Beijing Plain Area Research Articles

Optimum design of level monitoring points for land subsidence

Land subsidence caused by long-term over-exploitation of groundwater is the main geological disaster in the plain area of Beijing, China. To obtain accurate and dynamic monitoring information on land subsidence, primary level measurement is carried out every year. However, there are shortcomings in the existing level monitoring network and development of land subsidence, which require optimization of the level monitoring network for land subsidence. Using a GIS analysis method, a zonal map of influencing factors was created by overlaying three thematic maps including hydrogeological units; the decline rate of the groundwater level in the main mining layer; and the thickness of the compressible layer. The data were classified into 448 zones. Based on the zoning map, we created an optimal design for the location of level monitoring points, locating 220 new points. Kriging interpolation error variance was chosen to evaluate map accuracy. Standard deviation contour maps of the existing level network and the optimized level network were created, and the results showed that the error of the optimized level network was smaller than the existing level network. The method proposed by this paper was reasonable for optimizing a level monitoring network for land subsidence.

Characterization and causes of land subsidence in Beijing, China

ABSTRACTLong-term overexploitation of groundwater is the primary factor causing regional land subsidence in the Beijing plain area, China. Currently, large subsidence funnels exist, one each in southern and northern Beijing. We adopted the multi-temporal interferometric synthetic aperture radar (MT-InSAR) method, incorporating both persistent scatterer (PS) and small baseline (SB) approaches on 47 Envisat Advanced Synthetic Aperture Radar (ASAR) single look complex (SLC) images to map land subsidence in the Beijing plain area. The temporal and spatial variations of land subsidence and its seasonal variation were explained by the MT-InSAR results. Then, the InSAR results were combined with the dynamic monitoring of groundwater level, extensometer measurements, and hydrogeological data; the characterization and causes of land subsidence were analysed with Geographic Information System (GIS) spatial analysis methods. The results show the following. 1) Land subsidence developed rapidly in the Beijing plain area from 2003 to 2010, with obviously uneven settlement; settlement rates exceeded 100 mm year−1 in some areas. Seasonal variation in settlement rates may be affected by changes in the precipitation rates and the exploitation of groundwater. 2) The contribution of different aquifer systems to land subsidence varies. The variation in the groundwater level in the second confined aquifer, at a depth of 100–180 m, has the greatest impact on land subsidence. 3) The settlement is centred in the lower part of the Wenyu–Chaobai and Yongding alluvial fan areas, where the compressible layer is more than 100 m thick. Meanwhile, land subsidence forms a structural feature with larger differences in the deformation gradient on both sides of faults.

Distributed estimation and analysis of precipitation recharge coefficient in strongly-exploited Beijing plain area, China

The precipitation recharge coefficient (PRC), representing the amount of groundwater recharge from precipitation, is an important parameter for groundwater resources evaluation and numerical simulation. It was usually obtained from empirical knowledge and site experiments in the 1980s. However, the environmental settings have been greatly modified from that time due to land use change and groundwater over-pumping, especially in the Beijing plain area (BPA). This paper aims to estimate and analyze PRC of BPA with the distributed hydrological model and GIS for the year 2011 with similar annual precipitation as long-term mean. It is found that the recharge from vertical (precipitation + irrigation) and precipitation is 291.0 mm/yr and 233.7 mm/yr, respectively, which accounts for 38.6% and 36.6% of corresponding input water. The regional mean PRC is 0.366, which is a little different from the traditional map. However, it has a spatial variation ranging from –7.0% to 17.5% for various sub-regions. Since the vadose zone is now much thicker than the evaporation extinction depth, the land cover is regarded as the major dynamic factor that causes the variation of PRC in this area due to the difference of evapotranspiration rates. It is suggested that the negative impact of reforestation on groundwater quantity within BPA should be well investigated, because the PRC beneath forestland is the smallest among all land cover types.

