scholarly journals The Influence of Clay Content on Cave-ins in Tank Model Tests and Monitoring Indicators of Sinkhole Formation

2019 ◽  
Vol 9 (11) ◽  
pp. 2346 ◽  
Author(s):  
Sueng-Won Jeong ◽  
Byoung-Woo Yum ◽  
Dong-Woo Ryu ◽  
Hong-Jin Lee ◽  
Byeongju Jung
Keyword(s):  
Grain Size ◽  
Groundwater Level ◽  
Water Pressure ◽  
Clay Content ◽  
Model Tests ◽  
Water Levels ◽  
Groundwater Depletion ◽  
Kaolinite Clay ◽  
Tank Model ◽  
Upward Migration

Urban cave-ins may result from a sudden change in local hydrological, hydrogeological and anthropogenic conditions. Monitoring and predicting urban sinkholes is not straightforward, and solving the problem of urban cave-ins involves the incorporation of the fields of geodetics, geophysics and geochemistry. This paper examines the causes and consequences of sinkholes in sand-rich materials by using a small tank model apparatus. Tank model tests were conducted to simulate sinkhole formation, to gain a better understanding of the influencing factors of cavity formation, expansion and upward migration with different cavity water levels. Two commercial materials were used: Jumunjin sand and kaolinite clay. Materials with different grain-size distributions, i.e., sand (100% Jumunjin sand) and sand-clay mixtures (95% sand and 5% kaolinite clay), were considered to examine the roles of clay content in sinkhole risk. The test results show that the sand-rich materials exhibited a typical punching type of sinkhole subsidence and failure, and were very sensitive to changes in groundwater level, regardless of the grain-size distribution. The higher the groundwater level is, the higher the sinkhole risk is in terms of the speed of migration of the underground cavity fluids, cavity size and ground loosening. Therefore, sinkholes in urban areas covered with sand-rich materials are vulnerable to groundwater withdrawal. However, compared with pure sand, materials with small clay contents can reduce the time until collapse and the size of a sinkhole. Variations in pore water pressure may be used as a sinkhole indicator in areas where the ground deformation caused by groundwater depletion is considerable.

scholarly journals Water Budget Analysis Considering Surface Water–Groundwater Interactions in the Exploitation of Seasonally Varying Agricultural Groundwater

Hydrology ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 60
Author(s):  
Sun Woo Chang ◽  
Il-Moon Chung
Keyword(s):  
Groundwater Recharge ◽  
Groundwater Level ◽  
Water Budget ◽  
Artificial Recharge ◽  
Assessment Tool ◽  
Winter Season ◽  
Water Levels ◽  
Groundwater Depletion ◽  
Observation Data ◽  
Budget Analysis

In South Korea, groundwater intended for use in greenhouse cultivation is collected from shallow riverside aquifers as part of agricultural activities during the winter season. This study quantified the effects of intensive groundwater intake on aquifers during the winter and examined the roles of nearby rivers in this process. Observation data were collected for approximately two years from six wells and two river-level observation points on the study site. Furthermore, the river water levels before and after the weir structures were examined in detail, because they are determined by artificial structures in the river. The structures have significant impacts on the inflow and outflow from the river to the groundwater reservoirs. As a result, a decline in groundwater levels owing to groundwater depletion was observed during the water curtain cultivation (WCC) period in the winter season. In addition, we found that the groundwater level increased owing to groundwater recharge due to rainfall and induced recharge by rivers during the spring–summer period after the end of the WCC period. MODFLOW, a three-dimensional difference model, was used to simulate the groundwater level decreases and increases around the WCC area in Cheongwon-gun. Time-variable recharge data provided by the soil and water assessment tool model, SWAT for watershed hydrology, was used to determine the amount of groundwater recharge that was input to the groundwater model. The groundwater level time series observations collected from observation wells during the two-year simulation period (2012 to 2014) were compared with the simulation values. In addition, to determine the groundwater depletion of the entire demonstration area and the sustainability of the WCC, the quantitative water budget was analyzed using integrated hydrologic analysis. The result indicated that a 2.5 cm groundwater decline occurred on average every year at the study site. Furthermore, an analysis method that reflects the stratification and boundary conditions of underground aquifers, hydrogeologic properties, hydrological factors, and artificial recharge scenarios was established and simulated with injection amounts of 20%, 40%, and 60%. This study suggested a proper artificial recharge method of injecting water by wells using riverside groundwater in the study area.

