Lowering Of Groundwater Level Research Articles

Deformation mechanism and treatment effect of deeply excavated expansive soil slopes with high groundwater level: Case study of MR-SNWTP, China

Taking a 4 km long deeply excavated expansive soil canal segment of the South–North Water Transfer Project Middle Route (MR-SNWTP) in China as an example, a comprehensive investigation of the deformation mechanism and effect of treatment work on the slope with high groundwater level was carried out. First, the project background and initial behaviour were introduced. Second, a series of site investigation, including visual inspection, exploration pit, and geological penetrating radar, was employed to identify the deformation characteristics, appearance damage, and groundwater distribution. Third, the environmental factors were analyzed, and the spatio-temporal deformation characteristics were identified. Then the zoned numerical model was built to analyze the slope stability. Finally, the deformation mechanism and effect of treatment work were discussed. The results show that although the slope surface was replaced with a cement-treated weak expansive soil layer, the water vapor exchange between the undisturbed expansive soils and atmosphere is not completely isolated. The perched groundwater is also still replenished by precipitation infiltration. Groundwater, perched groundwater, long-large fissure and dense fissure zone induce the lateral creep deformation of the slope, and result in significant trend changes. The stability of the deformed body is in a critical state. The critical sliding surface is a broken line consisting of a gentle dip angle at the leading edge and a steep dip angle at the trailing edge. The depth of the potential sliding surface varies due to the geological condition and arrangement of anti-slide piles. Drainage wells can discharge deeper groundwater, thus can lower groundwater level and discharge perched groundwater. Supporting and unloading measures should also be taken to improve the slope stability.

The Rhine Catchment: A Review of Sediment-Related Knowledge, Monitoring, and a Future Research Perspective

The Rhine River is affected by major human interventions affecting its morphology and sediment regime, which have severely changed its flow and sediment transport. While channelization has increased the sediment transport capacity in the free-flowing sections, the sediment retention behind dams has caused a bedload deficit downstream and has additionally intensified riverbed erosion. The resulting consequences range from the exposure of less erodible sediment layers that pose obstacles for navigation, to the scouring of infrastructure, the lowering of groundwater levels, and multiple negative ecological consequences. To optimize the efficiency of countermeasures, a coherent overview of all sediment-related activities and the state of knowledge on the Rhine catchment is required. That is why the present study aims to give a catchment-wide overview in this regard, identify knowledge gaps and proposing a future research programme. The methodological approach includes a comprehensive literature review and online interviews with experts from six riparian countries working in the fields of sediment research and management. Based on our investigations, we have derived several research topics, each consisting of research questions. Three project ideas were defined that should primarily be realized: (i) the influence of climate change and land use change on the sediment regime; (ii) alteration and improvement of the sediment balance and continuity, sediment transport, and morphology; and (iii) national and bilateral projects on sediment transport processes and management.

Global analysis of groundwater pumping from increased river capture

In many regions globally, groundwater overuse exceeds natural replenishment, leading to immediate consequences such as reduced river flows and devastating impacts on freshwater ecosystems. In alluvial aquifers in particular, groundwater pumping contributes to river flow reduction in two significant ways: first, by intercepting water that would naturally discharge into the river, and second, by lowering groundwater levels below the riverbed, causing river water to infiltrate. Despite these critical interactions, large-scale water resources assessments often overlook the relationship between groundwater and surface water, hindering a comprehensive understanding of the consequences of groundwater pumping on both the groundwater and surface water systems. Our study, utilizing a coupled global-scale groundwater–surface water model, reveals that approximately 20% of globally pumped groundwater stems from diminished streamflow, while 16% results from reduced storage. Projections for the end of the century, accounting for climate change, suggest potential increases to 30% from reduced streamflow and a decrease to 12% from reduced storage. Notably, our results highlight that the impact on streamflow is more widespread and linked to smaller pumping rates, contrasting with impacts on storage associated with higher pumping rates. This study shows the crucial need to include groundwater–surface water interactions in large-scale water resources assessments, not only for accurate estimates of freshwater availability but also for a comprehensive understanding of the far-reaching impacts of groundwater overuse related to increasing water demands and climate change.

