• 한국지구물리탐사학회:학술대회논문집
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• 2000.09a
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• pp.19-40
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• 2000

We applied both SP monitoring and pole-pole array resistivity surveys and SP survey and dipole-dipole array resistivity survey to leakage problems in several embankments and dike, respectively, to estimate and detect the zone of leakage. The embankment is generally affected by tidal variation and has low resistivity characteristics due to the high saturation of seawater. According to this situation, SP monitoring and resistivity survey using pole-pole electrode array, which is relatively more effective to the conductive media, were carried out to delineate the leakage zones of sea water through the embankment. We checked out electrical conductivity(EC) and temperature variations along the inner part of the embankment to detect the zone of seawater leakage and found that the measured EC value agreed to that of seawater in the leakage zone and the temperature was lower than that of the vicinity of leakage zone. SP monitoring results were coincide with tidal variations at each embankment. Based on the survey results, it is concluded that both SP monitoring and the pole-pole array resistivity method are quite effective for investigation of seawater leakage zones in the embankment.

• Journal of Korea Water Resources Association
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• v.56 no.10
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• pp.679-690
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• 2023

Leakage is one of the representative abnormal conditions in Water distribution systems (WDSs). Leakage can potentially occur and cause immediate economic and hydraulic damage upon occurrence. Therefore, leakage detection is essential, but WDSs are located underground, it is difficult. Moreover, when multiple leakage occurs, it is required to prioritize restoration according to the scale and location of the leakage, applying for an optimal restoration framework can be advantageous in terms of system resilience. In this study, various leakage scenarios were generated based on the WDSs hydraulic model, and leakage detection was carried out containing location and scale using a Deep learning-based model. Finally, the leakage location and scale obtained from the detection results were used as a factor for the priority of leakage restoration, and the results of the priority of leakage restoration were derived. The priority of leakage restoration considered not only hydraulic factors but also socio-economic factors (e.g., leakage scale, important facilities).

• Geophysics and Geophysical Exploration
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• v.25 no.3
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• pp.120-128
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• 2022

There are 17,000 reservoir dams in Korea, of which more than 85% were built over 50 years ago. Old embankment dams are weakened by internal erosion and suffusion phenomena due to preferential leakage paths and this ongoing weakening can cause their failure. Therefore, early warning associated with leakage in an embankment dam is crucial to prevent its failure. An electrical resistivity survey is a non-destructive, real-time and in-situ technique for detecting the development of leakage zones and general conditions of embankment dams. Because of its advantages, the electrical resistivity survey is widely used for reservoir safety inspections. However, the electrical resistivity survey is still not officially included in the precise safety inspection of reservoir dams because it cannot present a quantitative index of dam safety. In this study, we propose a method for calculating the leak index according to the water content evaluated from the electrical resistivity survey and/or induced polarization survey. Particularly, by proposing a quantitative leak index calculation method from monitoring surveys and independent surveys, we provide a theoretical basis for including electrical resistivity and induced polarization surveys as components of the precise safety inspection of reservoirs dams.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.240-257
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• 1999

More than 16 percent of the total 18,032 reservoirs over the country were reported to have leakage problems and need to be improved. Recently, a great deal of progress was made in geophysical survey techniques, particularly in electrical resistivity, and the techniques are used for variety of Purposes in groundwater and dam management due to its economical advantages. This document describes the re-evaluation of existing resistivity data including newly surveyed data, mapping of modeled value in 2-D analysis to locate seepage pathways, This contains also discussion results of more than eighteen years of professional experiences in the field of dam efficiency improvement. In comparison of surface resistivity data with several soil analysis data in laboratory, it is evident that the surface resistivity value shows a qualitative proportionality with the sand contents of the filling materials in earth dam. The result from the study also indicates that the SP method in subsurface investigation is effective to detect seepage in earth filled dam as well as piping through rock/earthfill dike.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1271-1274
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• 2006

지하레이다(Ground Penetrating Radar, GPR)를 이용하여 지표하의 상수관로를 지표에서 송신안테나와 수신안테나를 이용해서 손쉽게 측정하게 된다. 송신안테나는 지표하에 전자기파를 송신하고 지하 매질을 투과한 파가 수신안테나에 도달하는 시간을 측정하여 지표하 매질의 특성을 파악할 수 있다. 수신파의 도달시간은 지표하 매질의 특성에 따라서 변화하며, 이를 통해 지표하 매질과 매질 깊이 등을 파악할 수 있다. 일반적으로 상수관로를 매설할 경우 관로 주변의 토양은 균등하게 되므로 기 매설된 상수관로 주변에 누수가 발생하게 되면, 관로 주변의 토양은 포화상태이거나 수압으로 인해서 공동이 형성될 경우가 많다. 이때 반사에너지의 유전율 증가 혹은 감소 특성으로 인해서 주변 매질과는 매우 상이한 결과를 보이게 된다. GPR탐사는 단순히 반사된 신호진폭의 크기를 나타내며 이러한 반사에너지의 크기에 관계되는 것은 매설물의 유전율이 주위 지반이 갖는 유전율과의 차이에서 기인하기 때문이다. 탐사 대상 상수관로에 대한 정보를 확보하여 GPR 탐사를 수행한 결과 관로 탐사를 위한 GPR의 결과는 매우 유용하게 사용될 것으로 판단되며, 이를 바탕으로 누수 발생 이력이 있는 다양한 관로주변 조건을 대상으로 탐사를 실시할 경우 상수관망시스템의 효율적인 관리 및 보수에 매우 유용한 방법이 될 수 있을 것으로 판단된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.616-624
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• 2003

