The objective of this study is to understand the validity of salinity vertical profiles collected from shallow piezometers that are not previously flushed. This study shows that salinity data collected from boreholes ...The objective of this study is to understand the validity of salinity vertical profiles collected from shallow piezometers that are not previously flushed. This study shows that salinity data collected from boreholes are only an average value along the entire screened section of the piezometer. In order to collect data that is rep-resentative for the salinity of the adjacent aquifer, a new monitoring strategy has been developed. This strat-egy includes measurement of the salinity at the top of the watertable in an auger hole which is a shallow boreholes made with an handheld drill. This should be combined with measurements in piezometers that are first flushed to take out stagnant water. From the piezometers on can measure the average salinity of the screened part and the salinity at the bottom of the aquifer. By using this monitoring strategy it is also possi-ble to define where the piezometers screens are located if this is not known beforehand.展开更多
It is very important for secure mining under water bodies to study the effects of Iongwall mining on the underground water. In order to study this problem, piezometers for monitoring underground water levels were esta...It is very important for secure mining under water bodies to study the effects of Iongwall mining on the underground water. In order to study this problem, piezometers for monitoring underground water levels were established in an American coalmine. Large amounts of pre-mining and post-mining monitoring data were collected. Based on the data the effects of Iongwall mining on the underground water was studied. The results demonstrate that when the piezometer monitoring wells have an interburden thickness less than 72.7 m, the groundwater level decreases immediately to immeasurable levels and go dry after undermining. The height of the fractured zone in is 72.7-85.3 m in this geological and mining conditions. The results also show that the calculated value of fractured zone by the empirical formulae used in China is smaller than the actual results. Therefore, it is not always safe to use them in analysis of mining under water bodies.展开更多
Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of th...Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. Here we compare the seismic measurements with actual piezometric data acquired on the Crépieux-Charmy (Lyon, France) groundwater exploitation field. We show the excellent correspondance between variations in the groundwater level and seismic velocity variations. We present hereafter the time and space monitoring of an hydraulic dome formed to prevent biological and chemical pollutions to enter the exploitation field. The horizontal resolution is solely limited by the number of seismic stations used, and is about 30 m in the present study. The vertical resolution of seismic measurement is impaired by spurious artifacts linked to the intermittent sources of noise. In average, the sensitivity of the seismic velocity change corresponds to a 50 cm change of waterlevel. This study confirms the possibility of groundwater monitoring in an industrial context with ambient seismic noise.展开更多
Nowadays underground structures are very important. Based on observations of engineering;properties during geotechnical construction are an integral part of the design of underground structures. This research presents...Nowadays underground structures are very important. Based on observations of engineering;properties during geotechnical construction are an integral part of the design of underground structures. This research presents instrumentation as a tool to assist with these measurement observations, determine the need for modifications to loading or support arrangement. Also apart from above construction control, instrumentation is also indispensable for site investigation, design verification and safety of the structure. Instrumentation used in the construction of tunnels and subways can be implemented in three stagesbefore, during operation and during operation are examined. Metro Railway Tunnels are constructed in populated area and have a more comprehensive instrumentation and monitoring program that additionally includes monitoring of ground conditions, underground water levels, tilt and settlement of nearby buildings or other structures of interest in the vicinity of the tunnel alignment. Instrumentation monitoring for metro railway tunnels includes monitoring of the structures under construction together with the ground, buildings and other facilities within the predicted zone of influence. Furthermore, instrumentation and subway tunnels in and around them increase accuracy of the different layers of the earth and excavation of the surrounding structures and make safety and accuracy. This paper presents the features of sophisticated instrumentation available today for geotechnical monitoring. A wide range of sophistic have been described with their applications ted electronic and mechanical instrumentation with different instrumentation schemes used to meet the requirements of different types of structures.展开更多
The effect of the vertical flow direction of hyporheic flux on the bacterial community is examined.Vertical velocity change of the hyporheic zone was examined by installing a piezometer on the site,and a total of 20,2...The effect of the vertical flow direction of hyporheic flux on the bacterial community is examined.Vertical velocity change of the hyporheic zone was examined by installing a piezometer on the site,and a total of 20,242 reads were analyzed using a pyrosequencing assay to investigate the diversity of bacterial communities.Proteobacteria(55.1%)were dominant in the hyporheic zone.展开更多
In recent years,water levels in some of the most heavily tapped aquifers(Upper Cretaceous)in the Beninese Mono River basin have fallen to the point where some boreholes,which used to have a permanent regime,now have a...In recent years,water levels in some of the most heavily tapped aquifers(Upper Cretaceous)in the Beninese Mono River basin have fallen to the point where some boreholes,which used to have a permanent regime,now have a temporary regime,raising questions among the population.This study attempts to answer these questions by analyzing the behavior of the Upper Cretaceous aquifer reservoir at the Athiéméoutlet,in the Benin portion of the Mono River watershed.It was based on statistical tests.To this end,the Students’t-test at 95%confidence for linear trend analysis was applied to static data collected from 5 piezometric stations around the Cretaceous aquifer recharge zone,covering the period from 2007 to 2020.Next,Pettitt break detection tests and the Bayesian method of LEE and HEGHINIAN were used to study the homogeneity of the various static levels of the aquifer’s wells and boreholes around its recharge zone on these data.The results showed that four(04)of the five(05)piezometric stations used are representative of the hydrodynamic functioning of the aquifer,with the exception of the Volly-Latadji piezometer in Aplahoué.These piezometric stations showed a significant downward trend in static levels until 2020,with a clear break in 2013.Compared with the 2007-2013 sub-period,water levels in the aquifer’s catchment structures(wells and boreholes)rose by 23%in the center of the aquifer,10%in the northeast and south,and 11%in the southwest,between 2014 and 2020.This increase in the aquifer’s water resources,which today contrasts with the realities on the ground,raises concerns about the future of the area’s groundwater resources,and calls for in-depth reflection on the part of all concerned(decision-makers,craftsmen,scientists...).展开更多
文摘The objective of this study is to understand the validity of salinity vertical profiles collected from shallow piezometers that are not previously flushed. This study shows that salinity data collected from boreholes are only an average value along the entire screened section of the piezometer. In order to collect data that is rep-resentative for the salinity of the adjacent aquifer, a new monitoring strategy has been developed. This strat-egy includes measurement of the salinity at the top of the watertable in an auger hole which is a shallow boreholes made with an handheld drill. This should be combined with measurements in piezometers that are first flushed to take out stagnant water. From the piezometers on can measure the average salinity of the screened part and the salinity at the bottom of the aquifer. By using this monitoring strategy it is also possi-ble to define where the piezometers screens are located if this is not known beforehand.
