Torleif Dahlin

Lund University | LU · Division of Engineering Geology

Periodic dredging of harbors and other waterways is carried out to ensure sufficient depth for navigation. The Stabilization/Solidification method (S/S) is the global approach for improving the geotechnical characteristics and stabilizing pollutions in the low-compressive-strength dredged sediment (DS) for land reclamation. For this, different bind...

Quality control of stabilized dredged sediment (DS) presents significant challenges due to its high-water content. Nowadays, many in-situ and laboratory tests have been used to evaluate the quality of treated DS, and the dominant method is 28-day unconfined compressive strength that can be done on undisturbed samples from the field and the laborato...

Incidents of waste and biofuel fires are common at all stages of the waste recycling chain and have grave implications for business, employees, firefighters, society, and environment. An early detection of waste and biofuel fires in the smouldering stage could save precious lives, resources, and our environment. Existing fire detection methodologie...

Electrical resistivity tomography (ERT) is a potential-based method for detecting internal erosion in the core of embankment dams using the electrodes installed outside. This study aims at evaluating the practical capability of ERT monitoring for detecting internal defects in embankment dams. A test embankment dam with in-built well-defined defects...

• Infrastructure projects depend on a reliable characterization of the subsurface. • Information about groundwater is crucial to protect resources and avoid stability problems. • Aim is to develop a reliable and time and cost efficient methodology for spatially mapping of the groundwater conditions.

Time-lapse resistivity surveys are commonly used to monitor temporal changes in the subsurface. In certain cases, it is known from other information that the resistivity will only decrease or increase with time. The 4-D resistivity smoothness-constrained inversion method reduces artifacts due to noise by including a temporal roughness filter constr...

We present a solution for long-term direct current resistivity and time-domain induced polarization (DCIP) monitoring, which consists of a monitoring system and the associated software that automates the data collection and processing. This paper describes the acquisition system that is used for remote data collection and then introduces the routin...

Negative induced polarization (IP) time-domain transients, sign-changing or non-monotonically decaying transients are currently often considered as measurement errors and removed in the data processing. These transients, here named heterodox in the sense of other than generally accepted signals, might originate from measurement errors, inductive ef...

The knowledge about the hydraulic conductivity of the subsurface is crucial to know as it is a main parameter for groundwater flow characterization within an aquifer. The geophysical method time-domain Induced Polarisation has been shown to be useful for estimating the hydraulic conductivity. By using a new inversion approach, where we directly inv...

Electrical resistivity tomography has potential as a complementary long-term monitoring method in embankment dams; however, the 3D character of the geometry including the shape of the embankment, its internal zoned construction and the reservoir water make interpretation challenging. To tackle this problem, a qualified inversion model considering t...

Renovation of water and central heating pipelines is a very costly and time‐consuming process, so a way to prioritize the limited resources between different parts of the systems is very important. The risk for corrosion damage can be assessed from the resistivity of the ground, due to the processes facilitating the metal oxidation also affecting t...

Spectral induced polarization (SIP) measurements have been demonstrated to correlate with important parameters in hydrogeological and environmental investigations. Although SIP measurements were often collected in the frequency domain (FDIP), recent developments have demonstrated the capabilities to solve for the frequency-dependence of the complex...

This study investigates the potential for Electrical Resistivity Tomography (ERT) to detect buried glass ‘hotspots’ in a glass waste dump based on results from an open glass dump investigated initially. This detection potential is vital for excavation and later use of buried materials as secondary resources. After ERT, test pits (TPs) were excavate...

Spectral induced polarization is a well-established geophysical method that can be measured in both time- and frequency domain. Time- and frequency domain methods are theoretically equivalent via the Fourier transform. However, data acquisition parameters such as the sampling frequency and pulse length affect the actual spectral content of real tim...

Soil contamination is a widespread problem and action needs to be taken in order to prevent damage to the groundwater and the life around the contaminated sites. In Sweden, it is estimated that more than 80,000 sites are potentially contaminated, and therefore, there is a demand for investigations and further treatment of the soil. In this paper, w...

