Monitoring of regional groundwater levels provides important information for quantifying groundwater depletion and assessing impacts on the environment. Historically, groundwater level monitoring wells in Beijing Plai...Monitoring of regional groundwater levels provides important information for quantifying groundwater depletion and assessing impacts on the environment. Historically, groundwater level monitoring wells in Beijing Plain, China, were installed for assessing groundwater resources and for monitoring the cone of depression. Monitoring wells are clustered around well fields and urban areas. There is urgent need to upgrade the existing monitoring wells to a regional groundwater level monitoring network to acquire information for integrated water resources management. A new method was proposed for designing a regional groundwater level monitoring network. The method is based on groundwater regime zone mapping. Groundwater regime zone map delineates distinct areas of possible different groundwater level variations and is useful for locating groundwater monitoring wells. This method was applied to Beijing Plain to upgrade a regional groundwater level monitoring network.展开更多
Objective LGM is a critical climate period in the late Quaternary and is the most recent extreme cold event. Clark et al. （2009） used 4271^14C records and 475 cosmogenic nuclide datings to define LGM be in 26.5-19....Objective LGM is a critical climate period in the late Quaternary and is the most recent extreme cold event. Clark et al. （2009） used 4271^14C records and 475 cosmogenic nuclide datings to define LGM be in 26.5-19.0 kaBP. LGM age often changes with time in different regions （Mix et al., 2001; Zhang Zhigang et al., 2015）. However, LGM has not been described to date in the Beijing region. During our field work in 2015-2017, LGM event stratigraphy was discovered from sevral boreholes in the middle and lower region of Yongding river basin, Southern Beijing plain.展开更多
Through a wide-spread groundwater sampling mainly at nested monitoring wells in the Beijing Plain area, combined with data collection, the study analyzes water level, hydrochemistry, temperature, tritium, deuterium, 1...Through a wide-spread groundwater sampling mainly at nested monitoring wells in the Beijing Plain area, combined with data collection, the study analyzes water level, hydrochemistry, temperature, tritium, deuterium, 180, 14C and other aspects, and in- dicates that there exits an obvious stratification phenomenon of the groundwater in the alluvial plain area down in the middle part of alluvial-pluvial fans, and the hydraulic connection between layers is very weak. The analysis of the tritium concentra- tion suggests that the average influence depth of the modem precipitation is approximately 120 m. Based on the analysis of the 22 paleowater samples through the D-~80 method and 14C isotopic dating, the deep groundwater circulation in the fine sedi- ments area of Beijing Plain down in the fringe part of alluvial-pluvial fans is relatively slow. On average the paleowater point occurs approximately below the 180 m at these points. The main reasons for the formation of stratification and paleowater points are the water-blocking effect of the clay type strata and the compaction effect during the sedimentary process, especially the differential compaction, which could form closed or relatively closed stagnant aquifers. Groundwater in this kind of stagnant aquifers to some degree belongs to non-renewable resource, and should be reconsidered and re-arranged in the water resources management strategy.展开更多
An abundance of the phenomena of tectonic deformation and paleoseismic events of different times and their recurrent interval, as well as coseismic vertical displacements is exposed in Jiuxian trenches across the Nank...An abundance of the phenomena of tectonic deformation and paleoseismic events of different times and their recurrent interval, as well as coseismic vertical displacements is exposed in Jiuxian trenches across the Nankou-Sunhe fault zone in Changping County. The research result shows three paleoearthquakes occurring during the Holocene. They were dated as 10643 ± 250 a B.P.—9706 ± 1235 a B.P., 7894±150 a B.P.—7640 ± 650 a B.P, and 3987+100 a B.P.—3670 ± 310 a B.P, respectively. The coseismic vertical displacements are 1.0 m, 2.0 m, and 2.0 m, respectively. From a statistical formula of relation between historic earthquake magnitudes and surface seismic dislocations in North China, the magnitudes of these paleoearthquakes are inferred to be in a range fromM 7.7 toM 7.9. The research shows that the Holocene fault activity in the plain can be traced in the trenches according to the micro-geomorphic features. Many micro-structural phenomena are also found in these trenches. Identification of the paleoearthquakes in the Nankou-Sunhe fault zone during the Holocene time is of significance for assessment of future seismic risk in Beijing area.展开更多
文摘Monitoring of regional groundwater levels provides important information for quantifying groundwater depletion and assessing impacts on the environment. Historically, groundwater level monitoring wells in Beijing Plain, China, were installed for assessing groundwater resources and for monitoring the cone of depression. Monitoring wells are clustered around well fields and urban areas. There is urgent need to upgrade the existing monitoring wells to a regional groundwater level monitoring network to acquire information for integrated water resources management. A new method was proposed for designing a regional groundwater level monitoring network. The method is based on groundwater regime zone mapping. Groundwater regime zone map delineates distinct areas of possible different groundwater level variations and is useful for locating groundwater monitoring wells. This method was applied to Beijing Plain to upgrade a regional groundwater level monitoring network.
