Influence of Subway Construction on Groundwater Environment in Downtown Area of Chengdu

2020 ◽  
Author(s):  
zhang qiang ◽  
sun jinyu ◽  
tamg jinping ◽  
zhang jiashen ◽  
huang sishuang
Keyword(s):  
Groundwater Flow ◽  
Groundwater Level ◽  
Flow Direction ◽  
Underground Space ◽  
Seepage Field ◽  
Groundwater Seepage ◽  
Downtown Area ◽  
Groundwater Environment ◽  
Subway Construction ◽  
Groundwater Flow Direction

<p>Located at the southeast of the Minjiang alluvial-proluvial fan, the downtown area of Chengdu mainly composed of sand gravel layer. Now Chengdu has 8 subway lines operated; in the next 10 years, more than 34 routes will be constructed. Metro Line 7 forming a transfer relationship with multiple urban MRTS and urban commuter radiation built completly in downtown area, with depth of subway station 1.73-11.3 m, and the depth of interval tunnel 6.47-28.01 m. In order to study how the groundwater will be influenced, 3 3d groundwater numerical models in different scales have been constructed using FeFlow software, the results illustrated regional groundwater seepage field and local seepage field.</p><p>Baed on 1 regional model (417 km2 for downtown Chengdu ) and 2 models of typical underground space (Taipingyuan station and Yipintianxia station), at the same time with the basic geology and hydrogeology Analysis, shows that:</p><p>(1) The influence of metro line 7 on the seepage field is relatively limited in regional scale, and the change of groundwater level is very little(4-10cm) at several typical observation points; in the long-term, the raising of groundwater level will decrease gradually.</p><p>(2) Comparing the simulation results of Taipingyuan station and Yipintianxia station shows the impact of subway construction on the groundwater environment in the downtown Chengdu. In the big view, from northwest to southeast, the phenomenon of underground water interception or raising in subway stations decrease gradually, this is owing to the influence of aquifer thickness, groundwater flow direction and the direction of underground station structure.</p><p>(3) As the main body or long section of the underground structure is coincide with the groundwater flow direction, the cross-section blocking the groundwater is minimized, so its influence on the groundwater seepage field is not notable even with development of the underground space, this is also help avoiding the floatation effect on the building foundation due to the raising of the groundwater flow.</p>

scholarly journals KONDISI SUMUR DAN PEMODELAN ARAH ALIRAN AIRTANAH BEBAS PADA BENTUKLAHAN FLUVIOMARIN DI JAKARTA

2016 ◽  
Vol 16 (2) ◽  
pp. 1-9
Author(s):  
Cahyadi Setiawan ◽  
Suratman Suratman ◽  
Muh Aris Marfa,i
Keyword(s):  
Groundwater Flow ◽  
Groundwater Level ◽  
Rainy Season ◽  
Flow Direction ◽  
Dry Season ◽  
Population Characteristics ◽  
Sample Survey ◽  
The North ◽  
Groundwater Wells ◽  
Groundwater Flow Direction

ABSTRACT Growing population have an impact on the strategy of fulfillment the water need and degradation of groundwater quality in Jakarta, especially in fluviomarine landforms in Jakarta. The purpose of this study was to determine the condition of wells and create a model of groundwater flow direction on fluviomarine landforms based on the season. Methods in this research study include three main aspects, namely population, characteristics of the object under study, and analysis. The population in this study using 30 groundwater wells sample representative of the population. Relating to the characteristics of the object under study, this study using a survey method. The survey is a sample survey on wells population who still use unconfined groundwater. About data analysis, then in this study used quantitative and qualitative approaches to the modeling of the groundwater flow direction using the Inverse Distance Weighted (IDW) in ArcGIS. The results showed that the unconfined groundwater wells in the study area consisted of dug wells and pantek wells. It is generally known that groundwater levels in the rainy season are higher than the dry season with a depth of groundwater level in the dry season to be deeper than the rainy season. Most of the groundwater level in organic settlements in the study area is below sea level, whereas in planned settlements is rarely found people who use groundwater. The depth of unconfined groundwater well less than 20 m with a thickness of water on the wells in the rainy season are thicker than the dry season. Groundwater flow direction along the north coast of central and western parts likely to lead to the mainland, while the southern part has a groundwater flow that is likely to lead to the North. Keywords: Fluviomarine Landforms In Jakarta; Unconfined Groundwater; Groundwater Flow Direction

