicity of precipitation is 8 years, and of spring discharge is 3 years. The difference of periodicity between the precipitation and the spring discharge reveals that the processes of precipitation recharging groundwater and groundwater transport are regulated or controlled by karst aquifer. Because of heterogeneity of karst aquifer, the quick flow and base flow occur during the groundwater propagation, which causes the periodicity of spring discharge is not coincidence with of precipitation.  相似文献   

7.
岩溶地下水位对降雨响应具有时空变异性,甑皮岩遗址地下水动力系统结构的认识存在分歧。利用高分辨率降雨水位数据,将研究区分割为不同含水体,通过水位动态、相关分析、滑动窗口采样相关分析等方法,探讨岩溶地下水对降雨响应时空变异特征及成因。结果表明,岩溶强发育、扩散流导水的含水体水位对降雨的响应表现为缓升缓降,水位自相关性强;发育岩溶管道的含水体水位表现为陡升陡降,水位自相关系数衰减速率快,对降雨响应的滞后时间短,互相关函数图呈多峰型;岩溶发育的极不均匀性是造成空间响应差异的主要原因。雨季地下水位对降雨响应的滞后时间远小于枯季;雨季累积降雨量大、水位埋深浅、包气带长期处于饱和或者近饱和状态,降雨垂直入渗补给历时短;雨季暴雨频繁导致含水体地下水短期内形成较大水力梯度,径流补给速度加快。综合分析认为,甑皮岩遗址地下水动力系统由NE向岩溶管道、NS向管道-裂隙以及NE向强径流带3个子径流系统组成。  相似文献   

8.
The Gihon Spring, Jerusalem, is important for the major monotheistic religions. Its hydrogeology and hydrochemistry is studied here in order to understand urbanization effects on karst groundwater resources, and promote better water management. High-resolution monitoring of the spring discharge, temperature and electrical conductivity, was performed, together with chemical and bacterial analysis. All these demonstrate a rapid response of the spring to rainfall events and human impact. A complex karst system is inferred, including conduit flow, fissure flow and diffuse flow. Electrical conductivity, Na+ and K+ values (2.0 mS/cm, 130 and 50 mg/l respectively) are very high compared to other nearby springs located at the town margins (0.6 mS/cm, 15 and <1 mg/l respectively), indicating considerable urban pollution in the Gihon area. The previously cited pulsating nature of the spring was not detected during the present high-resolution monitoring. This phenomenon may have ceased due to additional water sources from urban leakage and irrigation feeding the spring. The urbanization of the recharge catchment thus affects the spring water dramatically, both chemically and hydrologically. Appropriate measures should therefore be undertaken to protect the Gihon Spring and other karst aquifers threatened by rapid urbanization.  相似文献   

9.
Over a period of three hydrological years during which precipitation was highly variable, measurements of discharge, electrical conductivity, temperature and chemical components of the water at the Cañamero spring (southern Spain) were taken in order to characterise the hydrogeological functioning of the karst aquifer that it drains. The results obtained from analysis of the frequency distribution of electrical conductivity data revealed histograms with a plurimodal morphology (up to 5 modes) and a range of variation that increased with greater pluviometry during the study period. The discharge from this spring increased sharply a few days after major rainfall episodes and, when the discharge reached a value of approximately 3.73 m3/s, an overflow spring started to function. During high-water periods, there were sudden and large falls in EC, temperature and all the chemical components dissolved in the water. This high variability reflects the predominance of groundwater flow through karst drains, a typical feature of conduit flow systems. The considerable hydrochemical heterogeneity observed is caused by the mobilisation of important volumes of recharge waters from shallow areas of the aquifer (soil, epikarst) towards the discharge point, with greater participation of the unsaturated zone during high-water conditions, and a more active role played by the saturated zone during low-water conditions. In karst systems such as the one drained by the Cañamero spring, it is important to monitor several responses (hydrodynamic, hydrothermal, hydrochemical, etc.), with an appropriate sampling frequency and under different hydrometeorological conditions, in order to achieve an adequate hydrological characterisation. This is fundamental for planning, management and protection of groundwater in karst aquifers.  相似文献   

10.
A series of long karst spring discharges have been analysed to determine trends, fluctuations and relationship to rainfall. Data come from aquifers in southern Italy, and in some cases cover more than one hundred years of records. Based on yearly discharge data, hydrological series show the drop of the discharge after 1986, which has been interrupted by the recent wet years of 2009 and 2010. This drop is connected to the decrease in annual rainfall, but other factors also seem to contribute to this phenomenon. Based on monthly scale data series, the relationship between meteorological and hydrological droughts has been analyzed, using the standard precipitation index (SPI). As karst systems are large reservoirs, only longer meteorological droughts induce groundwater droughts, and the start, duration and time-lag of the hydrological droughts have been evaluated.  相似文献   

