Water Table Research Articles

Green Manuring and Irrigation Strategies Positively Influence the Soil Characteristics and Yield of Coriander (Coriandrum sativum L.) Crop under Salinity Stress

This study shows the influence of soil salinity and irrigation dose on biomass production and its impact on some edaphic indicators and functions. For this purpose, an experiment was carried out in two representative soils from Murcia (SE Spain), one slightly saline (LS) and the other saline (S), where an oat–vetch green manure was intercalated between a spinach cycle and a coriander cycle; the latter being subjected to three different irrigation doses (deficient, optimum and surplus). Rapid response indicators (ECext, cations and anions in the soil solution, etc.) were monitored, as well as the material balances, in particular C and salts. Green manure and crop residues increased soil OC by 12.5% and reduced Na+ and NO3− concentrations. Total biomass production was also affected by salinity, both in oat–vetch, 35.9 and 31. 9 tm ha−1 in LS and S, respectively, and in the coriander crop, where the irrigation dose was decisive, obtaining around 29 tm ha−1 with the optimum and surplus doses and significantly lower amounts with the deficit dose: 20.4 tm ha−1 in LSD and 14. 0 in SD. Therefore, it is necessary to adjust the irrigation doses, since deficit irrigation significantly reduces production and the surplus does not lead to an increase with respect to the optimum, while also causing ions to leach to depth horizons, as is the case for NO3−, Cl− and Na+, with the consequent risk of contaminating the water table.

Integrated study of GIS and Remote Sensing to identify potential sites for rainwater harvesting structures

Water accessibility is necessary for agricultural and socioeconomic development in the area. One of the best solutions to the water crisis in the Kohat region is to build rainwater harvesting structures (RWH) to collect water from local watersheds for artificial groundwater recharge. Our main objective was to identify suitable RWH locations in the study area. However, the optimum site selection for RWH in regional areas is crucial. In such a case, geospatial techniques have revealed decisive in optimum site selection for RWH structures. In the current study, we have used GIS-based models like the Analytical Hierarchy Process (AHP) and Weight of Evidence (WOE) to identify suitable sites for rainwater harvesting. Seven influential parameters, i.e., LULC, rainfall, drainage density, slope, lineament density, soil, and lithology, were considered, reclassified, and assigned ranks according to literature for analysis to produce potential site maps for RWH structures. The findings of the current study indicate that, based on the Analytic Hierarchy Process (AHP), 44% (1320 km2) of the study area is classified as highly suitable for rainwater harvesting, while 40% (1200 km2) is considered moderately appropriate, and 16% (470 km2) is deemed unsuitable. In contrast, when utilizing the Weight of Evidence (WOE) approach, the high suitability class encompasses 32% (956.8 km2) of the area, the moderate suitability class covers 43% (1285.7 km2), and the low suitability class accounts for 25% (748 km2) of the study area. The outcome of the current study aims to contribute and assist the planner, manager, and officials in finding sites for RWH structures to overcome the water table, irrigation demand, and agricultural issues in the study area.

Impact of some amendments on kinetics of leaching dissolved organic carbon and ammonium in calcareous sandy soil under vinasse addition