Nature-based solution enhances resilience to flooding and catalyzes multi-benefits in coastal cities in the Global South

Coastal cities are facing a rise in groundwater levels induced by sea level rise, further triggering saturation excess flooding where groundwater levels reach the topographic surface or reduce the storage capacity of the soil, thus stressing the existing infrastructure. Lowering groundwater levels is a priority for sustaining the long-term livelihood of coastal cities. In the absence of studies assessing the possibility of using tree-planting as a measure of alleviating saturation excess flooding in the context of rising groundwater levels, the multi-benefit nature of tree-planting programs as sustainable Nature-based solutions (NBSs) in coastal cities in the Global South is discussed. In environments where groundwater is shallow, trees uptake groundwater or reduce groundwater recharge, thereby contributing to lower groundwater levels and increasing the unsaturated zone thickness, further reducing the risk of saturation excess flooding. Tree-planting programs represent long-term solutions sustained by environmental factors that are complementary to conventional engineering solutions. The multi-benefit nature of such NBSs and the expected positive environmental, economic, and social outcomes make them particularly promising. Wide social acceptance was identified as crucial for the long-term success of any tree-planting program, as the social factor plays a major role in addressing most weaknesses and threats of the solution. In the case of Nouakchott City (Mauritania), where a rise in groundwater levels has led to permanent saturation excess flooding, a tree-planting program has the potential to lower the groundwater levels, thereby reducing flooding during the rainy season.

Using stable isotopes in deciphering climate changes from travertine deposits: the case of the Lapis Tiburtinus succession (Acque Albule Basin, Tivoli, Central Italy)

Quaternary stable isotope records of marine and lacustrine carbonate deposits as well as speleothems were extensively studied to reconstruct global and regional climatic evolution. This study demonstrates how stable isotope records of travertine provide fundamental information about climate and the consequences of its evolution on groundwater level fluctuations. The deposition of the Lapis Tiburtinus travertine succession occurred during the Late Pleistocene (150–30 ka), coeval with the last activity of the Colli Albani volcanic complex. Two boreholes (Sn1 and Sn2) were drilled into the Acque Albule Basin (23 km E of Rome), crossing the entire Lapis Tiburtinus succession. The Sn1 borehole in the central part of the basin crosscuts a travertine succession of 62.1 m in thickness, while the Sn2 borehole in the southern part of the basin is characterized by a travertine succession 36.3 m in thickness. Carbon and oxygen stable isotope ratios were analysed on 118 samples (59 samples both for Sn1 and Sn2 boreholes) representative of the entire Lapis Tiburtinus travertine succession crossed by the boreholes. Values, measured and correlated in the two drilled boreholes, permitted determination of the sensitivity of the travertine depositional system to glacial and interglacial cycles, unravelling the complex oxygen and carbon cycle dynamic recorded in such sedimentary succession. Moreover, the results obtained correlated with available pollen curves of the Mediterranean area (from the Castiglione crater, 25 km E of Rome). Regional and global oxygen isotope continental and marine curves, calibrated with the stratigraphy of the Acque Albule Basin, and available U/Th dating allow the identification of at least three phases of the last interglacial (Marine Isotope Stage 5-MIS5). The carbon isotope record, compared with CO2 flux reconstructed and associated with the volcanic activity of the Colli Albani volcanic complex, instead shows an influence from groundwater level changes. In particular, positive shifts that occurred during arid phases are associated with a lower groundwater level and increased CO2 degassing, inducing a major fractionation effect on carbon isotopes. Instead, the negative shifts occurring during more humid periods indicate the inhibition of CO2 degassing and increase in pressure, attesting to a rise in groundwater level. In this view, travertine deposits, frequently studied to define the tectonic setting and activity of the area where they develop, can thus also be used as a tool to understand climate changes and groundwater variations apparent in their stable oxygen and carbon isotope signature.