11.
In order to quantify the quality of the rainfall/discharge relationship across time-scales, we propose the use of both orthogonal wavelet multiresolution analysis and cross-correlation analysis. By using the two techniques together, it is possible to show, scale-by-scale, the influence of the input to the system (rainfall) on the response (discharge) of the aquifer and also to relate these results to the internal structure of the aquifer and to the degree of organisation of the karst drainage. An application of this method to three Pyrenean karsts is also shown. To cite this article: D. Labat et al., C. R. Geoscience 334 (2002) 551–556.  相似文献   

12.
利用MODFLOW-CFP建立湖南省香花岭渗流-管道流耦合模型,并使用降雨量系数法实现非线性入渗过程,以探讨此方法在模型中的适用性。通过人工试错反演参数,得出6个不同降雨强度区间的降雨量系数;非线性入渗处理后,地下河流量模拟结果的纳什系数提高至0.91。结果表明:降雨量系数法可使该模型更好地模拟地下河流量变化,此方法也适用于一些岩溶小流域的数值模拟工作。   相似文献   

13.
《China Geology》2021,4(3):433-445
In order to study the hydrodynamic characteristics of the karst aquifers in northern China, time series analyses (correlation and spectral analysis in addition with hydrograph recession analysis) are applied on Baotu Spring and Heihu Spring in Jinan karst spring system, a typical karst spring system in northern China. Results show that the auto-correlation coefficient of spring water level reaches the value of 0.2 after 123 days and 117 days for Baotu Spring and Heihu Spring, respectively. The regulation time obtained from the simple spectral density function in the same period is 187 days and 175 days for Baotu Spring and Heihu Spring. The auto-correlation coefficient of spring water level reaches the value of 0.2 in 34–82 days, and regulation time ranges among 40–59 days for every single hydrological year. The delay time between precipitation and spring water level obtained from cross correlation function is around 56 days for the period of 2012–2019, and varies among 30–79 days for every single hydrological year. In addition, the spectral bands in cross amplitude functions and gain functions are small with 0.02, and the values in the coherence functions are small. All these behaviors illustrate that Jinan karst spring system has a strong memory effect, large storage capacity, noticeable regulation effect, and time series analysis is a useful tool for studying the hydrodynamic characteristics of karst spring system in northern China.© 2021 China Geology Editorial Office.  相似文献   

14.
为揭示太行山东缘小南海泉流量变化特征及规律,基于小南海泉1971-2016年的流量资料,采用R/S分析法、Mann-Kendall趋势分析法和小波分析法,探讨小南海泉流量变化规律及特征。结果表明:小南海泉年流量呈显著下降趋势,年变化幅度为0.05 m3·s-1;未来泉流量的变化趋势和过去一致,具有持续性特征,且持续性强烈;泉流量的变化存在约15、27年的主周期与6年的次周期。降水量的减少和气温的增加是导致泉流量减少的主要气象因素,且这种暖干化现象会持续发展。泉流量对降雨的响应存在一定的滞后,流量与前五个月的月降水量均呈高度相关,其中与前2月的降水相关性最高,研究成果可为小南海泉水资源合理开发和保护提供依据。   相似文献   

15.
In northern Puerto Rico (USA), subsurface conduit networks with unknown characteristics, and surface features such as springs, rivers, lagoons and wetlands, drain the coastal karst aquifers. In this study, drain lines connecting sinkholes and springs are used to improve the developed regional model by simulating the drainage effects of conduit networks. Implemented in an equivalent porous media (EPM) approach, the model with drains is able to roughly reproduce the spring discharge hydrographs in response to rainfall. Hydraulic conductivities are found to be scale dependent and significantly increase with higher test radius, indicating scale dependency of the EPM approach. Similar to other karst regions in the world, hydraulic gradients are steeper where the transmissivity is lower approaching the coastline. This study enhances current understanding of the complex flow patterns in karst aquifers and suggests that using a drainage feature improves modeling results where available data on conduit characteristics are minimal.  相似文献   

16.
基于多元线性回归的表层岩溶泉流量预测   总被引：2，自引：2，他引：0  
利用贵州省安顺市普定县陈旗小流域泉流量动态变化及降雨观测资料,根据泉流量系列自相关和偏自相关以及降雨-泉流量系列互相关分析,确定泉流量系列以及降雨-泉流量响应滞时,建立泉流量与降雨及前期泉流量的多元线性回归模型。率定期(模型参数率定的时段)模型的输出结果与实测流量过程线较为吻合,效率系数为0.996,均方误差为3.0×10-7m3/s,平均相对误差为2.12%。验证期效率系数为0.985,均方误差为3.96×10-7m3/s,平均相对误差为5.36%。研究也同时表明,随着预测时段的增长,泉流量消退阶段的预测误差增大,因此文中所建模型用于10小时之内泉流量预测较为可靠,六场降雨后泉流量退水过程预测的泉流量相对误差平均值小于5%。   相似文献   