The access of vinasse leachates to water bodies and groundwater exacerbates environmental problems, especially eutrophication. Therefore, a column experiment was performed to examine the effect of adding zeolite (ZL), bone char (BC), and wood chips biochar (WCB) in the presence of vinasse on carbon dioxide (CO2) emission, leaching dissolved organic carbon (DOC) and ammonium (NH4+) in calcareous sandy soil, as well as studying the kinetics of leaching dissolved organic carbon and ammonium. This column experiment contains four treatments: soil alone (CK), soil + zeolite (SZL), soil + bone char (SBC), and soil + wood chips biochar (SWCB). These amendments were applied to the soil at a level of 4%. Vinasse was added to all treatments at a level of 13 mL per column. The leached total cumulative DOC and total cumulative soluble ammonium amounts decreased significantly with applying ZL, BC, and WCB compared with the soil alone. The effectiveness of these amendments in lowering the total cumulative DOC leaching is in the order of SBC > SWCB > SZL > CK. However, the effectiveness of these amendments in decreasing the total cumulative NH4+ leaching is in the order of SZL > SWCB > SBC > CK. The rate constant (k) of DOC leaching decreased significantly with the application of bone char compared to soil alone treatment. In the presence of vinasse, the apparent half-life of leached DOC from the soil was 8.1, 12.9, 36.7, and 15.5 days for soil CK, SZL, SBC, and SWCB treatments, respectively. Half-life values of leached soluble ammonium from the soil in the presence of vinasse addition were 10.1, 39.5, 28.5, and 37.9 days for CK, SZL, SBC, and SWCB treatments, respectively. Amending soil with BC increased significantly the phosphorus availability, however, applying ZL and BC caused a significant increase in the available potassium in calcareous sandy soil compared to the control treatment. According to these results, it is recommended not to add vinasse alone to sandy soils, but it is preferred to be co-applied with BC amendment at the level of 4% better than ZL and WCB. This would decrease leaching DOC and ammonium to the water table and groundwater as well as enhance nutrient retention in the soil, which in turn, plays a vital role in reducing the harmful effect of vinasse and improving soil fertility.

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.

Water Table Estimation in Attaragoda GN Division in Galle, Sri Lanka

The fluctuation of the groundwater table depends on geology, topography, climate and human consumption pattern. Long-term reduction of groundwater table caused by global climatic changes and overexploitation. However, short-term fluctuation is caused by climatic variations such as rainfall patterns and evaporation. Groundwater consumption is increasing at an alarming speed due to the increasement in the population, and it directly affects the reduction of the water table. Attaragoda GN division is considered a rural area in the wet zone of Sri Lanka. Most households utilize groundwater as their principal water source. There is no research conducted to assess the water table in the Attaragoda GN division. A preliminary study tried to determine the water table in Attaragoda GN division, Galle to fill this research gap. As a tropical country, the month of November is considered the second inter-monsoon season in Sri Lanka. Randomly selected 33 groundwater wells were considered as the sample size from 142/A Attaragoda GN division. The study was conducted in November 2021 from 8.00 am to 2.00 pm. Elevation was recorded using ―My elevation mobile app,‖ and the depth of the wells was measured using the measuring rope at the field in November 2021. The water table was calculated using the standard formula for all 33 sampling locations (Z=h–X; Z=depth of water table, X=elevation, h=depth measured in well). Data analysis was done using plotting the water table graph against elevation. Regarding land elevation, the water table fluctuated in the 4 m-20 m range in the Attaragoda GN area due to geographic locations. The lowest water table was recorded at a well in the highland area, and the highest was recorded at a well in the lower land. Based on the results in a plotted graph indicated that the same elevation had different groundwater table levels. Main reasons for this different water table recorded in the same elevation identified as overused groundwater for maintaining a fish farm, watering flower nurseries, and animal husbandry practices. At the same elevation, the well that recorded the low water table caused overexploitation of groundwater than the well which had a higher water table level. Water table levels can change in the same area due to their native geographic features. However, at the same elevation water table might be adjusted according to the consumption pattern of the households. 
 Keywords: Elevation, Geology, Ground water, Water table

Shrub Age and Water Dynamics Influence Primary Production, Carbon, and Nitrogen Stocks in a Coastal Environment