基金financially supported by Beijing 1:50 000 Liulihe,Panggezhuang,Ancixian regional geological survey Projects of China Geological Survey(grant No.12120114007701)
文摘Objective LGM is a critical climate period in the late Quaternary and is the most recent extreme cold event. Clark et al. （2009） used 4271^14C records and 475 cosmogenic nuclide datings to define LGM be in 26.5-19.0 kaBP. LGM age often changes with time in different regions （Mix et al., 2001; Zhang Zhigang et al., 2015）. However, LGM has not been described to date in the Beijing region. During our field work in 2015-2017, LGM event stratigraphy was discovered from sevral boreholes in the middle and lower region of Yongding river basin, Southern Beijing plain.
基金supported by the Groundwater Contamination Investigation Project of Beijing Plain Area (Grant No. PXM2009-158305-074498)
文摘Through a wide-spread groundwater sampling mainly at nested monitoring wells in the Beijing Plain area, combined with data collection, the study analyzes water level, hydrochemistry, temperature, tritium, deuterium, 180, 14C and other aspects, and in- dicates that there exits an obvious stratification phenomenon of the groundwater in the alluvial plain area down in the middle part of alluvial-pluvial fans, and the hydraulic connection between layers is very weak. The analysis of the tritium concentra- tion suggests that the average influence depth of the modem precipitation is approximately 120 m. Based on the analysis of the 22 paleowater samples through the D-~80 method and 14C isotopic dating, the deep groundwater circulation in the fine sedi- ments area of Beijing Plain down in the fringe part of alluvial-pluvial fans is relatively slow. On average the paleowater point occurs approximately below the 180 m at these points. The main reasons for the formation of stratification and paleowater points are the water-blocking effect of the clay type strata and the compaction effect during the sedimentary process, especially the differential compaction, which could form closed or relatively closed stagnant aquifers. Groundwater in this kind of stagnant aquifers to some degree belongs to non-renewable resource, and should be reconsidered and re-arranged in the water resources management strategy.
基金The important item of the Ninth Five-Year Program of China Seismological Bureau. Contribution No.2001A0002, Institute of Crustal Dynamics, China Seismological Bureau.This work was one of the key projects supported by the Ninth Five-Year Program of China
文摘An abundance of the phenomena of tectonic deformation and paleoseismic events of different times and their recurrent interval, as well as coseismic vertical displacements is exposed in Jiuxian trenches across the Nankou-Sunhe fault zone in Changping County. The research result shows three paleoearthquakes occurring during the Holocene. They were dated as 10643 ± 250 a B.P.—9706 ± 1235 a B.P., 7894±150 a B.P.—7640 ± 650 a B.P, and 3987+100 a B.P.—3670 ± 310 a B.P, respectively. The coseismic vertical displacements are 1.0 m, 2.0 m, and 2.0 m, respectively. From a statistical formula of relation between historic earthquake magnitudes and surface seismic dislocations in North China, the magnitudes of these paleoearthquakes are inferred to be in a range fromM 7.7 toM 7.9. The research shows that the Holocene fault activity in the plain can be traced in the trenches according to the micro-geomorphic features. Many micro-structural phenomena are also found in these trenches. Identification of the paleoearthquakes in the Nankou-Sunhe fault zone during the Holocene time is of significance for assessment of future seismic risk in Beijing area.