With advances in data acquisition and processing methods, spectral inversion of time domain induced polarization (IP) data is becoming more common. Geological interpretation of inverted spectral parameters, for instance Cole-Cole parameters, often relies on results from systematic laboratory measurements. These are most often carried out with frequ...

With advances in data acquisition and processing methods, spectral inversion of time domain induced polarization (IP) data is becoming more common. Geological interpretation of inverted spectral parameters, for instance Cole-Cole parameters, often relies on results from systematic laboratory measurements. These are most often carried out with frequ...

The signal level and shape of induced polarization responses are significantly affected by the current pulse duration and waveform. If not accounted for, this data dependency on the current will propagate trough the inversion to results rendering unquantifiable subsurface models. While this problem has been addressed in full-response induced polari...

Resistivity data constitute the largest part of the available information to assess the hydrogeological characteristics of the aquifer system near Oruro, in the central part of the Bolivian Altiplano. Two aquifers are part of this system; top unconsolidated sediments storing fresh water in their granular voids, overlying fractured hard rock formati...

Although many studies have been performed to investigate the spectral induced polarization (SIP) response of nonaqueous phase liquid (NAPL)-contaminated soil samples, there are still many uncertainties in the interpretation of the data. A key issue is that altered pore space geometries due to the presence of a NAPL phase will change the measured IP...

Oruro city in the Bolivian highlands depends solely on groundwater to supply domestic consumption and irrigation. The top porous aquifer currently exploited is not fully understood in aspects like geometry, hydrogeological properties and interaction with other aquifers in the region. Recent studies detected traces of fractures in the bedrock beneat...

The porous aquifers in the area called Challapampa are the most important groundwater reservoirs that supply drinking water to Oruro city in the highlands of Bolivia. They consist of unconsolidated fluvial–lacustrine deposits, resting on a complex sedimentary bedrock and covered by a thin surficial clay layer. The settings of these geological units...

Due to the overpopulation in the main cities and shortage of water in Egypt, finding new possible reclamation areas becomes an urgent necessity. The area northwest of El Sadat city can be considered one of the most promising new reclamation areas. This study focuses on detecting the groundwater aquifers, delineating the best localities to drill gro...

Underground constructions for public traffic purposes are becoming increasingly important for urban areas in order to use the limited space more efficiently. Several electric resistivity tomography and seismic refraction tomography measurements were performed crossing a water passage near Stockholm during the pre-investigation phase of a tunnel bui...

There is an increasing demand for trustworthy engineering geological conceptual models in urban areas due to an increasing trend in the underground infrastructure construction. Good‐quality site investigations can reduce the risk of encountering unexpected geological conditions during construction. Geoelectrical measurements can be used as a tool f...

We present an approach to underwater electrical resistivity tomography surveying under conditions with several water layers with different resistivity in the water above the electrode layout. The approach is verified against a synthetic model example and tested in full scale on data from a field survey. The field survey was carried out in central S...

The electrical resistivity tomography (ERT) method provides moderately good constraints for both conductive and resistive structures, while the radio-magnetotelluric (RMT) method is well suited to constrain conductive structures. Additionally, RMT and ERT data may have different target coverage and are differently affected by various types of noise...

The semiarid Punata alluvial fan is located in the central part of Bolivia. The main activity of this region is the extensive agriculture, and groundwater is the main water supply. Local villagers who use groundwater reported that in some places groundwater has a salty taste. In order to investigate the origin of this problem, several TEM soundings...

An investigation of geological conditions is always a key point for planning infrastructure constructions. Bedrock surface and rock quality must be estimated carefully in the designing process of infrastructures. A large direct‐current resistivity and time‐domain induced‐polarization survey has been performed in Dalby, Lund Municipality, southern S...

A geophysical site investigation using ERT and refraction seismic was done to detect the bedrock interface and possible weakness zones. For the purpose of a more realistic subsurface model a joint inversion was done.

Geoelectrical techniques have long standing potential for imaging sites contaminated by dense non-aqueous phase liquids (DNAPLs). Recent work explored the effectiveness of time-lapse DC resistivity to monitor DNAPL source zone remediation. A fundamental component of the work was the development of a unique and comprehensive linkage between well-est...

The authors wish to make the following corrections to this paper [1]: [...]

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 on the subsurface are neces...

