Increase In Groundwater Level Research Articles

A causal physics-informed deep learning formulation for groundwater flow modeling and climate change effect analysis

In this study, we propose and test a formulation for building causal physics-informed hybrid models over traditional physics-informed hybrid models (H-HBVo) and a convolutional neural network (1D-CNN) in groundwater level (GWL) modeling. Two types of models are built based on our formulation and named H-HBV and H-Lin, because they integrate two different hydrological models. The comparison is made in terms of performance and ability to learn cause-and-effect relationships between inputs and outputs. The novelty of this study lies in the CRC (Causal Relationship Constraints) conditions, derived from a mathematical development, that are imposed on the layers of the physics-informed hybrid model to force it to learn causal relationships. The results showed that the 1D-CNN algorithm performed slightly better than the hybrid algorithms, and that the H-Lin and H-HBV algorithms together achieved slightly better results than the traditional hybrid algorithm, H-HBVo. It is also obtained that the algorithms subjected to our formulations (H-Lin and H-HBV) are the ones with satisfactory causality properties and that the integration of domain knowledge is not sufficient to obtain causal and interpretable models within the framework of hybrid algorithms. Subsequently, an analysis of the effect of climate change is carried out for Quebec (Canada) using H-HBV models. The results show that the RCP and SSP scenarios give fairly similar results, i.e. an increase in GWL between 2011 and 2090 with median amplitudes varying between + 5.6 and + 7 cm. In some cases, the amplitude of increase can exceed between + 14 and + 23 cm, and even reach between + 35 and + 70 cm. The results of the climate change analysis are consistent with changes in vertical inflow and potential evapotranspiration, the input variables, for the different climate scenarios, confirming the robustness of our formulation.

Estimating Groundwater Level in Peatlands by Using Submersible Sensor

Peatland fires pose a significant challenge in peatland management, with declining groundwater levels being a contributing factor. Real-time monitoring of groundwater levels (GWL) is essential to address this issue effectively. This study examines GWL data collected from submersible sensors and manual readings in peatlands of Tangkit Baru and Pematang Rahim villages, Jambi Province. Results reveal an increase in GWL in Tangkit Baru coinciding with rising precipitation, while Pematang Rahim experiences a contrasting decrease despite heavy rainfall. Statistical analysis, specifically t-tests, indicates no significant difference (p > 0.05) between the two measurement methods. However, slight discrepancies (0.1-1 cm) between submersible sensor and manual measurements underscore the importance of sensor maintenance for accurate GWL assessment. Keywords: Peatlands, sensors, groundwater level

Hydrogeochemical processes as a conditioner of freshwater lenses associated with coastal deposits

AbstractThe aim of this work was to study the processes and factors conditioning the hydrochemistry of freshwater lenses associated with Holocene coastal deposits in an area of the Argentinean Atlantic coast. For this purpose, geomorphological units were mapped and a shallow groundwater monitoring network was established, including pre‐existing boreholes and shallow exploration wells. During the construction of the shallow exploration wells, sediment samples were extracted to determine the texture and mineralogical characteristics. Four samplings were carried out to measure in situ physicochemical parameters and to determine majority ions in the water. The chemical data were analysed considering the associated geomorphology, lithology, water balance and hydrodynamics. The geomorphological and lithological characteristics are the combined factors that favour the preferential rainwater recharge processes. Geoforms with greater topography and extension (continental and coastal dunes) tend to store freshwater lenses, while those with lower topography and little areal extension (sand sheets and beach ridges) have very thin lenses and tend to become salinized. Climate and local water balance are factor that determines that groundwater recharge occurs preferentially in winter. This causes increases in groundwater levels and a decrease in the groundwater EC. On the other hand, mineralogy is a factor that conditions the geochemical processes associated with the water–sediment interaction. Within the main geochemical processes, the dissolution and/or mineral weathering, the dissolution of CO2(g) and ion exchange determine the presence of different hydrochemical facies, where Ca‐HCO3 facies dominates in elevated geoforms, while Na‐Cl in lower ones. The results obtained in this work have provided an understanding of the factors and processes that condition groundwater chemistry in coastal deposits, being of vital importance for the management of water resources.

