Article

Analyse statistique des hydrogrammes de decrues des sources karstiques statistical analysis of hydrographs of karstic springs

January 1972
Journal of Hydrology 15(1):49-68

January 1972
15(1):49-68

Authors:

Université de Montpellier

The decrease in flow of a karstic spring can be defined by the following equation: with n having the values of , and 2 according to the difference between the initial and final discharges.Of 100 discharges studied, 73 discharges can be satisfactorily represented by a hyperbolic curve employing one of the above three coefficients.Of these curves, the model: is the most representative since it accords with 58 discharges out of 100.We have introduced a coefficient β independent of Q0 in the hyperbolic curve which can be written:This coefficient, which indicates a slope, represents a spring; its value is related to the characteristics of the spring and its recharge basin. It may be written: with R = karst area E = moisture condition of the karst and of the soil due to precipitation prior to the discharge K = permeability of the karst S = storage coefficient of the karst.

KarstID: an R Shiny application for the analysis of karst spring discharge time series and the classification of karst system hydrological functioning

Article

Full-text available

Mar 2023
ENVIRON EARTH SCI

Karst spring discharge time series analyses are often used to gain preliminary insights into the hydrological functioning of a karst system. KarstID is an R Shiny application that facilitates the completion of such analyses and allows the identification of karst system hydrological functioning. The application permits (i) to perform statistical, recession curves, classified discharges and signal (simple correlational and spectral) analyses; (ii) to calculate relevant indicators representative of distinct hydrological characteristics of karst systems, (iii) to classify karst systems hydrological functioning; and (iv) to compare the results to a database of 78 karst systems. The KarstID software is free, open source, and actively developed on a developer community platform. The user-friendly installation and launch make it especially accessible even for non-programmers; therefore, KarstID can be used for both research and educational purposes. The application and its user manual are both available on the French SNO KARST website (https://sokarst.org/en/softwares-en/karstid-en/).

Identification of relevant indicators for the assessment of karst systems hydrological functioning: Proposal of a new classification

Article

Full-text available

Oct 2021
J HYDROL

Classification is a first-line tool for understanding the main characteristics of a natural system’s response. We propose a new classification of karst systems hydrological functioning that is based on spring discharge time series and takes profit of spring discharge databases to encompass the high diversity of karst hydrological functioning. It discriminates six different classes based on three relevant indicators of karst hydrological functioning. A core dataset made of 10 karst systems was first considered for the set-up of the classification. The spring discharge time series were investigated according to recession curves, statistical and signal analyses to identify relevant indicators of hydrological functioning. The selection of the most relevant indicators and the proposal of the classification were based on multivariate analyses. The classification was then tested on spring discharge time series of 78 karst systems located worldwide. All the systems homogeneously spread among the six proposed classes, which highlights the relevance of the approach and the representativeness of the various classes of hydrological functioning. Results from the proposed methodology were finally discussed to explore its limitations and define guidelines for its application.

Výtokové čiary banských vôd a krasových prameňov. [Recession curves of mine drainage and karstic springs; in Slovak with English summary]

Article

Full-text available

Oct 2020

V práci sú analyzované hydrogramy drenáží banských vôd z 20 štôlní, ktoré boli v historickej minulosti vyrazené v horninách kryštalinika – granitoidoch a metamorfitoch rôzneho stupňa metamorfózy, ako aj v neovulkanických horninách Slovenska. Z údajov o pozorovaniach priebehu ich výdatností v čase boli zostavené typické výtokové čiary. Následná analýza jednotlivých zložiek odtoku prítomných v typických výtokových čiarach odhalila dominanciu exponenciálnych zložiek (laminárnych subrežimov) nad lineárnymi odtokovými zložkami (turbulentnými subrežimami). Pretože gravitačné odvodňovanie banských diel charakterizované prepojením individuálnych štôlní a šácht do kontinuálnej odvodňovacej siete svojou koncentráciou odtoku podzemnej vody pripomína obeh podzemnej vody v krasových horninách, boli tieto porovnávané s typickými výtokovými čiarami 10 krasových prameňov. Vybrané krasové pramene sa nachádzajú pod okrajmi krasových planín Slovenského krasu a Muránskej planiny tvorených stredno– a vrchnotriasovými karbonátmi (vápencami a dolomitmi). Na rozdiel od banských vôd, boli analýzou výtokových čiar krasových prameňov identifikované lineárne aj exponenciálne zložky odtoku pri objemovej dominancii lineárnych zložiek (turbulentných subrežimov). Lineárne zložky odtoku v krasových prameňoch by mohli súvisieť s lepším odvodňovaním podzemnej vody z epikrasu v dôsledku lepšej vertikálnej komunikácie vôd v krasovom prostredí. V prípade nekrasovatejúcich hornín je táto miera veľkosti vertikálneho prepojenia medzi nenasýtenou zónou, resp. zónou pripovrchového rozvoľnenia masívu menšia, čo má za následok nižšie objemové zastúpenie turbulentných subrežimov pri odtoku banských vôd. ***/*** Hydrographs of mine waters discharging from 20 adits, excavated in the past centuries in crystalline, metamorphic and volcanic hard rocks of Slovakia were analysed and master recession curves were assembled. Following flow component analyses revealed dominance of exponential shapes of recession curves over the linear ones. Gravitational drainage of mine works with typical interconnection of adits and shafts resembles groundwater circulation in karstified rocks with typical flow concentration. Master recession curves of 10 typical karstic springs were used for comparison with mine works. Selected karstic springs were located under the edges of karstic plateaus built by Middle and Upper Triassic carbonates of the Slovenský Kras and Muránska planina Mts. Contrary to the mine drains, both linear and exponential shapes of recession curves were found by flow component analyses of karstic springs, with the quantitative dominance of linear flow components (turbulent sub-regime) volumes. The linear flow components in karst springs could be perhaps related to better groundwater drainage from the epikarst due to the better vertical water communication in the karst environment. In the case of non-karstic rocks, the vertical connection between the unsaturated zone / the zone of subsurface loosening of the rock mass is much narrower, which results in lower volumes of linear flow components in the outflows of the mine drainages.

Flow Recession Equations for Karst Systems

Article

Full-text available

Jul 2020
WATER RESOUR RES

Haidy Basha

The proper management and exploitation of karst water resources require first and foremost an accurate characterization of the karst aquifer. Analysis of the recession curve of a spring hydrograph is one efficient approach of determining the hydraulic characteristics of a karst system. In the present work, six flow recession equations for various flow conditions are presented that highlight the dichotomy of the dual flow characteristics between the fissured matrix and the conduit system. They are defined in terms of lumped physical parameters that characterize the dominant flow processes occurring in a karst aquifer. The processes consist either of a pressure‐driven flow or a gravity‐driven flow in a conduit that is interacting laterally with the groundwater flow in the surrounding matrix. The recession equations are composed of two distinct functions that represent separately the flood flow component and the base flow component. They allow the separate evaluation of the conduit and matrix drainage processes and capture the strongly varying recession in the early stages as well as the slow decline in the latter stages of the spring recession hydrograph. Approximate equations for large times are also developed that allow the direct estimation of the model parameters of the karst system using simple algebraic formulas. The flow recession equations were applied to three real karst systems and proved to be effective in simulating the observed recession hydrographs and estimating its hydraulic properties.

Comparison of Mine Drainage/Karst Springs Discharge Recession Curves

Chapter

Jan 2017

Gravitational dewatering of mine works—interconnected network of adits and shafts—in certain aspects of flow concentration resembles groundwater circulation in karstified rocks. To compare similarities and differences in these groundwater circulation types, hydrographs of mine waters discharging from eight adits in the past centuries excavated in crystalline, metamorphic and volcanic hard rocks of Slovakia were analysed. Discharges here were gauged on weekly bases in the periods counting several years or even several decades. After creation of discharge recessional master curves, flow component analyses revealed the presence of one or several exponential shapes of recession curves, while linear recessional mode was present only marginally or not at all. Gauging results and subsequently constructed master recession curves of 10 typical karstic springs located under the edges of karstic plateaus were compared to the previous set of results. Middle and Upper Triassic carbonates of the Slovenský Kras and Muránska planina plateaus (Slovakia) were in the past subject to intensive karstification processes, so that hydraulic behaviour of the analysed karstic springs shows typical intensive discharge response to recharge impulses, visible as steep peaks in hydrographs. Although discharges of all 10 karstic springs were gauged on daily bases, before recessional master curves creation and flow component analyses the time series were transformed to weekly data, to keep the results comparable. Contrary to the mine drains, both linear and exponential shapes of recession curves were found by flow component analyses of karstic springs. Although interconnected network of shafts and adits in mine works might be perhaps similar to conduits in karstic environment, the main difference between those two different groundwater circulation environments (karstified rocks vs. insoluble fractured solid rocks opened by mining activities) is the absence of epikarst layer in the second one. Comparison of the shapes of master recession curves here shows that the linear shapes of flow components should be linked to the influence of groundwater stored in the epikarst layer of karstified aquifers.

