Breaks in Resistivity Sounding Curves as Indicators of Hard Rock Aquifers

In a previous paper (Nordic Hydrology, Vol. 12, 1981), the authors have discussed the inadequacies in the technique of resistivity method for location of sites for constructing deep water walls in hard rock areas. It was pointed out that the water bearing fracture zones in the bed rock could not be identified by merely considering geoelectrical parameters such as layer resistivity. An empirical study based on the correlation of minor irregularities or deviations – “BREAKS” – in the normally smooth sounding curves with the actual driller's logs reveals that under normal geo-electric conditions these water bearing zones (hard rock aquifers) are indicated in the curve by a perceptible lowering of apparent resistivity and hence could be used as a guide for locating well sites. As such breaks may also be caused by other conditions such as lateral inhomogeneities, certain methods for distinguishing them are discussed.

Download Full-text

Groundwater Potential Assessment Using 2-D Resistivity Method In Kluang, Johor (Malaysia)

Warta Geologi ◽

10.7186/wg463202009 ◽

2020 ◽

Vol 46 (3) ◽

pp. 220-224

Author(s):

Nazrin Rahman ◽

◽

Edy Tonnizam Mohamad ◽

Rosli Saad ◽

◽

...

Keyword(s):

Surface Waters ◽

Hard Rock ◽

Water Source ◽

Unconfined Aquifer ◽

Groundwater Potential ◽

Suitable Alternative ◽

Resistivity Method ◽

Hard Rock Aquifers ◽

Increasing Demand ◽

Groundwater Source

Sources of clean water are decreasing due to rapid usage, contaminated surface waters, pollution and dry season. The dependence on the existing water source is not enough to fulfil the increasing demand of population in Malaysia. In order to overcome the problem, groundwater source is the most suitable alternative. 2-D resistivity method was carried out in a granitic area of Kluang, Johor to delineate and locate groundwater resource. 5 survey lines were conducted by using ABEM SAS4000 terrameter and electrode selector which were connected to 41 electrodes through lund cables. Pole-dipole array was chosen in this study for deeper penetration. Collected data were processed by using RES2DINV software to produce inversion model which was then exported to Surfer8 software for visualisation and interpretation. The result shows that most of the study area consist of granite with different level of fracturing. Unconfined aquifer was found at depths of 0 to 50 m. Confined aquifers can be seen at two different zones. They exhibit same properties at three parallel lines, R1-R3 and show continuity between them. It is predicted that the aquifers flow in the southwest to northeast direction. The hard rock aquifers are highly recommended to be drilled as they contain a large amount of fresh water for further usage.

Download Full-text

Estimation of recharge in mountain hard-rock aquifers based on discrete spring discharge monitoring during base-flow recession

Hydrogeology Journal ◽

10.1007/s10040-021-02317-z ◽

2021 ◽

Author(s):

Stefano Segadelli ◽

Maria Filippini ◽

Anna Monti ◽

Fulvio Celico ◽

Alessandro Gargini

Keyword(s):

Hard Rock ◽

Monitoring Program ◽

Base Flow ◽

Low Flow ◽

Reliable Estimate ◽

Spring Discharge ◽

Aquifer Recharge ◽

Clear Cut ◽

Groundwater Circulation ◽

Hard Rock Aquifers

AbstractEstimation of aquifer recharge is key to effective groundwater management and protection. In mountain hard-rock aquifers, the average annual discharge of a spring generally reflects the vertical aquifer recharge over the spring catchment. However, the determination of average annual spring discharge requires expensive and challenging field monitoring. A power-law correlation was previously reported in the literature that would allow quantification of the average annual spring discharge starting from only a few discharge measurements in the low-flow season, in a dry summer climate. The correlation is based upon the Maillet model and was previously derived by a 10-year monitoring program of discharge from springs and streams in hard-rock aquifers composed of siliciclastic and calcareous turbidites that did not have well defined hydrogeologic boundaries. In this research, the same correlation was applied to two ophiolitic (peridotitic) hard-rock aquifers in the Northern Apennines (Northern Italy) with well-defined hydrogeologic boundaries and base-outflow springs. The correlation provided a reliable estimate of the average annual spring discharge thus confirming its effectiveness regardless of bedrock lithology. In the two aquifers studied, the measurable annual outputs (i.e. sum of average annual spring discharges) could be assumed equal to the annual inputs (i.e. vertical recharge) based on the clear-cut aquifer boundaries and a quick groundwater circulation inferable from spring water parameters. Thus, in such setting, the aforementioned correlation also provided an estimate of the annual aquifer recharge allowing the assessment of coefficients of infiltration (i.e. ratio between aquifer recharge and total precipitation) ranging between 10 and 20%.