Suitability of treated wastewater for irrigation and its impact on groundwater resources in arid coastal regions: Insights for water resources sustainability

Water scarcity threatens agriculture and food security in arid regions like Saudi Arabia. The nation produces significant quantities of municipal wastewater, which, with adequate treatment, could serve as an alternative water source for irrigation, thereby reducing reliance on fossil and non-renewable groundwater. This study assessed the appropriateness of using treated wastewater (TWW) for irrigation in a dry coastal agricultural region in Eastern Saudi Arabia and its impact on groundwater resources. Field investigations were conducted in Qatif to collect water samples and field measurements. A multi-criteria approach was applied to evaluate the TWW's suitability for irrigation, including complying with Saudi Standards, the Irrigation Water Quality Index (IWQI), the National Sanitation Foundation water quality index (NSFWQI), and the individual irrigation indices. In addition, the impact of TWW on groundwater was assessed through hydrogeological and isotope approaches. The results indicate that the use of TWW in the study area complied with the Saudi reuse guidelines except for nitrate, aluminum, and molybdenum. However, irrigation water quality indices classify TWW as having limitations that necessitate the use for salt-tolerant crops on permeable and well-drained soils. Stable isotopic analysis (δ2H, δ18O) revealed that long-term irrigation with TWW affected the shallow aquifer, while deep aquifers were minimally impacted due to the presence of aquitard layer. The application of TWW irrigation has successfully maintained groundwater sustainability in the study area, as evidenced by increased groundwater levels up to 2.3 m. Although TWW contributes to crop productivity, long term agricultural sustainability could be enhanced by improving effluent quality, regulating irrigation practices, implementing buffer zones, and monitoring shallow groundwater. An integrated approach that combines advanced wastewater treatment methods, community involvement, regulatory oversight, and targeted monitoring is recommended to be implemented.

Enterococci pathways to coastal waters and implications of sea level rise

Highly urban coastal communities in low lying areas and with high water tables are vulnerable to sea-level rise and to corresponding increases in coastal groundwater levels. Stormwater conveyance systems are under increased risk. Rising groundwater levels affect the hydraulics of the stormwater system thereby increasing contaminant transport, for example the fecal indicator bacteria enterococci, to coastal waters. This study offers a unique opportunity to evaluate the impacts of increased contaminant transport on marine coastal environments. Here we assessed historic and recent coastal water quality, stormwater sampling data, groundwater monitoring and tidal elevations near the coastline, in the context of altered hydraulics within the system. Two pathways of enterococci to marine waters were identified. Direct discharge of contaminated stormwater runoff via the stormwater outfalls and tidally driven contaminated groundwater discharge. As sea level continues to rise, we hypothesize that a diminished unsaturated zone coupled with altered hydraulic conditions at the coastal groundwater zone will facilitate the transport of enterococci from urban sediments to the study site (Park View Waterway in Miami Beach, FL USA). We recommend improvements to the stormwater conveyance system, and maintenance of the sanitary sewer system to mitigate these impacts and minimize transport of enterococci, and other stormwater pollutants to coastal waters. The results of this study can be useful to interpret high enterococci levels in low lying coastal areas where groundwater is influenced by rising sea water levels.

Методология влияния свободной порозности и водоотдачи на процессы, происходящие в почвогрунтах оросительных каналов с земляным руслом

Purpose of the research: to consider the influence of free porosity and water loss on the filtration of water from channels with an earthen bed. Explore existing calculation methods taking into account the parameters of free porosity and fluid loss. Collect calculation material that can form the basis of a program for calculating the filtration of channels with an earthen bed, taking into account the factors influencing the first and second stages of filtration in the channels. Materials and research methods: The work used theoretical methods for calculating filtration in channels with an earthen bed, presented the calculation of the loss of flow rate Qf for filtration per 1 km of length with a steady free surface for different types of channel cross-sections, considered the basic formulas proving that water supply changes with changes in transverse cross-section of the canal, the change in the stability of the canal slopes is shown, a test calculation of the canal for filtration strength according to the maximum pressure gradients is presented, the need to compare the excess of the critical filtration pressure gradient with the permissible pressure gradient is considered. Results and its discussion. The relationship between the total, capillary and minimum moisture capacity and water yield in the thickness of soils is presented, the dependence of free porosity on the groundwater level, and the change in water permeability of soils over time are considered. As a result of the research, material was collected on the influence of free porosity and water loss on the movement of water in soils and the influence on the increase in groundwater levels in the zone of influence of canals, a methodology was presented for the influence of free porosity and water loss on the processes occurring in the soils of irrigation canals in an earthen channel, which will allow its use for modeling these processes on a computer.

