Assessment of Diaphragm Wall's Structural Impact on Groundwater Hydrology

2011 ◽  
Vol 250-253 ◽  
pp. 1098-1104
Author(s):  
Te Hsing Chang
Keyword(s):  
Groundwater Level ◽  
High Speed ◽  
Vibration Reduction ◽  
High Water ◽  
Diaphragm Wall ◽  
Wall Structure ◽  
Groundwater Hydrology ◽  
Groundwater Levels ◽  
Diaphragm Walls ◽  
The Impact

The Southern Taiwan Science Park (STSP) is located between Hsinshi Township and Shanhua Township of Tainan County, with the newly-built, high-speed railway running through its eastern side. The low-frequency vibration which was generated by passing high-speed trains causes environmental disturbances to industries within the Park. To address this issue, the implementation of vibration-reduction project with detailed design and construction was provided. The diaphragm wall-type vibration reduction walls will be built along the borderline between Hsinshi Township and Shanhua Township to reduce the impact on industries. The diaphragm wall structure will block groundwater from flowing to affect the underground hydrology. This study was aimed to discuss and assess the best configuration for the vibration reduction effects and environmental impacts. Numerical analysis of the impacts on groundwater hydrology was conducted in two cases. The simulation results indicated that both sides of diaphragm walls developed gaps in groundwater levels. Hence, diaphragm walls effectively reduced adverse impacts on groundwater hydrology with openings at locations where underground pipelines ran. Such variations were within the scope of groundwater level of high water and low water periods. Therefore, surface runoff and land subsidence resulting from the diaphragm wall construction were not severe. As diaphragm walls were made of impermeable materials, pumping water nearby made the groundwater level drawdown effects worse. Groundwater level variations resulting from pumping water were far greater than the regional groundwater level variations after the establishment of diaphragm walls. Special attention must be paid to this situation in follow-up management.

Simulation of drip-rain effects by tribofatigue loading

2020 ◽  
Author(s):  
A.A. Aliev ◽  
A.Yu. Ampilogov
Keyword(s):  
Polymer Coating ◽  
High Speed ◽  
Erosion Resistance ◽  
High Water ◽  
Contact Spot ◽  
Vertical Load ◽  
Rigid Substrate ◽  
Rain Drop ◽  
The Impact ◽  
Rain Erosion

The outer surfaces of aircraft are periodically subjected during flight to intense rain causing hydroerosion of the outer paintwork. The experimental evaluation of hydroerosion resistance is based on testing in high-speed water flow. The main drawback of such research is the bulkiness of the stands, high water and energy consumption, and, as a result, increased cost. As an alternative to drip-rain tests, their simulation by kinetically similar tribofatigue test according to the “ball on plate” scheme is proposed (vertical load is applied to the polymer coating on a rigid substrate through a steel ball). The process is cyclically repeated until the coating is worn to the specified thickness. The experimentally obtained tribofatigue characteristics then can be converted into close-meaning estimates of erosion resistance. CAAPCOAT-B274-ASP108 polyurethane, previously tested for rain erosion, was selected as the sample. For quantitative evaluation of the transition from drip-rain loading to equivalent tribofatigue one the contact mechanics formulas were used by calculating the force of the drip impact and the stress in the contact spot. Tribofatigue tests were conducted on the UMT-2 TriboLab unit. At equal calculated contact stress levels the wear rate under tribofatigue loading was almost 7 times higher compared to the conditions of rain-drop erosion. The reason may be a scale factor due to the actual difference in contact areas under drip and tribofatigue loading, as well as the failure to take into account the dynamics of waves after the impact of drops. The obtained results of tribofatigue tests can give an estimated value of the hydroerosion resistance of the coating.

scholarly journals Spatio-temporal impact of climate change on the groundwater system