On the use of spring baseflow recession for a more accurate parameterization of aquifer transit time distribution functions

Article

Full-text available

May 2013

Baseflow recession analysis and groundwater dating have up to now developed as two distinct branches of hydrogeology and have been used to solve entirely different problems. We show that by combining two classical models, namely the Boussinesq equation describing spring baseflow recession, and the exponential piston-flow model used in groundwater dating studies, the parameters describing the transit time distribution of an aquifer can be in some cases estimated to a far more accurate degree than with the latter alone. Under the assumption that the aquifer basis is sub-horizontal, the mean transit time of water in the saturated zone can be estimated from spring baseflow recession. This provides an independent estimate of groundwater transit time that can refine those obtained from tritium measurements. The approach is illustrated in a case study predicting atrazine concentration trend in a series of springs draining the fractured-rock aquifer known as the Luxembourg Sandstone. A transport model calibrated on tritium measurements alone predicted different times to trend reversal following the nationwide ban on atrazine in 2005 with different rates of decrease. For some of the springs, the actual time of trend reversal and the rate of change agreed extremely well with the model calibrated using both tritium measurements and the recession of spring discharge during the dry season. The agreement between predicted and observed values was however poorer for the springs displaying the most gentle recessions, possibly indicating a stronger influence of continuous groundwater recharge during the summer months.

Contribution of the Brinkman equation to simulate the water flow and solute transport within the karst aquifer: application to the karst system of the Val d'Orléans

Article

Aug 2009

Ali Salim Joodi

The karst aquifers are characterized by a fast flow in the karstic conduits and a slow flow in the matrix. Because of this fast flow, these aquifers are strongly vulnerable to pollution. The main aim of this thesis is to evaluate the importance of water exchanges at the interface between the conduits and the matrix and by consequence the impact of these exchanges on the solute transport in the karst system. To investigate the contribution of the Brinkman equation to the evaluation of the water flows, a model whose geometry of the conduit is described by the sine function was established. Two scenarii are applied. Scenario A employs Darcy's law in the conduit and the matrix. The scenario B employs the Brinkman equation and Darcy's law in the conduit and the matrix, respectively. The additional term of the Brinkman equation describing the shear stress plays a predominant role on the water exchange between the conduit and the matrix when the conduits are sinuous. The hydrodynamic - transport model was applied to the karst system of the Val d'Orléans. The calibration showed that the best average diameter of the conduit is of 5 m, the permeability in the hosted rock is of 5.7×10-10 m2 and that of the conduit of 1.65×10-5 m2 to 5.5×10-5 m2. The results of the hydrodynamic - transport model were compared to floods of the Loire observed in the years 1992 and 1993 during which the chloride concentrations (tracer conservative naturalness) were proportioned in the Loire and Bouillon Spring. With a storage coefficient in the matrix 0.9 m-1, the distance penetrated by the water in the matrix is approximately 530 m in two months for a rising of 2 meters (example of 1993).

An approximation to statistical analysis of recession curves of a karst system in a plain

Article

Jun 2023

Roger Gonzalez-Herrera

A number of models exists to analyze discharge recession curves (RC), such as Boussinesq (BM) and Maillet (MM) models, which were derived from theoretical equations of groundwater flow. This paper presents the results of a study, analyzing water table recession curves, whose objective was to determine the model that best represents the dynamics of the karst aquifer in the northern plain of Yucatan, Mexico. The above was achieved defining statistical criteria to select the model; implementing a statistical analysis strategy to compare the estimates of the parameters of greatest hydrological interest of the chosen decay models. Two scenarios were considered for the analysis: I.- Two wells with the same time intervals with standardized data of: different initial hydraulic head (ho); similar ho; modified ho. II.- A single well, starting from an established hydraulic head and discharge in the same period of time. Numerical methods were used to fit models to the observed RCs and a maximum likelihood function for parameters estimation. Statistical criteria were established to choose the best model. The Boussinesq model proved to be the most appropriate, whose estimates of the parameter α were explored, using fixed values of the parameter n. The comparison between the estimates of α was made based on hypothesis tests (t to compare between two values of α and F for the comparison between more than two values of α). Quasiprobability distributions obtained by a maximum likelihood estimator were also used. The best estimates of α(BM) are obtained with values of the parameter n between 0.5 and 2.

Mathematical Modeling of the Scirca Spring (Central Apennines, Italy). PhD.Thesis.Unipg.it

Thesis

Full-text available

Mar 2012

Adolfo Mottola

One of the techniques which are used to increase the water yield of springs during droughts, is the drilling of wells upstream or downstream the springs (BONI, 1968; CELICO, 1982; BONI & PETITTA, 1994). This technique implies low well efficiency, high drawdowns, high cost of withdrawals and it can lead to spring drainage. In this work a finite difference mathematical model of the Scirca spring (Umbria - Marche Apennines) was developed, which allows to simulate the effects of pumping wells located at different distances from the spring; the model was built by means of the modflow code (MCDONALD & HARBAUGH, 1984), using the porous equivalent approach (ANDERSON & WOESSNER, 1992; ANGELINI & DRAGONI, 1997; SCANLON ET ALII, 2003). The only input parameter for the model is the aquifer recharge, which tends to nil during the dry season, when effective rainfall is very low. The implemented model is able to simulate both the spring discharge during recession, and the variations of daily discharges, continuously measured from 1996 to 2011. Due to the lack of piezometric data and of direct measurements of hydrogeological parameters (hydraulic conductivity and effective porosity), it has been necessary to run different simulations in order to obtain a set of Trasmissivity and Specific Yield values able to reproduce the average recession curve of Scirca spring. Afterwards a process of “inverse modelling” (DOHERTY, 2000; CARRERA ET ALII, 2005; HILL & TIEDEMAN, 2007) was performed to estimate, by means of calibration, the daily recharge of the hydro-geological system of Scirca spring throughout several years. In order to investigate the degree of correlation between daily rainfall and simulated recharge, the two time series data sets had undergone MA Analysis; this kind of analysis allowed to “clean up” the data from the influence of short precipitations close to each other, and to highlight a periodic, similar and in phase trend of rain and recharge. An absolute maximum of recharge in the fall-winter period and a relative maximum in the spring season, were detected. Finally, the efficiency of the management schemes was evaluated by simulating the reaction of the spring, in terms of discharge, to different pumping scenarios; in every scheme the total withdrawal (spring + well) during summer was much larger than the natural spring discharge. The wells were located at different distances from the spring (maximum 2850 m, minimum 100 m), the pumping time span was fixed to 90 days, and 3 pumping rate were used (60, 90, 120 l/s). Results show that the maximum discharge for which the drainage of the spring is avoided and the minimum vital flow (MVF) is guaranteed is 90 l/s. The higher water volumes extracted during summer are balanced by a lowering of the maximum natural discharges. Simulations indicate that, by drilling pumping wells far from the spring, it is possible to optimize the efficiency of the whole system in terms of total withdrawal, drilling and management costs, and to reduce the environmental impact. According to the model, for the Scirca system, the optimum distance of a pumping well from the spring is 2850 m, whereas the optimum pumping scheme is a discharge of 90 l/s, running three months a year (June, July and August). The mathematical model shows that the Scirca hydrogeological system needs 625 days to restore its “undisturbed” state, with a tolerance of 0.5 l/s. The model highlights the possibility to force the system to supply a lower amount of water in winter, with the aim to increase the summer yield. Such a management scheme can be of use to better meet the water demand during dry seasons.

XLKarst, an Excel tool for time series analysis, spring recession curve analysis and classification of karst aquifers

Article

Full-text available

Oct 2023
HYDROGEOL J

Karst aquifers are complex hydrogeological systems that require numerous in-situ measurements of hydrological and physico-chemical parameters to characterize transfer processes from the recharge area to the karst spring. Numerous graphical, statistical or signal processing methods have been developed for decades to interpret these measurements, but there is no simple and standardized tool that can be used for this purpose, which is necessary for a rigorous comparison of results between case studies. This Technical Note presents XLKarst, which has been developed to provide a simple and easy-to-use tool to process a selection of proven methods that characterize the functioning of karst systems. This tool allows (i) time series analysis based on correlation and spectral analysis and, for flow measurements, the use of other statistics and base flow separation, (ii) calculation of the cumulative distribution function to build a spring flow probability plot, and (iii) analysis of spring flow recession and expression of the results in a karst system classification scheme. These methods are first described by providing the key elements of their use and interpretation in the scientific literature. Then, an application to the Fontaine de Nîmes karst system (southern France) is used to highlight the complementarity of the methods proposed by XLKarst to describe the hydrodynamic behavior of a karst system based on daily data of rainfall and discharge over 22 years.