Interaction between water pressure in the basal drainage system and discharge from an Alpine glacier before and during a rainfall-induced subglacial hydrological event

1997 ◽  
Vol 24 ◽  
pp. 288-292 ◽  
Author(s):  
Andrew P. Barrett ◽  
David N. Collins
Keyword(s):  
Water Level ◽  
Water Pressure ◽  
Drainage System ◽  
Water Levels ◽  
Drainage Network ◽  
Alpine Glacier ◽  
Hydraulic Conditions ◽  
Borehole Water ◽  
Progressive Growth ◽  
Resultant Increase

Combined measurements of meltwater discharge from the portal and of water level in a borehole drilled to the bed of Findelengletscher, Switzerland, were obtained during the later part of the 1993 ablation season. A severe storm, lasting from 22 through 24 September, produced at least 130 mm of precipitation over the glacier, largely as rain. The combined hydrological records indicate periods during which the basal drainage system became constricted and water storage in the glacier increased, as well as phases of channel growth. During the storm, water pressure generally increased as water backed up in the drainage network. Abrupt, temporary falls in borehole water level were accompanied by pulses in portal discharge. On 24 September, whilst borehole water level continued to rise, water started to escape under pressure with a resultant increase in discharge. As the drainage network expanded, a large amount of debris was flushed from a wide area of the bed. Progressive growth in channel capacity as discharge increased enabled stored water to drain and borehole water level to fall rapidly. Possible relationships between observed borehole water levels and water pressures in subglacial channels are influenced by hydraulic conditions at the base of the hole, distance between the hole and a channel, and the nature of the substrate.

scholarly journals Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

2021 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
Jae Min Lee ◽  
Sang-Ho Moon ◽  
Kyoochul Ha ◽  
Yongcheol Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Level ◽  
Seismic Waves ◽  
Groundwater Resources ◽  
Fluid Pressure ◽  
Water Levels ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Gyeongju Earthquake

AbstractHydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with ML 5.8 and ML 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The ML 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.

scholarly journals Analysis of Pore Water Pressure and Piping of Hydraulic Well

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Jinman Kim ◽  
Heuisoo Han ◽  
Yoonhwa Jin
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydraulic Gradient ◽  
Water Levels ◽  
Seepage Velocity ◽  
Seepage Analysis

This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.

Research on Simulation of Land Subsidence Characteristics under the Groundwater Level Fluctuation

2013 ◽  
Vol 368-370 ◽  
pp. 1697-1700
Author(s):  
Long Zhang ◽  
Xue Wen Lei ◽  
Qing Shang Meng
Keyword(s):  
Finite Element ◽  
Land Subsidence ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Level Fluctuation ◽  
Finite Element Software ◽  
Coastal Cities ◽  
Groundwater Level Fluctuation

Based on the characteristics of frequent land subsidence events caused by groundwater level fluctuation in coastal cities in China and studying on the quaternary sedimentary soft clay in Shanghai, the effects of groundwater level fluctuation on the deformation of soft clay is simulated by Geo-Studio finite element software. It has summarized the law of deformation, effective stress with the change of groundwater level fluctuation, especially the process of dissipation of pore water pressure with the groundwater level fluctuation. The low can be sued as a reference for similar engineering and land subsidence prevention.

Detecting land deformation due to groundwater changes with InSAR observations - the case of the island of Gotland, Sweden

2021 ◽  
Author(s):  
Mehdi Darvishi ◽  
Fernando Jaramillo
Keyword(s):  
Land Subsidence ◽  
Groundwater Level ◽  
Ground Deformation ◽  
Soil Depth ◽  
Ground Surface ◽  
Groundwater Depletion ◽  
Groundwater Levels ◽  
Small Baseline Subset ◽  
Small Baseline ◽  
The Baltic

<p>In the recent years, southern Sweden has experienced drought conditions during the summer with potential risks of groundwater shortages. One of the main physical effects of groundwater depletion is land subsidence, a geohazard that potentially damages urban infrastructure, natural resources and can generate casualties. We here investigate land subsidence induced by groundwater depletion and/or seasonal variations in Gotland, an agricultural island in the Baltic Sea experiencing recent hydrological droughts in the summer. Taking advantage of the multiple monitoring groundwater wells active on the island, we explore the existence of a relationship between groundwater fluctuations and ground deformation, as obtained from Interferometric Synthetic Aperture Radar (InSAR). The aim in the long-term is to develop a high-accuracy map of land subsidence with an appropriate temporal and spatial resolution to understand groundwater changes in the area are recognize hydroclimatic and anthropogenic drivers of change.</p><p>We processed Sentinel-1 (S1) data, covering the time span of 2016-2019, by using the Small BAseline Subset (SBAS) to process 119 S1-A/B data (descending mode). The groundwater level of Nineteen wells distributed over the Gotland island were used to assess the relationship between groundwater depletion and the detected InSAR displacement. In addition to that, the roles of other geological key factors such as soil depth, ground capacity in bed rock, karstification, structure of bedrock and soil type in occurring land subsidence also investigated. The findings showed that the groundwater level in thirteen wells with soil depths of less than 5 meters correlated well with InSAR displacements. The closeness of bedrock to ground surface (small soil depth) was responsible for high coherence values near the wells, and enabled the detection land subsidence. The results demonstrated that InSAR could use as an effective monitoring system for groundwater management and can assist in predicting or estimating low groundwater levels during summer conditions.</p>

Direct Measurement of Basal Water Pressures: a Pilot Study

1976 ◽  
Vol 16 (74) ◽  
pp. 205-218 ◽  
Author(s):  
Steven M. Hodge
Keyword(s):  
Pilot Study ◽  
Direct Measurement ◽  
Water Pressure ◽  
Water System ◽  
Water Levels ◽  
Hole Drilling ◽  
Glacier Surface ◽  
Term Trend ◽  
Long Term Trend

