Timothy Saey

• Ghent University

Integrated research using aerial photography, proximal soil sensing, historical research and excavations of an unusual First World War site in Flanders (Belgium) is presented. Aerial photography revealed a grid of 5x6 huts unusually close to the front line. Geophysical research indicates good preservation of these structures. A targeted excavation...

Frequency domain electromagnetic (FDEM) responses can be related to electrical conductivity (EC) and magnetic susceptibility of the subsurface. Strides in FDEM instrumentation and EM modelling drive the rapid growth of land-based applications. However, the ease of use of FDEM instruments is starkly contrasted by data complexity and laborious calibr...

Over the course of four years (2012–2015) the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archeology (LBI ArchPro), in collaboration with the Central Institute for Meteorology and Geodynamics (ZAMG) and on behalf of the provincial government of Lower Austria, has conducted the comprehensive, non-invasive archaeological pro...

Geophysical prospection as a non-invasive archaeological survey technique has become a widely applied discipline that is currently finding its way into the former World War One (WW1) battlefields. Because of the imminent danger of unexploded ordnances, non-invasiveness is the key to exploring the subsurface containing our buried heritage. Fluxgate...

The First World War (WWI) had a notable influence on the landscape at the former Western Front in Belgium. Research on a landscape scale is necessary to understand the destructive and constructive impact of the war and its consequences for the postwar landscape in a holistic manner. This paper focuses on the trajectory and impact analysis of three...

Since the end of World War One, only few research is performed to understand the extend of the destruction of the first meters of soil archive at the former Belgian front zone. The only existing sources to identify the by artillery destroyed landscape are maps indicating destruction at the level of administrative communities, based on war damage in...

In light of the growing interest in the Great War – stimulated by the ongoing centennial commemorations – the conflict landscape in Belgium and France is currently the subject of scientific research projects, archaeological excavations, heritage-related initiatives and exhibitions. However, the extent of the archaeological heritage and surface rema...

Archaeological prospection with magnetometer instruments is performed in a wide range of field configurations, ranging from single probe setups to mobile arrays that allow combining multiple sensors. The latter type, whereby instruments are mounted onto a cart system, are particularly prone to motion-induced noise. Sensor tilt, for example, causes...

During the First World War, the stalemate in the trenches resulted in the creation of a vast network of field defences in different theatres of war. The rediscovery of ancient siege techniques, such as military mining and the ever-increasing power of artillery fire, resulted in the creation of an underground world of tunnels and mine galleries deep...

As the centenary commemorations of the Battle of Passchendaele approach, this article is a timely demonstration of how archaeology can provide new insights into the landscape of the Western Front. Assessment of over 9000 aerial photographs taken during the First World War, integrated with other approaches to landscape archaeology, offers a new pers...

We explore the usefulness of FDEM conductivity mapping for hydrogeological investigations by surveying farming land overlying a salt plume. Specifically the potential for reconstructing the salinity distribution of the subsurface is researched. To this end, calibration of the collected FDEM data and accuracy of the inverted responses are looked int...

Without any demining regulation or active search approach mission, the Belgian WW1 front zone produces each year a minimum of 100 tons unexploded ordnances. In this area, multi-receiver EMI as a large scale mapping technique, showed that high percentages of the remains of the 1914-18 war are still present beneath the surface. Because of the complex...

Well-preserved prehistoric landscapes and sites have been found, buried deeply below the Holocene peat or floodplain deposits of “Waasland Scheldt polders.” During the mid-to-late Holocene, Late Weichselian (river) dunes within the floodplain and river flanks were favored locations for Final Early Neolithic occupation. Available living space was de...

When regarding evolutions in land-based, motorized sensor data collection it can be generalized that the speed of surveying, sampling rates, digital communications speed and survey resolutions have increased over the last years. Possibilities for accurate positioning have been following pace. However, a spatial offset between sensor and position da...

World War I (WWI) battlefields contain a large diversity of buried features that are situated just below the plough layer. A noninvasive interdisciplinary approach is preferred to characterize the buried heritage embedded within its soil landscape. In this study, the potential of integrating both electrical conductivity and magnetic susceptibility...