VS30Empirical Prediction Relationships Based on a New Soil‐Profile Database for the Beijing Plain Area, China

Earthquake ground‐motion prediction models usually define site conditions based on the time‐averaged shear‐wave velocity in the upper 30 m ( V S 30). Proxy‐based estimations of V S 30 are commonly used, if velocity measurements are not available. We compile a soil‐profile database for the Beijing plain area (China), using data from research documents and technical reports. The database contains 479 soil profiles, 463 of which have depths greater than 30 m. We develop regional relationships for the Beijing plain area for extrapolating the time‐averaged shear‐wave velocity to a given depth less than 30 m to V S 30, and then compare the performance of available models. We find that the second‐order polynomial model (Boore et al. , 2011), based on data from Japan, provides an overprediction, whereas the linear model (Boore, 2004) calibrated on data from California underestimates V S 30. We develop relationships for estimating V S 30 based on proxies such as ground slope gradients from radar‐derived digital elevation models (DEMs) and surface geology at different scales. We find that local V S 30 data in the Beijing plain are generally lower than existing 30 arcsec gradient‐based global models. Regression results show a modest correlation between V S 30 and topographic ground slope for several DEM resolutions (3, 15, 30, and 60 arcsec). Geology‐based proxies are more effective than ground slope for V S 30 estimation in the analyzed area. We propose a bilinear model based on geologic ages and depositional environments for estimating V S 30, which shows a statistically significant trend for application in the Beijing plain area. Online Material: Figures showing topographic ground slopes and correlations of V S 30 with topographic slope from digital elevation model (DEM) data and a table summarizing data from the 463 boreholes.

The deformation behavior of soil mass in the subsidence region of Beijing, China

Abstract. Land subsidence induced by excessive groundwater withdrawal has been a major environmental and geological problem in the Beijing plain area. The monitoring network of land subsidence in Beijing has been established since 2002 and has covered the entire plain area by the end of 2008. Based on data from extensometers and groundwater observation wells, this paper establishes curves of variations over time for both soil mass deformation and water levels and the relationship between soil mass deformation and water level. In addition, an analysis of deformation behavior is carried out for soil mass with various lithologies at different depths depending on the corresponding water level. Finally, the deformation behavior of soil mass is generalized into five categories. The conclusions include: (i) the current rate of deformation of the shallow soil mass is slowing, and most of the mid-deep and deep soil mass continue to compress at a more rapid speed; (ii) the sand strata behaves elastically, while the clay soil mass at different depths is usually characterized by elastic-plastic and creep deformation, which can be considered as visco-elastoplastic.

Characterization of land subsidence induced by groundwater withdrawals in Wenyu River alluvial fan, Beijing, China

Abstract. The Beijing plain area has suffered from severe land subsidence owing to groundwater overdraft. A major example is the Wenyu River alluvial fan in the Beijing plain area. This area has experienced as much as 10 m of land subsidence through 2000s. An integrated subsidence-monitoring program, including borehole extensometer and multilayer monitoring of groundwater, has been designed to meet the needs of monitoring land subsidence in this region. This work has allowed us to characterize land subsidence and understand the mechanical properties of the strata. The analysis results show the development of the land subsidence in this area is consistent with water-level change. The major strata contributing to compression deformation are Mid-Pleistocene stratum which contributed around 70 % of total subsidence. The shallow stratum and deep stratum show elastic mechanical behavior the intermediate stratum exhibit elastic-plastic mechanical behavior.

Effects of Groundwater Heat Pump Systems on the Temperature and Quality of Groundwater in Recharged Aquifer

Groundwater heat pump (GWHP) systems in three different hydrogeological fields, Beijing were selected, and their effects on temperature of groundwater in recharged aquifer were researched for three years. Results showed that the degree of thermal breakthrough was controlled by the distance between pumping wells and injection wells, and the temperature of groundwater with high flow rate can recover to normal faster than those with low flow rate. When distance between pumping wells and injection wells were shorter than 30m, thermal breakthrough may happen and the variation range of groundwater temperature during one heating or cooling period was 8~12°C.However, thermal breakthrough can be negligible and the temperature of groundwater may be steady when the distance between those wells was longer than 50m. Furthermore, GWHP in two different hydrogeological fields were selected to observe their effects on groundwater quality for one year. One GWHP was situated on the northwest piedmont alluvial fan of Beijing and the other was located in the southeast plain area of Beijing. Groundwater was sampled from those fields and thirty-two inorganic components were analyzed. Heavy metals were not detected, and calcium, magnesium, chloride, sulfate, fluoride and other ten inorganic components were studied. Groundwater quality in the northwest of Beijing was relatively steady because that aquifer was in relative oxidation environment. However, groundwater quality in the southeast of Beijing was subject to change because that aquifer was in relative reduction environment. Nitration reaction happened in the plain area, and ammonia, nitrite converted into nitrite nitrogen and nitrate nitrogen, respectively. Simultaneously, pH, concentrations of iron and manganese decreased, and total hardness increased.