2012 ◽  
Vol 16 (5) ◽  
pp. 1517-1531 ◽  
Author(s):  
J. Dams ◽  
E. Salvadore ◽  
T. Van Daele ◽  
V. Ntegeka ◽  
P. Willems ◽  
...  
Keyword(s):  
Climate Change ◽  
Groundwater Recharge ◽  
Groundwater Level ◽  
Climate Change Scenarios ◽  
Close Monitoring ◽  
Reference Period ◽  
Groundwater System ◽  
Groundwater Levels ◽  
Impact Of Climate Change ◽  
The Impact

Abstract. Given the importance of groundwater for food production and drinking water supply, but also for the survival of groundwater dependent terrestrial ecosystems (GWDTEs) it is essential to assess the impact of climate change on this freshwater resource. In this paper we study with high temporal and spatial resolution the impact of 28 climate change scenarios on the groundwater system of a lowland catchment in Belgium. Our results show for the scenario period 2070–2101 compared with the reference period 1960–1991, a change in annual groundwater recharge between −20% and +7%. On average annual groundwater recharge decreases 7%. In most scenarios the recharge increases during winter but decreases during summer. The altered recharge patterns cause the groundwater level to decrease significantly from September to January. On average the groundwater level decreases about 7 cm with a standard deviation between the scenarios of 5 cm. Groundwater levels in interfluves and upstream areas are more sensitive to climate change than groundwater levels in the river valley. Groundwater discharge to GWDTEs is expected to decrease during late summer and autumn as much as 10%, though the discharge remains at reference-period level during winter and early spring. As GWDTEs are strongly influenced by temporal dynamics of the groundwater system, close monitoring of groundwater and implementation of adaptive management measures are required to prevent ecological loss.

The impact of groundwater level on soil seed bank survival

1998 ◽  
Vol 8 (3) ◽  
pp. 399-404 ◽  
Author(s):  
R. M. Bekker ◽  
M. J. M. Oomes ◽  
J. P. Bakker
Keyword(s):  
Water Level ◽  
Seed Bank ◽  
Groundwater Level ◽  
Soil Seed Bank ◽  
Soil Surface ◽  
High Water ◽  
Stellaria Media ◽  
Grassland Community ◽  
High Water Level ◽  
The Impact

AbstractSeed longevity of plant species is an important topic in restoration management, and little is known about the effects of environmental conditions on seed survival and longevity under natural conditions. Therefore, the effect of groundwater level on the survival of seeds in the soil seed bank of a natural grassland community was investigated. Large soil cores, mesocosms, were sampled from a grassland site and transferred to two basins under a glass roof. The mesocosms were subjected to different groundwater-level treatments (high and low, respectively 5 and 30 cm below the soil surface) for nearly three years. After that period the soil seed bank of the mesocosms was sampled. In total 15 789 seeds of 38 taxa emerged from the experiment. Significant differences between the number of viable seeds that emerged in the two treatments were found for several species. More seeds ofGlyceria fluitans, Cardamine pratensisandMyosotis palustrisgerminated in the high water-level treatment, whereas fewer seeds ofJuncusspp.,Cerastium fontanumandStellaria mediawere found in this treatment than in the low water-level treatment. The experiment showed that the anoxic conditions prevailing in the high water-level treatment were beneficial to the survival of seeds of species of wet grassland communities. Species of dry grasslands, although represented by only two species, survived better under aerobic conditions.

scholarly journals Concrete properties in diaphragm walls embedded in non-cohesive soils

2018 ◽  
Vol 174 ◽  
pp. 01007 ◽  
Author(s):  
Magdalena Czopowska-Lewandowicz
Keyword(s):  
Diffraction Method ◽  
Physical And Mechanical Properties ◽  
Diaphragm Wall ◽  
Concrete Mixture ◽  
Cohesive Soils ◽  
Existing Building ◽  
Concrete Quality ◽  
Diaphragm Walls ◽  
Bentonite Suspension ◽  
The Impact

