scholarly journals GEOPHYSICAL CHARACTERIZATION OF AQUIFERS IN THE SALITRE RIVER BASIN, BAHIA STATE, BRAZIL, USING RESISTIVITY SOUNDINGS AND ELECTRICAL TOMOGRAPHIES

2014 ◽  
Vol 32 (4) ◽  
pp. 637
Author(s):  
Olivar Antônio Lima de Lima
Keyword(s):  
River Basin ◽  
Water Table ◽  
Industrial Development ◽  
Karst Aquifer ◽  
Three Dimensional ◽  
Northeastern Brazil ◽  
Karst Water ◽  
Aquifer System ◽  
Tomographic Section

ABSTRACT. The Salitre River basin, which is located in the semi-arid land of northeastern Brazil, is annually faced with severe surface-water scarcity. Twomain aquifersystems, which are distributed in depth, can be exploited to supply the water needs of the population and its present agro-industrial development: (i) a fractured-karst,water-table component, totally developed within the upper carbonate sequence of the Salitre Formation; and (ii) a fractured-clastic, semi-confined component, mostlikely associating lower Salitre limestones with the meta-sandstones of the Morro do Chap´eu Formation. Geophysical efforts have been useful in developing a regional,three-dimensional characterization of these two aquifer components of the Salitre river aquifer system and in detailing a useful electric tomographic scheme to implementtheir exploration. The geophysical survey, which comprised 64 Schlumberger electrical soundings of resistivity and five tomographic sections, was combined with welldata to define the geometric and hydraulic characteristics of these aquifer components. The inversion of the resistivity data, under the control of the well data, was usefulto reduce electrical ambiguities and to better define the depth of the water table and that of the thick, impervious aquifer substrate. The lateral and depth boundaries of thefracture-karst aquifer zones were outlined, allowing the estimation of a total reserve of approximately 100 billion m3 of groundwater. Chemical analysis of water samplescollected at production wells was used to define a water quality zoning within the basin. These results are very important to define an optimum exploration regime for thegroundwater available in the basin.Keywords: electrical sounding, tomographic section, Salitre aquifer system. RESUMO. A bacia hidrogáafica do rio Salitre faz parte da região semiárida da Bahia e, por isso, apresenta severa escassez de água superficial. Dois principais componentes aquíferos, distribuídos em profundidade, podem ser explorados para suprir as necessidades hídricas da população humana e de seu incipiente desenvolvimento agroindustrial: (i) um componente cárstico-fraturado, de natureza livre, desenvolvido nas rochas carbonáticas superiores da Formação Salitre; e (ii) um componentefraturado, semi-confinado, combinando rocha basais da sequência Salitre e unidades meta-quartzíticas da Formação Morro do Chapéu. Foram executadas 64 sondagens elétricas verticais usando o arranjo Schlumberger de eletrodos, centradas em pontos selecionados da bacia, e cinco seções tomográficas de resistividade, para detalhara estrutura subsuperficial de locais selecionados. A inversão dos dados de resistividade aparente, com controle de informações de poços, foi útil para reduzir ambiguidades elétricas e melhor definir as profundidades do nível estático e do topo do espesso substrato impermeável do sistema aquífero Salitre. Esses estudos permitiramavaliar, regionalmente, os recursos hídricos subterrâneos da bacia, em termos de geometria e características hidráulicas, bem como propor um procedimento para efetuar tomografia elétrica bidimensional, visando sua efetiva exploração por meio de poços. Os limites laterais e em profundidade das zonas de maior carstificação e de densos fraturamentos foram delineados, possibilitando estimar uma reserva total de água no sistema do rio Salitre em cerca de 220 bilhões de m3. Análises físico-químicas deamostras de água coletadas em poços foram usadas para caracterizar a variabilidade na qualidade da água subterrânea na bacia. Tais resultados podem ser usados paraplanejar um regime de exploração eficiente e conservativo das reservas de água subterrânea disponíveis.Palavras-chave: sondagem elétrica, seção tomográfica, sistema aquífero Salitre.

scholarly journals A quasi three dimensional model of water flow in the subsurface of Milano (Italy): the stationary flow

2000 ◽  
Vol 4 (1) ◽  
pp. 113-124 ◽  
Author(s):  
M. Giudici ◽  
L. Foglia ◽  
G. Parravicini ◽  
G. Ponzini ◽  
B. Sincich
Keyword(s):  
Water Table ◽  
Water Demand ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Predictive Tool ◽  
Aquifer System ◽  
Conservative Finite Difference Scheme ◽  
Comparison Of The Results

