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1D Vertical Electrical Sounding (VES) with LandMapper Procedure

standard big manual VES cable set by LandviserThe technique and procedure described here can be performed with LandMapper ERM-01 or ERM-02 (set in resistivity mode). The electrode spacings provided in this example are identical to Landviser's supplied "big manual VES" cable set made to measure 16 layers of topsoil down to approximately 9 m. The worksheet for pre-set electrode spacings in such cable re-calculating measured resistivities to 1D VES profile can be downloaded as Manual 1D VES workbook (MS Excel format).

Other electrode spacings are possible for custom-made cable arrays to reach deeper profiles. For example, we developed and tested with LandMapper a 60m-long cable, measuring down to ~ 20 m for one custom hydrology project

This manual VES technique is most convenient to use with three people. Follow step-by-step instructions below. If you need further help, do not hesitate to contact Landviser, LLC @ +1-609-412-0555 or info@landviser.com. Register on our site and download 7 related publications and software!

Locations

San Antonio 29° 25' 26.8392" N, 98° 29' 37.0608" W
Dmitrov 56° 20' 39.0192" N, 37° 31' 2.5716" E

Vertical Electrical Sounding to Detect Groundwater Levels in Arid Areas

hydrology of delta Volga, RussiaWater and salt content distributions within the soil profile are the main properties causing considerable variations in electrical resistivity. In arid areas, the water content and salt distributions are determined mainly  by the saline groundwater, rather then by precipitation. 

 

The soil profile is divided into a top unsaturated layer with high resistivity and a bottom layer saturated by saline groundwater with low resistivity. Considering large differences in electrical resistivity between the unsaturated and saturated zones, the VES method was applied to detect the saline groundwater level. 

Местоположение

Gandurino, AST 45° 50' 56.4" N, 48° 0' 23.04" E

Vertical Electrical Sounding to Detect Soil Salinity in Arid Areas

total soil salinity vs resistivity by VESWater and salt content distributions within the soil profile are the main properties causing considerable variations in electrical resistivity or conductivity.  Since the evaporation in the arid areas (Astrakhan, Russia) is about five times higher than the precipitation, the water content and salt distributions are determined mainly by the saline groundwater.

The differentiation of salinity in the unsaturated zone of the soil profiles was revealed by small fluctuations of electrical resistivity in upper part of the VES profiles. We thoroughly interpreted the VES results to estimate the layers with different electrical conductivities (EC) for 12 soil profiles. The total salt content was measured in soil samples collected from the layers of the profiles as shown in Table (columns 1 and 2) for one example profile. 

Evaluation of stone contents in soils with electrical geophysical methods to aid orchard planning

VES of stony soils in Crimea

Establishments of orchards and vineyards are long-term and money-intensive, but highly pay-off projects. This study allowed developing procedure for incorporating geophysical survey data into recommendations of usage skeletal soils under orchards. Geophysical methods of electrical resistivity, such as VES and four-electrode profiling provided the information about spatial distributions of stones in skeletal soils.  The resistivity of rocks or stones is much higher (about 104-1012 ohm m) than the resistivity of soil horizons with any texture. Therefore, high resistivity will indicate the presence of stones in soil profiles.

Study was conducted on skeletal soils (Paleoxerolls and Lithic Xerorthents) formed on carbonate-cemented marine deposit, limestone, or pebbles of alluvial origin in western part of Crimea Peninsula, Ukraine. The stone content varied from 2 to 90% of fragments coarse than 2 mm by volume and stony layers occurred in soil profiles at the depth as shallow as 12 cm.

Местоположение

Saky

Applications of LandMapper handheld for near-surface soil surveys and beyond

LandMapper - fast, portable, versatile, affordableOn-the-go sensors, designed to measure soil electrical resistivity (ER) or electrical conductivity (EC) are vital for faster non-destructive soil mapping in precision agriculture, civil and environmental engineering, archaeology and other near-surface applications. Compared with electromagnetic methods and ground penetrating radar, methods of EC/ER measured with direct current and four-electrode probe have fewer limitations and were successfully applied on clayish and saline soils as well as on highly resistive stony and sandy soils. However, commercially available contact devices, which utilize a four-electrode principle, are bulky, very expensive, and can be used only on fallow fields. Multi-electrode ER-imaging systems applied in deep geophysical explorations are heavy, cumbersome and their use is usually cost-prohibited in many near-surface applications, such as forestry, archaeology, environmental site assessment and cleanup, and in agricultural surveys on farms growing perennial horticultural crops, vegetables, or turf-grass. In such applications there is a need for accurate, portable, low-cost device to quickly check resistivity of the ground on-a-spot, especially on the sites non-accessible with heavy machinery.

Four-electrode principle of EC/ER measurements

Our equipment utilizes well-known four-electrode principle to measure electrical resistivity or conductivity (Fig).