Estimation of specific yield in bedrock near-surface zone of hilly watersheds by examining the relationship between base runoff, storage and groundwater level

Article

Full-text available

Jul 2023

A catchment-scale method for estimation of specific yield (Sy) in the zone of groundwater level fluctuation is proposed. It is applicable to hilly watersheds, where deep groundwater discharge – not drained by local streams as baseflow – is small and can be neglected. Therefore, it is mostly employable for bedrock flow systems, dominated by shallow unconfined fractured rock aquifers. Method provides an estimate of specific yield (Sy) by combined analysis of streamflow recession, storage/runoff relationship and groundwater level fluctuation (Q-S-H). For groundwater storage (S) values evaluation, river discharge (Q) master recession curves are constructed and interpreted. The method produces as more reliable results as number of groundwater level observation sites increases. As example, it is demonstrated at the Levočský potok Brook watershed (Western Carpathians, Slovakia), built by fracture porosity dominated Paleogene sediments. Estimated characteristic Sy value is from the interval 0.001–0.002 and 0.002–0.005 for low and medium storage/runoff conditions – or bottom and middle part of GWL fluctuation zone – respectively. ---/--- Práca prezentuje návrh metóda stanovenia regionálneho odhadu vododajnosti (koeficientu zásobnosti Sy) horninového prostredia na úrovni povodia. Metóda je aplikovateľná na zvodnence v povodiach horských oblastí a pahorkatín, kde je zanedbateľný cezhraničný odtok (do vedľajších povodí) a zanedbateľná je aj hlbinná cirkulácia podzemnej vody, ktorá by nebola z povodia odvádzaná základným odtokom. Z tohto dôvodu je metóda vhodná najmä pre masívy skalných hornín s prevažujúcim plytkým obehom podzemných vôd v ich zvetralinovom plášti, resp. v zóne pripovrchového rozvoľnenia. Odhad hodnôt koeficientu zásobnosti (Sy) je realizovaný kombináciou využitia poznatkov o reprezentatívnych výtokových krivkách odtokového hydrogramu toku, vzťahu odtoku a zmeny zásob vody v povodí ako aj zmien úrovní hladiny podzemnej vody v povodí (Q-S-H). Zostrojenie a interpretácia reprezentatívnych výtokových kriviek prietoku rieky (Q) slúži na vyhodnotenie zmien zásob podzemnej vody (S). Čím je vyšší počet pozorovacích objektov hladiny podzemnej vody (H), tým spoľahlivejšie výsledky uvedená metóda poskytuje. Použitie metódy Q-S-H je názorne aplikované pre povodie Levočského potoka v Západných Karpatoch, ktoré je budované paleogénnymi sedimentmi s dominujúcou úlohou puklinovej priepustnosti. Charakteristické hodnoty Sy pre pripovrchovú zónu hydrogeologického masívu v tomto povodí boli vyššie uvedeným postupom odhadnuté v intervale 0,001 – 0,002 pre nízke hodnoty základného odtoku a v intervale 0,002 – 0,005 pre stredný základný odtok. Viac podrobností o použitej metóde v slovenskom jazyku je uvedených v resumé nachádzajúcom sa na konci článku.

Maillet or not Maillet? - What the recession curves of the Fontaine de Vaucluse (France) tell us about the structure of karst

Conference Paper

Full-text available

Dec 2021

Bernard Collignon

Following the publication of Maillet’s model (1905), hydrologists became accustomed to using decreasing exponentials to model river flows after floods (recession). This law has the advantage of being very simple and it allows us to characterize drying-up using only two numbers: the flow at the beginning of the recession curve and the rate of decrease (expressed in % per day). Due to its simplicity, this model is commonly applied by hydrogeologists in karstic aquifers. However, this is not justified from a theoretical point of view (this type of exponential behaviour does not construe the emptying of a karstic aquifer). We will show that it is also not justified from the observations made on the largest spring in Europe: the Fontaine de Vaucluse (France). The drying curves there are better modelled by the succession of straight lines and hyperboles, accompanied by abrupt variations in flow. We then propose a hydraulic interpretation of this behaviour, which is due to the drainage of the karstic massif by a limited number of main channels in which the flow conditions vary with the water level and saturation of karst conduits. Recession curve details then represent a kind of X-ray of this network.

An alternative method for groundwater recharge estimation in karst

Article

Sep 2021
J HYDROL

Aquifers with time variant catchment boundaries, regional flows, and inflows from surface streams and accumulations are common in karst areas. Due to the lack of reliable methods for determination of water balance in the phreatic zone of such aquifers, groundwater recharge estimation is a challenge task. This paper introduces a new method for estimation of groundwater recharge in karst – the so-called partial correlation method (PCM). The basic hypothesis is that the groundwater recharge rates can be determined from the time series of precipitation, air temperature, relative humidity, and spring discharge, by using a partial cross-correlation function as objective function. Following this hypothesis, a simple conceptual model of water balance in the soil cover, epikarst and vadose zone is developed, and an objective function for estimation of the optimal value of parameter of this model is proposed. PCM is applied on the catchment of Žrnovnica Spring located in the Dinaric karst area of Croatia. The results of application are compared with the results of previous studies, as well as with the results obtained by five empirical models that have been used for estimation of groundwater recharge in the Mediterranean karst. The effective infiltration coefficients obtained by PCM for the Žrnovnica Spring are generally in accordance with the previously published ones.

Detection and estimation of stage-discharge rating shifts for retrospective and real-time streamflow quantification

Thesis

Full-text available

Feb 2021

Matteo Darienzo

River discharge time series are established using "rating curves", which are models with stage as input and discharge as output. Unfortunately, many hydrometric stations have an unstable stage-discharge relation, particularly because of the change in the river bed during floods. These "rating shifts" pose a problem both for the establishment of long-term hydrological series (retrospective analysis) and for the delivery of real-time data, for example for flood forecasting, with quantified and reliable uncertainties. The existing methods for updating the rating curve are based on a statistical analysis of past calibration data (the gaugings) or on empirical rules. This thesis aims at developing some original methods for the automatic detection of rating shifts and the estimation of their magnitude in both retrospective and real time: a method of segmentation of the residuals between the gaugings and a base rating curve, an analysis of the stage recessions and a method for detecting potential shifts from an indicator available in real time (e.g. cumulative sediment transport). The probabilistic approach allows on the one hand to take into account the uncertainty of the information on the shift and on the other hand to quantify the uncertainties of the calculated streamflow. The combination of the three methods has been applied to the Ardèche at Meyras, France, which shows net shifts after each major flood. Good detection and estimation of the rating shift has been observed retrospectively and in real time. The method is generic and, after further validation, operationally applicable to other sites.

A methodology for the assessment of groundwater resource variability in karst catchments with sparse temporal measurements

Article

Oct 2020

In karst catchments where only sparse temporal monitoring is performed, it is generally difficult to correctly assess the overall hydrodynamics of the basin. However, sparse temporal spring-discharge data may contain information of major importance for the characterization of such catchments, especially when sparse spring-discharge data over a long period are available and combined with higher frequency discharge and/or piezometric-level data. This paper proposes a methodology for the characterization and hydrodynamic modeling of karst catchments by coupling sparse temporal data of discharge at a karstic spring over a 30-year measurement period, with higher frequency (i.e. hourly) data of hydrodynamic (piezometry, discharge), physicochemical (temperature, electrical conductivity) and meteorological data over a short monitoring period of 21 months. The study area is the Oeillal spring catchment, one of the main outlets of the Fontfroide-Montredon limestone aquifer located at the border of the Narbonne-Sigean sedimentary basin, southern France. The present study focuses on the use of numerical tools, such as time-series analysis (recession analysis, auto-correlation and cross-correlation analysis) coupled with a lumped-parameter modeling approach, to assess the hydrodynamic behaviour of the karst system. The main results of the study highlight the necessity to couple the results from lumped-parameter rainfall-runoff modeling with results from high-resolution time-series analysis to evaluate the physical significance of the model, since classical numerical performance criteria, such as the Nash-Sutcliff efficiency, Kling-Gupta efficiency and balance error, can be poorly estimated when only sub-sampled time series exist for model calibration.

Hétérogénéité géologique, spéléogenèse et hydrodynamique du karst : du concept à la modélisation numérique

Thesis

Nov 2019

Lucie Dal Soglio

Cette thèse a pour but d'intégrer explicitement la géométrie des conduits karstiques dans les modèles numériques d'écoulement. A partir d'observations du développement des réseaux de conduits karstiques sur le terrain et de modélisations des processus spéléogénétiques et hydrogéologiques, trois sujets scientifiques sont développés dans ces travaux. Premièrement, les investigations sur le système de la fontaine de Vaucluse, essentiellement en zone non saturée, permettent d'identifier les principaux paramètres qui contrôlent la géométrie des réseaux de conduits karstiques. Ces paramètres géologiques et hydrologiques impactent les écoulements préférentiels et les niveaux saturées en eau. Sur la base des connaissances acquises, le développement des conduits est ensuite étudié par le biais de la modélisation 3D. Des modèles synthétiques permettent d'étudier les relations entre les contrastes de conductivité hydraulique de la matrice, l'architecture et l'hétérogénéité des failles et l'architecture du réseau de conduits qui en résulte. De plus, les concepts établis et la méthodologie de spatialisation des données sont améliorés et critiqués sur une partie du système d'étude.Troisièmement, des modèles hybrides sont construits pour étudier l'effet sur le comportement hydrodynamique de la représentation explicite conjointe des conduits karstiques et de la zone non saturée. Ces modèles sont confrontés aux concepts de la littérature à l'échelle du voisinage d'un conduit karstique et à l'échelle du réservoir. Les expériences numériques réalisées permettent de valider l'utilisation de ces modèles hybrides pour reproduire les comportements hydrodynamiques attendus. Elles permettent de quantifier l'influence des propriétés des réseaux de conduits et des propriétés pétrophysiques de la matrice sur les écoulements. En synthèse de cette thèse, une méthodologie de travail est proposée pour modéliser les réservoirs karstiques en intégrant au mieux leur hétérogénéité, de la matrice aux réseaux de conduits.

