scholarly journals River sedimentation modeling using ground-penetrating radar

2021 ◽  
Vol 873 (1) ◽  
pp. 012041
Author(s):  
M A Firdaus ◽  
Widodo ◽  
Fatkhan
Keyword(s):  
Water Quality ◽  
Ground Penetrating Radar ◽  
Rapid Decline ◽  
Subsurface Imaging ◽  
Geophysical Method ◽  
Geological Models ◽  
Different Depths ◽  
Set Up ◽  
Ground Penetrating ◽  
Synthetic Models

Abstract In recent years, siltation has become quite a problem. It has been the main cause of flooding and a rapid decline in water quality. It is usually caused by a high river sedimentation rate and/or uncontrolled waste disposal. The increased rate of erosion also means that river sedimentation occurs faster than normal and could lead to environmental hazards, wildlife deaths, and the disruption of food and drinking water supply among other things. The question is how to monitor the sedimentation process of rivers without damaging the river itself. The suitable geophysical method is GPR. GPR is an active, non-intrusive geophysical method in which electromagnetic radiation and the reflected signals in the form of radar pulses are used for subsurface imaging. The objective is to investigate river sedimentation using GPR, we created the synthetic models based on geological models of rivers with different depths to create their 2-D radargrams to predict the actual model. We set up the first model RSM-I as control which consists of a layer of freshwater with ρ = 16 Ωm, k = 81 and μ r = 1 of depth 5 m, two layers of sandstone with ρ = 850 Ωm, k = 2.5 and μ r = 1 of total depth 4 m, and a layer of claystone with ρ = 120 Ωm, k = 11 and μ r = 1 of depth 1 m. RSM-II and III are added with a buildup of saturated sediment with ρ = 30 Ωm, k = 15, and μ r = 1 of depth 2.5 and 4 m, respectively. The radargrams’ reflector for each model shows a two-way travel time of 300-350, 150-200, and 60-90 ns in their respective order. GPR models can differentiate between the saturated sediment and freshwater, it shows good results regarding sediment investigation in rivers.

REFLECTIVITY OF ELECTROMAGNETIC (EM) WAVE IN SHALLOW GROUND PENETRATING RADAR (GPR) SURVEY

2016 ◽  
Vol 78 (7-3) ◽  
Author(s):  
Nur Azwin Ismail ◽  
Nordiana Mohd Muztaza ◽  
Rosli Saad
Keyword(s):  
Dielectric Properties ◽  
Ground Penetrating Radar ◽  
Geophysical Method ◽  
Wave Reflections ◽  
Material Parameters ◽  
Geophysical Surveys ◽  
Underground Utilities ◽  
Dielectric Contrast ◽  
Different Depths ◽  
Ground Penetrating

Ground Penetrating Radar (GPR) is a geophysical method that is widely used in geophysical surveys, civil engineering applications, archaeological studies and locating underground utilities or hidden objects. It works by sending electromagnetic (EM) wave into the ground by transmitter and recording the returning signals by receiver. The returning signals bring information about the materials and changes in material parameters at different depths. The changes in dielectric properties () of two adjacent media result in EM wave reflections. In this study, several types of materials with different dielectric properties () are used in order to identify the reflectivity of the EM wave. Results prove that the larger the dielectric contrast, the higher the reflection coefficient thus the stronger the reflection.

Exploring the Japan Cave in Taman Hutan Raya Djuanda, Bandung Using GPR

2018 ◽  
Vol 23 (3) ◽  
pp. 377-381
Author(s):  
Widodo Widodo ◽  
Azizatun Azimmah ◽  
Djoko Santoso
Keyword(s):  
Dielectric Permittivity ◽  
Ground Penetrating Radar ◽  
Field Data ◽  
Geophysical Methods ◽  
Forward Modeling ◽  
Additional Line ◽  
Reflection Amplitude ◽  
Underground Cavities ◽  
Ground Penetrating ◽  
Synthetic Models

Investigating underground cavities is vital due to their potential for subsidence and total collapse. One of the proven geophysical methods for locating underground cavities at a shallow depth is ground penetrating radar (GPR). GPR uses contrasting dielectric permittivity, resistivity, and magnetic permeability to map the subsurface. The aim of this research is to prove that GPR can be applied to detect underground cavities in the Japan Cave of Taman Hutan Raya Djuanda, in Bandung, Indonesia. Forward modeling was performed first using three representative synthetic models before field data were acquired. The data acquisition was then conducted using a 100 MHz GPR shielded antenna with three lines of 80 m and one additional line 10 m long. The result showed a region of different reflection amplitude, which was proven to be the air-filled cavities.

scholarly journals Use of Ground Penetrating Radar, Hydrogeochemical Testing, and Aquifer Characterization to Establish Shallow Groundwater Supply to the Rehabilitated Ni-les’tun Unit Floodplain: Bandon Marsh, Coquille Estuary, Oregon, USA

2020 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Curt D. Peterson ◽  
Harry M. Jol ◽  
David Percy ◽  
Robert Perkins
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Ground Penetrating Radar ◽  
Capillary Rise ◽  
Shallow Groundwater ◽  
Shallow Aquifer ◽  
Salinity Intrusion ◽  
Channel Network ◽  
Groundwater Supply ◽  
Ground Penetrating