Drivers of shrub primary production and associated landscape impacts of encroachment are well known in drylands but have not been thoroughly studied in mesic and coastal habitats. The native, nitrogen-fixing shrub, Morella cerifera, has expanded into coastal grassland along the US Atlantic coast due to warming temperatures, but impacts on ecosystem function are not well known. Annual net primary production (ANPP) of Morella cerifera and key environmental drivers were measured long-term (1990 – 2007) across a chronosequence of shrub age on a mid-Atlantic barrier island. Soil and groundwater nutrients were compared with un-encroached grassland soil to evaluate impacts of vegetation on nutrient dynamics. Shrub ANPP declined with age at the same rate among all thickets, but there was variability from year to year. When climate variables were included in models, shrub age, precipitation, and freshwater table depth were consistent predictors of ANPP. Water table depth decreased over time, reducing ANPP. This may be due to rising sea-level, as well as to feedbacks with shrub age and evapotranspiration. Soil N and C increased with shrub age and were higher than adjacent grassland sites; however, there was a significant loss of N and C to groundwater. Our results demonstrate that drivers influencing the encroachment of shrubs in this coastal system (i.e., warming temperature) are not as important in predicting shrub primary production. Rather, interactions between shrub age and hydrological properties impact ANPP, contributing to coastal carbon storage.

Rainfall Infiltration through Stratified Colluvial Deposits: Analytical Approach vs. Numerical Modelling

This work investigates the rainfall infiltration process within homogeneous and stratified colluvial deposits caused by short (1–3 h) and intense (40–90 mm/h) rainfall, using both analytical and numerical infiltration modelling. The findings of the investigation demonstrate that the classic Green–Ampt model can be employed effectively to study homogeneous colluvial covers with permeability equal to or lower than kw = 10−5 m/s and that are subject to a 1 h rainfall with intensity I ≥ 45–50 mm/h. In these circumstances, a top-down saturation front forms within the colluvial deposit, leading to the saturation of a 70–100 cm-thick layer. This critical condition occurs every 5–10 years in the mountain area of the Friuli Venezia Giulia Region (NE Italy), which corresponds to a lower return period of critical hydrologic events when compared with other mountain basins in the Alps due to the higher initial degree of saturation characterising colluvial covers in this area (70–95%). When analysing stratified colluvial covers, the Dagan–Bresler approximate model, as well as the numerical modelling, emphasised the strong influence that abrupt variations in the permeability of the various soil layers have on the infiltration process at depth. In particular, the presence of a top organic soil horizon that is rich in macro-pores and is characterised by a higher permeability (k = 10−4 m/s) actually reduces the possibility of surficial ponding, which is the basic condition of the “piston” models. The highly permeable top soil allows for a rapid downward infiltration up to contact with the underlying colluvial material, which is less permeable (k = 10−5 m/s). Therefore, a perched water table forms starting from the organic soil–colluvium interface, originating pore–water overpressures within the colluvial deposit, with maximum values in the order of 5–10 kPa.

Estimation of Depth to Water Table within a Tropical University Campus Using Direct Current Resistivity Method

Ensuring access to clean and potable water is a global challenge, especially in regions like Nigeria where it is a pressing concern. Understanding the hydrogeological conditions, particularly the depth of the water table, is crucial for sustainable water resource management. In this study, we employed the direct current (DC) resistivity method to investigate the depth of the water table at the University of Calabar, Nigeria. Our approach involved measuring the electrical resistivity of subsurface materials to delineate the water table depth. The DC resistivity method emerged as a reliable and efficient tool for estimating the water table depth in our study area. By constructing a resistivity profile of the university campus, we uncovered valuable information about the subsurface hydrogeological conditions. Utilizing a multi-electrode resistivity system, we collected data at various depths and locations within the campus. These measurements were then processed using inversion techniques to produce a 2D resistivity image of the subsurface. This image revealed intriguing variations in subsurface resistivity, indicative of changes in composition and saturation of underground materials. Most importantly, our findings shed light on the depth of the water table, which ranged between 5.5m and 34.5m below the mean sea level. This information not only enhances our understanding of the University of Calabar’s hydrogeology but also contributes to broader efforts in sustainable water management and development strategies.