Spatiotemporal Variation and Long-Range Correlation of Groundwater Levels in Odessa, Ukraine

Increasing groundwater levels (GWLs) may become one of the most serious issues for the city of Odessa, Ukraine. This study investigated the spatial distribution characteristics and multifractal scaling behaviour of the groundwater-level/-depth fluctuations for a Quaternary aquifer in the city of Odessa using a geostatistical approach and multifractal detrended fluctuation analysis (MF-DFA). These two methods were applied to monthly GWL fluctuation time series from 1970 to 2020 to monitor 72 hydrogeological wells situated in different parts of the city of Odessa. The spatial distribution of the GWLs revealed an overall trend of decline and recovery from 1970 to 2020 in the study area, except for most of the southern region, where a persistent recovery of the groundwater depth was observed. The MF-DFA results suggest that the dynamics of the GWL fluctuations have multifractal characteristics in the Odessa area. In addition, both long-range correlations and fat-tail probability distribution contribute to the multifractality. However, long-range correlations among the fluctuations made a major contribution to the observed multifractality of the GWL fluctuation time series. The generalised Hurst exponents show a wide range of change (0.20 < h(q) < 2.85), indicating the sensitivity of the GWL fluctuations to changes in small-scale factors and large-scale factors. Regarding the long-range correlations of the GWL depths, the Hurst exponents (q = 2) demonstrated the positive persistence of groundwater-depth recovery in the southern region and the persistence of groundwater-depth variation in the other regions of the study area. The dynamic changes in the GWL depths in the Odessa area may be influenced by both natural and anthropogenic factors.

The potential of industrial green stormwater infrastructure to provide long-term supplementary flood mitigation for low-lying coastal cities under climate change

Coastal city flooding is projected to worsen in low-lying cities with climate change. Planners are concerned about the inadequacy of their current flood mitigation strategies, and the expense and risk of investing in expensive grey infrastructures, such as levees, under climate uncertainty. Implementing green stormwater infrastructure (GSI) on large privately-owned industrial land may be an attractive alternative; however, little is known about its potential for providing supplementary flood mitigation with climate change. Using Christchurch, New Zealand, as a case study, we applied hydrological modelling and spatial analysis to assess its potential to keep the impact of the increased rainfall intensities within the current flood protection capacity. Increasing groundwater levels due to rising sea levels were also considered to determine land capability for in-ground retention of stormwater. Findings demonstrate significant capability in four out of six catchments to reduce the impact of climate change–induced increased runoff volume to within the current flood protection level in the medium term (2030–2050). Two of the catchments also reduced runoff to this level in the long term (2080–2100), and under much larger storm events than the design storm, though not under all climate scenarios. Long-term flood mitigation capability can be provided where industrial land occupies a large proportion of a catchment’s area, is able to capture runoff from upstream, and where the high water table is deeper than 2 m. Industrial GSI has the potential to provide supplementary surface runoff containment through an adaptive flood mitigation planning strategy in response to unfolding climate change conditions.

Study on the Variation in Coastal Groundwater Levels under High-Intensity Brine Extraction Conditions

The excessive exploitation of groundwater is becoming a serious global issue. Different from other regions, groundwater extraction in coastal areas usually stops and moves inland after causing seawater intrusion. The abundant salt fields in the Laizhou Bay area of China provide a unique case of maintaining high-intensity underground brine mining even after seawater intrusion. The intensive exploitation of underground brine has led to significant changes in the groundwater flow field. However, there is still a lack of research on how different factors affect the groundwater level in this mining situation. In this paper, time series analysis methods were used to investigate the impact of brine water extraction, tidal fluctuations, and precipitation on the groundwater level in the Laizhou Bay area. The results indicate that brine extraction is the main factor controlling the changes in groundwater level, with the cessation and resumption of extraction resulting in a 93.4 cm increase and a 122.5 cm decrease, respectively. Different rainfall patterns can also lead to an increase in groundwater levels, especially when a heavy rainfall event can cause a 61.2 cm increase. Tidal fluctuations can cause periodic fluctuations in the groundwater level, with a variation amplitude of approximately 11% of the tide itself.

