Airborne geophysics: a novel approach to assist hydrogeological investigations at groundwater-dependent wetlands

Beamish, David; Farr, Gareth

doi:10.1144/qjegh2012-019

Cited by 6 publications

(5 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus the geophysical observations appear capable of predicting new zones of enhanced moisture levels within afforested peat zones. This general predictive ability of the geophysical data was a conclusion of the wetland study conducted by Beamish and Farr [24].…”

Section: Afforested Peatsupporting

confidence: 53%

Peat Mapping Associations of Airborne Radiometric Survey Data

Beamish

2014

Remote Sensing

Self Cite

View full text Add to dashboard Cite

This study considers recent airborne radiometric (gamma ray) survey data, obtained at high-resolution, across various regions of the UK. The datasets all display a very evident attenuation of signal in association with peat, and intra-peat variations are observed. The geophysical response variations are examined in detail using example data sets across lowland areas (raised bogs, meres, fens and afforested peat) and upland areas of blanket bog, together with associated wetland zones. The radiometric data do not map soils per se. The bedrock (the radiogenic parent) provides a specific amplitude level. Attenuation of this signal level is then controlled by moisture content in conjunction with the density and porosity of the soil cover. Both soil and bedrock variations need to be jointly assessed. The attenuation theory, reviewed here, predicts that the behaviour of wet peat is distinct from most other soil types. Theory also predicts that the attenuation levels observed across wet peatlands cannot be generally used to map variations in peat thickness. Four survey areas at various scales, across England, Scotland, Wales and Ireland are used to demonstrate the ability of the airborne data to map peat zones. A 1:50 k national mapping of deep peat is used to provide control although variability in the definition of peat zones across existing databases is also demonstrated.

show abstract

Section: Afforested Peatsupporting

confidence: 53%

Peat Mapping Associations of Airborne Radiometric Survey Data

Beamish

2014

Remote Sensing

Self Cite

View full text Add to dashboard Cite

show abstract

“…The next step was to analyze the airborne electromagnetic (HEM) data in order to derive estimates for the location of the peat base. This interface should be detectable, if the resistivity of peat differs significantly from the resistivity of the substrate [11][12][13][14]. The resulting peat thickness could then be used to scale the HRD data (exposure rate).…”

Section: Peat Volume Estimationmentioning

confidence: 99%

“…In model 2, the resistivity of the second layer of constant thickness (d 2 = 3 m) was changed (ρ 2 = 1-200 Ωm). The model parameters used were adapted from field results and literature values [11,12]. In order to simulate realistic field data, 1% random noise was added to the synthetic data.…”

Section: Hem Analysismentioning

confidence: 99%

“…Examples for AEM peat surveys are rare. Puranen et al [11] and Airo et al [7] published results from Finland, and Beamish and Farr [12] from Wales, using fixed-wing frequency-domain systems. More recently, Silvestri et al [13,14] presented peat thickness results acquired by helicopter-borne time-domain electromagnetic devices in Norway and Indonesia.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Airborne Electromagnetic and Radiometric Peat Thickness Mapping of a Bog in Northwest Germany (Ahlen-Falkenberger Moor)

2020

View full text Add to dashboard Cite

Knowledge on peat volumes is essential to estimate carbon stocks accurately and to facilitate appropriate peatland management. This study used airborne electromagnetic and radiometric data to estimate the volume of a bog. Airborne methods provide an alternative to ground-based methods, which are labor intensive and unfeasible to capture large-scale (>10 km2) spatial information. An airborne geophysical survey conducted in 2004 covered large parts of the Ahlen-Falkenberger Moor, an Atlantic peat bog (39 km2) close to the German North Sea coast. The lateral extent of the bog was derived from low radiometric and elevated surface data. The vertical extent resulted from smooth resistivity models derived from 1D inversion of airborne electromagnetic data, in combination with a steepest gradient approach, which indicated the base of the less resistive peat. Relative peat thicknesses were also derived from decreasing radiation over peatlands. The scaling factor (µa = 0.28 m−1) required to transform the exposure rates (negative log-values) to thicknesses was calculated using the electromagnetic results as reference. The mean difference of combined airborne results and peat thicknesses of about 100 boreholes is very small (0.0 ± 1.1 m). Although locally some (5%) deviations (>2 m) from the borehole results do occur, the approach presented here enables fast peat volume mapping of large areas without an imperative necessity of borehole data.

show abstract

“…Geophysical data can also be collected from airborne surveys, although the cost of this is significant and airborne surveys are often used to look at landscape-scale rather than site-scale detail. Beamish and Farr (2013) show that airborne geophysics can be useful to help characterize wetlands on a landscape scale, potentially helping to guide ground investigations. The attenuation of airborne radiometric data can identify areas of water saturation near the surface, while conductivity data appears capable of mapping the occurrence of clay concealed beneath peat.…”

Section: Wetland Substratementioning

confidence: 99%