文摘It is very important for secure mining under water bodies to study the effects of Iongwall mining on the underground water. In order to study this problem, piezometers for monitoring underground water levels were established in an American coalmine. Large amounts of pre-mining and post-mining monitoring data were collected. Based on the data the effects of Iongwall mining on the underground water was studied. The results demonstrate that when the piezometer monitoring wells have an interburden thickness less than 72.7 m, the groundwater level decreases immediately to immeasurable levels and go dry after undermining. The height of the fractured zone in is 72.7-85.3 m in this geological and mining conditions. The results also show that the calculated value of fractured zone by the empirical formulae used in China is smaller than the actual results. Therefore, it is not always safe to use them in analysis of mining under water bodies.
文摘Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. Here we compare the seismic measurements with actual piezometric data acquired on the Crépieux-Charmy (Lyon, France) groundwater exploitation field. We show the excellent correspondance between variations in the groundwater level and seismic velocity variations. We present hereafter the time and space monitoring of an hydraulic dome formed to prevent biological and chemical pollutions to enter the exploitation field. The horizontal resolution is solely limited by the number of seismic stations used, and is about 30 m in the present study. The vertical resolution of seismic measurement is impaired by spurious artifacts linked to the intermittent sources of noise. In average, the sensitivity of the seismic velocity change corresponds to a 50 cm change of waterlevel. This study confirms the possibility of groundwater monitoring in an industrial context with ambient seismic noise.
文摘Nowadays underground structures are very important. Based on observations of engineering;properties during geotechnical construction are an integral part of the design of underground structures. This research presents instrumentation as a tool to assist with these measurement observations, determine the need for modifications to loading or support arrangement. Also apart from above construction control, instrumentation is also indispensable for site investigation, design verification and safety of the structure. Instrumentation used in the construction of tunnels and subways can be implemented in three stagesbefore, during operation and during operation are examined. Metro Railway Tunnels are constructed in populated area and have a more comprehensive instrumentation and monitoring program that additionally includes monitoring of ground conditions, underground water levels, tilt and settlement of nearby buildings or other structures of interest in the vicinity of the tunnel alignment. Instrumentation monitoring for metro railway tunnels includes monitoring of the structures under construction together with the ground, buildings and other facilities within the predicted zone of influence. Furthermore, instrumentation and subway tunnels in and around them increase accuracy of the different layers of the earth and excavation of the surrounding structures and make safety and accuracy. This paper presents the features of sophisticated instrumentation available today for geotechnical monitoring. A wide range of sophistic have been described with their applications ted electronic and mechanical instrumentation with different instrumentation schemes used to meet the requirements of different types of structures.
基金supported by the National Research Foundation of Korea funded by the International Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP),granted financial resource from the Ministry of Trade,Industry&Energy,Republic of Korea.(No.20168510050070)the National Research Council of Science&Technology(NST)grant by the Korea government(MSIP)(No.CAP 1705 KIGAM).
文摘The effect of the vertical flow direction of hyporheic flux on the bacterial community is examined.Vertical velocity change of the hyporheic zone was examined by installing a piezometer on the site,and a total of 20,242 reads were analyzed using a pyrosequencing assay to investigate the diversity of bacterial communities.Proteobacteria(55.1%)were dominant in the hyporheic zone.
文摘In recent years,water levels in some of the most heavily tapped aquifers(Upper Cretaceous)in the Beninese Mono River basin have fallen to the point where some boreholes,which used to have a permanent regime,now have a temporary regime,raising questions among the population.This study attempts to answer these questions by analyzing the behavior of the Upper Cretaceous aquifer reservoir at the Athiéméoutlet,in the Benin portion of the Mono River watershed.It was based on statistical tests.To this end,the Students’t-test at 95%confidence for linear trend analysis was applied to static data collected from 5 piezometric stations around the Cretaceous aquifer recharge zone,covering the period from 2007 to 2020.Next,Pettitt break detection tests and the Bayesian method of LEE and HEGHINIAN were used to study the homogeneity of the various static levels of the aquifer’s wells and boreholes around its recharge zone on these data.The results showed that four(04)of the five(05)piezometric stations used are representative of the hydrodynamic functioning of the aquifer,with the exception of the Volly-Latadji piezometer in Aplahoué.These piezometric stations showed a significant downward trend in static levels until 2020,with a clear break in 2013.Compared with the 2007-2013 sub-period,water levels in the aquifer’s catchment structures(wells and boreholes)rose by 23%in the center of the aquifer,10%in the northeast and south,and 11%in the southwest,between 2014 and 2020.This increase in the aquifer’s water resources,which today contrasts with the realities on the ground,raises concerns about the future of the area’s groundwater resources,and calls for in-depth reflection on the part of all concerned(decision-makers,craftsmen,scientists...).