Floods in Dinaric Karst fields: a case study of the Dicmanjsko-Bisko Polje (Croatia)

ABSTRACT Karst areas are characterized by extreme heterogeneity and variability of geologic, morphologic, hydrogeologic, hydrologic, hydraulic, ecologic and other parameters in space and time. Therefore, the occurrence of floods under such condition manifests in different forms, intensities, and durations. Heavy precipitation in karst areas leads to a considerable increase in groundwater levels and the activation of temporary springs. Karst fields that have not been properly meliorated are particularly vulnerable to such phenomena and, can remain flooded for several weeks. In Dalmatia, in the southern Croatian region, there are 12 karst poljes with an area larger than 1000 ha, including Dicmanjsko-Bisko polje (1700 ha). Our study presents a conceptual model of the interaction of underground and surface water in the Dicmanjsko-Bisko polje, as well as the process of flooding. The input data were geological mapping and measured precipitation. The paper describes the December 2021 flood in detail. The average 11-day precipitation recorded in the field catchment area was 292 mm, which led to the flooding of 230 ha (approximately 14% of the field area). The main cause of the flooding in the western part of the field was a large amount of surface runoff, resulting in insufficient capacity of the existing drainage channels. In the eastern lowest part of the field, flooding was even more intense due to the insufficient capacity of the sinkhole. The flood caused damage to agricultural lands, infrastructure, and economic facilities. The paper proposes flood mitigation measures. The study is an example of the practical application of karst research, that can be used for different purposes (spatial planning, hydrologic monitoring, modeling hydrogeological processes).

USING GRACE AND GLDAS DRIVEN DATA TO ASSESS GROUNDWATER FLUCTUATIONS OF NIGER-SOUTH HYDROLOGICAL AREA OF NIGERIA

Gravitational Recovery and Climate Experiments Terrestrial Water Storage and Global Land Data Assimilation Systems Surface Water and Soil Moisture including Nigerian Hydrological Service Agencys Groundwater Level were used to assess the temporal groundwater fluctuations of Niger-south Hydrological Area of Nigeria. The study adopted a cross-sectional research design; descriptive and inferential statistics was used for data analysis; Table was used for presentation. The study finds that there is no statistical significant difference between average monthly net recharge and average month storage changes at 95% probability level, it further concluded that the use of these satellites to acquire data and make decision will mark a new era and bring about fewer causalities on natural event(s), and therefore recommended us to take advantage of this free available resource to ameliorate challenges trying to extinct the existence of man from earth surface; therefore, increasing groundwater levels in Niger-south Hydrological Area needed to be properly managed because of rising groundwater flooding. KEY WORDS: GRACE, GLDAS, QGIS, Groundwater, Fluctuation

CHANGES IN HYDROGEOLOGICAL CONDITIONS DURING BOGGING IN THE SOUTHEAST OF THE WEST SIBERIAN PLAIN

Link for citation: Savichev O.G. Changes in hydrogeological conditions during bogging in the southeast of the West Siberian plain. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 187-198. In Rus. Relevance of the research is determined by the need to understand the mechanisms of interaction between groundwater, swamp and river waters in conditions of severe swampiness in the taiga zone of Western Siberia to solve a number of scientific and engineering problems both at present and in the future. The aim: quantitative assessment of changes in the levels of groundwaters during the characteristic periods of swamping of the southeast of the West Siberian Plain: 1) the beginning of an intensive spread of peat swamps with a peat deposit thickness of 0,3 m or more; 2) oligotrophization of swamps. Methods: methods of mathematical modeling, statistical methods. Results and conclusions. The author has carried out the analysis of peat deposit structure in the southern part of the Chaya river (a tributary of the Ob river) catchment area. The large-scale formation of peat swamps (with a peat thickness of 0,3 m or more) in the area under consideration occurred approximately 4 thousand years ago; the oligotrophization of the peat deposit (on a regional scale) occurred approximately 2,0…1,5 thousand years ago. In both cases, the main part of the swamps presumably could be attributed to the lowland type, but compared with the modern period in the first case their total area was 2 times less, and in the second was 1,7 times more. Taking into account these estimates, the average values of infiltration Inf and filtration coefficients Kf were determined, the ratio Inf/Kf dependence on the area of low-moor peat swamps was obtained, and groundwater levels were calculated at the present time and for periods of 1,7 and 4,1 thousand years ago. During the oligotrophization of the peat deposit (approximately 2,0...1,5 thousand years ago), with a high probability, there was a deterioration in water exchange between swamps and underground aquifers and an increase in groundwater levels. The beginning of intensive regional swamping (about 4 thousand years ago) occurred against the background of intense water-erosion processes. This results in accumulation of river alluvium accompanied by a rise in the levels of river water and then groundwater.