Groundwater flow simulation and its application in GaoSong ore field, China

2018 ◽  
Vol 10 (2) ◽  
pp. 276-284 ◽  
Author(s):  
Gang Chen ◽  
Shiguang Xu ◽  
Chunxue Liu ◽  
Lei Lu ◽  
Liang Guo
Keyword(s):  
Numerical Model ◽  
Flow Field ◽  
Groundwater Flow ◽  
Mine Water ◽  
Permeability Coefficient ◽  
Water Inrush ◽  
Seepage Field ◽  
Groundwater Seepage ◽  
Calculation Results ◽  
Groundwater Flow Field

Abstract Mine water inrush is one of the important factors threatening safe production in mines. The accurate understanding of the mine groundwater flow field can effectively reduce the hazards of mine water inrush. Numerical simulation is an important method to study the groundwater flow field. This paper numerically simulates the groundwater seepage field in the GaoSong ore field. In order to ensure the accuracy of the numerical model, the research team completed 3,724 field fissure measurements in the study area. The fracture measurement results were analyzed using the GEOFRAC method and the whole-area fracture network data were generated. On this basis, the rock mass permeability coefficient tensor of the aquifer in the study area was calculated. The tensor calculation results are used in the numerical model of groundwater flow. After calculation, the obtained numerical model can better represent the groundwater seepage field in the study area. In addition, we designed three different numerical models for calculation, mainly to explore the influence of the tensor assignment of permeability coefficient on the calculation results of water yield of the mine. The results showed that irrational fathom tensor assignment would cause a significant deviation in calculation results.

Electrode arrays for measuring groundwater flow direction and velocity

Geophysics ◽  
1994 ◽  
Vol 59 (2) ◽  
pp. 192-201 ◽  
Author(s):  
P. A. White
Keyword(s):  
Groundwater Flow ◽  
Apparent Resistivity ◽  
Salt Water ◽  
Flow Direction ◽  
Water Injection ◽  
Electrode Arrays ◽  
Seepage Velocity ◽  
Maximum Decrease ◽  
Schlumberger Sounding ◽  
Groundwater Flow Direction

The movement of 2000 liters of salt water after injection into groundwater within gravels a few meters below the ground surface at three injection sites was traced by six different resistivity monitoring arrays; the resistivity rectangle, Schlumberger sounding, Wenner sounding, Wenner fixed‐spacing, mise‐à‐la‐asse and downhole electrode array. Five of the arrays indicated groundwater flow direction and seepage velocity. As evidence indicates, similar geological and hydrogeological conditions exist at the injection sites. Therefore, comparisons between the sensitivity of the five arrays can be made and are as follows: resistivity rectangle—maximum decrease of 60 percent in derived potential differences; Schlumberger sounding— maximum decrease of 28 percent in measured apparent resistivity; Wenner sounding—maximum decrease of 20 percent in measured apparent resistivity, Wenner fixedspacing—maximum decrease of 22 percent in apparent resistivity; downhole electrode—maximum decrease of 38 percent in measured resistance. Measured potentials and derived values of potential gradient measured by the mise‐à‐la‐masse array indicated groundwater flow direction but not seepage velocity. Estimates of seepage velocity given by the resistivity arrays for the three salt water injection sites are between 260 ± 40 m/day and 700 ±100 m/day. These estimates are in broad agreement with values of seepage velocity derived from the point‐dilution technique, from previous salt water injection experiments, and from groundwater conductivity measurements using downhole probes.