Although diaphragm walls are massive and responsible structures whose building history has many years' tradition, the discovery of a variety of material faults is still common throughout their exploitation. Some of the most common ones are associated with the occurrence of leaks along the wall surface. This paper reports on the results of a study conducted into concrete quality in an existing building structure. The issues identified in this case include the potential penetration of groundwater and particles suspended in non-cohesive soils into the bentonite suspension and into the concrete mixture. The scope of the analysis also involved the possible occurrence of a mixing zone of bentonite suspension with the concrete mixture. The solutions presented in this paper were practically tested using an existing structure and the results confirm that the adopted approach needs to be thoroughly researched. The laboratory specimens derived from an unreinforced diaphragm wall were subjected to the following tests: concrete bulk density in the air-dried state, water absorption by concrete, depth of water penetration under pressure, compressive strength and determination of the quantitative phase composition test using X-ray diffraction method. The results clearly demonstrate the decrease of the concrete quality applied in a monolithic diaphragm wall in comparison to the reference samples taken at the phase when it was built. Due to the fact that it was impossible to identify the impact of the particular variables on the investigated structure, this paper focuses on their descriptive assessment. This discussion is based on the analysis of the results defining the physical and mechanical properties of the examined concrete coupled with observations made by the author and insights derived from literature.

scholarly journals The impact of raindrops on Salvinia molesta leaves: effects of trichomes and elasticity

2021 ◽  
Vol 18 (185) ◽  
Author(s):  
Wilfried Konrad ◽  
Anita Roth-Nebelsick ◽  
Benjamin Kessel ◽  
Tatiana Miranda ◽  
Martin Ebner ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
High Speed ◽  
Water Repellency ◽  
High Water ◽  
Rain Water ◽  
Residual Water ◽  
Intense Rainfall ◽  
Salvinia Molesta ◽  
Aquatic Fern ◽  
The Impact

The floating leaves of the aquatic fern Salvinia molesta are covered by superhydrophobic hairs (=trichomes) which are shaped like egg-beaters. These trichomes cause high water repellency and stable unwettability if the leaf is immersed. Whereas S. molesta hairs are technically interesting, there remains also the question concerning their biological relevance. S. molesta has its origin in Brazil within a region exposed to intense rainfall which easily penetrates the trichome cover. In this study, drop impact on leaves of S. molesta were analysed using a high-speed camera. The largest portion of the kinetic energy of a rain drop is absorbed by elastic responses of the trichomes and the leaf. Although rain water is mostly repelled, it turned out that the trichomes hamper swift shedding of rain water and some residual water can remain below the ‘egg-beaters’. Drops rolling over the trichomes can, however, ‘suck up’ water trapped beneath the egg-beaters because the energetic state of a drop on top of the trichomes is—on account of the superhydrophobicity of the hairs—much more favourable. The trichomes may therefore be beneficial during intense rainfall, because they absorb some kinetic energy and keep the leaf base mostly free from water.

scholarly journals Analysis of groundwater levels in piezometers in the Vipava Valley

2020 ◽  
pp. 61-78
Author(s):  
Mateja Jelovčan ◽  
Mojca Šraj
Keyword(s):  
Surface Water ◽  
Water Level ◽  
Groundwater Level ◽  
Tectonic Structure ◽  
Unique Region ◽  
Groundwater Levels ◽  
Groundwater Level Fluctuations ◽  
The Third ◽  
Autumn And Winter ◽  
The Impact