Effect of Groundwater Level Rise on the Critical Velocity of High-Speed Railway

The increasing frequency of extreme rainfall is leading to a rise in groundwater levels in coastal areas, significantly affecting high-speed railway operations. To address this concern, this study developed a 2.5-dimensional finite element model of a coupled track-embankment-ground system based on Biot’s porous media theory to analyze the effect of groundwater level rise on the critical velocity of high-speed railways and vibration responses. The findings reveal a consistent decrease in the critical velocity of high-speed railways with rising groundwater levels. Particularly, the increase in groundwater levels within the embankment significantly influences the critical velocity compared to a similar rise in the foundation’s groundwater level. Furthermore, deformations induced by passing trains significantly increase as groundwater levels rise. Specifically, when the groundwater level rises from the foundation bottom to the subgrade surface, subgrade surface deformation increases by approximately 55%. As trains approach the critical velocity, significant vibration phenomena, known as the “Mach effect,” occur at the foundation surface. Importantly, as groundwater levels rise, the “Mach effect” intensifies. Analyzing the vibrating frequency spectrum of the displacement response demonstrates a substantial increase in vibration amplitude, particularly in the high-frequency region, as groundwater levels rise. This study highlights that the rise in groundwater level not only amplifies vibrations but also extends the propagation of high-frequency vibrations, underscoring the importance of effective embankment waterproofing in controlling track vibrations.

Relationship between the trait response of aboveground and belowground parts of dominant plant species to groundwater depth change in Horqin Sandy Land, eastern China

Climate change and human development will lead to an increase in groundwater levels. This will have a particularly severe impact on arid ecosystems that are highly dependent on groundwater, as overconsumption and pollution of water resources can lead to faster depletion of groundwater. This not only exacerbates the problem of groundwater scarcity, but also may have profound impacts on local ecological environment and biodiversity. However, previous research has focused on aboveground trait responses to precipitation deficits, with less emphasis on concomitant belowground impacts and deep soil drought from groundwater depletion. Therefore, it remains unclear how groundwater depletion affects above and belowground traits of plant to jointly regulate aboveground biomass. In this study, we assessed morphological and ecophysiological traits of two dominant species (herb: Pennisetum centrasiaticum and shrub: Artemisia halodendron) across three groundwater depth (50 cm, 100 cm, and 200 cm) in the Horqin Sandy Land in China, within which photosynthetic rate (Photo), stomatal conductance (Cond), transpiration rate (Tr), internal CO2 concentration (Ci), instantaneous water-use efficiency of leaves (Lwue), total nitrogen (LN) and phosphorus (LP) content of the leaves, root to shoot ratio (RSR), root length density (RLD), total root length (RTL), root length ratio (RLR) were measured. The result showed that the two species growing with increased groundwater depth had reduced photosynthetic rate, and regulated stomatal close to aggregate ability of instantaneous water use efficiency, which may allow plants to meet resource demands under drought stress avoiding transpiration water loss. Plants also reduced the density of all roots and adjusted the vertical distribution of coarse root by changing biomass distribution to acquire deeper soil available water. Correlation analysis showed that the vital traits for aboveground biomass responses appear to be groundwater depth, soil moisture, leaf area, photosynthesis, water use efficiency, and root traits. Overall, the biomass production response of two dominant species may be greatly influenced by the interaction between aboveground and belowground traits in response to changes in groundwater depth. This result contributes to our understanding of adaptive strategies of vegetation in sandy soils and provides additional support for enhancing vegetation productivity in semi-arid ecosystems. The ability of semi-arid ecosystems to predict vegetation dynamics under current and future increasing groundwater depths is crucial.