To: “Electrode arrays for measuring groundwater flow direction and velocity,” by P.A. White (February 1993 GEOPHYSICS, 59, 192–201)

Geophysics ◽  
1994 ◽  
Vol 59 (7) ◽  
pp. 1172-1172 ◽  
Keyword(s):  
Groundwater Flow ◽  
Flow Direction ◽  
Accurate Information ◽  
Intrinsic Permeability ◽  
Electrode Arrays ◽  
Equation Error ◽  
Groundwater Flow Direction

The author has noted an equation error in Fig. 2. The vertical anisotropic intrinsic permeability should be: [Formula: see text] In addition, a reference used in the paper was incomplete. The accurate information appears below and we regret the omission.

Groundwater dynamics and groundwater surface-water exchange in the near-stream zone across the hydrologic year

2021 ◽  
Author(s):  
Enrico Bonanno ◽  
Günter Blöschl ◽  
Julian Klaus
Keyword(s):  
Groundwater Flow ◽  
Water Exchange ◽  
Flow Direction ◽  
Groundwater Table ◽  
Stream Channel ◽  
Fractured Bedrock ◽  
Groundwater Dynamics ◽  
Groundwater Response ◽  
Hydrologic Conditions ◽  
Groundwater Flow Direction

<p>Groundwater dynamics and flow directions in the near-stream zone depend on groundwater gradients, are highly dynamic in space and time, and reflect the flowpaths between stream channel and groundwater. A wide variety of studies have addressed groundwater flow and changes of flow direction in the near-stream domain which, however, have obtained contrasting results on the drivers and hydrologic conditions of water exchange between stream channel and near-stream groundwater. Here, we investigate groundwater dynamics and flow direction in the stream corridor through a spatially dense groundwater monitoring network over a period of 18 months, addressing the following research questions:</p><ul><li>How and why does groundwater table response vary between precipitation events across different hydrological states in the near-stream domain?</li> <li>How and why does groundwater flow direction in the near-stream domain change across different hydrological conditions?</li> </ul><p>Our results show a large spatio-temporal variability in groundwater table dynamics. During the progression from dry to wet hydrologic conditions, we observe an increase in precipitation depths required to trigger groundwater response and an increase in the timing of groundwater response (i.e. the lag-time between the onset of a precipitation event and groundwater rise). This behaviour can be explained by the subsurface structure with solum, subsolum, and fractured bedrock showing decreasing storage capacity with depth. A Spearman rank (r<sub>s</sub>) correlation analysis reveals a lack of significant correlation between the observed minimum precipitation depth needed to trigger groundwater response with the local thickness of the subsurface layer, as well as with the distance from and the elevation above the stream channel. However, both the increase in groundwater level  and the timing of the groundwater response are positively correlated with the thickness of the solum and subsolum layers and with the distance and the elevation from the stream channel, but only during wet conditions. These results suggest that during wet conditions the spatial differences in the groundwater dynamics are mostly controlled by the regolith depth above the fractured bedrock. However, during dry conditions, local changes in the storage capacities of the fractured bedrock or the presence of preferential flowpaths in the fractured schist matrix could control the spatially heterogeneous timing of groundwater response. In the winter months, the groundwater flow direction points mostly toward the stream channel also many days after an event, suggesting that the groundwater flow from upslope locations controls the near-stream groundwater movement toward the stream channel during wet hydrologic conditions. However, during dry-out or long recessions, the groundwater table at the footslopes decreases to the stream level or below. In these conditions, the groundwater fall lines point toward the footslopes both in the summer and in the winter and in different sections of the stream reach. This study highlights the effect of different initial conditions, precipitation characteristics, streamflow, and potential water inflow from hillslopes on groundwater dynamics and groundwater surface-water exchange in the near stream domain.</p>

scholarly journals Detecting groundwater flow direction from infrared thermal images

2009 ◽  
Vol 51 (2) ◽  
pp. 113-126
Author(s):  
Akhundzadah Noor AHMAD ◽  
Hirotaka SAITO ◽  
Kei ASADA ◽  
Makoto KATO
Keyword(s):  
Groundwater Flow ◽  
Flow Direction ◽  
Thermal Images ◽  
Infrared Thermal Images ◽  
Groundwater Flow Direction
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