Analysis of Subsurface Water Content with Integrated Techniques.

10.3383/1.1.8 ◽  
2008 ◽  
Vol 1 (1) ◽  
pp. 109-123 ◽  
Author(s):  
G. LEUCCI ◽  
R. CATALDO ◽  
G. DE NUNZIO
Keyword(s):  
Water Content ◽  
Subsurface Water

scholarly journals Identification of the groundwater existence by geoelectrical method

2020 ◽  
Vol 4 (2) ◽  
pp. 36-42
Author(s):  
I Ketut Sukarasa ◽  
Ida Bagus Alit Paramarta
Keyword(s):  
Surface Water ◽  
Water Content ◽  
Subsurface Water ◽  
Rock Layer ◽  
Work Process ◽  
Electric Currents ◽  
Subsurface Structures ◽  
On Line ◽  
Bearing Layer ◽  
2D Images

Research has been carried out to identify the presence of subsurface water in Selulung Village, Kintamani District, Bangli Regency using 2D geoelectric methods. The work process of this research is the first to collect data directly by using a geoelectric device with Wenner configuration. Electric currents are injected from the surface to the subsurface through the current electrodes which are put on the earth's surface. The collected data is then processed using the Res2Din software version 3.71.118. The software results in the form of 2D images are direct lateral images of subsurface structures. From the three trajectories identified, namely at the coordinates  8°12'18.7"S 115°16'08.3"E the lowest resistivity value was 178 Ohm m with a depth of 10 m which was thought to be a rock layer with surface water content. On line 2 at coordinates 8°12'16.1"S 115°16'09.7"E the resistivity value is 6 ohm.m up to 660,000 ohm.m, the maximum depth obtained is 24 m. This line is thought to be a water-bearing layer because the value of resistance is low. Line 3 which is in the coordinates 8°12'16.3"S 115°15'50.0"E the distribution of resistivity values varies from 42 - 9,400 Ohm m.

Inverse Methods to Improve Accuracy of Water Content Estimates from Multi-offset GPR

2018 ◽  
Vol 23 (3) ◽  
pp. 349-361
Author(s):  
Andrew D. Parsekian
Keyword(s):  
Water Content ◽  
Careful Analysis ◽  
Subsurface Water ◽  
Geologic Materials ◽  
Improve Accuracy ◽  
The Subject ◽  
Interval Velocities ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Impact

Ground penetrating radar (GPR) is a powerful hydrogeophysical tool for estimating porosity and water content of geologic materials using radar wave velocities and appropriate petrophysical relations. In substrates with more than one layer of interest, surface-based multi-offset measurements require careful analysis to accurately retrieve physical properties for each layer. Frequently, Dix inversion is used to calculate interval velocities, however the assumptions and limitations of this approach are widely known. In particular for survey geometries and targets encountered with GPR, the assumptions inherent to Dix inversion are readily violated, and therefore inverse modeling is required to avoid velocity error. While the impact on velocity incurred by violating the assumptions of Dix inversion is well understood, the effects on water content estimates have not been widely reported and are therefore the subject of this work. In a subsurface representative of an unsaturated zone overlying an aquifer, error in excess of 50% in water content due to violating the assumptions of Dix inversion is demonstrated. Examples are shown using raytracing inversion to solve for subsurface water content structure that avoids the errors inherent to Dix inversion. These results are intended to underscore the importance of minimizing assumptions and using more correct physics when analyzing multi-offset GPR data, particularly due to the large potential errors that may be encountered if water content estimation is the main objective.

Algorithms for removing surface water signals from surface nuclear magnetic resonance infiltration surveys

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. WB97-WB107 ◽  
Author(s):  
Samuel Falzone ◽  
Kristina Keating
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Surface Water ◽  
Magnetic Resonance ◽  
Water Content ◽  
Water Resource Management ◽  
Measurement Techniques ◽  
Subsurface Water ◽  
Aquifer Storage ◽  
Water Signal ◽  
Nuclear Magnetic

Surface nuclear magnetic resonance (surface NMR) is a geophysical method that directly detects water and can be used to determine the depth profile of water content within the subsurface. Although surface NMR has proven useful for investigating groundwater in the saturated zone, its use to study the vadose zone is still in development. A recent study for the South Avra Valley Storage and Recovery Project (SAVSARP) demonstrated that surface NMR can be used to monitor infiltrating water associated with aquifer storage and recovery, a water resource management method in which surface water is stored in local aquifers during wet periods for use during dry periods. However, one of the major issues associated with using surface NMR to monitor infiltrating water is the influence of large bodies of surface water. We have examined the effect that large bodies of surface water have on the surface NMR signal, and we have developed three algorithms (the a priori, late-signal, and long-signal-inversion [LSI] algorithms) to remove this signal. Using synthetic data sets, we have assessed the efficacy of each algorithm and determined that, although each algorithm is capable of suppressing the signal from a water layer with a thickness [Formula: see text], the LSI algorithm provides the most accurate and consistent results. Using a field example from the SAVSARP survey, we have evaluated the use of the LSI algorithm to suppress the surface water signal. Our results have indicated that the signal from surface water detected in a surface NMR survey can be suppressed to obtain the subsurface water content without the use of new measurement techniques or additional equipment.