Unlocking the hidden potential: groundwater zone mapping using AHP, remote sensing and GIS techniques

Groundwater resource problems are increasing development and planning challenges due to climate change and overexploitation, necessitating assessments of their potential and productivity. The study area has been facing a groundwater level decline problem for many years, and these results can help increase the groundwater level in the basaltic rock area. In this research, we have worked on the demarcation and suitability of groundwater potential zones using GIS and Analytical Hierarchical Process (AHP) methods for the Urmodi River Basin. This research prepared eight thematic maps, that is, geomorphology, geology, drainage density, land use/land cover, elevation, lineament density and slope from satellite data and GIS methods, which play a primary factor in determining the proper groundwater potential zones. In this study, every thematic map was allocated weights depending on its specific characteristics and contribution to the groundwater potential capacity. The weights were determined using the AHP method, which considers the comparative significance of every layer about others. This weighting procedure allowed for a comprehensive assessment of the factors influencing groundwater potential in the Urmodi River basin. The resulting groundwater potential map was divided into four classes, that is, good, excellent, moderate, and poor. The study revealed that approximately 22.69% of the basin had excellent groundwater potential, 28.96% had good potential, 25.32% had moderate potential, and 22.92% had poor potential. These study findings suggest that a significant portion of the Urmodi River Basin exhibits good to moderate groundwater potential, indicating promising opportunities for sustainable groundwater utilization in the region. The groundwater potential zone map accuracy is 84% based on the Receiver Operating Characteristic (ROC) method. These results can have implications for sustainable groundwater resources and provide a framework for conducting similar assessments in other regions. The results can be more important for sustainable development goals and helpful in increasing groundwater levels in the area.

Spatiotemporal analysis of groundwater level trends and recharge rate estimation in the unconfined aquifer of Yogyakarta-Sleman Groundwater Basin, Indonesia

Groundwater is the primary water resource used for domestic, industrial, and agricultural needs for the community in the Yogyakarta-Sleman Groundwater Basin area. The urbanization rate has increased since the 1970s and has made massive use of groundwater, causing environmental problems, including the quality and quantity of groundwater. Therefore, this study aimed to investigate the spatiotemporal groundwater fluctuation trends based on the non-parametric Mann-Kendall test and recharge rate estimation using the water table fluctuation (WTF) method. The groundwater level data were collected from monitoring wells across the study area during 2018-2022, particularly emphasizing 8 wells representing recharge, transition, and discharge areas. The results showed that the groundwater fluctuation pattern generally followed the season. During the rainy season from January to April, groundwater reached the shallowest level and began to decline gradually when it entered the dry season from May to October. Groundwater recharge rate was estimated to vary from 171.49 to 1,505.56 mm/year. Meanwhile, the Mann-Kendall test showed that most of the Yogyakarta-Sleman Groundwater Basin area did not experience significant fluctuation trends, except for two monitoring wells in the center of Yogyakarta City which had increasing groundwater level trends. The rising groundwater levels were expected to be caused by urban wastewater recharge. This study has provided a new description and insights into spatiotemporal changes in the groundwater table and the quantification of groundwater recharge.

Soil Water Regime, Air Temperature, and Precipitation as the Main Drivers of the Future Greenhouse Gas Emissions from West Siberian Peatlands