AbstractBore-hole drilling techniques have been used to connect with the subglacial water system of the temperate South Cascade Glacier. The water level in a connecting bore hole probably represents a direct measurement of the basal water pressure over an area at least to m in extent. Fluctuations of up to 40 m in bore-hole water levels occur typically over periods of several days and often peak about 2 d after large changes in water input at the glacier surface. The long-term trend in bore-hole water levels supports the idea of seasonal storage and release of liquid water.

scholarly journals Combined measurements of Subglacial Water Pressure and Surface Velocity of Findelengletscher, Switzerland: Conclusions about Drainage System and Sliding Mechanism

1986 ◽  
Vol 32 (110) ◽  
pp. 101-119 ◽  
Author(s):  
Almut Iken ◽  
Robert A. Bindschadler
Keyword(s):  
Functional Relationship ◽  
Water Pressure ◽  
Drainage System ◽  
High Water ◽  
Water Levels ◽  
Surface Velocity ◽  
Glacier Surface ◽  
Measured Velocity ◽  
Sliding Mechanism ◽  
Velocity Variations

AbstractDuring the snow-melt season of 1982, basal water pressure was recorded in 11 bore holes communicating with the subglacial drainage system. In most of these holes the water levels were at approximately the same depth (around 70 m below surface). The large variations of water pressure, such as diurnal variations, were usually similar at different locations and in phase. In two instances of exceptionally high water pressure, however, systematic phase shifts were observed; a wave of high pressure travelled down-glacier with a velocity of approximately 100 m/h.The glacier-surface velocity was measured at four lines of stakes several times daily. The velocity variations correlated with variations in subglacial water pressure. The functional relationship of water pressure and velocity suggests that fluctuating bed separation was responsible for the velocity variations. The empirical functional relationship is compared to that of sliding over a perfectly lubricated sinusoidal bed. On the basis of the measured velocity-pressure relationship, this model predicts a reasonable value of bed roughness but too high a sliding velocity and unstable sliding at too low a water pressure. The main reason for this disagreement is probably the neglect of friction from debris in the sliding model.The measured water pressure was considerably higher than that predicted by the theory of steady flow through straight cylindrical channels near the glacier bed. Possible reasons are considered. The very large disagreement between measured and predicted pressure suggests that no straight cylindrical channels may have existed.

scholarly journals STUDY OF THE PROGRESS OF SEAWATER INTRUSION WITHIN A PLAIN AREA OF RHODOPE PREFECTURE

2004 ◽  
Vol 36 (4) ◽  
pp. 2057 ◽  
Author(s):  
Φ. Πλιάκας ◽  
I. Διαμαντής ◽  
A. Καλλιώρας ◽  
Χ. Πεταλάς
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Seawater Intrusion ◽  
Groundwater Level ◽  
Specific Electrical Conductivity ◽  
Chemical Analyses ◽  
Conductivity Measurements ◽  
Groundwater Level Fluctuations ◽  
Plain Area ◽  
Groundwater Samples

This paper investigates the progress of seawater intrusion within the plain area of Xylagani - Imeros, in SW part of Rhodope Prefecture, as well as the suitability of groundwater for several purposes, after qualitative valuation of groundwater samples from selective wells of the study area. The conclusions also include some managerial suggestions for the confrontation of seawater intrusion. The investigation in question took place between 1994-1997 and 2002-2003, and involves the installation of piezometric wells, geoelectric sounding measurements, grain size analyses, monitoring of the groundwater level fluctuations in selective wells, specific electrical conductivity measurements and chemical analyses of water samples from selective wells of the study area.

scholarly journals Determination of diurnal water level fluctuations in headwaters

2016 ◽  
Vol 47 (4) ◽  
pp. 888-901 ◽  
Author(s):  
Marek Marciniak ◽  
Anna Szczucińska
Keyword(s):  
Water Temperature ◽  
Water Level ◽  
Air Temperature ◽  
Hyporheic Zone ◽  
Water Pressure ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Diurnal Changes ◽  
Atmospheric Conditions ◽  
Diurnal Fluctuations

The aim of this paper is to study diurnal fluctuations of the water level in streams draining headwaters and to identify the controlling factors. The fieldwork was carried out in the Gryżynka River catchment, western Poland. The water levels of three streams draining into the headwaters via a group of springs were monitored in the years 2011–2014. Changes in the water pressure and water temperature were recorded by automatic sensors – Schlumberger MiniDiver type. Simultaneously, Barodiver type sensors were used to record air temperature and atmospheric pressure, as it was necessary to adjust the data collected by the MiniDivers calculate the water level. The results showed that diurnal fluctuations in water level of the streams ranged from 2 to 4 cm (approximately 10% of total water depth) and were well correlated with the changes in evapotranspiration as well as air temperature. The observed water level fluctuations likely have resulted from processes occurring in the headwaters. Good correlation with atmospheric conditions indicates control by daily variations of the local climate. However, the relationship with water temperature suggests that fluctuations are also caused by changes in the temperature-dependent water viscosity and, consequently, by diurnal changes in the hydraulic conductivity of the hyporheic zone.

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