Ground Penetrating Radar for Water Content and Compaction Evaluation: A Laboratory Test on Construction Material

2020 ◽  
Vol 25 (2) ◽  
pp. 169-179
Author(s):  
Hashem Ranjy Roodposhti ◽  
Mohammad Kazem Hafizi ◽  
Mohammad Reza Soleymani Kermani
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Ground Penetrating Radar ◽  
Large Scale ◽  
Construction Material ◽  
Construction Materials ◽  
Dielectric Constants ◽  
Base Layer ◽  
Subsurface Water ◽  
Ground Penetrating

With the aid of ground penetrating radar (GPR), it is possible to evaluate physical properties of a constructed base layer in engineered structures (pavement, land consolidation projects, etc.) non-destructively, quickly, and accurately. High spatial variations of subsurface water content and deficient compaction can lead to unexpected damage and structural instability. In this research, we established a relationship between the dielectric constant, water content, and compaction, whereby, an interactive relationship between these parameters is presented. To achieve this, large-scale laboratory experiments were carried out on construction materials to simulate field conditions. According to USCS, the tested soil type was GW-GM (type E base layer according to Iran's highway specifications code). Furthermore, water content and compaction were changed between 4% -12.9% and 84.7% -94.9%, respectively. The travel-times in each test, including three profiles with more than 210 traces, are measured automatically. Additionally, the calculated dielectric constants were compared with the Topp and Roth equations. R-square and RMS error of the final interactive equation between dielectric constant and water content-compaction were 0.95 and 0.41, respectively. Moreover, the sensitivity analysis of the proposed interactive equation shows that changes in water content of soil have greater impact on dielectric constant than soil compaction changes. The data also indicate the importance of considering the compaction changes of soil to reduce the error in dielectric constant estimation.

Detection of subsurface water storage dynamics with combined gravity - vertical gravity gradient monitoring and hydrological simulation

2020 ◽  
Author(s):  
Anne-Karin Cooke ◽  
Cédric Champollion ◽  
Pierre Vermeulen ◽  
Camille Janvier ◽  
Bruno Desruelle ◽  
...  
Keyword(s):  
Water Content ◽  
Water Storage ◽  
Subsurface Water ◽  
Precipitation Event ◽  
Gravity Gradient ◽  
Small Scale ◽  
Heterogeneous Distribution ◽  
Near Surface ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity

<p>Time-lapse ground-based gravimetry is increasingly applied in subsurface hydrology, providing mass balance constraints on water storage dynamics. For a given water content change as e.g. after a precipitation event, the simplest assumption is that of a homogeneous, infinite slab (Bouguer plate) of water column causing the measurable increase in gravitational attraction. For heterogeneous subsurface environments such as karst aquifers at field scale this assumption may not always hold. The gravity signal is depth-integrated and non-unique, hence indistinguishable from a heterogeneous distribution without further information.</p><p>Exploiting the different spatial sensitivities of gravity and vertical gravity gradient (VGG) data can shed light on the following questions:</p><p> </p><ul><li> <p>Is the subsurface water content within the gravimeter’s footprint likely to be homogeneous or showing small-scale heterogeneity?</p> </li> <li> <p>If not, at which distance are these mass heterogeneities and how large are they?</p> </li> <li> <p>Which monitoring set-ups (tripod heights, number of and distance between VGG measurement locations) are likely to detect mass heterogeneity of which spatial characteristics?</p> </li> </ul><p>One year of monthly vertical gravity gradient surveys has been completed in the geodetic observatory in karstic environment on the Larzac plateau in southern France. We interpret the VGG observations obtained in this field study in the context of further available hydraulic and geophysical data and hydro-gravimetrical simulation. Finally, practical applications in view of detecting near-surface voids and reservoirs of different porosities as well as their storage capacity and seasonal dynamics are evaluated.</p>

What Can Thermal Sensing Reveal in a Forest Tree Nursery?

1983 ◽  
Vol 59 (2) ◽  
pp. 70-73 ◽  
Author(s):  
J. Vlcek ◽  
D. King
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Surface Soil ◽  
Forest Tree ◽  
Subsurface Water ◽  
Typical Result ◽  
Near Surface ◽  
Tree Nursery ◽  
Thermal Sensing

Close range and airborne thermal studies were conducted to examine the near-surface soil water content – surface temperature relationship both quantitatively and qualitatively. A typical result showing the linear correlation between the diurnal surface soil/canopy temperature difference and soil water content at a depth of 5-7 cm for fields covered by seedlings in a forest tree nursery is presented. Interpretation of several thermal images reveals details of natural and artificial surface and subsurface drainage systems in a nursery that are not visible on the ground or on aerial photography. Thermal patterns related to irrigation systems, wind and forest canopies are also examined. Such information is useful in studying subsurface water migration and irrigation efficiency and is an aid to drainage system design and water management practices. Key Words: Thermal sensing, Tree nursery, Subsurface soil moisture, Thermal image interpretation, Artificial, natural draining, Irrigation.

Sign in / Sign up

Export Citation Format

Share Document