Groundwater Circulation in Fractured and Karstic Aquifers of the Umbria-Marche Apennine

Article

Full-text available

Apr 2020

The Umbria-Marche Apennine has a large number of springs that drain water stored in carbonate formations. Spring groundwater constitutes a crucial freshwater resource for many countries, regions, and cities around the world. This study aimed to understand the hydrological mechanisms behind groundwater circulation and their relationship to the structural and stratigraphic settings of specific aquifers. Recession analysis and time series analysis were applied to the daily discharge of six springs monitored over eight years. Both analyses indicated the presence of two types of aquifers: aquifer with unimodal behavior and aquifer with bimodal behavior. The first are characterized by two hydrodynamic sub-regimes, in which fracture networks control the baseflow and conduit networks control the quickflow. In contrast, other springs present only one hydrodynamic sub-regime related to fracture network drainage. Time series analysis confirms the results of recession analysis, showing a large memory effect and a large response time, implying the dominance of the baseflow sub-regime. These results indicate that the Maiolica Formation is characterized by a high degree of fracturation and slight karstification, which control infiltration and percolation, whereas the Calcare Massiccio Formation regulates groundwater circulation in the deeper zones of the aquifer, characterized by a high degree of karstification through moderately developed conduit networks.

Karst Springs' Hydrograph Separation into Flow Components Using Parameters of The Master Recession Curve

Conference Paper

Full-text available

Sep 2013

Peter Malík

Presented hydrograph separation principle is based on presumption, that karst spring’s hydrograph is built by superposition of several exponential and linear equation members. Generally, outflows from smaller fissures (laminar flow from karst rock matrix) are exponential and linear equation members describe flow through karst conduits (turbulent flow). Quantitative behaviour (discharge) of karstic aquifer (spring) is described by set of unique constant values of starting discharges Q0, as well as set of unique recession coefficients (α or β) for each detected flow component. The main idea behind the method is based on a simplified understanding of reality: the same discharge should reflect the same water saturation (piezometric) level in the system. Separation method requires detailed studies of spring’s recession to create master recession curve. In the process of hydrograph separation, each measured discharge value is understood as a result of superposition of several flow components, corresponding to the current state of aquifer saturation (general piezometric level). Every measured discharge value Qt is then determined just by a representative time t – theoretically elapsed time from the global maximum discharge Qmax. Subsequently, discharges of different flow components can be calculated by using the t value in their partial equations, where different partial Qmax and individual recession coefficients (α, β) are used. As the exponential equation has no analytical solution, each discharge value Qt has to be solved by iteration process. However, principle of general piezometric level is only a rough simplification. In real karst aquifers, several piezometric levels should exist at least for each saturated system (small fissures, medium fissures, karst conduits), if not for their different parts. By offering a clear solution for every discharge value, presented method still can be helpful for quantitative referencing of flow components for further interpretations.

Zastúpenie izotopov kyslíka v rôznych výtokových subrežimoch prameňov Brezovských Karpát

Article

Full-text available

Jun 2013

Nedávno vyvinutá metóda separácie hydrogramov výdatnosti krasových prameňov, založená na iteratívnom riešení niekoľkých exponenciálnych a lineárnych rovníc, bola aplikovaná na analýzu časových radov výdatností štyroch krasových prameňov v Brezovských Karpatoch, pozorovaných v týždenných intervaloch v období 1987 – 1989. Pramene Vítek pri Chtelnici, Stužková pri Jablonici, Spod javora pri Prašníku, resp. Vrbovom, a Tri mlynky pri Hradišti pod Vrátnom vyvierajú zo skrasovatených vápencov a dolomitov stredného a vrchného triasu. Výtoková čiara každého z prameňov bola jednoznačne opísaná súborom hodnôt počiatočných výdatností Q0, koeficientov vyčerpávania α (pre laminárne zložky prúdenia opísateľné exponenciálnou rovnicou), a ß (pre turbulentné zložku prúdenia opísateľné lineárnou rovnicou). Tieto parametre boli stanovené na základe predchádzajúcej analýzy výtokových čiar, pričom boli detegované aj jednotlivé zložky odtoku (subrežimy). Každá meraním zistená výdatnosť v reálnom čase t, Qt, môže byť determinovaná pomocou reprezentatívneho času t, ktorý by teoreticky uplynul od absolútneho maxima výdatnosti prameňa Qmax. Pre stanovenie tohto reprezentatívneho času t bolo aplikované iteratívne riešenie súboru exponenciálnych a lineárnych rovníc, ktoré bolo realizované pre každú nameranú hodnotu výdatnosti Qt. Zmena kvalitatívnych vlastností vody v čase môže byť chápaná ako dôsledok miešania podzemnej vody rôzneho pôvodu, resp. rozličných zložiek odtoku, resp. subrežimov. Pokus o interpretáciu, resp. "rekonštrukciu" vlastností podzemnej vody jednotlivých odtokových zložiek (subrežimov) môže byť realizovaný riešením zmiešavacej rovnice (koreluje sa pomerné zastúpenie odtokovej zložky na celkovej výdatnosti v % a veľkosť vtedy nameraného kvalitatívneho parametra). Následnou štatistickou extrapoláciou na určenie veľkosti kvalitatívneho parametra pri 100 % zastúpení odtokovej zložky (subrežimu) na celkovej výdatnosti prameňa sa určia vlastnosti nezriedenej, „100 %“ formy odtokovej zložky. Takto boli vypočítané teoretické zastúpenie izotopov kyslíka δ18O a teplota vody pre každú zložku odtoku/výdatnosti. Získané výsledky sú založené iba na málopočetných súboroch dát a manuálnom meraní výdatností, prezentovaný prístup však môže predstavovať perspektívnu metódu pre interpretáciu automaticky zaznamenávaných údajov a odberu vzoriek s oveľa vyššou frekvenciou. ***/*** A recently developed method of karst spring hydrograph separation, based on an iterative solution of several simple exponential and linear equations, was applied to two-year (1987-1989) weekly discharge time series of four karstic springs in the Brezovské Karpaty Mts. in Slovakia. These mountains mainly comprise karstified Middle and Upper Triassic dolomites and limestones. Each spring was described by unique sets of starting discharge Q0 and recession coefficients α (the laminar flow component in exponential equations) and ß (the turbulent flow component in linear equations). Discharge components were detected by recession curve analyses of the springs’ discharge time series. Each measured discharge value, Qt, was determined by a representative time, t : being the theoretical elapsed time t from the total maximum discharge value Qmax. The iteration process was used to obtain representative time t for each discharge Qt. Variations in different flow component discharges over a given time were linked to simultaneously measured water quality parameters to obtain the end members of the theoretical mixture. Additional characteristics of end members were calculated; including the groundwater temperature and δ18O content. Although this method was based on relatively scant datasets and manual discharge records, it represents a perspective approach for future interpretations of datasets with higher frequency of monitoring.

The Hellenic karst. Propositions for research methodologies and application examples. Το Ελληνικό κάρστ. Προτάσεις μεθοδολογιών έρευνας και παραδείγματα εφαρμογών

Presentation

Full-text available

Oct 2017

N. J. Lambrakis

THE HELLENIC KARST. PROPOSITIONS FOR RESEARCH METHODOLOGIES AND APPLICATION EXAMPLES LAMBRAKIS N., Professor of Hydrogeology, Panepistimioupoli Patron, 265 04, nlambrakis@upatras.gr Abs tract The carbonate rocks of the Hellenic geotectonic zones are mostly karstified and host important aquifers with hydraulic transmissivity values varying between 10 -3 και 10 -2 m2/s. The Hellenic karst is described as mature and morphological characteristics like karents, dolines, polges, caves etc. are abudant in such areas. The epikarstic zone, where present, controls the groundwater infiltration and thus the aquifer recharge. Difficulties in research due to inaccessibility of mostly of the karst areas can be compensated satisfactorily by applying statistical analysis to the spring’s time series, and by evaluating the groundwater’s quality. For a ll available springs,s and the corresponding aquifers that are presented in the current manuscript, data processing clearly showed that karst aquifers display an important storage that could be explained by the presence of a dense network of small voids characterized by slow laminar flow or/and the presence of the epikarst zone that controls the water infiltration into the phreatic zone. Although karst displays all elements of a telogenetic formation, yet the data processing indicated that it has not reached maturity. Properties such as the complexity, the homogeneity, the degree of the karst structure development are also obvious. Individual karst units may be simple or complex, some exhibiting the characteristics of homogeneous formations, however for all of them, the phreatic zone is relatively well drained. Moreover, the hydrochemical and isotopic approach decisively contributed to the delimitation of karst aquifers, the emergence of their relationship with others, and the presence of the dominant minerals and hydrochemical processes that regulate the groundwater quality. 2 /s. The Hellenic

TEMPO DE TRÂNSITO DA ÁGUA NO CARSTE: COLOMBO (PR, BRASIL) - TRANSIT TIME OF WATER IN KARST: COLOMBO (PR, BRAZIL)

Article

Full-text available

Jan 2017

The transit time of water in karst systems is extremely variable and relevant for their exploitation. To estimate this property, the correlogram technique was tested, comparing some discontinuous time series, precipitation and well yield, in karst terrain of high complexity. The investigated area is the karst of the Alto Iguaçu-Ribeira watershed (southern Brazil, north of Curitiba). The metamorphic character and intense fracture is a peculiar condition of dolomite limestone occurring in narrow northeast strips. They are confined by phillite and intercepted by northwest diabase dykes. The existence of an epikarst, hidden by superficial formations, adds particularities which give unique character to the karst of this region. The comparison of the precipitation and variation of the dynamic (piezzometric) level curves for a constant productivity in four wells investigated does not reveal an evident correlation. Variable transformations and methodological adjusting were adopted reaching robust results, which indicate pulses of recharge lags with reference to the precipitation picks: short lags (1 to 5 days), medium lags (5 to 10 days), and long lags were discriminated. Wells productivity immediately dependent from precipitation been interpreted as direct entrances to the aquifer in the epikarst, probably through surface connected cavities. Others wells show that dynamic level reacts immediately with the rain event, but maintain continuous and progressive intake of water. Long term flow lags, up to 90 days, reflect entrances and diffuse flow from others sources of karst related to fractured zones.