Effects of Groundwater Heat Pump Systems on the Temperature and Quality of Groundwater in Recharged Aquifer

Groundwater heat pump (GWHP) systems in three different hydrogeological fields, Beijing were selected, and their effects on temperature of groundwater in recharged aquifer were researched for three years. Results showed that the degree of thermal breakthrough was controlled by the distance between pumping wells and injection wells, and the temperature of groundwater with high flow rate can recover to normal faster than those with low flow rate. When distance between pumping wells and injection wells were shorter than 30m, thermal breakthrough may happen and the variation range of groundwater temperature during one heating or cooling period was 8~12°C.However, thermal breakthrough can be negligible and the temperature of groundwater may be steady when the distance between those wells was longer than 50m. Furthermore, GWHP in two different hydrogeological fields were selected to observe their effects on groundwater quality for one year. One GWHP was situated on the northwest piedmont alluvial fan of Beijing and the other was located in the southeast plain area of Beijing. Groundwater was sampled from those fields and thirty-two inorganic components were analyzed. Heavy metals were not detected, and calcium, magnesium, chloride, sulfate, fluoride and other ten inorganic components were studied. Groundwater quality in the northwest of Beijing was relatively steady because that aquifer was in relative oxidation environment. However, groundwater quality in the southeast of Beijing was subject to change because that aquifer was in relative reduction environment. Nitration reaction happened in the plain area, and ammonia, nitrite converted into nitrite nitrogen and nitrate nitrogen, respectively. Simultaneously, pH, concentrations of iron and manganese decreased, and total hardness increased.

Estimating Cenozoic Thickness in the Beijing Plain Area Using Array Microtremor Data

Online Material: Table of observation radius for microtremor measurements and inverted V S structure. With the rapid expansion of large cities around the world, urban geological surveys provide key information regarding resource development and urban construction. Detailed geological information (e.g., sediment thickness, water table, bedrock structure, rock strength, faults, etc.) is critical to safeguarding large‐structure stability and its operational safety. China’s capital city, Beijing, is one of the largest cities around the world that possesses complex geological structures. Beijing (N39.5°∼41°, E115.5°∼117.5°) is located in the northern area of the Bohai Bay basin, which is surrounded by the Taihang Mountains fold belt to the west, Yanshan fold belt to the north, and Jiliao (Hebei–Liaoning) Rift basin to the southeast (Fig. 1). The structural pattern in the area was formed primarily by the Yanshan tectonic movement, which occurred during the mid‐Jurassic to late Cretaceous. Because of the lack of major tectonic events during the Cenozoic period, the geological structure pattern in the area has remained almost unchanged, as evidenced by the topography seen today (mountainous area in the west and plain area in the east). Numerous major faults exist beneath the Beijing Plain area, acting as the major control factor of the well‐known Beijing Rift Basin (Cai et al. , 2009). The west of the basin is enclosed by the Huangzhuang–Gaoliying fault followed by the Jingxi Uplift, and its east is adjacent to the Nanyuan–Tongxian fault followed by the Daxing Uplift. The resulting structural framework is characterized by two uplifts sandwiching a depression in the center (Jiao and Qiu, 2006; Cai et al. , 2009). The Beijing depression is further divided by smaller northwest–southeast faults, forming smaller structural highs and sags. From the southwest to northeast, there exist the Liangxiang High, Fengtai Sag, Laiguangying High, and Houshayu Sag (see Fig. 1; Luo …