The estimation of infiltration and inflow in a sewage network by combining continuous monitoring of hydrological parameters, flow and temperature with stable isotopes of oxygen and hydrogen

The failure of sewage network systems can lead to the introduction of external water, impacting the capacity, performance, and environmental sustainability of urban infrastructures. This study examined methods for identifying and quantifying external water in a sewage system in cold climate conditions through the analysis of stable isotope of oxygen (δ18O) and hydrogen (δ2H) from samples, and continuous temperature monitoring, followed by the simulation of the network's hydraulics and temperature profile. The assessment was conducted during periods of low and high groundwater levels, specifically during dry weather flow. In comparison, the yearly trends of infiltration and inflow rates were assessed utilizing the moving minimum method. Using δ18O as a tracer, daily infiltration rates of 5.8 % and 35 % were estimated for periods of low and high groundwater levels, respectively. Using the outputs of the thermodynamic model, temperature was used as a tracer and the daily infiltration rates were found to be 1.5 % and 21.9 % for the same periods. The infiltration and inflow rate for the year in question was estimated to be 23 % using the moving minimum method. The findings of this study demonstrate the temporal variability of infiltration in networks and highlight the need for, as well as the potential of, a multi-faceted approach and continuous monitoring for the accurate estimation of external water before sewage network renovations are carried out.

A multi-scenario multi-model analysis of regional climate projections in a Central–Eastern European agricultural region: assessing shallow groundwater table responses using an aggregated vertical hydrological model

The 2022 drought highlighted Hungary's vulnerability to climate change, especially the Great Hungarian Plain. Soil moisture, which is crucial for agriculture, depends on the position of the shallow groundwater table. This study investigated the effects of climate change on groundwater table fluctuations in more than 500 wells on the plain. An integrated vertical hydrological model, assuming negligible horizontal subsurface flows, employed the Dunay–Varga-Haszonits methodology for evaporation and Kovács approach for the water retention curve. Verified with two meteorological databases, the model was accepted for 463 wells based on NSE > 0.4 and RMSE < 0.5 m criteria. The FORESEE HUN v1.0 dataset proved suitable after spatial consistency tests. Examining 28 bias- and discontinuity-corrected climate model projections on these wells revealed a general decline in the groundwater table. Differences between trends to 2050 and 2100 suggested lower groundwater levels by mid-century. This research highlights climate change impacts in a crucial Central-European agricultural region in the Carpathian Basin and emphasizes the importance of modeling climate change-induced changes in shallow groundwater levels in water resources management.

Divergent future drought projections in UK river flows and groundwater levels

Abstract. Hydrological drought is a serious issue globally, which is likely to be amplified by 21st century climate change. In the UK, the impacts of changes in river flow and groundwater drought severity in a future of climate change and higher water demand are potentially severe. Recent publication of a new nationally consistent set of river flow and groundwater level projections (the eFLaG dataset), based on state-of-the-art UKCP18 climate projections, offers a unique opportunity to quantitatively assess future UK hydrological drought susceptibility. The dataset includes a transient, multi-model ensemble of hydrological projections driven by a single regional climate model (RCM), with a 12-member perturbed-parameter ensemble, for 200 catchments and 54 boreholes spanning a period from 1961 to 2080. Assessment of a baseline period (1989–2018) shows that the RCM-driven projections adequately reproduce observed river flow and groundwater level regimes, improving our confidence in using these models for assessment of future drought. Across all hydrological models and most catchments, future low river flows are projected to decline consistently out to 2080. Drought durations, intensities and severities are all projected to increase in most (over 90 %, pooling across different drought characteristics) UK catchments. However, the trajectory of low groundwater levels and groundwater drought characteristics diverges from that of river flows. Whilst groundwater levels at most (&gt; 85 %) boreholes are projected to decline (consistent with river flows), these declines are relatively modest (&lt; 10 % reduction) in transient low groundwater levels by 2080, and, in fact, six show moderate increases. Groundwater drought characteristics in the far future (2050–2079) are often similar to those of the baseline (1989–2018), with only 33 % of boreholes showing an increase (towards worsening drought) of more than 10 % for drought severity (48 % of boreholes for drought intensity). Interestingly, for some boreholes, droughts are projected to be more prolonged and severe in the near future (2020–2049) before returning to shorter durations and lower severity in the far future. A number of explanatory factors for this divergence between river flow and groundwater are discussed. The sensitivity to seasonal changes in precipitation and potential evapotranspiration is proposed as a principal driver of divergence because low river flows are more influenced by shorter-term rainfall deficits in the summer half-year, whilst groundwater drought appears to be offset somewhat by the wetter winter signal in the RCM projections. Our results have important implications for water management, demonstrating a widespread increase in river flow drought severity and diminishing low flows that could have profound societal and environmental impacts unless mitigated. Furthermore, the divergence in projections of drought in river flows and groundwater levels brings into question the balance between surface and subsurface water resources. The projected contrast in fortunes of surface and subsurface water resources identified for the UK may be replicated in other parts of the world where climate projections suggest a shift towards drier summers and wetter winters.