Modélisation des hydrosystèmes par approche systémique

Thesis

Jun 2018

Frédéric Bardolle

Dans l'état actuel des connaissances, il est impossible de poser correctement toute la physique permettant de modéliser les hydrosystèmes dans leur ensemble, notamment à cause de la dynamique très contrastée des différents compartiments. Les modèles systémiques simplifient la représentation des hydrosystèmes en ne considérant que leurs flux d’échange. L’objet de ce travail est de proposer un outil de modélisation systémique fournissant des informations sur le fonctionnement physique des hydrosystèmes, tout en étant simple et parcimonieux. Ce modèle nommé MASH (pour Modélisation des Hydrosystèmes par Approche Systémique) est basé sur l’utilisation de fonctions de transfert paramétriques choisies en fonction de leur faible paramétrisation, leur caractère général et leur interprétation physique. Il est versatile, dans le sens que son architecture est modulable et que le nombre d’entrées, le nombre de fonctions de transfert en série et le type de fonctions de transfert utilisé est laissée à la discrétion de l’utilisateur. Ce modèle est inversé en utilisant de récentes avancées en apprentissage automatique grâce à une famille d’heuristiques basée sur l’intelligence en essaim nommé « optimisation par essaim de particule » (ou PSO pour « Particle Swarm Optimization »). Le modèle et ses algorithmes d’inversion sont testés sur un cas d’école synthétique, puis sur un cas d’application réel.

Groundwater-flow characterization in a multilayered karst aquifer on the edge of a sedimentary basin in western France

Article

Sep 2018
J HYDROL

On the edge of sedimentary basins, burial of geological layers can involve the formation of confined karst aquifers. In some cases, relationships between confined and unconfined karst aquifers can exist and imply an increased difficulty in delineating contributive areas of karst system outlets with accuracy. This work aims to develop a multi-disciplinary approach to highlight groundwater exchanges between multilayered karst aquifers feeding a single spring. Toulon Springs, located in western France, provides the opportunity to study relationships between two multilayered karst aquifers. Hydrograph and chemograph analysis coupled with principal component analysis (PCA) are used to evaluate groundwater-flow origins on the northern edge of a sedimentary basin. Natural hydrodynamic responses (baseflow recession analysis, auto-cross correlation function) show an important volume of water located in a saturated zone of the Toulon karst system. Significant contrasts in water quality as a function of the hydrological regime (flood, recession, and baseflow regime) and comparison with shallow and deep water show the participation of a deep aquifer supporting the flow of Toulon Springs.

An alternative approach in hydrograph decomposition and separation of the baseflow

Article

Full-text available

Nov 2017

Groundwater flow mechanism in the well-developed karst aquifer system in the western Croatia: Insights from spring discharge and water isotopes

Article

Feb 2018
CATENA

Karst aquifers have a fundamental importance to water supply in many countries. Due to their specific hydrogeologic properties, these aquifers are sometimes difficult to use because of the high discharge variations of the karst springs and are almost always sensitive to pollution. With an aim to better understand karst aquifers, different research methods are used to study the karst groundwater system in Croatia. The spring hydrograph and the stable isotope (δ¹⁸O, δ²H) compositions in the water samples collected from the Rječina and Zvir springs and precipitation were analysed and used to characterize the karst aquifer. The recession coefficient obtained from the hydrograph analysis indicates only a fast-flow spring component at the Rječina spring. The lack of the base-flow spring component is the primary reason for the spring drying out during the dry periods. The low recession coefficient of the Zvir spring indicates a base-flow and discharge from well-drained fissures and fractures in the spring catchment area during the low water stage. A mean residence time (MRT) of groundwater was calculated for stable isotope δ¹⁸O using lumped parameter approach by applying the exponential model, combined exponential-piston and dispersion models to isotopic input (rainfall) and output (spring) data sets during 2011–2013. The MRT of 3.24 and 3.6 months for the Rječina spring and 7.2 months for the Zvir spring suggests recent groundwater recharge from precipitation.

An alternative approach in hydrograph decomposition and separation of the baseflow

Article

Full-text available

Jun 2017
J HYDROL HYDROMECH

The identification of the moment when direct flow ends and baseflow begins is one of the biggest challenges of hydrological cycle modeling. The objectives of this research were: to characterize the recession curves (RC) and to separate the components of the hydrograph in a compact model. The RC were extracted from time series in three subwatersheds in Mexico. An expo-linear model was adapted and fitted to the master recession curves to find the transition point of the hydrograph and separate the baseflow. The model discriminated the RC in two decreasing ratios: one linear associated to the direct flow, and one exponential linked to the baseflow. The transition point between these two flows was obtained analytically by equaling both ratios. The derivation of a model parameter allowed to find the maximum points in the hydrometric time series, which were the criterion to separate the baseflow. The application of this model is recommended in the analysis of RC with different magnitudes from the flexibility and attachment to the fundaments of exhaustion of a reservoir.

Modelovanie podzemného odtoku v priestorovo distribuovanom hydrologickom modeli pomocou výtokového koeficienta – aplikácia na územie Slovenska v projekte ISSOP [Baseflow simulation using the recession coefficent in a spatially distributed hydrologic model – ISSOP project application in Slovakia, in Slovak with English Summary]

Article

Full-text available

Dec 2016

The ISSOP project (integrated system of runoff processes simulation) enabled the authors to analyse runoff and recession in a great number of small and medium catchments with differing geological backgrounds. Recession coefficient a was adopted as the spatially distributed parameter for base flow modeling in the ISSOP project’s hydrologic model development. This coefficient forms part of the equation S = aQb, which describes the nonlinear relationship between base flow Q and water storage S in a catchment. The characteristic a values were determined by master recession curves (MRC) for 293 small or medium mountainous catchment areas in Slovakia. Relationships of the recession coefficient and catchment characteristics were then examined by multiple regression analysis, and statistically significant dependencies of a value on the catchment mean elevation H and catchment slope were found. While catchment characteristics for the entire set of the catchments are able to explain only about 50 % of the recession coefficient variability, higher correlation was found for two of the eighth catchment groups, represented by crystalline rocks and carbonates. The influence of remaining six different basic types of hydrogeological environment was lower and almost similar.

Approches physique, conceptuelle et statistique du fonctionnement hydrologique d'un karst sous couverture (Physical, conceptual and statistical approaches of the hydrologic functionning of covered karstic systems)

Thesis

Full-text available

Dec 2015

Léa Duran

Karstic aquifers are complex systems whose study is particularly essential for water management worldwide. Their structure and functioning has been studied for decades using various methods, in order to understand their infiltration patterns, the way they react to rainy events, how does their genesis occurs, and how to estimate their underground resources (among many other questions). The aim of this thesis is to improve the understanding of relationships between the hydrological response at the outlet, and the general functioning of the karstic system. We used a multi-approach on a small study site: Norville karstic system (Normandy, France), part of the French National Karst Observatory (INSU-CNRS). Geophysics methods, tracer tests, statistical methods, rainfall-runoff modelling and signal analysis were used on this sinkhole-spring and covered system. A 3D geological model was built using geophysical and geological data. The different patterns of infiltration through the basin were also described. Then the variations of the response of the system were assessed using a tracer tests campaign and statistical methods. A model of simulation of the response was proposed, based upon a symbolic regression algorithm. Rainfall-runoff modelling and signal analysis were used together to study the ability of time series analysis approaches to extract meaningful components of karst spring hydrographs. The reservoir model (KARSTMOD) comprised four reservoirs E, L, M and C (interpreted as epikarst, high-inertia/highly capacitive matrix, fissure network and conduits). KARSTMOD internal flow components were analyzed with correlation and Fourier spectral analysis, and compared to statistical components extracted from spring discharge by wavelet multiresolution analysis and Ensemble Empirical Mode Decomposition (EEMD). We analyzed how the hydrological signal acquired its statistical characteristics while propagating through the conceptual model. The trend of the discharge signal (given by the residue of EEMD) appeared very similar to the variation in reservoir L and well correlated to the variation of the water level within the aquifer. Exchanges between fissured matrix and conduits (reservoirs M and C) were investigated: a high frequency pressure pulse-controlled flow from C to M (intermittent recharge from the conduits) was identified. This was interpreted as a fissured matrix flow in the surroundings of the conduit network usually feeding the conduit discharge but reversing when the conduits were in charge after intense rain events. Flows between the different reservoirs were compared to different combinations of spring discharge wavelet components, with good correlations : the information given by multiresolution analysis were similar to information given by the model. Reservoir E and M effects on the characteristics of the final spring discharge were assessed (cut-off frequencies, physical interpretation). The internal components of the model were also compared to natural tracers: conductivity and turbidity measured at the spring. The internal discharges between reservoirs M and C were very highly correlated to the measured time series. This study highlighted that both statistical components extracted from a karstic spring discharge signal and internal discharges of reservoirs models can provide meaningful hydrological information.