Characteristics of carbonaceous aerosol in the region of Beijing, Tianjin, and Hebei, China

More than 400 PM2.5 samples were collected at four urban sites in Beijing (BJ), Tianjin (TJ), Shijiazhuang (SJZ), and Chengde (CD), and also one site in Shangdianzi (SDZ), which was used as a regional background station, over four seasons from 2009 to 2010. The organic carbon (OC) and elemental carbon (EC) in each sample were analyzed. The average annual concentrations were 71.8–191.2 μg m−3 for PM2.5, 10.8–26.4 μg m−3 for OC, and 3.9–9.7 μg m−3 for EC at the five sites. OC and EC concentrations were lower in the spring and summer and much higher in the autumn and winter, mainly due to aerosol emissions from additional fuel combustion for heating. OC/EC ratios were lowest in the summer and highest in the winter at SDZ, BJ, TJ, and SJZ. These seasonal trends indicate that the characteristics of carbonaceous aerosol pollution were spatially similar and season-dependent in the plain area of Beijing, Tianjin, and Hebei (BTH). An EC tracer method was used to calculate the concentrations for secondary organic carbon (SOC); SOC concentrations were also higher in the autumn and winter and lowest during the summer at all five sites. A stable atmosphere and low temperatures, which were more frequent during the winter and autumn, facilitated the accumulation of air pollutants and accelerated the condensation or adsorption of volatile organic compounds in the BTH area. Over the past ten years (1999–2009), Beijing had observed a decrease in the EC concentrations during every season and a remarkable reduction in aerosol emissions from coal combustion for heating.

Restudy of the storage and migration model of the Quaternary groundwater in Beijing Plain area

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, 18O, 14C and other aspects, and indicates 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 concentration suggests that the average influence depth of the modern precipitation is approximately 120 m. Based on the analysis of the 22 paleowater samples through the D-18O method and 14C isotopic dating, the deep groundwater circulation in the fine sediments 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.

Comprehensive rehabilitation planning of deserted pits and the case study in plain area of Beijing, China

Deserted pits left from urban development and construction are degraded ecosystems which cause numerous environmental, ecological and landscape problems. The rehabilitation practices for individual deserted pit can be found in many sites. However, the discussion on comprehensive rehabilitation planning strategy from the point views of urban planning is still rare. A comprehensive rehabilitation planning process was developed in this study using the plain area of Beijing as a case study. A thorough investigation of deserted pits in the plain area of Beijing was conducted using remote sensing techniques and on-site surveys. Data on site features such as location, depth, areas, volume, soil composition, and current status were carefully analyzed. A classification index system was developed to group deserted pit sites into different rehabilitation planning categories based on their characteristics. Specific rehabilitation plan included soil modification, slope eco-engineering, vegetation re-establishment, and landscaping. Rehabilitation actions were designed for flood water retention, rainwater utilization, natural recovery, green space & public parks, and reserved lands. The benefits from rehabilitation were then evaluated including efficient flood control, rainwater utilization and groundwater replenishment, dust pollution reduction, as well as ecology and landscape improvement. The plan has been adopted by Beijing government to rehabilitate the desert pits. The comprehensive planning method can be applied to other locations.

A Comprehensive Study of Buried Structures in the Beijing Plain Using Multi‐Temporal Remote Sensing Data Processing And Multiple Information Sources

Abstract Proceeding from gaining a knowledge of the structural settings in this area, the authors applied remote sensing techniques and selected multi‐temporal image processing to extract information of buried structures in the Beijing plain area. Good results have been achieved. Through an integrated analysis of remote‐sensing, geological, seismic and aeromagnetic data, it is pointed out that there exist two sets of buried fractures of differing trends and orders—the northeast set and the northwest set, forming a rhombic framework in the images. The two sets of fractures have still been active since the Quaternary, which is of practical signifcance for geological study, earthquake prevention and planning of urban construction in the area. The results demonstrate that the selection of multi‐temporal processing of remote sensing images and the integrated analytic method are important in the study of buried structures.