In spite of an increase in World War I (WWI)-related excavations in Flanders (Belgium), little is known about the nature and extent of the buried heritage of WWI from research on a landscape scale. This paper examines the combination of historical aerial photographic evidence and geophysical soil sensing. A case study in Comines-Warneton compares d...

During the First World War, ancient siege techniques were used in an attempt to break through the stalemate in the trenches. This paper approaches the mine crater war from a completely new perspective and focuses on a landscape-scale approach rather than on fragmented individual sites. Thousands of contemporary aerial photographs have been used as...

The Western Front of World War I is one of the largest continuous archaeological sites in the world. Although fragmented archaeological surveys and inventories of related conflict heritage have been conducted, an overall landscape-scale archaeological investigation of the area has not yet been achieved. The nature and extent of the buried heritage...

To evaluate the degree of loss of positional accuracy when a spatial offset is present between position and sensor data, we have simultaneously collected GNSS data (with RTK correction) using a GNSS receiver that was mounted on an ATV and two other receivers that were mounted on the front and end of an elongate sled. Comparing the predicted locatio...

In environmental assessments, the characterization of urban soils relies heavily on invasive investigation, which is often insufficient to capture their full spatial heterogeneity. Non-invasive geophysical techniques enable rapid collection of high-resolution data and provide a cost-effective alternative to investigate soil in a spatially comprehen...

Different EMI inversion procedures were evaluated.•A 1D-laterally constrained and a non-constrained, robust 1D-inversion procedure were compared.•LIN approximations were compared with the full solution of the Maxwell's equations.•2D inversions of the EMI and ERT data were matched.•A robust calibration proved essential to attribute absolute values t...

The soil at industrial sites is frequently characterized by very heterogeneous properties, which are often related to physical disturbance and contamination. A conventional approach to characterize the soil, with only a limited number of invasive observations, fails to capture the full extent of soil heterogeneity. Proximal soil sensing provides ef...

Increasingly, conventional soil sampling procedures face restrictions because of their destructive character. Hence there is a growing interest in non-invasive techniques, on which proximal soil sensors are based. There is great interest in applying proximal soil sensing to improve the characterization of the buried heritage embedded in the soil la...

Given the upcoming centennial commemoration of the beginning of the Great War (WW I), the international attention for this conflict grows considerably. Questions will be raised about the nature of this heritage. In this study, we focus on a WW I training trench which was built in the Stonehenge (UK) World Heritage landscape where no fighting took p...

Archaeological research at Stonehenge (UK) is increasingly aimed at understanding the dynamic of the wider archaeological landscape. Through the application of state-of-the-art geophysical techniques, unprecedented insight is being gathered into the buried archaeological features of the area. However, applied survey techniques have rarely targeted...

Paddy being the main crop and staple food greatly influences on the socio-economy of Sri Lanka. At present, nutrient management in paddy soils is of prime concern due to heavy dependence on fertilizer inputs amid stagnated productivity and potential environmental risks. Therefore, alternative nutrient management strategies are in need. Site Specifi...

Today, most surveys in archaeogeophysical prospection use magnetic properties to detect archaeological features. Such magnetic surveys are usually conducted with magnetometers and, to a lesser extent, with magnetic susceptibility meters and electromagnetic induction (EMI) sensors. Although the latter are the only instruments that allow mapping mult...

A key characteristic of flooded paddy fields is the plough pan. This is a sub-soil layer of greater compaction and bulk density, which restricts water losses through percolation. However, the thickness of this compacted layer can be inconsistent, with consequences such as variable percolation and leaching losses of nutrients, which therefore requir...

Sophisticated techniques of archaeological survey, including airborne imaging spectroscopy, electromagnetic induction and ground-penetrating radar, are opening up new horizons in the non-invasive exploration of archaeological sites. One location where they have yielded spectacular results is Carnuntum in Austria, on the south bank of the Danube, ca...

Paddy rice (Oryza sativa L.) fields are repeatedly puddled at water saturation to loosen the top soil and to form a uniformly compacted plow pan required to reduce losses of water and nutrients. In paddy growing conditions however, the non-invasive detection of compaction variation within the plow pan layer is challenging. This paper evaluates a pr...

Recently, the unique foundations of a school of gladiators were discovered in the Roman town of Carnuntum (40 km southeast of Vienna, Austria) by applying a combination of non-invasive archaeological prospection techniques such as magnetometry, ground penetrating radar, aerial photography, airborne laser scanning and airborne imaging spectroscopy....