Oxygen Isotopes in Different Recession Subregimes of Karst Springs in the Brezovské Karpaty Mts. (Slovakia)

Article

Full-text available

Jun 2010

Karst spring hydrograph separation method based on quick iterative solution of several simple exponential and linear equations, was developed for linking small datasets of samples to various hydrologic situations. The method is based on a presumption, that a spring's discharge depends on the level of aquifer saturation by groundwater, and that the same discharge reflects the same groundwater saturation (piezometric level) in the aquifer. Every spring can be described by unique sets of constant starting discharges, Q0 values, recession coefficients α (laminar flow components in exponential equations), and β (turbulent flow components in linear equations). Each subregime can be detected by recession curve analyses of the complete spring's discharge time series. In this hydrograph separation, every measured discharge value, Qt, is then determined by a representative time, t; i.e., theoretical elapsed time t from the total maximum discharge value Qmax. The aim of the iteration process is to obtain this representative time t for each discharge. The individual flow components are calculated using the same t value. These variances in subregime discharges in a certain moment can be linked to the components analysed in the same moment, in order to obtain the end members of the theoretical mixture. This technique was developed and applied on the discharge time series of the four karstic springs in the Brezovské Karpaty Mts. (Slovakia), built mainly by karstified Middle and Upper Triassic dolomites and limestones. Groundwater of individual springs were characterised by δ18O (SMOW) and groundwater temperature values and end members of two laminar and one turbulent subregimes were calculated. Results were based on sparsely populated datasets and manual discharge records, but represent a perspective method for future development and interpretations on limited dataset results.

Evaluating Discharge Regimes of Karst Aquifer

Chapter

Feb 2015

Peter Malík

Karst springs are typical for abrupt changes of discharge immediately following recharge events. Monitored discharges of springs are used to determine quantitative variability over the period of time, showing their reliability as dependable water sources. Karst aquifers also exhibit (at least) dual ground-water flow regimes, that is, fast (conduit-dominated) flow and slow (diffuse) flow. This is something that can be observed in nature as the fast change of water amount outflowing from the groundwater source, or described by rapidly responding hydrographs, recording water levels or discharges. Selection of proper investigative techniques characterizing discharge regime properties of a karst aquifer is therefore important in order to identify possible theoretical background models describing this behaviour. On this basis, we can also find a particular method of hydrograph separation into flow components linked to the fast-flow regime, slow-flow regime, or intermediate regimes as well. With this point in mind, several quantitative methods that might be particularly useful in hydrograph analysis of water outlets from the karst aquifer system are briefly discussed here.

Laboratory Analog Analysis of Spring Recession Curve in a Karst Aquifer with Fracture and Conduit Domains

Article

Sep 2015

Karst aquifers differ from other types of hydrogeological systems because of their complex behavior, which originates from strong heterogeneity. A karst spring carries an imprint of hydrologic information for the karst aquifer. The shape of the outflow hydrograph recorded at a spring is a unique reflection of the aquifer's response. A karstic aquifer consisting of a fracture network and a conduit was proposed, and the spring recession curves generated from the designed karst aquifer were analyzed in this study. The purpose of the study was to discuss the influence of the main spring conduit diameter and the saturated thickness of the aquifer on spring recession curves. A combination of 7 groups of outlet pipes with different diameters and 7 initial water levels were used to simulate changes in diameter and saturated thickness, respectively. Thus, a total of 49 experimental tests were carried out in the laboratory karst aquifer. The results indicate that spring recession curves can be separated into two flow segments, and that the main spring conduit diameter has a remarkable influence on the initial flow of recession, recession duration, and recession coefficient. The results also show that the saturated thickness of the aquifer has a great effect on the initial flow of the recession and recession duration, but that its effect on the recession coefficient and the shape of the recession curve is slight.

Development of an autonomous probe for drowned karst conduits mapping. Groundwater flow simulation with a coupled discrete conduits - double porosity approach.

Article

Dec 2013

Vivien Hakoun

Groundwater flow in karst aquifers are particularly located in the main conduits fractures. In this work, we aim to describe and investigate the behavior of the flow at different scales. At the local scale, the flow modeling considers a continuum approach. At the regional scale, discrete features such as conduits are added to the continuum model (hybrid approach). For the continuum approach, we use a double-porosity flow model. The analytical solution of this model allows to investigate the transitions phases while a constant pressure boundary conditions is applied. Such a boundary condition, in a well may represent a constant head hydraulic test. In order to specify different boundaries conditions (for instance impervious barriers) and an irregular geometry of the flow domain, we developed and applied a numerical code based on the boundary element method. This allows to put into practice the hybrid method (continuum model with discrete conduits) in which we consider the local vertical and horizontal conduits intersections. This type of modeling allows to consider a larger and more complex domain than analytical solution alone. Moreover in this work we conceived and developed an experimental laboratory model. This model has been used in order to investigate the transitions phases which appears from the outflow of heterogeneous media. This approach is complementary to the analytical and numerical modeling. Last, part of this work was dedicated to the development and preliminary experiment of a new probe system. This new probe is an autonomous sensor which aim to map inaccessible drowned karst conduits. With this new tool, the geometry of the discrete conduit network in the aquifer could be known. The gathered informations could be used to represent the geometry of the conduit network used more realistically in the hybrid modeling approach. The main conclusions of this work are the following : at the local and regional scales, the transitions phases of the flow depends on the hydraulic properties of the continuum (when a continuum approach is used). The numerical solution developed allows to investigate the influence of the domain's geometry and complex boundaries conditions on the flux response. The experimental model used in the laboratory allows to reproduce qualitatively different transition phases of the flux at the outlet. Finally, the probe proved the feasibility to map its path in controlled experimental conditions. These new methods contribute to the characterization of the hydrodynamical behavior that takes place in karstified limestone aquifers.

Evaluation of spring flows using recession flow analysis techniques

Article

May 2024

This study delves into the analysis of recession characteristics of spring base flow, focusing on the Hill Campus Spring (elevation of approximately 2,150 m) and Fakua spring (elevation of approximately 1,850 m) in the Tehri Garhwal district of Uttarakhand, India. Spanning from January 1999 to December 2004, discharge data from G.B. Pant University of Agriculture and Technology's Hill Campus are employed. The research employs an automated, objective-based method to generate master recession curves (MRCs) and categorize them into early, intermittent, and late recession segments. Statistical parameters and low-flow indices from flow duration curves (FDCs) are utilized for flow assessment, while base flow indices (BFIs) are analyzed using the Web-based Hydrograph Analysis Tool (WHAT). The findings highlight the importance of water storage strategies during the rainy season for the sustainable utilization of spring water. The study suggests that the techniques applied are equally applicable for analyzing river flow recession characteristics, emphasizing the broader implications for integrated water resources planning and management in mountainous regions.

Assessing karst landscape degradation based on the void development of karst aquifers in Gunungsewu, Indonesia

Article

Full-text available

Apr 2024

Compared to other landforms, karst areas are among those emerging from the dissolution process that have a higher risk of land degradation. The likelihood of karst landforms being harmed is increased by urbanization and other human activities like extensive agriculture. Subsurface streams' water quality gets worse when surface pollutants infiltrate through developed karst features like sinkholes and karst ponors. There is a greater risk of land degradation as more karst features, in this case void size, develop. The purpose of this research is to assess how void development, or the degree of karstification, relates to the potential for karst spring pollution in the event that land degradation occurs on the surface of the Karst Drainage System (KDS). This research was conducted at the KDS of Beton and Gremeng Spring in the Gunungsewu karst area, Indonesia. In addition, this study also provides recommendations related to environmental management on the basis of the level of development of voids at both sites. The degree of karstification represents the phase at which a hydrogeological system has been developing, and this information was later considered in formulating strategies for protecting karst groundwater from contamination. The results show that Beton and Gremeng had a complex discharge regime with degrees of karstification at 8 and 5.5, respectively. Based on flood hydrograph components, it was further confirmed that both areas were in the mature phase. The higher the degree of karstification, the higher the vulnerability to pollution.