ASSESSMENT OF FOREST VEGETATION POTENTIAL OF RECLAIMED AREAS AFTER ILMENITE MINING USING THE REMOTE EARTH SENSING METHOD

The mining of ilmenite has irreversible negative environmental impacts on the ecosystem of the area where mining companies operate. First of all, it leads to disturbance of the soil and vegetation layer, changes in the natural landscape, formation of depression sinkholes, which causes changes in water flow and water distribution in the mining area, lowering of groundwater levels, pollution of the atmosphere, soil and water bodies, and loss of species diversity of flora and fauna. In general, the mining process lasts for decades, during which time the territory is subject to irreversible changes and disturbances and requires high-quality restoration after the completion of ilmenite mining. The article suggests a methodology for assessing the forest vegetation potential of soils in areas disturbed by ilmenite mining using remote earth sensing (RES). Based on satellite images and spectral characteristics, we determined the parameters of soil type and moisture, as well as the vegetation and moisture index of the forest vegetation layer The results of the remote earth sensing were compared with the results of laboratory analyzes of soil samples from the territory operated by the branch of the Irshansk Mining and Processing Plant of PJSC UMCC. Normalized Difference Vegetation Index, Normalized Difference Moisture Index, soil type and moisture were calculated and identified using QGIS software from data obtained from free-access satellite images. The results showed that a combination of laboratory and remote sensing methods can be quite effective for studying areas disturbed by mining activities and the state of their recovery after reclamation.

Why Rivers Disappear—Remote Sensing Analysis of Postmining Factors Using the Example of the Sztoła River, Poland

The impact of mining effects is undoubtedly an important research topic, especially in the case of assessing the effects of postmining factors. This study examines the drought in the Olkusz region using satellite imagery (Sentinel-2) and remote sensing indices. The analysis reveals that the region experienced multiple types of drought, including hydrogeological drought due to groundwater level lowering caused by mining activities, agricultural drought resulting from insufficient soil moisture, hydrological drought characterized by reduced water flow in rivers, and meteorological drought linked to decreased precipitation and high temperatures. This study demonstrates the usefulness of optical imaging and remote sensing indices in monitoring and assessing drought conditions. The results indicate significant changes in vegetation health and water content, as well as alterations to the natural environment within the region. This research highlights the importance of considering both human-induced and natural factors when evaluating drought phenomena. Continued monitoring and expansion of the study area would provide valuable insights into the long-term effects of weather conditions and the broader impacts on the ecosystem.

Fee for Reducing Natural Field Retention as an Instrument of Sustainable Public Finance

Theoretical background: Active national fiscal policy is an important determinant of sustainable development. Poland falls below the water security level, which is why natural retention is a particularly important issue, as the poverty of societies begins with a lack of access to water. This also poses a challenge for public finance, which should encourage specific behaviors. As of 1 January 2018, a fee for the reduction of natural land retention is levied in Poland. Purpose of the article: The aim of the article is to analyze and evaluate the fee for reducing natural field retention as an instrument of sustainable public finance and to assess its fiscal efficiency in terms of its ability to raise public revenue, in particular the revenue of municipalities on the example of cities with county rights in the Silesian Voivodeship. Research methods: The paper draws on literature reviews and the conducted empirical research. Data were collected using the direct method via access to public information. First, an analysis was carried out on the amount of revenue generated from the fee for reducing natural field retention, constituting the income of the State Water Holding – Polish Waters. Subsequently, an analysis was made on the amount of revenue generated from the fee for reducing natural field retention in municipalities with county rights in the Silesian Voivodeship. The study covered the years 2018–2022, i.e. from the introduction of the fee until the last year for which the data are available. Main findings: The fee for reducing natural field retention is a sustainable public finance instrument designed to shape attitudes and influence behavior. Although levying a fee for reducing natural field retention does not solve the problem of insufficient retention, it encourages discussion and implementation of measures to improve it. The mandatory fee is intended to discourage the construction of impervious surfaces and, at the same time, encourage property owners to incorporate retention systems into their construction plans to counteract the lowering of groundwater levels. It is of great importance, not in an economic or fiscal sense (public revenue), but rather in a social sense, by raising public awareness of the problem of natural retention.