Innovative methodology for estimating Mountain-Front Recharge in data-scarce regions: A case study in Mexico City

Despite the critical role mountainous regions play in the hydrological cycle, the scarcity of subsurface hydrogeological data hampers accurate estimations of mountain-front recharge (MFR) and its components. This research proposes a cost-effective and replicable methodology for the preliminary estimation of MFR components in conditions of data scarcity. The proposed methodology, encompassing three phases, involves developing a hydrological conceptual model, creating a rainfall-runoff model, and estimating MFR values and their components (surface mountain-front recharge and mountain-block recharge); it enhances understanding of hydrologic processes in mountain zones by interpreting relationships among precipitation, altitude, and geology, influencing variations in recharge and water table position. A key contribution is the methodology's replicability in any mountainous area, even in the absence of detailed information, such as in protected natural areas. A case study is presented by estimating MFR in the Conservation Area of Mexico City (officially known as Suelo de Conservación), composed by the mountain ranges of Sierra de las Cruces and Chichinautzin Volcanic Field. The results emphasize the distinct distribution of MFR components and water table position in the two mountain regions, suggesting a need for a tailored approach to water management in the basin. The proposed methodology is cost-effective to understand the water dynamics in data-scarce regions, contributing to mountain-front recharge management.

Productivity, water use efficiency and soil properties of sugarcane as influenced by trash mulching and irrigation regimes under different planting systems in sandy loam soils

IntroductionIn the era of climate change, sugarcane used to face a problem associated with water shortage due to erratic rainfall patterns and lowered water tables. Improved water use efficiency using innovative crop management strategy is needed for sustainable sugarcane production. Trash mulching with different irrigation regimes can effectively modify the plant's hydrothermal micro-environment for increasing cane yield and water productivity.MethodsKeeping this in the background, a field experiment was conducted at Sugarcane Research Institute, RPCAU, Pusa, India, from 2016–17 to 2018–19 to investigate the effects of trash mulching and irrigation regimes on sugarcane productivity, water use efficiency (WUE) and soil properties in different planting systems. The field experiment comprised 12 treatments including four planting methods viz. conventional flat planting (CF; 75 cm row spacing) with trash mulching (6 t ha−1), CF planting (75 cm row spacing) without trash mulching (6 t ha−1), paired row trench (PT) planting (30: 120 cm row spacing) with trash mulching (6 t ha−1), PT planting (30: 120 cm row spacing) without trash mulching (6 t ha−1) and three irrigation schedules consisted of irrigation water (IW); cumulative pan evaporation (CPE) ratio of 0.60, 0.80, and 1.00 was laid out in strip plot design with three replications.Results and discussionThe cane yield (103.5 t ha−1) was found significantly higher in PT planting with trash mulching over the CF planting method with or without mulching. Concerning irrigation regimes using the IW/CPE ratio, it was found that the IW/CPE of 0.6 resulted in 16.9, 13.3% higher water-use efficiency, and 37.1, 40.7% higher water productivity over those under IW/CPE of 0.8, and 1.00, respectively. Furthermore, soil parameters like soil microbial biomass carbon (SMBC) and dehydrogenase activity were increased by 12.5, and 17.5 % due to trash mulching with trench planting as compared to those under conventional flat planting without mulching. The results suggest that planting sugarcane in paired rows and irrigation scheduling at 1.00 IW/CPE with the adoption of trash mulching practices is effective for increasing profitability by way of higher sugarcane productivity and water productivity and also in sustaining soil health.

Ground Water Resource and Their Characteristics of the Eastcentral Rajmahal Highlands, Jharkhand, India

This study examines the ground water resources and their characteristics of the Eastcentral Rajmahal Highlands in Jharkhand, India, The study aims to provide a comprehensive analysis of the ground water resources in the region and their geographical distribution. The study categorizes the area into four water table classes on the basis of 67 water samples sites, and explores the role of ground water in maintaining agriculture, the economy, and the environment in the region. The results of the study will provide valuable information for water resource management, agricultural planning, and sustainable development in the Eastcentral Rajmahal Highlands in Jharkhand.