The archaeological evaluation of landscapes in the framework of developer-led archaeology is often based on extensive trenching programmes complemented with auger surveys in wetland environments. During the archaeological evaluation of a 90 ha polder site in the north-west of Belgium, a mobile multi-receiver electromagnetic induction (EMI) survey w...

At present, spatially very detailed data sets can be obtained about soil, landscape and crop variability. However, there is a need to select independent key properties to identify management classes needed for precise land management. In a previous study performed in the European loess belt, topsoil pH, apparent electrical conductivity (ECa) and el...

The commonly used variogram function is incapable of modelling complex spatial patterns associated with repetitive, connected or curvilinear features, because it is a two‐point statistic. Because this was strongly limiting to petroleum‐ and hydrogeologists, they developed multiple‐point geostatistics (MPG), an approach that replaces the variogram b...

Studies of past human-landscape interactions rely upon the integration of archaeological, biological and geological information within their geographical context. However, detecting the often ephemeral traces of human activities at a landscape scale remains difficult with conventional archaeological field survey. Geophysical methods offer a solutio...

Supplementary information: figures

Multi-receiver electromagnetic induction (EMI) sensors are increasingly being used to map soil spatial variability by measuring the apparent electrical conductivity (ECa) of multiple soil volumes. We present a procedure to process such measurements to identify both large-scale soil variability patterns and small-scale features such as archaeologica...

The prospection and evaluation of former battlefields of the Great War or the First World War (WW I) poses specific challenges. For several reasons, large-scale excavation campaigns of this conflict landscape are problematic. The vastness of the former Western Front (one of the largest archaeological sites in the world), the large amounts of buried...

Ground Penetrating Radar (GPR) reflections occur at sharp interfaces between contrasting soil layers. Generally, the depth of the interface is expressed as the two-way travel time from the transmitting to the receiving antenna. Converting these travel times to depths requires knowledge of the propagation speed of the GPR wave in the soil.This veloc...

In the Roman town of Carnuntum 40 km south-east of Vienna (Austria) the unique discovery of a school of gladiators was made using a multi-disciplinary approach based on high-resolution near-surface geophysical prospection. The outstandingly well preserved architecture was revealed through non-invasive mapping using latest highly efficient multichan...

Mobile multi-receiver electromagnetic induction sensors provide simultaneous readings of the apparent electrical conductivity (ECa) from overlapping soil volumes. Therefore, small contrasting features can be difficult to identify because they have a limited contribution to the bulk measurement, especially if they are present in the subsoil (i.e. be...

Most geological and soil maps are not detailed enough to represent the high lateral and vertical textural variability in the subsoil of coastal lowlands. Intensive sampling campaigns need to be carried out to quantify this variability. As an alternative, a proximal soil sensing procedure based on a single survey with an electromagnetic induction in...

Although the Belgian lowlands witnessed a dense rural occupation in Roman and especially in medieval times, the exact nature of the settlement patterns, the farms and the interaction with the landscape is still poorly understood archaeologically, both scientifically and from a heritage curatorship point of view. Archaeogeophysical research has rema...

Multiple apparent electrical conductivity (ECa) measurements with an electromagnetic induction (EMI) sensor frequently reveal analogue patterns caused by conductive features in the soil. A procedure was proposed to highlight different archaeological anomalies based on combinations of the simultaneous ECa measurements with the DUALEM-21S instrument....

Paddy rice fields are kept inundated during most of the growing period. This requirement is challenging to achieve because of the lack of suitable technologies to detect rapidly percolation prone zones within these fields. The objective of this study was to evaluate a methodology to identify water leakage areas to support precision soil–water manag...

Images of the morphology of a polygonal network of ice-wedge casts are a valuable aid to paleoclimatological reconstructions. Usually such images are obtained by aerial photography showing polygonal crop marks reflecting textural differences between wedge filling and host material. Our objective was to investigate an alternative method by measuring...

Buried unexploded ammunition is a major problem on arable land in former battle areas. Many battlefields of the First World War (WWI) still contain a lot of unexploded shells just below the plough layer, posing serious threats to soil editors and trenchers. Electromagnetic induction (EMI) sensors have been used for a variety of agricultural and arc...