Locations

Jonesboro, AR 35° 50' 32.2692" N, 90° 42' 15.4044" W
Krasnoyarsk 56° 0' 38.8404" N, 92° 51' 9.99" E

ELECTRICAL POTENTIAL (Self-Potential) MEASUREMENTS with LandMapper ERM-02

Self-potential map to detect directions of water fluxes, KievThe self-potential (SP) method was used by Fox as early as 1830 on sulphide veins in a Cornish mine, but the systematic use of the SP and electrical resistivity methods in conventional geophysics dates from about 1920 (Parasnis, 1997). The SP method is based on measuring the natural potential differences, which generally exist between any two points on the ground. These potentials are associated with electrical currents in the soil. Large potentials are generally observed over sulphide and graphite ore bodies, graphitic shale, magnetite, galena, and other electronically highly conducting minerals (usually negative). However, SP anomalies are greatly affected by local geological and topographical conditions. These effects are considered in exploration geophysics as “noise”. The electrical potential anomalies over the highly conducting rock are usually overcome these environmental “noise”, thus, the natural electrical potentials existing in soils are usually not considered in conventional geophysics.

LandMapper ERM-02, equipped with proper non-polarizing electrodes, can be used to measure such “noise” electrical potentials created in soils due to soil-forming process and water/ion movements. The electrical potentials in soils, clays, marls, and other water-saturated and unsaturated sediments can be explained by such phenomena as ionic layers, electro-filtration, pH differences, and electro-osmosis.

Another possible environmental and engineering application of self-potential method is to study subsurface water movement. Measurements of electro-filtration potentials or streaming potentials have been used in USSR to detect water leakage spots on the submerged slopes of earth dams (Semenov, 1980). The application of self-potential method to outline water fluxes in shallow subsurface of urban soils is described in (Pozdnyakova et al., 2001). The detail description of self-potential method procedure is provided in LandMapper manual.

Another important application of LandMapper ERM-02 is measuring electrical potentials between soils and plants. Electrical balance between soil and plants is important for plant health and electrical potential gradient governs water and nutrient uptake by plants. Monitoring of electrical potentials in plants and soils is a cutting-edge research topic in the leading scientific centers around the world.

Locations

Zamboanga 7° 1' 27.3612" N, 122° 11' 20.0544" E
Kiev-Pechersk Lavra Kiev 50° 24' 59.1768" N, 30° 33' 55.836" E

Mapping Alluvial Soils of Humid Areas with Electrical Geophysical Methods

Valley soils of humid areas are comprised of various peat and sandy soils of alluvial or lacustrine origins. These soils are located in subordinated positions in a landscape and accumulated high amounts of organic matter and mineral nutrients. Fluctuation of the river bed in space often causes highly complex soil cover in a valley. Studying those soils with conventional methods of soil mapping is very time and resource consuming. Therefore, we tested the electrical geophysical methods of non-contact electrical profiling (NEP) and electrical profiling (EP) for mapping peat and mineral alluvial soils formed in the glacial valley of Yachroma river.

The distinction in botanical structure of peat and hydrology conditions at the different zones of the valley causes distinction in physical and chemical properties of sedge-mossy, grass-woody, and mineral-peat layered soils (Figure).  The sedge-mossy peat typically has lower ash content and bulk density, and higher water content, than the grass-woody peat. Electrical resistivity of sedge-mossy peat soil is minimal (<20 ohm m) in comparison with resistivity of grass-woody (30-40 ohm m) and mineral-peat layered soils (50-60 ohm m).

Местоположение

CPBRS Горшково, MOS 56° 22' 30.2448" N, 37° 25' 8.724" E

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Electrical Geophysical Methods in Agriculture

Agriculture: a budding field in geophysicsMapping alluvial soils of humid areas with electrical geophysical methods: We tested the electrical geophysical methods of non-contact electrical profiling (NEP) and electrical profiling (EP) for mapping peat and mineral alluvial soils formed in the glacial valley of Yachroma river. More >>

Vertical Electrical Sounding to detect groundwater levels in arid areas: The approximate location of the groundwater table was estimated by a visual inspection of the VES curve. The AB/2 value with the sharp change to the low resistivity (3-20 ohm m) was selected from each VES profile...More >>

Evaluation of stone contents in soils with electrical geophysical methods to aid orchard planning: Geophysical methods of electrical resistivity, such as VES and four-electrode profiling provided the information about spatial distributions of stones in skeletal soils.  High resistivity will indicate the presence of stones in soil profiles. More >>

Application of the geophysical methods of electrical resistivity in precision farming:  One of the challenges facing the adoption of precision agriculture technology is the identification of productivity-related variability of soil properties accurately and cost-effectively. More >>

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