The Vipava Valley is a unique region in south-western Slovenia. In addition to surface water, groundwater is also important, although it is hidden from the eye. The paper presents an analysis of groundwater levels in piezometers in the Vipava Valley. The analysis was performed on 10 piezometers, which are still operating today, and includes a display of levels and basic statistics, correlations, the impact of distance from the Vipava riverbed, trends, and seasonality. According to the groundwater level, piezometers in the Vipava Valley can be divided into three groups. The first group with the highest levels includes piezometers Gradišče, Vipavski Križ, and Ajdovščina, the second group piezometers Prvačina, Šempeter, Volčja Draga, Renče, and Vrtojba, and the third group with the lowest groundwater levels includes the piezometers Miren and Orehovlje. The results of the analyses showed good or bad connections between groundwater levels in piezometers, as well as between groundwater levels and the Vipava River water level at various gauging stations. The fluctuation of the groundwater level is conditioned by the distance from the Vipava riverbed and the area’s geological or tectonic structure. An unambiguous trend of groundwater levels cannot be determined. The seasonality of groundwater level fluctuations is not pronounced, but the highest values of groundwater levels occur in autumn and winter, and the lowest in summer.

scholarly journals Assessment of Causes and Effects of Groundwater Level Change in an Urban Area (Warsaw, Poland)

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3107
Author(s):  
Ewa Krogulec ◽  
Jerzy J. Małecki ◽  
Dorota Porowska ◽  
Anna Wojdalska
Keyword(s):  
Urban Area ◽  
Water Table ◽  
Groundwater Level ◽  
Anthropogenic Factors ◽  
Groundwater Levels ◽  
Quaternary Aquifers ◽  
Groundwater Quantity ◽  
The Impact ◽  
Long Term Measurement

Monitoring the data of groundwater level in long-term measurement series has allowed for assessment of the impact of natural and anthropogenic factors on groundwater recharge. It allows for assessing the actual groundwater quantity, which constitutes the basis for balanced and sustainable groundwater planning and management in an urban area. Groundwater levels in three aquifers were studied: the shallow and deeper Quaternary aquifers and the Oligocene aquifer in Warsaw (Poland). Statistical analysis was performed on a 27-year (1993–2019) cycle of daily measurements of groundwater levels. The studies focused on determining the range and causes of groundwater level changes in urban-area aquifers. The groundwater table position in the Quaternary aquifer pointed to variable long-term recharge and allowed for the identification of homogenous intervals with identification of water table fluctuation trends. A decrease in the water table was observed within the Quaternary aquifers. The Oligocene aquifer displayed an opposite trend.

scholarly journals Study of historical groundwater level changes in two Belgian chalk aquifers in the context of climate change impacts

2021 ◽  
pp. SP517-2020-212
Author(s):  
Pascal Goderniaux ◽  
Philippe Orban ◽  
Alain Rorive ◽  
Serge Brouyère ◽  
Alain Dassargues
Keyword(s):  
Groundwater Level ◽  
Groundwater Resources ◽  
Summer Drought ◽  
Aquifer Recharge ◽  
Groundwater Abstraction ◽  
Groundwater Levels ◽  
Future Evolution ◽  
Precipitation Decrease ◽  
Chalk Aquifer ◽  
The Impact

AbstractIn Southern Belgium, 23% of abstracted groundwater volumes are from chalk aquifers which represent strategic resources for the region. Due to their specific nature, these chalk aquifers often exhibit singular behaviour and require specific analysis. The quantitative evolution of these groundwater resources is analysed for the Mons Basin and Hesbaye chalk aquifers as a function of past evolution, in the short and long terms. Groundwater level time series exhibit decreases when analysed over different periods. This is particularly visible for the Hesbaye chalk aquifer when comparing the 1960-1990 and 1990-2020 periods. Such decreases are associated to observed temperature increase and a precipitation decrease, inducing a decrease of aquifer recharge, and a probable increase of groundwater abstraction in the adjacent catchment. Past evolution is also discussed considering recent winter and summer drought events. The aquifers exhibit long delays in response to recharge events, particularly where the thickness of the partially saturated zone plays a crucial role in observed delays. Regarding future evolution, simulations of the impact of climate changes using medium-high emission scenarios indicate a probable decrease of the groundwater levels over the Hesbaye chalk aquifer.

scholarly journals Spatio-temporal impact of climate change on the groundwater system