Fluvial-tidal wetlands in the Ni-les’tun Unit (~200 hectares) of the Bandon Marsh, Coquille Estuary, Oregon, were analyzed for shallow aquifer conditions that could influence surface water-qualities in reconstructed marsh, pond, and discharge/tidal channels. The wetlands were surveyed for pre-historic channel features, depth to groundwater surface (GWS), and subsurface salinity intrusion by ground penetrating radar (GPR) in 50 profiles, totaling 11.1 km in track line distance. Only small flood-discharge/tidal channel features (<10 m width and 1–2 m depth) were recorded in the interior floodplain areas. GWS reflections were observed at 0.5–2.0 depth, where the GPR signal was not obscured by localized salinity intrusion (~0.5 km landward distance) from the adjacent Coquille Estuary channel. Top-sealed piezometers (1.5–2.0 m depth) were installed at 10 sites, where in-situ groundwaters were monitored for temperature (8.5–16.5° C), conductivity (<100–18,800 μS cm-1), and pH (2.5–7.8) on a seasonal basis. Dissolved oxygen was semi-quantitatively measured (ChemSticks) at some sites, and all sites were monitored (fall, winter, summer) for GWS level. Low dissolved oxygen (DO <1 ppm) at four sites was of particular concern for potential discharge into small channels that were to be constructed for juvenile salmonid nursery habitat. The horizontal and vertical asymmetries of conductivity (salinity), used as a conservative groundwater source tracer, and measured GWS elevation trends (gradients) led to a four-part flow model for shallow groundwater supply in the Ni-les’tun floodplain. Freshwater supplied, in part, by hillslope discharge contributes to low pH and low DO water quality in the shallow aquifer. Saline water, supplied by subsurface salinity intrusion and evaporative capillary rise, could introduce salinity toxicity to isolated (stagnant) surface ponds. Following construction of a dense channel network (2009–2011) by the Bandon Marsh National Wildlife Refuge, selected Ni-les’tun channel waters (13 sites) were monitored (2011-2012) for resulting water-quality. The tidally-connected channels generally showed improved water-quality relative to groundwater in some nearby piezometer sites. However, low-quality groundwater supply compromised some channel reaches (DO ~2.0–4.7 ppm) that depended on groundwater recharge from hillslope discharge during either summer or winter conditions.

scholarly journals Underground Pipeline Identification into a Non-Destructive Case Study Based on Ground-Penetrating Radar Imaging

2021 ◽  
Vol 13 (17) ◽  
pp. 3494 ◽  
Author(s):  
Nicoleta Iftimie ◽  
Adriana Savin ◽  
Rozina Steigmann ◽  
Gabriel Silviu Dobrescu
Keyword(s):  
Ground Penetrating Radar ◽  
Multiple Interfaces ◽  
Background Removal ◽  
Subsurface Sensing ◽  
Different Depths ◽  
Location Depth ◽  
And Migration ◽  
Ground Penetrating ◽  
Non Destructive

Ground-penetrating radar (GPR) has become one of the key technologies in subsurface sensing and, in general, in nondestructive testing (NDT), since it is able to detect both metallic and nonmetallic targets. GPR has proven its ability to work in electromagnetic frequency range for subsoil investigations, and it is a risk-reduction strategy for surveying underground various targets and their identification and detection. This paper presents the results of a case study which exceeds the laboratory level being realized in the field in a real case where the scanning conditions are much more difficult using GPR signals for detecting and assessing underground drainage metallic pipes which cross an area with large buildings parallel to the riverbed. The two urban drainage pipes are detected based on GPR imaging. This provides an approximation of their location and depth which are convenient to find from the reconstructed profiles of both simulated and practical GPR signals. The processing of data recorded with GPR tools requires appropriate software for this type of measurement to detect between different reflections at multiple interfaces located at different depths below the surface. In addition to the radargrams recorded and processed with the software corresponding to a GPR device, the paper contains significant results obtained using techniques and algorithms of the processing and post-processing of the signals (background removal and migration) that gave us the opportunity to estimate the location, depth, and profile of pipes, placed into a concrete duct bank, under a structure with different layers, including pavement, with good accuracy.

Side‐looking underground radar (SLUR): Physical modeling and case history

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1925-1932 ◽  
Author(s):  
Jeffrey J. Daniels ◽  
James Brower
Keyword(s):  
Cross Sections ◽  
Ground Penetrating Radar ◽  
Physical Modeling ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Plan View ◽  
Different Depths ◽  
Ground Penetrating ◽  
Oriented Object ◽  
Horizontal Layers

A modification of conventional surface ground‐penetrating radar (GPR) was conceived, tested, and successfully applied in the field at Brookhaven National Laboratory (BNL) to investigate waste pits. The modified GPR method consists of making measurements along a traverse line in a sloping trench with the radar’s antenna oriented at an angle of up to 45° from the horizontal. The direction of propagation of the electromagnetic field for this configuration is not vertical, and the amount of energy scattered from objects that are oriented vertically relative to the energy scattered from horizontal layers is increased. This fundamental feature of side‐looking underground radar (SLUR) measurements is illustrated by physical modeling. Measurements made along parallel trenches that are offset at different distances from a vertically oriented object provides GPR cross‐sections with a primary plane of investigation that intersects the vertical feature at different depths. SLUR was used at BNL in conjunction with conventional surface GPR measurements (displayed as 3-D blocks and plan‐view time slices) to enhance the vertical definition and improve the depth estimates of the waste pits.

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