Abstract. A quasi three-dimensional model is developed to simulate the behaviour of the aquifer system which is the resource of drinkable water for the town of Milano (Italy). Non continuous semipermeable layers locally separate permeable levels in a multilayered system, consisting of a phreatic and three confined aquifers. The numerical model is a conservative finite difference scheme based on the discretisation of the water balance equation for stationary flow. The grid spacing is 500 m and has been chosen, taking into account the distribution of the data in an area of about 400 km2. The model has been calibrated with a "trial and error" procedure, by comparison of the results of the model with the observations for three years (1950, 1974 and 1982) which correspond to different flow situations. Once calibrated, the model has been used as a predictive tool, to forecast the behaviour of the aquifer system for other years of the 20th century; the comparison between the model forecasts and observations is good. The model is capable of describing both the strong drawdown of the water table in the 1970s, when the water demand for domestic and industrial needs was very high, and the rise of the water table in the 1990s, when water extraction decreased. The results of the model confirm that the phreatic level is controlled largely by the local extraction of water; moreover, the aquifer system reacts to an increasing water demand with a small increase of the inflow and with a strong decrease of the outflow from its boundaries.

scholarly journals Hydrodynamic Characterization of Mugla Karst Aquifer Using Correlation and Spectral Analyses on the Rainfall and Springs Water-Level Time Series

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 85
Author(s):  
Çağdaş Sağır ◽  
Bedri Kurtuluş ◽  
Moumtaz Razack
Keyword(s):  
Time Series ◽  
Water Level ◽  
Time Series Data ◽  
Karst Aquifer ◽  
Series Data ◽  
Karst Aquifers ◽  
Wet Season ◽  
Spectral Analyses ◽  
Aquifer System

Karst aquifers have been an important research topic for hydrologists for years. Due to their high storage capacity, karst aquifers are an important source of water for the environment. On the other hand, it is safety-critical because of its role in floods. Mugla Karst Aquifer (SW, Turkey) is the only major water-bearing formation in the close environs of Mugla city. Flooding in the wet season occurs every year in the recharge plains. The aquifer discharges by the seaside springs in the Akyaka district which is the main touristic point of interest in the area. Non-porous irregular internal structures make the karsts more difficult to study. Therefore, many different methodologies have been developed over the years. In this study, unit hydrograph analysis, correlation and spectral analyses were applied on the rainfall and spring water-level time series data. Although advanced karst formations can be seen on the surface like the sinkholes, it has been revealed that the interior structure is not highly karstified. 100–130 days of regulation time was found. This shows that the Mugla Karst has quite inertial behavior. Yet, the storage of the aquifer system is quite high, and the late infiltration effect caused by alluvium plains was detected. This characterization of the hydrodynamic properties of the Mugla karst system represents an important step to consider the rational exploitation of its water resources in the near future.

scholarly journals Hydrogeological Characteristics of the Area of Intermittent Karst Lakes of Pivka

2016 ◽  
Vol 34 (3) ◽  
Author(s):  
Metka Petrič ◽  
Janja Kogovšek
Keyword(s):  
Surface Water ◽  
Flow Regime ◽  
Water Table ◽  
Karst Aquifer ◽  
Karst Water ◽  
Karst Springs ◽  
Water Flows ◽  
Karst Lakes ◽  
Hydrogeological Characteristics ◽  
Hydrological Feature

Poseben hidrološki pojav zahodnega dela kraškega masiva Javornikov so presihajoča Pivška jezera. Za celotno območje je značilna tesna povezava podzemnih in površinskih voda. V kraškem vodonosniku se vode pretakajo večinoma podzemno, ob močnejših in dolgotrajnejših padavinah pa se nivo podzemne vode dvigne in voda se na številnih mestih preliva na površje. Tako postanejo aktivni občasni kraški izviri ob reki Pivki, z vodo pa se napolnijo tudi kraške depresije in nastane večje število presihajočih kraških jezer. Nekatera se pojavljajo dokaj pogosto in imajo vodo tudi do pol leta, večinoma pa so bolj redka ali so zalita samo izjemoma v času močnejših poplav. V članku so predstavljene hidrogeološke značilnosti območja, ki se odražajo v režimu pretakanja kraške vode in načinih njenega pojavljanja na površju. A special hydrological feature of the western part of the Javorniki karst massif is the intermittent karst lakes of Pivka. For the whole area a close connection between underground and surface water is characteristic. In the karst aquifer water flows mostly underground, but after more intensive or long-lasting precipitation the water table rises and water emerges on the surface at different locations. Intermittent karst springs along the Pivka river are activated. Also karst depressions are filled with water and several intermittent karst lakes can be formed. Some of them appear very often and contain water for up to six months, but mostly they are very rare and filled up only exceptionally in the time of big floods. In the article the hydrogeological characteristics of the area are presented, which are reflected in the flow regime of karst water and in the forms of its appearance on the surface. 