Mechanism of denitrification in subsurface-dammed Ryukyu limestone aquifer, southern Okinawa Island, Japan

Denitrification crucially regulates the attenuation of groundwater nitrate and is unlikely to occur in a fast-flowing aquifer such as the Ryukyu limestone aquifer in southern Okinawa Island, Japan. However, evidences of denitrification have been observed in several wells within this region. This study analyzed environmental isotopes (δ15NNO3 and ẟ18ONO3) to derive the rationale for denitrification at this site. Additionally, the presence of two subsurface dams in the study area may influence the processes involved in nitrate attenuation. Herein, we analyzed 150 groundwater samples collected spatially and seasonally to characterize the variations in the groundwater chemistry and stable isotopes during denitrification. The values of δ15NNO3 and δ18ONO3 displayed a progressive trend up to +59.7 ‰ and + 21 ‰, respectively, whereas the concentrations of NO3−–N decreased to 0.1 mg L−1. In several wells, the enrichment factors of δ15NNO3 ranged from −6.6 to −2.1, indicating rapid denitrification, and the δ15NNO3 to δ18ONO3 ratios varied from 1.3:1 to 2:1, confirming the occurrence of denitrification. Denitrification intensively proceeds under conditions of depleted dissolved oxygen concentrations (<2 mg L−1), sluggish groundwater flow with longer residence times, high concentrations of dissolved organic carbon (>1.2 mg L−1), and low groundwater levels during the dry season with precipitation rates of <100 mm per month (Jun–Sep). SF6 analysis indicated the exclusive occurrence of denitrification in specific wells with groundwater residence times exceeding 30 years. These wells are located in close proximity to the major NE–SW fault system in the Komesu area, where the hydraulic gradient was below 0.005. Detailed geological and lithological investigations based on borehole data revealed that subsurface dams did not cause denitrification while the major NE–SW fault system uplifted the impermeable basement rock of the Shimajiri Group, creating a lithological gap at an equivalent depth that ultimately formed a sluggish groundwater area, promoting denitrification.

Determination of groundwater pumpage for dewatering construction site of Happy complex in Tay Ho district, Hanoi

Groundwater is unfavorable for construction activities, so groundwater dewatering or freezing needs to be carried out. The Happy complex is located in Tay Ho District, Hanoi city. The complex is to be constructed with 47 stations which are evenly distributed over a construction area of 10,000 m2 in the depth from 12.1 to 18.25 m below the ground surface. It is required to dewater groundwater to have the groundwater level to be 1.5 m lower the bottom of the stations. Vertical groundwater wells have been selected for the. The determination of groundwater pumping rates for the dewatering had been carried out by numerical modeling. GMS10.3.2 software had been used to model the groundwater flow using the MODFLOW modul. The modeling area is expanded to cover the construction site with dimensions of 370m x 420m. The grid cells are 4m x 4m. The groundwater pumping rates were determined by solving forward analysis of different options to select the optimal solution, which includes 29 pumping wells with the same well pumping rate of 1,040 m3/day. The lowered groundwater levels at all the construction stations have met the requirement.