The exhaustion of our water resource due to the leakage of waterworks renders it urgent to detect water leakage effectively. In the paper, the detection of water leakage makes use of a pound-penetrating radar(GPR). The region of water leakage is implemented by an acryl box filled with methanol, and then the scale-down experiments are performed by using the GPR system developed in our laboratory. The validity of GPR experiments is assured by showing that the measured data agree well with those finite-difference time-domain(FDTD) simulated results in the same situation. The feasibility of GPR system for the detection of water leakage is investigated by displaying B-scan images according to the distribution of water leakage.

• Economic and Environmental Geology
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• v.46 no.2
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• pp.105-121
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• 2013

This study introduces integrated approach on detection of a leakage in a sea wall based on remote sensing, electric resistivity survey, electromagnetic survey, and borehole survey for the Seosan A-Region sea wall. The satellite temperature distribution from Landsat ETM+ data identifies water leakage distribution and period by analyzing temperature mixing patterns between sea water and fresh water. Electric resistivity survey provides both horizontal and vertical anomaly distributions over the sea wall showing below average electric resistivity. Electromagnetic survey(electrical conductivity survey) reveals the potential possible leakage areas with minimal background impact by comparing electrical conductivity values between high and low tides. Borehole image processing system confirmed the locations of anomalies identified from the other survey methods and distributions of vertical fracture zones. The integrated approach identified 41.7% of the sea wall being the most probable area vulnerable to water leakage and effectively approximated both horizontal and vertical distribution of water leakage. The integrated analysis of remote sensing, electric resistivity survey, electromagnetic survey and borehole survey is considered to be an optimal method in identifying water leakage distribution, period, and extent of fractures knowledged from the boreholes.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.5-13
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• 2013

The water leakage of reservoir embankment usually occurs around channelling pipes, which gives little influence on the embankment in a normal state. However, the embankment can be destroyed when the water level of reservoir increases with heavy rain and the rainy season in summer. Investigating the water vein and its path is therefore very important from the viewpoint of disaster prevention and embankment maintenance. The water leakage in dams and levees where the channelling pipes are working as weak zone was analyzed by using both numerical simulation and experimental method in this study. To detect the water leakage, an electrical resistivity survey was used and investigated for its' usability. The numerical results show the size and location of weak zone increases the importance of selection of electrode spacing. The leakage experiments of model embankment present the best result is obtained under the conditions of electrode spacing of 0.3m and dipole-dipole array. By studying the water leakage in dams and levees, the electrical resistivity survey is observed it is a very useful method to predict the leakage.

• 한국지구물리탐사학회:학술대회논문집
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• 2002.09a
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• pp.179-195
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• 2002

This paper examined the applicability of geophysical prospecting for water leakage detection of the water utilization facilities. Electrical resistivity survey and spontaneous-potential survey were carried out for the water leakage detection of dike and embankment, and the applicability was confirmed from many case studies. However, in order to efficiently maintain and detection of the more accurate water points in the embankment, the efficiently maintain and detection of the more accurate water leakage points in the embankment, the requirements are as follows; 1) It is necessary to use the electrical resistivity survey jointly with the spontaneous-potential survey in order to improve the reliability of water leakage information. 2) It is important to understand physical properties of the soil which influences the electrical resistivity of embankment in order to accurately grasp the water leakage points from the result of the electrical resistivity survey. 3) It is necessary to introduce the three-dimensional prospecting in order to improve the reliability of the measured value. 4) Introductions of the monitoring measurement system are necessary in order to efficiently and economically maintain of the water utilization facilities.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.397-406
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• 2010

Resistivity method is a practical and effective geophysical technique to detect leakage zones in embankment dams. Generally, resistivity survey conducted along the crest assumes that the embankment dam has a 2D structure. However, the 3D topography of the embankment distorts significantly resistivity data measured on anywhere of the dam. This study evaluates the influence from 3D effects created by specific dam geometry and effects of water level fluctuations through the 3D finite element modeling technique. Also, a comparison between different locations of survey line are carried out, and topographic correction technique is developed for the resistivity data obtained along the embankment dam. Furthermore, using synthetic resistivity data for an embankment dam model with leakage zone, detectability of leakage zones is estimated through 2.5D inversion.