17.
Epigenic karst systems exhibit strong connectivity to surface recharge. In land use dominated by extensive agriculture and farming, epigenic karst aquifers are highly vulnerable to surface contaminants from point and nonpoint sources. Currently, the karstic landscapes of the southeastern Kentucky platform (USA) are impacted by agriculture and the rapid proliferation of concentrated-animal-feeding operations. Analysis of karst aquifer responses to storm events provides qualitative information regarding aquifer–recharge flow paths and groundwater residence time, and knowledge of spatial and temporal variations in recharge and flow is crucial to the understanding of the fate of surface contaminants. Time-series correlation analyses on long-term physicochemical data recorded at the outlet of Grayson Gunnar Cave, an epigenic karst system located along the Cumberland escarpment in southeastern Kentucky, revealed the existence of two separate conduit branches responding 4–8 h apart from each other. Recorded storm response times range from 4 h for flushing and dilution to 7 h for recovery. An estimated 6 million L of stored groundwater is discharged from both branches during major storms, and the fastest responding branch accounts for the majority (80%) of the groundwater reserve being discharged through the spring. As evidenced by groundwater residence time (7 days), recharge is likely characterized by localized infiltration of rain water from subsurface sinkholes to the conduit branches with no contribution of regional or lateral groundwater flow.  相似文献   

18.
The unique hydrogeology of karst makes the associated groundwater respond quickly to rainfall events and vulnerable to anthropogenic pollutions. In this study, high-frequency monitoring of spring discharge, temperature, electrical conductivity (EC) and pH, along with monthly hydrochemical and microbial analyses, was undertaken at the outlet of Laolondong karst underground river in Nanshan, southwestern China. The aim was to explore the environmental effects of the catchment’s urban area on the karst groundwater resources. The monitoring data of a tracer test and the response of discharge to rainfall events demonstrate that conduits and narrow fissures coexist in the Laolongdong karst aquifer. The EC, Na+, Cl? and SO42? values (840 μS/cm, 33.7, 38.6 and 137.2 μg/L, respectively), along with high concentrations of fecal coliform bacteria, at the outlet indicate considerable urban pollution in this area. The contaminants sulfate and nitrate showed different relationships with discharge and EC in different stages of a rainfall event. This behavior provided information about aquifer structure and the influence of transport properties. Meanwhile, the hydrological processes of groundwater flow could be modified by urbanization and result in increasing magnitude of urban floods in the underground river. In addition, sulfuric and nitric acids introduced by urbanization not only impact the karst groundwater quality, but also result in a significant perturbation to the carbon cycling system in the karst area.  相似文献   

19.
Some of the world’s deepest goldmines operate below dolomitic karst aquifers in the Far West Rand (FWR) goldfield, South Africa. Associated impacts include the continuous dewatering of karst aquifers for over six decades and irreversible changes of the hydrogeological setting. Affecting an area of approximately 400 km2 by drawing down the water table up to 700 m, these impacts, and the large amounts of data generated in the process, are used as unique research opportunities to better understand the complex karst hydrology. The focus of this study is on predicting final water table elevations in rewatered aquifers after mining ceases taking the fact that mines hydraulically linked previously disconnected aquifers into account. While part 1 of this series develops the conceptual model, this second part utilises large sets of pertinent data to calculate actual flow rates for predicting the fate of dried up springs after mine closure. Following a Darcy-based approach first applied by Swart et al. (Environ Geol 44:751–770, 2003a) it is not only predicted that the springs will flow again but also shown that linear relationships exist between flow rates through a combined system of karst-fractured aquifers overlying the mine void and the associated hydraulic head driving them. This suggests that—at this scale—porous media-based equations can be meaningfully used to predict flow in non-porous media.  相似文献   

20.
在岩溶含水系统中,作为主要排水通道的管道对泉流量动态具有一定的控制作用,而管道特征参数对流量变化亦有影响。为确定管道各参数的影响,前人以管道发育的岩溶水系统为研究对象,进行了短时间序列泉流量响应的分析探讨,而对岩溶管道不十分发育的岩溶水系统的研究较薄弱。为此,本研究结合北方岩溶水系统的发育特征,借助CFP管道流模型对管道各参数对岩溶系统流量和流态的影响程度及各参数的敏感性进行了分析,而后基于河南鹤壁许家沟泉域岩溶水文地质特征构建了泉域的MODFLOW-CFP模型,对泉域岩溶地下水渗流进行了模拟,并对不同降水保证率下的泉流量进行了预测。结果表明:管道流量与管壁渗透系数、管道坡度和管径呈正相关,而随弯曲度和埋深的增加管道流量呈先增大后减小的趋势。管壁粗糙度对流量的影响较小,且呈现出一定的波动性,尤其是当管壁粗糙度较小时,波动比较明显。经敏感性分析发现,管壁渗透系数和埋深的敏感性最高,其次为弯曲度和管道坡度,而管道直径和管壁粗糙度敏感性最低。许家沟泉域在25%降水保证率下,年最大泉流量为0.45 m3/s,平均泉流量为0.36 m3/s;在75%降水保证率下,年最大泉流量为0.41 m3/s,平均泉流量为0.31 m3/s,与实际情况吻合。该法可为我国北方岩溶区水资源评价及泉域水资源开发保护提供借鉴。  相似文献   

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