GROUNDWATER FLOW PATTERN AROUND GONOHARJO HOT SPRING, KENDAL REGENCY, CENTRAL JAVA

The Ungaran Mountain is a stratovolcano-type volcano with a geothermal system. On the northern side of Mount Ungaran, there are hot springs located in the Gonoharjo area, Kendal Regency, Central Java, Indonesia. These hot springs appear on the mountain slopes and are very close to the surface water. This research aims in analyzing the pattern of groundwater flow with surface water flow around the springs and identifying the relationship that occurs between the springs and the nearest river flow. Analysis of the groundwater flow pattern can be determined based on groundwater level contour maps and groundwater flow maps. Such mapping can occur by plotting groundwater level data measured from 16 springs scattered on the slopes of Mount Ungaran. As a result of the measurements taken, the groundwater level ranged from 298.02 m above sea level to 818.47 m above sea level. The highest groundwater level is in the Pakis area while the lowest groundwater level is in the Boja area. The groundwater flow pattern at the study site flows from the top of the mountain and spreads to the north, northwest, west, southwest. Based on the 15 cross sections conducted, it can be identified that in general the relationship between groundwater and rivers flow in the study area is that most of the groundwater supplies surface water.

A Study on How Climate Change Affects the Water, Sanitation, and Hygiene (Wash) Sectors in Barguna Sadar Upazila, Bangladesh

Aims and Study Area: A study conducted to identify how climate change affects water, sanitation, and hygiene (WASH) sector for Barguna Sadar Upazila.&#x0D; Methodology: This study applied inductive reasoning methods with inductive and statistical generalization criteria. Used mixed method approach where both qualitative and quantitative data were collected from study areas. However, this study also triangulated findings from literature review and conducted Geo Spatial Analysis that enhanced the strength of the study findings.&#x0D; Results: From the quantitative findings it was identified that 32% reported they don’t even know what the risk factors of climate change are, among them 41% female which is very alarming for WASH. However, from the KII respondents reported to have waterlogging, increase of temperature, heavy rainfall, and scarcity of water in their locality. 37% of respondents reported to not available the drinking water in all year round and they mentioned it happens due to lower groundwater level, increase salinity in water, damage of water source and draught. 60% of the respondents reported that their latrines were destroyed by a cyclone/tidal surge/water lodging and 33% reported to experience water borne disease in the past three months. Only 10% of respondents agreed that they have sufficient knowledge of the result of climate changes in the WASH sector. Only 5% of women agreed they have access to WASH Management systems during cyclone/tidal surge/water lodging. A total of 30% respondents reported that climate change resulted in extra burden for women and girls in WASH sector.&#x0D; Conclusion: This study identified that mostly climate change impacts women and girls as have less knowledge on impacts of climate changes in WASH. From those findings this study identified some recommendations which can improve the conditions in WASH sector in Barguna as well as Coastal belt of Bangladesh.

Recent impacts of water management on dryland’s salinization and degradation neutralization

Reducing soil salinization of croplands with optimized irrigation and water management is essential to achieve land degradation neutralization (LDN). The effectiveness and sustainability of various irrigation and water management measures to reduce basin-scale salinization remain uncertain. Here we used remote sensing to estimate the soil salinity of arid croplands from 1984 to 2021. We then use Bayesian network analysis to compare the spatial–temporal response of salinity to water management, including various irrigation and drainage methods, in ten large arid river basins: Nile, Tigris-Euphrates, Indus, Tarim, Amu, Ili, Syr, Junggar, Colorado, and San Joaquin. In basins at more advanced phases of development, managers implemented drip and groundwater irrigation and thus effectively controlled salinity by lowering groundwater levels. For the remaining basins using conventional flood irrigation, economic development and policies are crucial for establishing a virtuous circle of “improving irrigation systems, reducing salinity, and increasing agricultural incomes” which is necessary to achieve LDN.

Comprehensive approach to sustainable groundwater management in semi-arid Ninh Thuan plain, Vietnam

Vietnam is a country with a long coastline and a high population density residing in the coastal plains. The largest dry area in Vietnam, the coastal plain of Ninh Thuan province, always lacks water in the first dry months of the year (Jan., Feb., Mar., and Apr.). Groundwater is an extremely valuable resource for supplies at this time. Therefore, the objective of this study is to establish a comprehensive approach to sustainable groundwater management in this semi-arid region. This approach is not only mitigating the negative impacts of factors such as climate change, sea level rise, and socio-economic development but also suggesting measures for management of aquifer recharge. A groundwater model for a 3-layer system with variable density flow SEAWAT is built to predict the impacts of climate change and sea level rise without a change in groundwater abstraction. This model helps to understand the trend of salt intrusion and lowering groundwater level in the study area. Afterwards, scenarios with different ground water abstraction and groundwater development such as ground dam, infiltration basin have been set up to meet the demands of socio-economic development in the future. Predicted results will show the impacts of the groundwater systems in the area such as groundwater level change, and saltwater intrusion. Controlled groundwater abstraction and some measures of groundwater development such as infiltration basin, underground dam would allow for an increase of up to 50000m3/day in the year 2050 without negative impacts on the aquifer system.