Impacts of forestry drainage on surface peat stoichiometry and physical properties in boreal peatlands in Finland

Management of drained peatlands may pose a risk or a solution on the way towards climate change mitigation, which creates a need to evaluate the current state of forestry-drained peatlands, the magnitude of degradation processes and indicators for carbon (C) loss. Using a large dataset (778 profiles, 891 peat samples, collected between 1977 and 2017) from peatlands having different fertility classes across Finland, we investigate whether the surface peat profiles of undrained and forestry-drained peatlands differ in C:N, von Post and dry bulk density. The utility of element ratios (C:N:H stoichiometry) as site indicators for degradation were further analyzed from a subsample of 16 undrained and 30 drained peat profiles. This subsample of drained sites had carbon dioxide (CO2) and methane (CH4) fluxes measured allowing us to link peat element ratios to annual C gas effluxes. Element ratios H:C, O:C and C:N and degree of unsaturation (combining C, N, H changes) were found widely valid: they captured both differences in the botanical origin of peat as well as its potential decomposition pathway (C lost via a combination of dissolved organic C and C gas loss and/or the gaseous loss predominantly as CO2). Of the stoichiometric indexes, peat H:C ratio seemed to be the best proxy for degradation following drainage, it indicated not only long-term degradation but also explained 48% of the variation in annual CO2 emission. The O:C ratio positively correlated with annual CH4 flux, presumably because high O:C in peat reflected the availability of easily degradable substrate for methanogenesis. The differences in C:N ratio indicated notable decomposition processes for Sphagnum-dominated peatlands but not in Carex-dominated peatlands. Degree of unsaturation showed potential for an integrative proxy for drainage-induced lowering water table and post-drainage changes in peat substrate quality.

Adaptation of fen peatlands to climate change: rewetting and management shift can reduce greenhouse gas emissions and offset climate warming effects

In Germany, emissions from drained organic soils contributed approximately 53.7 Mio. t of carbon dioxide equivalents (CO2-eq) to the total national greenhouse gas (GHG) emissions in 2021. In addition to restoration measures, shifting management practices, rewetting, or using peatlands for paludiculture is expected to significantly reduce GHG emissions. The effects of climate change on these mitigation measures remains to be tested. In a 2017 experimental field study on agriculturally used grassland on organic soil, we assessed the effects of rewetting and of predicted climate warming on intensive grassland and on extensively managed sedge grassland (transplanted Carex acutiformis monoliths). The testing conditions of the two grassland types included drained versus rewetted conditions (annual mean water table of − 0.13 m below soil surface), ambient versus warming conditions (annual mean air temperature increase of + 0.8 to 1.3 °C; use of open top chambers), and the combination of rewetting and warming. We measured net ecosystem exchange of CO2, methane and nitrous oxide using the closed dynamic and static chamber method. Here, we report the results on the initial year of GHG measurements after transplanting adult Carex soil monoliths, including the controlled increase in water level and temperature. We observed higher N2O emissions than anticipated in all treatments. This was especially unexpected for the rewetted intensive grasslands and the Carex treatments, but largely attributable to the onset of rewetting coinciding with freeze–thaw cycles. However, this does not affect the overall outcomes on mitigation and adaptation trends. We found that warmer conditions increased total GHG emissions of the drained intensive grassland system from 48.4 to 66.9 t CO2-eq ha−1 year−1. The shift in grassland management towards Carex paludiculture resulted in the largest GHG reduction, producing a net cooling effect with an uptake of 11.1 t CO2-eq ha−1 year−1. Surprisingly, we found that this strong sink could be maintained under the simulated warming conditions ensuing an emission reduction potential of − 80 t CO2-eq ha−1 year−1. We emphasize that the results reflect a single initial measurement year and do not imply the permanence of the observed GHG sink function over time. Our findings affirm that rewetted peatlands with adapted plant species could sustain GHG mitigation and potentially promote ecosystem resilience, even under climate warming. In a warmer world, adaptation measures for organic soils should therefore include a change in management towards paludiculture. Multi-year studies are needed to support the findings of our one-year experiment. In general, the timing of rewetting should be considered carefully in mitigation measures.