Download Full-text

Magnetotelluric static shift: Estimation and removal using the cokriging method

Geophysics ◽

10.1190/1.2400625 ◽

2007 ◽

Vol 72 (1) ◽

pp. F25-F34 ◽

Cited By ~ 11

Author(s):

Benoit Tournerie ◽

Michel Chouteau ◽

Denis Marcotte

Keyword(s):

Apparent Resistivity ◽

A Priori ◽

Shift Factor ◽

Static Shift ◽

Geostatistical Model ◽

Data Set ◽

Resistivity Sounding ◽

The Difference ◽

Cross Variogram

We present and test a new method to correct for the static shift affecting magnetotelluric (MT) apparent resistivity sounding curves. We use geostatistical analysis of apparent resistivity and phase data for selected periods. For each period, we first estimate and model the experimental variograms and cross variogram between phase and apparent resistivity. We then use the geostatistical model to estimate, by cokriging, the corrected apparent resistivities using the measured phases and apparent resistivities. The static shift factor is obtained as the difference between the logarithm of the corrected and measured apparent resistivities. We retain as final static shift estimates the ones for the period displaying the best correlation with the estimates at all periods. We present a 3D synthetic case study showing that the static shift is retrieved quite precisely when the static shift factors are uniformly distributed around zero. If the static shift distribution has a nonzero mean, we obtained best results when an apparent resistivity data subset can be identified a priori as unaffected by static shift and cokriging is done using only this subset. The method has been successfully tested on the synthetic COPROD-2S2 2D MT data set and on a 3D-survey data set from Las Cañadas Caldera (Tenerife, Canary Islands) severely affected by static shift.

Download Full-text

A TRI‐POTENTIAL METHOD OF RESISTIVITY PROSPECTING

Geophysics ◽

10.1190/1.1438247 ◽

1956 ◽

Vol 21 (2) ◽

pp. 455-469 ◽

Cited By ~ 54

Author(s):

E. W. Carpenter ◽

G. M. Habberjam

Keyword(s):

Apparent Resistivity ◽

Potential Method ◽

Electrode Configuration ◽

Practical Application ◽

Resistivity Method

This paper describes a method whereby three resistances are measured for a four electrode configuration, and relations between these three resistances and their corresponding apparent resistivities are derived. The practical application of the resistance relation as a means of detecting observational and instrumental errors is indicated. The concept of apparent resistivity is examined and by means of examples it is shown that the apparent resistivity can take negative values. Finally, the possibility of using the triple resistivity method as a means of distinguishing between the effects of lateral and vertical resistivity changes on depth probes is discussed.

Download Full-text

Various Pumping Tests and Methods for Evaluation of Hydraulic Properties in Fractured Hard Rock Aquifers

Groundwater Dynamics in Hard Rock Aquifers ◽

10.1007/978-1-4020-6540-8_7 ◽

2008 ◽

pp. 100-111 ◽

Cited By ~ 2

Author(s):

J. C. Maréchal ◽

B. Dewandel ◽

K. Subrahmanyam ◽

R. Torri

Keyword(s):

Hydraulic Properties ◽

Hard Rock ◽

Pumping Tests ◽

Hard Rock Aquifers

Download Full-text

Sustainable Management of Groundwater in Hard Rock Aquifers of South Andaman and Rutland Islands, India

Ground Water Development - Issues and Sustainable Solutions ◽

10.1007/978-981-13-1771-2_5 ◽

2018 ◽

pp. 85-105

Author(s):

Amlanjyoti Kar

Keyword(s):

Sustainable Management ◽

Hard Rock ◽

Hard Rock Aquifers ◽

South Andaman

Download Full-text

Electric resistivity and seismic refraction tomography, a challenging joint underwater survey at Äspö Hard Rock Laboratory

10.5194/se-2016-157 ◽

2016 ◽

Cited By ~ 1

Author(s):

Mathias Ronczka ◽

Kristofer Hellman ◽

Thomas Günther ◽

Roger Wisen ◽

Torleif Dahlin

Keyword(s):

Nuclear Power ◽

Hard Rock ◽

Seismic Refraction ◽

Three Dimensional ◽

Test Site ◽

Fracture Zones ◽

Rock Laboratory ◽

Refraction Tomography ◽

Local Point ◽

General Test

Abstract. Tunnelling below water passages is a challenging task in terms of planning, pre-investigation and construction. Fracture zones in the underlying bedrock lead to low rock quality and thus reduced stability. For natural reasons they tend to be more frequent at water passages. Ground investigations that provide information of the subsurface are necessary prior to the construction phase, but can be logistically difficult. Geophysics can help close the gaps between local point information and produce subsurface images. An approach that combines seismic refraction tomography and electrical resistivity tomography has been tested at the Äspö Hard Rock Laboratory (HRL). The aim was to detect fracture zones in a well-known but logistically and, from a measuring perspective, challenging area. The presented surveys cover a water passage along a part of a tunnel that connects surface facilities with an underground test laboratory. The tunnel is approximately 100 m below and 20 m east of the survey line and gives evidence for one major and several minor fracture zones. The geological and general test site conditions, e.g. with strong powerline noise from the nearby nuclear power plant, are challenging for geophysical measurements. Co-located positions for seismic and ERT sensors and source positions are used on the 450 m long underwater section of the 700 m long profile. Because of a large transition zone that appeared in the ERT result and the missing coverage of the seismic data, fracture zones at the southern and northern part of the underwater passage cannot be detected by separated inversion. A simple synthetic study shows significant three dimensional artefacts corrupting the ERT model that have to be taken into account while interpreting the results. A structural coupling cooperative inversion approach is able to image the northern fracture zone successfully. In addition, previously unknown sedimentary deposits with a significant large thickness are detected in the otherwise unusually well documented geological environment. The results significantly improve imaging of some geologic features, which would have been not detected or misinterpreted otherwise, and combines the images by means of cluster analysis to a conceptual subsurface model.

Download Full-text