Field Experiments on 3D Groundwater Flow Patterns in the Deep Excavation of Gravel-Confined Aquifers in Ancient Riverbed Areas

In ancient riverbed areas, the hydro-geological conditions are extremely complex because of the cutting of ancient river channels during the sedimentary process. How to lower groundwater level in water-riched gravel-confined aquifer during deep excavation is vital for underground engineering. Groundwater flow patterns had to be understood during foundation pit dewatering. This paper presents a field case study conducted at the deep foundation pit of the Qianjiang Century City station on Hangzhou Metro Line 6, which is notable for its 52 m deep unclosed waterproof curtain. A total of 34 pumping wells were installed within the pit. During the tests, one well was subjected to a pumping well, while the others served as observation wells. The research included two sets of multi-depth pumping tests, which differed in terms of their filter lengths, aimed at investigating the flow pattern around pump wells and the roots of diaphragm walls. The study found that the use of longer filters, higher pump rates, and filters placed nearer to aquifer roofs enhances dewatering efficiency and minimizes impact on the surrounding geological environment. This paper introduces a novel concept known as the diaphragm wall–pumping well effect, which regulates the water head outside the pit and the subsidence, thereby optimizing the drawdown of the deep foundation pit with an unclosed waterproof curtain. The findings were applied in the foundation pit dewatering of Qianjiang Century City station, and the drawdown in and outside the pit was effectively controlled.

Changes in Groundwater Levels and its Salinity (Badra Basin Iraq)

A fact that human-induced greenhouse gas emissions have led to an increased frequency and/or intensity of some weather and climate extremes since pre-industrial time, in particular for temperature extremes which affected lots of regions by reducing precipitations. Accordingly, this reduction causes a lowering of groundwater levels which was adopted as a goal of this study and its effects on quality of it. The study area is Badra - Jassan basin located to the north of Kut city, the center of Wasit governorate, and bordered by the international boundary with Iran from the east and northern east covering an area of about (1020) Km2. Badra - Jassan basin is an important hydrogeological basin in which groundwater can be used for agricultural purposes; especially with decreasing surface water supply. The research studied a predictive mathematical model of groundwater by ten wells distributed randomly within the boundaries of the study area; all of them fall within the unconfined aquifer the mathematical model for the study area has been developed using the Geographic Information System (GIS) software. The Groundwater level map for the ten existing wells was drawn from data in (2021) and a comparison with else published in (2002) for the study area. Likewise, the salinity concentration map variations for the same periods were estimated. The present study showed a decline in groundwater levels which conjunction with an Increasing in the range and value of groundwater salinity concentrations.

BEACH GROUNDWATER IMPACTS ON WAVE OVERTOPPING FLOODING

Coastal flooding is a growing socioeconomic and humanitarian hazard (e.g., Nicholls, 2010). Increased beach groundwater levels may inundate low-lying areas and simultaneously propagate swash impacts onto higher beach and backshore elevations. Generally, coastal flood modeling and risk assessment characterize only surface flows, neglecting beach groundwater and swash zone processes such as infiltration and porous media flow. Numerous studies have considered the effects of swash on groundwater (e.g., Gourlay, 1992). Infiltration leads to reduced wave runup (Pintado-Patino et al., 2015) and is promoted by low beach groundwater levels (Bakhtyar et al., 2011), suggesting that beach groundwater plays a critical role in infiltration/exfiltration processes. Notably, the impacts of beach groundwater on swash flows and subsequent consequences on coastal flooding have not been explored. Coastal flooding from wave overtopping is expected to occur around the maximum tide. However, recent field observations suggest maximum overtopping lags behind high tide and is in phase with maximum groundwater levels. In this study, a turbulence and depth resolving numerical model is developed to examine the interaction between beach groundwater and wave overtopping processes.