Simulation of Groundwater Flow in Fractured-Karst Aquifer with a Coupled Model in Maling Reservoir, China

Article

Full-text available

Feb 2021

A coupled model has been developed to simulate groundwater flow in fractured karst systems according to the complex geological and karst hydrogeological conditions of the dam site, where a 3D mathematical model based on Boussinesq equation was used to describe the movement of groundwater flow in fractured medium, and a 1D conduit model for karst medium. The model was solved with the continuous hydraulic heads at the common boundaries. The hydraulic conductivities of karst medium were determined by geometrical parameters and flux of pipes. Furthermore, the permeability parameters for fractured medium were calibrated by the measured and calculated groundwater levels. The calibrated model was employed to predict the variation of groundwater flow field and leakage from the karst pipes and underground powerhouse during the reservoir operation. The simulated results showed that the groundwater level of the powerhouse had decreased by about 2–5 m. The water level of conveyance pipeline had risen by 10–20 m, and the water level on both banks had risen by 15–25 m. The leakage of karst conduits for impervious failure was larger than that for normal seepage control. In addition, the leakage of the powerhouse was estimated to be about 1000–3000 m3/d, and the seepage control of karst pipes had little influence on the leakage of underground powerhouse.

Discharge recession patterns of karstic springs as observed in Triassic carbonate aquifers of Slovakia

Article

Jan 2021

Master recession curves of 117 karstic springs from Middle and Upper Triassic carbonate aquifers in the Slovakian territory of the mountainous Western Carpathians were assembled from gauged discharge data. Identified slow-flow and fast-flow components were very diversely represented. Fast-flow components were missing in 47% of springs. In another 20% of springs, only fast-flow components were recognized, while slow-flow components were absent. Simultaneous discharge of both slow-flow and fast-flow components was found at 39 springs (33%). Known geology of recharge areas enabled examination of the impact that outcropping dolomites and/or limestones may pose to the discharge recession. It was found that dolomites in springsheds significantly affect slow-flow components, but do not influence the occurrence of the fast-flow ones. The purely fast-flow-driven recession was present both in limestone and dolomitic springsheds, but merely one fast-flow component was typical for the dolomitic ones. Two or three fast-flow components may appear in “purely limestone” springsheds. Recession coefficients of slow-flow components were within the interval of 0.0004–0.18 days−1 and those of fast-flow within 0.0017–0.31 days−1. The duration of the fast-flow components is mostly several days or several tens of days, while the theoretical duration of slow-flow may last for decades. Storage in matrix, fractures or conduits of the saturated zone cannot be separately estimated because, in discharged volumes, water from unsaturated and epikarst zones is included. Variable shapes of assembled master recession curves point to the important influence of unsaturated and epikarst zones on the discharge recessional patterns of karst springs.

Analysis of Hydrographs

Chapter

Jan 2021

Antonio Pulido-Bosch

For a long time, studies of karst hydrogeology were based essentially on analysis of a spring’s hydrographs. This analysis was the basis for elaborating on the various hypotheses on the structure and function of the karst environment.

Determination of recharge, storage and flow characteristics of a karst aquifer using multi-method approaches (Kocaeli, Turkey)

Article

May 2020

Recharge, storage and flow characteristics of a karst aquifer were identified by correlating the results acquired from hydrogeological and speleological studies, stream/spring hydrographs, dye tracer tests, and hydrogeochemical analyses. Drinking water needs of the city of Kocaeli (Turkey) are partly supplied by karst springs (discharge 20–843 L/s) and the karst aquifer provides baseflow to streams that flow into Yuvacık Reservoir. A multi-variate dataset for characterization of the hydrological behavior of the karst aquifer was created. Stream hydrographs indicated that the aquifer comprises interconnected multipartite reservoirs, exhibiting groundwater residence times of 11–125 days. Recession coefficients of these reservoirs, obtained from master baseflow-recession curves, were 0.008–0.092 day−1. Dye tracer tests showed that groundwater velocities between recharge and discharge points were 483–1,328 m/day. Conduit flow characteristics were generally dominant in the upper reservoirs of the karst aquifer, characterized with high recession coefficients (0.017–0.092 day−1). Deeper reservoirs had a small baseflow recession coefficient (0.008 day−1). Autogenic point infiltration mechanisms were important in the recharge of many karst springs that discharged at high elevations (603–830 m amsl). However, autogenic diffusive infiltration regions (e.g. karst plateaus at high elevations) contributed to the recharge. Dye tracer tests and cave mapping revealed that depression points, allowing fast recharge, require special attention for protection and sustainable management of the karst aquifer. The results obtained from multiple methods and their correlation help to characterize the complex hydrodynamics of karst systems, and they can guide local authorities when assigning protection zones to locally important karst aquifers.

Recession analysis revisited: impacts of climate on parameter estimation

Article

Full-text available

Mar 2020
HESS

Recession analysis is a classical method in hydrology to assess watersheds' hydrological properties by means of the receding limb of a hydrograph, frequently expressed as the rate of change in discharge (-dQ/dt) against discharge (Q). This relationship is often assumed to take the form of a power law -dQ/dt=aQb, where a and b are recession parameters. Recent studies have highlighted major differences in the estimation of the recession parameters depending on the method, casting doubt on our ability to properly evaluate and compare hydrological properties across watersheds based on recession analysis of -dQ/dt vs. Q. This study shows that estimation based on collective recessions as an average watershed response is strongly affected by the distributions of event inter-arrival time, magnitudes, and antecedent conditions, implying that the resulting recession parameters do not represent watershed properties as much as they represent the climate. The main outcome from this work highlights that proper evaluation of watershed properties is only ensured by considering independent individual recession events. While average properties can be assessed by considering the average (or median) values of a and b, their variabilities provide critical insight into the sensitivity of a watershed to the initial conditions involved prior to each recharge event.

Assessment of regional flow type and groundwater sensitivity to pollution using hydrograph analyses and hydrochemical data of the Selita and Blue Eye karst springs, Albania

Article

Full-text available

May 2019

The assessment of groundwater vulnerability/sensitivity to pollution in karstic aquifers usually concentrates on recognition of fast-flow (conduit flow) and slow-flow (diffuse flow) components or intermediate regimes and their ratio in the total discharged volume. Analysis of master recession curves and correlation between physical characteristics of springs and temporal variations in spring water chemistry were applied to two major karst springs of Albania: Selita Spring (mean discharge 510 L s⁻¹), exploited for Tirana water supply, and Blue Eye Spring (mean discharge 18,182 L s⁻¹), used for electric power generation. These springs are recharged by precipitation in two very different karst areas with respect to their karstification degree, which influences also groundwater circulation patterns within karstic aquifers. Different regional groundwater flow types are subsequently reflected in the different spring hydrographs and in the temporal hydrochemical variations. Based on the spring master recession curves, Selita Spring is characterised as a conduit spring where the fast-flow component represents the majority of groundwater flow, and its catchment area should be linked with a high degree of sensitivity to pollution. On the other hand, in the discharge regime of Blue Eye Spring, the slow-flow component dominates, and although having a discharge of one order of magnitude bigger, this is a diffuse-flow spring and its catchment area should have lower sensitivity to potential pollution. The same results were also confirmed by statistical treatment of the temporal variations in spring water chemistry and evidence of surface karst phenomena in their recharge areas.

Report for the getting of a full Kij tensor (2009)

Technical Report

Full-text available

Aug 2009

David Bailly

Description of a method for the getting of a full Kij tensor. Document de travail.

Mathematics of Planet Earth: Proceedings of the 15th Annual Conference of the International Association for Mathematical Geosciences

Book

Jan 2014

It is widely recognized that the degree of development of a science is given by the transition from a mainly descriptive stage to a more quantitative stage. In this transition, qualitative interpretations (conceptual models) are complemented with quantification (numerical models, both, deterministic and stochastic). This has been the main task of mathematical geoscientists during the last forty years - to establish new frontiers and new challenges in the study and understanding of the natural world. Mathematics of Planet Earth comprises the proceedings of the International Association for Mathematical Geosciences Conference (IAMG2013), held in Madrid from September 2-6, 2013. The Conference addresses researchers, professionals and students. The proceedings contain more than 150 original contributions and give a multidisciplinary vision of mathematical geosciences.

Characteristics determination of Barmejamal spring karst Aquifer by physico-chemical spring responses

Article

Full-text available

Jul 2008

Storage and Drainage Characteristics of a Highly Heterogeneous Karst Aquifer in Houzhai Basin: R. Zhang et al . Groundwater XX, no. X: xx-xxx

Article

Jun 2016
GROUND WATER

The characteristics of karst aquifers are difficult to be determined due to their heterogeneous physical properties and lack of hydrogeological information. In this case study, we applied two methods for a comparative analysis of storage and drainage characteristics in upstream, midstream, and downstream of Houzhai cave stream basin. In the first method, Minimum Smoothed Method (MSM) is used to determine the proportion of baseflow to the total flow (Baseflow Index, BFI). In the second method, a bicarbonate-base two-end member mixing model is used to quantify the slow flow component and fast flow component. For both methods, slow flow and quick flow are quantified at three sampling sites, which provide useful information for the analysis of storage and drainage characteristics. The results from flow separation method and hydrogeochemical analysis show a consistently increasing trend of the proportion of slow flow to total flow from the upstream to downstream which indicates that the voids of highly conductive conduits and well-connected fissures decrease along the flow paths in the Houzhai cave stream basin in southwest China. The upstream areas have a low proportion of baseflow which indicates a high drainage capacity due to high permeable conduits and well-connected fissures. The downstream areas, on the contrary, have a high proportion of baseflow which indicates a high storage capacity and slow infiltration due to the predominant presence of matrix and poorly-connected fissures. These numerical methods provide alternative ways to investigate the storage and drainage characteristics of karst aquifers where direct measurement are not available.