Holocene floodplain aggradation in the central Grampian Highlands, Scotland

ABSTRACT Radiocarbon ages for samples of organic material within and overlying the highest Holocene floodplain and fan terraces in Glen Feshie and Glen Tromie imply sediment aggradation after ∼4.3 cal ka and probably incision after ∼3.7 cal ka, and in the Edendon Valley aggradation after ∼2.8 cal ka, with incision after ∼2.7 cal ka. The timing of sediment aggradation at all three sites postdates the onset of pine forest decline (∼4.8 cal ka) at nearby high-level sites, and coincides with wet periods characterised by high water tables. This coincidence in timing suggests that forest decline may have caused upstream extension of the tributary network, headwater incision and flashier flood responses, and that increased rainfall enhanced sediment discharge from headwater tributaries, with consequent sediment accumulation downstream on low-gradient fans and floodplains. More speculatively, exhaustion of readily entrained sediment from headwater areas may have stimulated subsequent floodplain and fan incision. Our results show that the highest Holocene terrace (the Main Holocene Terrace) is a diachronous feature, even in valleys emanating from the same upland source area, and support the conclusions of simulation models that predict marked increases in sediment discharge when deforestation is succeeded by an episode of increased rainfall.

Quantifying water loss in leaky micro-dam reservoir through water balance analysis and high-resolution water level data modeling

Abstract This study aimed to assess the runoff, recharge, and response of a shallow aquifer to leakage from the Arato micro-dam reservoir (MDR). The assessment was conducted using the Soil Conservation Service Curve Number (SCS-CN), soil moisture balance (SMB), and diver (automatic data logger) measurements in both the MDR and a shallow hand-dug well. Recharge was estimated using the chloride mass balance (CMB) and water table fluctuation (WTF) methods. The results revealed that the annual runoff from the catchment was 48.8 mm, which accounted for approximately 0.71 million m3. The yearly groundwater recharge was estimated to be 104, 92.8, and 100 mm using the SMB, CMB, and WTF methods, respectively. Furthermore, the water balance model of the Arato MDR indicated a leakage rate of 13.2 mm/day. It is noteworthy that the estimated leakage exceeded the seepage initially anticipated during the project's design phase (9,965 m3/year). This research project highlights the significance of utilizing local climatic and physical data from the specific watershed under investigation when planning reservoirs and other water resources. It also underscores the importance of conducting thorough site investigations to accurately quantify hydraulic conductivity for leakage estimation purposes.

Evaluation of meteorological drought effects on underground water level fluctuations using data mining methods (case study: semi-deep wells of Golestan province).

In most arid and semi-arid environments, groundwater is one of the precious resources threatened by water table decline and desiccation, thus it must be constantly monitored. Identifying the causes influencing the variations of the subsurface water level, such as meteorological drought, is one approach for monitoring these fluctuations. In the present study, the effect of two meteorological drought indices SPI and SPEI on the fluctuations of the underground water level was evaluated, as was their relationship with the drought index of the subsurface water level (SWI) using multivariate linear regression and M5 decision tree regression. After calculating climatic and hydrological drought indices in a 6-month time window for a long-term statistical period (1989-2018), the semi-deep aquifers of Golestan province, which is located in northern Iran, were considered as a research location for this purpose. The results demonstrated that the effect of meteorological drought does not immediately manifest in the changes of the subsurface water table and the hydrological drought index. By adding the meteorological drought index with a 6-month lag step, the average air temperature, and the total rainfall from the previous 6months as new variables, the correlation with the SWI index increases, so that in the best-case scenario, the M5 decision tree model provides the best result in predicting the SWI index. The second half of the year yielded a coefficient of determination of 0.92 and an error value of RMSE = 0.27 for the SPEI index. Among the meteorological drought indices, the SPEI index, which is based on precipitation and evapotranspiration, created a stronger link with the SWI index, which highlights the significance of potential evapotranspiration. It is a warning that, as a result of global warming, subsurface water tables in this region may fall in the future.