Field methods to map and reconstruct the morphology of buried river systems are highly dependent on spatial interpolation. Conventional methods, such as standard borehole survey, allow a detailed vertical reconstruction of the shallow subsurface but leave lateral connections between sample locations open to interpretation. Geophysical survey techni...

Every growing season, paddy fields are kept both flooded and drained for a significant period of time. As a consequence, these soils develop distinct physico-chemical characteristics. For practical reasons, these soils are mostly sampled under dry conditions, but the question arises how representative the results are for the wet growing conditions....

As an alternative for the depth response approximations based on the theoretical Maxwell's equations, a procedure was proposed to fit depth response curves for different coil configurations. A 39ha study area was selected in the Belgian loess belt, where loess material was situated on a Tertiary substrate. A survey with the DUALEM-21S electromagnet...

The archaeological evaluation of project sites is often solemnly based on extensive trenching programmes complemented with auger surveys. However, these methods lack spatial continuity, which can make detected structures difficult to interpret. A mobile multi-signal electromagnetic induction (EMI) survey was therefore incorporated in the archaeolog...

Proximal soil sensing is a relatively new field within soil science defined as the use of mobile geophysical sensors at or near the soil surface. Most applied techniques are electromagnetic induction (EMI), electrical resistivity (ER) and ground penetrating radar. Electromagnetic and electrical properties of soil reflect well the most relevant soil...

Magnetic susceptibility is an important indicator of anthropogenic disturbance in the natural soil. This property is often mapped with magnetic gradiometers in archaeological prospection studies. It is also detected with frequency domain electromagnetic induction (FDEM) sensors, which have the advantage that they can simultaneously measure the elec...

During the last glacial period (Weichselian), wind-blown loess was deposited over the undulating landscape of central Belgium, which had been formed in surfacing Tertiary marine sediments. Since valleys were covered with a thicker loess layer than were elevated areas, the present topography is much flatter. Reconstructing the palaeolandscape at a d...

High-resolution proximal soil sensor data are an important source of information for optimising the prediction of soil properties. On a 10.5 ha arable field, an intensive EM38DD survey with a resolution of 2 m × 2 m resulted in 19,694 measurements of ECa-H and ECa-V. A large textural variation was present in the subsoil due to the presence of forme...

Electromagnetic induction soil sensors are an increasingly important source of secondary information to predict soil texture. In a 10.5-ha polder field, an EM38DD survey was performed with a resolution of 2 by 2 m and 78 soil samples were analyzed for sub- and topsoil texture. Due to the presence of former water channels in the subsoil, the coeffic...

Since soil texture is difficult to quantify, its determination is often restricted to the topsoil. To improve its mapping accuracy, observations of the apparent electrical conductivity (ECa) obtained from proximal soil sensors are increasingly being used due to its close relationship with soil texture under non-saline conditions. However, a single...

The multiple coil configurations of two electromagnetic induction sensors were tested on a field with strong electrical and magnetic contrasts. The first sensor, EM38DD, measures either the apparent electrical conductivity (ECa or σa) or the apparent magnetic susceptibility (MSa or χa) of the soil at two coil orientations. The second sensor, DUALEM...

Geophysical instruments show great potential for the detailed quantification of soil stratigraphy. In this study, two electromagnetic induction sensors were evaluated on their capacity to map small-scale variations of die depth to the interface (Z(in)) in a two-layered soil. On a 2-ha study site, z(in) between the silty topsoil and the contrasting...

Despite their shortcomings, choropleth soil maps remain the most widespread source of information on soil resources. Since most nationwide soil surveys were conducted in the second half of the previous century, a need for upgrading emerges. We evaluated the potential of detailed observations made by a mobile, non-invasive proximal soil sensor to up...

During the last glacial period (Weichselian), wind-blown loess was deposited over the undulating landscape of central Belgium, which had been formed in surfacing Tertiary marine sediments. Since valleys were filled up with a thicker loess layer than hill tops, the present topography is much smoother. This smoothing was enhanced by subsequent erosio...

At present, it is possible to obtain rich data sets on soil variability. However, there is a need to select independent key properties to identify management zones. In a previous study focusing on loess soil, we identified the electrical conductivity measured with a soil sensor, topsoil pH and elevation as key properties. In this study the number o...