This modeling study intended to solve a part of the global scientific problem related to increased concentrations of carbon dioxide in the atmosphere via emissions from terrestrial ecosystems that, along with anthropogenic emissions, make notable contributions to the processes of climate change on the planet. The main stream of CO2 from natural terrestrial ecosystems is related to the activation of biological processes, such as the production/destruction of plant biomass. In this study, the Wetland-DNDC computer simulation model with a focus on nitrogen and carbon biogeochemical cycles was used to study the effect of hydrothermal conditions on greenhouse gas fluxes in West Siberian peatlands. The study was implemented on the site of the world’s largest pristine wetland/peatland system, the Great Vasyugan Mire (GVM). The study was carried out based on data from permanent measurements at meteo stations and our own in situ measurements of hydrological and thermal parameters on sites, which allowed for testing different scenarios of changes in environmental conditions (temperature, precipitation, groundwater level) together with a change in GHG fluxes. The study revealed the air temperature and the level of groundwater as the main drivers controlling CO2 fluxes. The study of different scenarios of change in annual air temperature revealed the threshold of change in the wetland/peatland ecosystem from carbon sink to carbon source to the atmosphere to happen with an increase in the average annual air temperature by 3 °C with reference to the average annual air temperature values in 2019. Also, we found that the wetland/peatland ecosystem turned to act as an active carbon sink with about 7 cm increase in annual groundwater level, compared with its base level of −21 cm.

Impact of altered groundwater depth on soil microbial diversity, network complexity and multifunctionality.

Understanding the effects of groundwater depth on soil microbiota and multiple soil functions is essential for ecological restoration and the implementation of groundwater conservation. The current impact of increased groundwater levels induced by drought on soil microbiota and multifunctionality remains ambiguous, which impedes our understanding of the sustainability of water-scarce ecosystems that heavily rely on groundwater resources. This study investigated the impacts of altered groundwater depths on soil microbiota and multifunctionality in a semi-arid region. Three groundwater depth levels were studied, with different soil quality and soil moisture at each level. The deep groundwater treatment had negative impacts on diversity, network complexity of microbiota, and the relationships among microbial phylum unites. Increasing groundwater depth also changed composition of soil microbiota, reducing the relative abundance of dominant phyla including Proteobacteria and Ascomycota. Increasing groundwater depth led to changes in microbial community characteristics, which are strongly related to alterations in soil multifunctionality. Overall, our results suggest that groundwater depth had a strongly effect on soil microbiota and functionality.

Hydrochemical characterisation and identification of seawater intrusion in the Visakhapatnam coastal aquifer.

Groundwater dependency has increased due to several factors like population increase, industrialization, and climate change impact. Analysis of groundwater is important to know the present status and also for better management of natural resources. Groundwater samples from 41 locations were collected along the study area during the pre and post-monsoon seasons, and samples were analysed for pH, EC, total dissolved solids (TDS), major cations, and anions like Ca2+, Mg2+, Na+, K+, Cl-, HCO3- and SO42-. From the chemical analysis results, seawater intrusion is identified through qualitative approaches, i.e., Simson ratio (Cl/(HCO3 + CO3) and Na/Cl ratio. Simson ratio ranges between 0.316 to 2.119 during pre-monsoon and 0.124 to 3.947 during post-monsoon, and from Na/Cl ratio, 30 samples fell under seawater intrusion during pre-monsoon and 38 samples during post-monsoon. The Simpson ratio results also show that seawater intrusion is reducing during the post-monsoon due to increasing groundwater levels caused by rains. From the water quality index classification, 4.88% of the water samples fell under excellent in both seasons, and the rest of the samples were all in the remaining four classes. The spatial analysis was also done to understand the changes in groundwater quality and seawater intrusion over space.

Effect of groundwater level on slopes to construct the SWCC curve for unsaturated soil

The occurrence of landslides and rockfalls has been on the rise, leading to unfortunate consequences and instilling anxiety and fear within the population as the rainy season approaches. During this time, the soil experiences a significant influx of water, causing the water level to rise and the transition from unsaturated to saturated soil. As a result, the shear strength of the soil decreases, leading to gradual slope instability. While the parameters of unsaturated soil resemble those of saturated soil, the inclusion of a SWCC curve is necessary. This study aims to examine the impact of groundwater levels on slope stability by considering the SWCC curve of the soil using the finite element method. The findings reveal that with an increasing groundwater level, the safety factor remains constant when the slope is assumed to be fully saturated. However, when the slope is evaluated with both fully saturated and unsaturated components using the SWCC, the safety factor declines significantly from 1.82 to 0.393. Similarly, according to the Fredlund-Xing method, the safety factor decreases from 1.754 to 0.393. Regardless of the method used, the safety factor consistently decreases as the groundwater level rises, eventually converging to the same value when the groundwater level reaches the ground surface.