2011 ◽  
Vol 8 (6) ◽  
pp. 10195-10223 ◽  
Author(s):  
J. Dams ◽  
E. Salvadore ◽  
T. Van Daele ◽  
V. Ntegeka ◽  
P. Willems ◽  
...  
Keyword(s):  
Climate Change ◽  
Groundwater Recharge ◽  
Groundwater Level ◽  
Climate Change Scenarios ◽  
Close Monitoring ◽  
Reference Period ◽  
Groundwater System ◽  
Groundwater Levels ◽  
Impact Of Climate Change ◽  
The Impact

Abstract. Given the importance of groundwater for food production and drinking water supply, but also for the survival of groundwater dependent terrestrial ecosystems (GWDTEs) it is essential to assess the impact of climate change on this freshwater resource. In this paper we study with high temporal and spatial resolution the impact of 28 climate change scenarios on the groundwater system of a lowland catchment in Belgium. Our results show for the scenario period 2070–2101 compared with the reference period 1960–1991, a change in annual groundwater recharge between −20% and +7%. On average annual groundwater recharge decreases 7%. Seasonally, in most scenarios the recharge increases during winter but decreases during summer. The altered recharge patterns cause the groundwater level to decrease significantly from September to January. On average the groundwater level decreases about 7 cm with a standard deviation between the scenarios of 5 cm. Groundwater levels in interfluves and upstream areas are more sensitive to climate change than groundwater levels in the river valley. Groundwater discharge to GWDTEs is expected to decrease during late summer and autumn as much as 10%, though the discharge remains at reference-period level during winter and early spring. As GWDTEs are strongly influenced by temporal dynamics of the groundwater system, close monitoring of groundwater and implementation of adaptive management measures are required to prevent ecological loss.

scholarly journals Asymmetric impact of groundwater use on groundwater droughts

2020 ◽  
Vol 24 (10) ◽  
pp. 4853-4868
Author(s):  
Doris E. Wendt ◽  
Anne F. Van Loon ◽  
John P. Bloomfield ◽  
David M. Hannah
Keyword(s):  
Water Management ◽  
Groundwater Level ◽  
Short Term ◽  
Groundwater Use ◽  
Groundwater Levels ◽  
Groundwater Drought ◽  
Asymmetric Impact ◽  
The Impact ◽  
Drought Occurrence

Abstract. Groundwater use affects groundwater storage continuously as the removal of water changes both short-term and long-term groundwater level variation. This has implications for groundwater droughts, i.e. a below-normal groundwater level. The impact of groundwater use on groundwater droughts, however, remains unknown. Hence, the aim of this study is to investigate the impact of groundwater use on groundwater droughts in the absence of actual abstraction data. We present a methodological framework that consists of two approaches. The first approach compared groundwater droughts at monitoring sites that are potentially influenced by abstraction to groundwater droughts at sites that are known to be near natural. Observed groundwater droughts were compared in terms of drought occurrence, duration, and magnitude. The second approach investigated long-term trends in groundwater levels in all monitoring wells. This framework was applied to a case study of the UK, using four regional water management units in which groundwater levels are monitored and abstractions are licensed. Results show two asymmetric responses in groundwater drought characteristics due to groundwater use. The first response is an increase in shorter drought events and is found in three water management units where long-term annual average groundwater abstractions are smaller than recharge. The second response, observed in one water management unit where groundwater abstractions temporarily exceeded recharge, is a lengthening and intensification of groundwater droughts. Analysis of long-term (1984–2014) trends in groundwater levels shows mixed but generally positive trends, while trends in precipitation and potential evapotranspiration are not significant. The overall rising groundwater levels are consistent with changes in water use regulations and with a general reduction in abstractions during the period of investigation. We summarised our results in a conceptual typology that illustrates the asymmetric impact of groundwater use on groundwater drought occurrence, duration, and magnitude. The long-term balance between groundwater abstraction and recharge plays an important role in this asymmetric impact, which highlights the relation between short-term and long-term sustainable groundwater use.

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