scholarly journals FDOM Conversion in Karst Watersheds Expressed by Three-Dimensional Fluorescence Spectroscopy

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1427 ◽  
Author(s):  
Wen Liu ◽  
Liankai Zhang ◽  
Pengyu Liu ◽  
Xiaoqun Qin ◽  
Xiaojing Shan ◽  
...  
Keyword(s):  
Fulvic Acid ◽  
Karst Aquifer ◽  
Three Dimensional ◽  
Northern China ◽  
Flow Path ◽  
Fluorescence Properties ◽  
Anthropogenic Activity ◽  
Aquifer System ◽  
Karst Aquifer System ◽  
Groundwater Systems

A karst system, formed by the dissolution of carbonate rocks, is usually susceptible to contamination. Little is known about the composition of natural dissolved organic matter (DOM) in groundwater systems, especially in karstic groundwater. To reveal the characteristics of DOM in a karst aquifer, the Yufuhe River Basin, a typical karst watershed in northern China, was selected. DOM fluorescence (FDOM) was measured with the excitation-emission matrices (EEMs) spectroscopy technique. Parallel factor analysis (PARAFAC) was used to analyze the karst hydrogeological factors that affect FDOM biogeochemical behavior. Three fluorescent components, i.e., tyrosine-like, tryptophan-like, and ultraviolet fulvic acid were found. Their fluorescence properties were closely related to human activity and subterranean hydrology. Fluorescence properties suggested that FDOM in the Yufuhe River karst aquifer was predominant from anthropogenic activity. In addition, due to the effect of karstic heterogeneous hydrological conditions, FDOM showed obvious differentiation in the recharge, flow path, and discharge systems. The FDOM fluorescence intensity (FI) was weak in surface water and groundwater at the upper reaches (recharge area). In the middle of the flow path area, the percentage of tyrosine-like and tryptophan-like substances degraded and fulvic acid rose gradually. However, after infiltrating into the lower reaches (discharge area) of the deep karst aquifer system, the fulvic acid matter was consumed and protein-like matter accumulated.

scholarly journals WATER TABLE FLUCTUATION METHOD TO ESTIMATE THE RECHARGE OF THE FREE AQUIFER IN THE GUARIROBA RIVER BASIN, CAMPO GRANDE – MS

2021 ◽  
Vol 42 ◽  
pp. e57
Author(s):  
Daniel Russi ◽  
Giancarlo Lastoria ◽  
Guilherme Henrique Cavazzana ◽  
Sandra Garcia Gabas ◽  
Andressa Oliva
Keyword(s):  
River Basin ◽  
Water Table ◽  
Effective Porosity ◽  
Base Flow ◽  
Water Table Fluctuation ◽  
Aquifer System ◽  
Environmental Protection Area ◽  
Protection Area ◽  
Fluctuation Method ◽  
The One

The Guariroba river basin was decreed as an Environmental Protection Area (EPA), and with a surface of 360 km² it is of great importance to the municipality of Campo Grande because it supports almost half of the water supply system of the latter. The surface of the basin is predominantly covered by Cretaceous sediments of the Caiuá Group, which constitutes the free aquifer known as the Bauru Aquifer System (BAS). Recent studies have confirmed the contribution of the BAS in the maintenance of the base flow of surface drainage. Therefore, the quantification of groundwater recharge (GWR) becomes fundamental. This work used the water table fluctuation (WTF) method, based on variations in the piezometric surface-water measurement, to estimate the GWR of the basin. From Mar 2015–Feb 2017, monthly variations of the static level were registered in 13 tubular wells located in the Guariroba EPA. Considering a 1480 mm annual precipitation, the estimated average GWR was 356 mm⋅year–1, varying between 210–694 mm⋅year–1. Despite considering a lower value of the effective porosity parameter (Sy = 0.1) than the one suggested for the BAS, the estimated average GWR-to-precipitation ratio (24%) was more than double that the one adopted by the state environmental agency (10%).

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