Study on Numerical Simulation of Reactive-Transport of Groundwater Pollutants Caused by Acid Leaching of Uranium: A Case Study in Bayan-Uul Area, Northern China

Acid in situ leaching (ISL) is a common approach to the recovery of uranium in the subsurface. In acid ISL, there are numerous of chemical reactions among the injected sulfuric acid, groundwater, and porous media containing ore layers. A substantial amount of radioactive elements including U, Ra, Rn, as well as conventional elements like K, Na, and Ca, and trace elements such as As, Cd, and Pb, are released into the groundwater. Thus, in acid ISL, understanding the transport and reactions of these substances and managing pollution control is crucial. In this study, a three-dimensional reactive transport modeling (RTM) using TOUGHREACT was built to investigate the dynamic reactive migration process of UO22+, H+, and SO42− at a typical uranium mine of Bayan-Uul. The model considering the partial penetration through wellbore in confined aquifer and complex chemical reactions among main minerals like uranium, K-feldspar, calcite, dolomite, anhydrite, gypsum, iron minerals, clay minerals, and other secondary minerals. The results show that after mining for one year, from the injection well to the extraction well, the spatial distribution of uranium volume fraction does not consistently increase or decrease, but it decreases initially and then increases. After mining for one year, the concentration front of UO22+ is about 20 m outside the mining area, the high concentration zone is mainly inside the mining area. The concentration front of H+ is no more than 50 m. SO42− is the index with the highest concentration among the three indexes, the concentration front of SO42− is no more than 100 m. The concentration breakthrough curve of the observation well 10 m from the mining area indicates that the concentrations of the three indicators began to significantly rise approximately after mining 0.05 years, reached the maximum value after mining 0.08 to 0.1 years, and then stabilized. The parameter sensitivity of absolute permeability and specific surface area of minerals shows that the concentration of H+ and SO42− is positively correlated with absolute permeability. The concentration of H+ is negatively correlated with the specific surface area of calcite, anhydrite, K-feldspar, gypsum, hematite, and dolomite. The concentration of SO42− is positively correlated with the specific surface area of K-feldspar and Hematite, and negatively correlated with the specific surface area of calcite, anhydrite, gypsum, and dolomite. The influence analysis of pumping ratio and non-uniform injection ratio shows that the non-uniform injection scheme has a more significant impact on pollution control. The water table, streamline, capture envelope, and the concentration breakthrough curve of five schemes with different pumping ratios and non-uniform injection ratio were obtained. The water table characteristics of five schemes shown that increase in the pumping ratio and the non-uniform injection ratio, the water table convex near the outer injection well is weakened and the groundwater depression cone near the pumping well is strengthened. This characteristic of water table exerts a notable retarding influence on the migration of pollutants from the mining area to the outside. For the scheme with a pumping ratio is 0 (the total pumping flow rate is equal to the total injection flow rate) and a non-uniform injection ratio is 0 (the flow rate of inner injection well Q1,Q2,Q3 is equal to the flow rate of outer injection well Q4,Q5,Q6), the streamline characteristics shown that a segment of the streamline of is diverging from inner region to the outer region. For other schemes, the streamline exhibits a convergent feature. It is indicated that by increasing the pumping ratio and non-uniform injection ratio, a closure flow field can be established, confining the groundwater pollutants resulting from mining within the capture envelope. Hence, the best scheme for preventing pollution migration is the scheme with a pumping ratio is 0 (the total pumping flow rate is equal to the total injection flow rate) and a non-uniform injection ratio is 0.1 (the flow rate of inner injection well Q1,Q2,Q3 is 10% more than the flow rate of outer injection well Q4,Q5,Q6). In this scheme, the optimal stable concentration of UO22+, H+, and SO42− at the observation well obtained by RTM is lower than other schemes, and the values are 0.00316 mol/kg, 2.792 (pH), and 0.0952 mol/kg. The inner well injection rate is 194.09 m3/d, the outer well injection rate is 158.89 m3/d, and the pumping rate is 264.00 m3/d. Numerical simulation analysis suggests that a scheme with a larger non-uniform injection ratio is more conducive to the formation of a strong hydraulic capture zone, thereby controlling the migration of pollutants in the acid ISL. A reasonable suggestion is to adopt non-uniform injection mining mode in acid ISL.