Budget and General Assessment of Karst Groundwater Resources

Chapter

Feb 2015

Zoran Stevanovic

Groundwater budgeting as a process of definition or estimation of different input (recharge) and output (discharge) components is an important step in the process of utilization of karst aquifers. Following the general water budget equation, each of the involved input/output parameters is discussed and explained in this chapter. Some of these parameters, such as precipitation, runoff, spring discharge, or artificial withdrawal, can be easily determined, but others could only be estimated by some specific surveying methods or simply approximated, such as surface water infiltration, evapotranspiration, or subsurface aquifer drainage. For the former, some of the common instruments or methods are shown, while empirical formulae or helpful methods such as simultaneous river flow measurements, groundwater table observations, and base flow separation of hydrographs are identified as supportive to perceive “problematic” budget components. Water budget analysis and knowledge of budget elements is the best way to determine groundwater reserves. The classification of the reserves and suggested methods for their calculation is discussed. Here, attention is also paid to aquifer geometry and the specificity of the “breathing” catchment (changeable in time) as an important element for estimation of aquifer size and volume of stored waters.The table which can be used for a rough assessment of groundwater reserves and five case studies with solved practical problems are useful training tools and are also included in this chapter.

Hydrograph separation simulation of karst springs recession in Jinan area, China

Article

Jul 2007

Though hydrograph separation simulation of the spring discharge recession curves, this paper presents the result of the contrast between the rapidly recession curve after the peak flow and the very slowly recession curve in the domain of feeble discharges during the non-precipitation period in Jinan area. Like other springs in the world, Jinan Springs also have several sub-recession processes, which reflect the different status of karst flow transported in the various aquifer media such as cave, fracture, porous and other granular media.

Spring discharge hydrograph

Chapter

Full-text available

Dec 2010

The spring discharge hydrograph is the final result of various processes that govern the transformation of precipitation and other water inputs in the spring's drainage area into the single output at the spring. In many cases, the discharge hydrograph of a spring closely resembles hydrographs of surface streams, particularly if the aquifer is unconfined and reacts relatively quickly to water input. Springs draining karst and intensely fractured aquifers are typical examples-their discharge can increase several times or even orders of magnitude in a matter of hours after heavy rains. At the opposite spectrum are deep ascending springs isolated from a direct influence of surficial processes, such as infiltration of precipitation and showing only slight, delayed seasonal changes in discharge characteristics. The complexity of the water budget determination depends on many natural and anthropogenic factors present in the general area of interest, such as climate, hydrography and hydrology, geologic and geomorphologic characteristics, hydrogeologic characteristics of the surface soil and subsurface porous media, land cover and land use, presence and operations of artificial surface water reservoirs, surface water and groundwater withdrawals for consumptive use and irrigation, and wastewater management. The shape of a discharge hydrograph depends on the size and shape of the drainage area, as well as the precipitation intensity. Analysis of spring hydrographs always includes determination of the general statistical parameters of the time series, such as average, minimum, and maximum flows for the period of record; standard deviation of the flows; coefficient of variation; flow duration curves; and frequency of characteristic flows at the minimum.

A Particle Swarm Optimization for Parameter Estimation of a Rainfall-Runoff Model

Chapter

Oct 2014

Transfer function based models are widely used in hydrological modeling, especially for rainfall-runoff simulation. This paper deals with a new model associating three elementary transfer functions in series along four parallel branches. Each transfer function is a parametric probability density function with some physical meaning regarding hydrological transfers. Model inversion is performed using the so-called particle swarm optimization (PSO) technique. The systemic model and the PSO method were tested on the Sèvre Niortaise water catchment in France.

An Example of Karst Catchment Delineation for Prioritizing the Protection of an Intact Natural Area

Article

Apr 2015

The karstic spring Perućac as the main drainage area of the Tara Mt. in western Serbia was studied in order to assess its discharge regime, water reserves, and to delineate its catchment area. The spring is located in the northeastern, inner zone of the classic Dinaric karst, which is characterized by a dominant extension of highly karstified Triassic limestones, a poorly developed hydrographic network with many ponors, and dense forests. Tara Mt. is one of five national parks in Serbia. The goal of the project was to identify a high-priority protection zone within the preserved natural area which is also well known and actively used for tourism and recreation purposes. Based on data on the discharge regime of the Perućac Spring, and by applying the multiple non-linear correlation method, the size of the direct catchment area was assumed to be 79.3 km2, which was 5-18 % larger than that estimated by previous surveys. Proposal to extend preserved natural area and to include sanitary protection zone of the Perućac spring as well as to establish a common monitoring system for biodiversity and water has been made. In this way, not only native plants and animals but also their habitats would be better protected from potential pollution.

Karstification depth and storativity as main factors of karst aquifer regimes: some examples from southern Alpine branches (SE Europe and Middle East)

Article

Full-text available

Jan 2015

Karstic aquifers are the main groundwater source in Southeastern Europe and the Middle East. Many large springs and sources which drain Alpine orogenic belt and its branches are tapped and utilized for drinking water supply. Due to the unstable regime of the karstic springs, the main challenge for most of the waterworks is to ensure water supply during recession periods which coincide with the dry season, usually summer and early autumn months. Besides the problem of water shortage, water pollution of this open and generally very permeable type of aquifer is another major constraint in local water management. However, in comparison with other type of aquifers, the highly developed karst and its significant storage capacity as found in the studied areas may attenuate significant rainfall/runoff variations and possible climate changes. Most commonly, intensive rain episodes do not result in extreme floods in the studied karst terrains, while stored groundwater provides sufficient base flows for dependent ecosystems during the recession or periods of drought. Several typical hydrographs and results of some models applied for forecasting climate change impact presented in this paper represent a good example of specific karst aquifer behaviours and importance of considerable storage capacity in deeper parts of the aquifer.

The base-flow recession curve as an indicator of ground water

Article

Jan 1964

H.C. Riggs

Essai de détermination des composants de l'écoulement des sources karstiques

Article

Jan 1963

Claude Drogue

Le régime hydrogéologique des calcaires éocènes du synclinal du Dyr et Kef (Tunisie)

Article

H. Scholler

Courbe de tarissement, coefficient d'écoulement et perméabilité du bassin

Article

Jan 1960

Tison, G., Jr

Le régime de tarissement de la Foux de la Vis

Article

Jan 1965

Choix d'un modèle de décrue suivant la structure d'un réservoir simple schématique

Article

Jan 1967

J. Dauty

The ground-water depletion curve, its construction and uses

Article

Jan 1951

F. Grundy

Méthode de détermination de la capacité de rétention par fissures et microporosité des massifs karstiques, à partir des variations saisonnières des données hydrométriques

Article

Jan 1963

Claude Drogue

[Purification of water of hydrogen sulfide for drinking and industrial water supply].

Article

H. Rigg

The Baseflow-Duration Curve, a Technique for the study of Groundwater Discharge from a Drainage Basin

Article

Apr 1962

George R. Kunkle

The baseflow-duration curve provides a technique for the comparative study of base runoff from the same or different drainage basins. The curve is a cumulative frequency curve showing the percentage of time that specified base flows were equaled or exceeded during a given time period. Daily base flows are obtained from a hydrograph separation of base and surface runoff. Although the separation may not be precise, the value of the technique as a comparative tool is not lost as long as a consistent method of separation is followed. When bank storage is present within a basin, the base runoff can be separated on the hydrograph into two components, designated bank- and basin-storage discharge. These are differentiated on the baseflow–duration curve by the shape of the curve. Thus, the baseflow-duration curve allows comparisons not only of total base runoff but also of the base runoff components. Examples illustrating the use of the technique show that (1) the texture of the surficial deposits largely controls the discharge from basin storage, (2) the width of the permeable deposits adjacent to the river greatly influences the amount of bank storage discharged, (3) the mean annual amount and variation of bank storage may be several times that of basin storage, and (4) one typical water year provides enough hydrologic data for a valid comparative study of base runoff from segments of the same drainage basin.

Base Flow Recessions—a Review

Article

Oct 1968
WATER RESOUR RES

Francis R. Hall

Hydrologists have studied base-flow recessions for one hundred years or more. By the early nineteen hundreds much of the basic mathematical development was completed, and some methods of hydrograph analysis were known. Recent mathematical work, although repetitive to some extent of the earlier efforts, has the advantage that it assesses more closely the effects of the simplifying assumptions used to obtain solutions. Most workers have preferred to follow graphical or statistical rather than mathematical approaches. The reasons appear to lie mainly in problems caused by the assumptions and in difficulties in interpreting the real stream hydrograph. Also, base flow can come from numerous sources besides ground water. Other complications arise from the question of whether the basin response is linear or nonlinear, because the response is a function of various geologic and hydrologic factors in addition to those considered in the mathematical derivations.

L'écoulement de la fontaine de Vaucluse

Jan 1967

Aigrot

Analyse statistique des hydrogrammes de decrues des sources karstiques statistical analysis of hydrographs of karstic springs

Abstract

No full-text available

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