Electrical resistivity tomography (ERT) and refraction seismics are among the most frequently used geophysical methods for site-investigations and the combined results can be very helpful to fill in the gaps between the point measurements made by traditional geotechnical methods such as Cone Penetration Test (CPT), core-drilling and geophysical bor...

In Nampula province, Mozambique, there is a high number of water wells considered as having failed for having too low a pumping yield. Two Electrical Resistivity Tomography (ERT) measurement campaigns were conducted in the area for evaluating the reasons of failures. However, in some cases it was difficult to verify and interpret the ERT results by...

Vertical electrical sounding was used for assessing the suitability of the drill sites in crystalline areas within a water supply project in Nampula Province in Mozambique. Many boreholes have insufficient yield (<600 L/h). Electrical resistivity tomography (ERT) was carried out over seven boreholes with sufficient yield, and five boreholes with in...

In continental margin basins, the hydrogeological setting is complex due to transgression/regression events that removed old sediments in the basin and formed new geologic units. Due to the geological complexity, the use of vertical electrical sounding has proven to be insufficient for groundwater explorations. The lack of understanding the geologi...

Characterization of varying bedrock properties is a common need in various contexts, ranging from large infrastructure pre-investigations to environmental protection. A direct current resistivity and time domain induced polarization (IP) survey aiming to characterize properties of a Cretaceous limestone was carried out in the Kristianstad basin, Sw...

Conceptual models of aquifer systems can be refined and complemented with geophysical data, and they can assist in understanding hydrogeological properties such as groundwater storage capacity. This research attempts to use geoelectrical methods, Electrical Resistivity Tomography and Induced Polarization parameters, for mapping the subsurface in al...

Natural hazards such as landslides, floods, rockfalls, earthquakes, volcanic eruptions, sinkholes, and snow avalanches represent potential risks to our infrastructures, properties, and lives. That potential will continue to escalate with current and continued human encroachment into risk areas. With the help of geophysical techniques many of those...

Globally, an enormous number of polluted areas are in need of remediation to prevent adverse effects on health and environment. In situ remediation and especially the monitoring thereof needs further development to avoid costly and hazardous shipments associated with excavation. The monitoring of in situ remediation actions needs easier and cheaper...

The extraction of spectral information in the inversion process of time-domain (TD) induced polarization (IP) data is changing the use of the TDIP method. Data interpretation is evolving from a qualitative description of the subsurface, able only to discriminate the presence of contrasts in chargeability parameters, towards a quantitative analysis...

An underwater ERT survey was made along a planned road tunnel for The Stockholm Bypass Project (Forbifart Stockholm). The aim was to assess the ability to identify variations in the depth of the bottom sediments, as well as variations in rock quality and the possible presence of weak zones in the rock. Reference data from a seismic survey and geote...

The application of geophysics may assist in solving environmental, geotechnical and exploration problems. One commonly used method in such applications is electrical resistivity tomography (ERT). In order to interpret the results, inversion is needed to create models estimating distribution of resistivity in the ground. Several inversion programs a...

The extraction of spectral information in the inversion process of time-domain (TD) induced polarization (IP) data is changing the use of the TDIP method. Data interpretation is evolving from a qualitative description of the subsurface, able only to discriminate the presence of contrasts in chargeability parameters, towards a quantitative analysis...

In this work we explore the potential of combined time-lapse ERT and induced polarization (IP) techniques for monitoring the remediation of DNAPL source zones. Recently, we have established a realistic DNAPL-geoelectrical ERT linkage model within the time-lapse monitoring framework and we are now seeking to extend this particular approach by also i...

This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater in...

Electrode grounding resistance is a major factor affecting measurement quality in electric resistivity tomography (ERT) measurements for cryospheric applications. Still, little information is available on grounding resistances in the geophysical literature, mainly because it is difficult to measure. The focus-one protocol is a new method for estima...

Although electric resistivity tomography (ERT) is now regarded as a standard tool in permafrost monitoring, high grounding resistances continue to limit the acquisition of time series over complete freeze-thaw cycles. In an attempt to alleviate the grounding resistance problem, we have tested three electrode designs featuring increasing sizes and s...