Recent hummock establishment in the margin of a subarctic fen, Finnish Lapland

Northern fens, that host unique biota and form a remarkable carbon stock, are sensitive to changes in the moisture balance and, therefore, may be strongly affected by climatic fluctuations. However, long‐term monitoring and palaeoecological studies of fens are relatively rare and, as a result, their responses to past and current climatic fluctuations are poorly known. In this study, we examined the recent vegetation change as well as changes in testate amoeba communities in the mire margin of a subarctic fen in Finnish Lapland with four peat profiles. Testate amoebae were used as indicators of past fluctuations in water table depth. The vegetation showed a drastic shift from sedge‐dominated fen to Sphagnum‐dominated communities during the late 20th and the early 21st centuries. This shift was accompanied by a turnover in the testate amoeba community. Testate amoeba‐based water table reconstructions indicated recent drying. This may be due to the lowering of the water table either from accelerated Sphagnum increment or enhanced evaporation. The observed hummock establishment concurs with the documented hemisphere‐wide expansion trend of hummock communities in fens. This change may strengthen the carbon sink and storage capacity of these peatlands, which could be viewed as a welcome negative feedback process to the ongoing climate warming. However, the change also poses a threat to biodiversity since fens are not only species‐rich habitats but are also endangered ecosystems.

Monitoring the Impacts of Artificial Recharge Structures on Water Table at Ambedkar Nagar, Uttar Pradesh, India

To study the groundwater recharge through rainfall and artificial recharge structures in selected dry well in different locations of UP was experimented. The data was recorded (1998-2017) to execute the artificial recharge structure at the appropriate locations with best geological condition to enhance the recharge rate at least cost for control of declining groundwater level. Study reveals that the stochastic auto regressive lime series model is an effective tool for management of ground water resource at pre and post monsoon. The variation of pre and post monsoon ground water level is maximum as the physical soil characteristics including hydraulic conductivity may enhance the recharge rate at least cost.

Hydrological effects of open ditch damming and controlled subsurface drainage in a Nordic agricultural field

Abstract Controlled drainage (CRD) is an agricultural water management practice designed to adjust the capacity of a drainage system under varying hydrological conditions. This simulation study aimed to quantify the potential of combining a controlled subsurface drainage (CS) with open ditch damming (CD) to manage the water table depth (WTD) and field water balance in Nordic conditions. Simulations with and without controlled drainage were run using a hydrological model that had been set up for a flat loamy field in Northern Ostrobothnia, Finland, for the period 2010–2021. All CRD scenarios reduced the probability of deep WTDs during growing seasons (May–Sep). The impact of CS on WTDs was greater and more uniform than CD. The CRD effects on water balance were seen in water outflow pathways, as CS reduced drain discharge while CD had the opposite effect. When both methods were applied simultaneously, annual evapotranspiration increased 5–12% compared with the free drainage scenario. The effects of CRD on evapotranspiration were greatest during the dry years indicating that CRD has potential to reduce drought in food production areas. None of the CRD scenarios could maintain optimal WTDs during the entire growing season, highlighting the complexity of optimizing field water management using CRD alone.