Rising Groundwater Levels Research Articles

Application of the electrical resistivity tomography in groundwater detection on loess plateau

Agricultural irrigation of the South Jingyang tableland in Shaanxi Province, China has led to a continuous rise of the groundwater level and has triggered a series of loess landslides, thereby seriously affecting the life and property safety of local residents. Research shows that the major cause of the landslide in the loess layer of the South Jingyang tableland is the rising groundwater level. Therefore, the research on the formation mechanism of landslide in this area should include the investigation of the stratigraphic structure and groundwater level distribution characteristics. On this basis, a series of approaches, such as electrical resistivity tomography (ERT), borehole, and laboratory tests, was carried out on the South Jingyang tableland, and the groundwater level distribution and stratigraphic structure in the study area were determined. The qualitative relationship between resistivity value and water content at different depths was detected using the inversion results of ERT and borehole data. Through laboratory tests, the quantitative relationship between resistivity values under different water contents was established. The precise depth of the groundwater level was inferred by connecting the qualitative relationship with the quantitative relationship, and then a detailed 3D geological model was established by linking the inversion results of ERT with the field borehole lithology data and geological survey data. The detection results show that when the qualitative and quantitative analyses of the ERT inversion results were combined, the distribution of the groundwater level was accurately judged. The ERT is effective in reflecting the stratigraphic structure and hydrological characteristics of the Loess Plateau, and its potential as a supplementary technology for detecting the groundwater level is reasonable. This study addresses the limitation and inaccuracy in determining the stratum structure and groundwater level by solely relying on borehole information or ERT. The established 3D geological model not only provides a basis for the study of groundwater table fluctuation, but also a technical guidance for the stability evaluation of loess slope, landslide prediction, and early warning in the study area.

Testing of a GPR equipment to assess the integrity condition of a subway tunnel located under groundwater level

AbstractDetermining the condition of underground concrete tunnels is fundamental for ensuring continuity and safety of operations, as well as for deploying efficient maintenance plans. The increased traffic volumes in early infrastructures, which are characterized by outdated construction techniques and potential approximated realization, as well as rising groundwater levels due to variations in urban industrialization patterns, are among the main causes of current concerns regarding their performance. Such uncertainties and constraints push towards the use of non‐destructive techniques, rather than direct methods, to gather the required knowledge on the actual status of structures. This study presents the results of a ground penetrating radar (GPR) investigation carried out in a subway tunnel segment to characterize the thickness of its underlying concrete elements, namely the tunnel invert and the concrete filling, deemed necessary after relevant flooding events prompted the evaluation of its overall integrity condition. A preliminary step was performed to define the optimal frequency and polarimetric antenna configuration, given the resolution and penetration requirements and considering the high electromagnetic interference characterizing the site. The selected configuration was then assembled in a dedicated survey platform, and an entire 650 m long segment surveyed, producing a high resolution delineation of the concrete elements thickness. The accuracy of the estimation has been validated through nine core samples, demonstrating the reliability and consistency of the conceptualized GPR platform.

Carbon Dioxide, Methane and Nitrous Oxide Fluxes from Tree Stems in Silver Birch and Black Alder Stands with Drained and Naturally Wet Peat Soils

The aim of this study was to evaluate the impact of groundwater level, soil temperature and general soil chemistry on greenhouse gas (GHG)—carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)—fluxes from tree stems in deciduous stands with nutrient-rich naturally wet and drained peat soils. In total, nine sample plots were established in the central and north-eastern part of Latvia. The studied tree species were silver birch (Betula pendula Roth.) and black alder (Alnus glutinosa (L.) Gaertb.). Tree stands of different ages and tree dimensions were selected for the study. GHG fluxes were measured with a circular-type non-transparent chamber of fixed area and volume, which was connected to the “Gasmet DX4040” mobile spectrometer. Ambient and soil temperature at a depth of 10 cm were measured, soil parameters (pH and content of carbon (C), nitrogen (N), potassium (K), phosphorus (P)) down to 30 cm depth were analyzed, and groundwater levels and weather conditions (wind, cloudiness, precipitation) were determined. The study found that CO2 fluxes from tree stems show a distinct seasonal pattern and a strong positive correlation with soil temperature. Significant differences in CO2 fluxes were found between temperature ranges below and above 5 °C, indicating that this temperature represents a threshold value. CH4 emissions from the tree stems increased with increasing groundwater levels. The impact of groundwater level becomes insignificant if the depth of the groundwater exceeds 30 cm. No significant N2O fluxes from tree stems were detected for most of the study period, except for March, April and June in black alder stands. As with CH4, N2O emissions exhibit an increase as groundwater levels rise. The C and N contents in soil have a significant impact on N2O fluxes from tree stems. There is a tendency for the N2O flux to increase along with increasing C and N contents in soil.

Projected Climate‐Driven Changes of Water Table Depth in the World's Major Groundwater Basins

AbstractAs groundwater found in aquifers is the main reservoir of freshwater for human activity, knowledge of the future response of groundwater to climate change is key for improving water management adaptation plans. We analyze the climate‐driven evolution of future levels of unconfined aquifers in the 218 world's major groundwater basins in global climate simulations following the latest Intergovernmental Panel on Climate Change scenarios, run with models able to capture feedbacks among climate, land use and groundwater. We find a rising of groundwater levels on global average, which is consistent with the projected global intensification of precipitation. This signal presents large regional disparities which mostly match the patterns of precipitation changes. As the climate models we used do not simulate human groundwater withdrawals (irrigation as well as domestic and industrial uses) which represent the other main driver of groundwater levels evolution, we also use Food and Agriculture Organization maps of present‐day irrigated areas and projections of population in 2100 to identify regions where groundwater withdrawals could exacerbate the projected depletion, or even reverse a projected rise into a depletion. Depending on the scenario, we then find a rise (respectively a depletion) of groundwater levels in 2100 over 33%[28–39]% to 42%[41–45]% (respectively 26%[25–32]% to 37%[36–40]%) of the area covered by the 218 world's major groundwater basins. And we estimate that 31%[29–36]% to 43%[42–44]% of the world's population could be affected by these groundwater changes, facing either water scarcity issues (for 29%[27–33]% to 40%[39–40]% of the population), or increased risks of flooding (for 1.7%[1.5–2.2]% to 2.2%[2.2–2.4]% of the population).

Emerging Issues and Problems of Soil Salinity and Water Logging

Soil salinity negatively affects plant growth and induces soil degradation. Saline soils indicate lower agricultural productivity and their impact on the livelihood security of farmers and the socio-economic status of the Indira Gandhi Canal region, Rajasthan. In the context of irrigation development, problems of rising groundwater levels and the development of salinity have arisen in the Indira Gandhi Nahar Priyojana (IGNP) area. The irrigation has recently decreased to about 1 meter, much higher than the specified value of 0.51 m in phase I. In phase I, severe inundation was observed. found in a variety of locations. It is anticipated that by the end of this century, roughly 49.6 percent of the region being studied will be at risk of experiencing flooding. The waterlogging, soil salinity, and alkalinity that plague India's agricultural landscape pose a challenge to the viability of irrigated farming. It has been determined that the most effective technique for halting the reduction in agricultural output is to use enhanced irrigation management in conjunction with a combination of surface and subsurface drainage. The method of reclaiming waterlogged lands by bio drainage is one that is efficient and economical. For the objectives of rehabilitation, species such as Salvador, Tamarix, Eucalyptus, and Prosopis Juliflora are among those that are recommended for planting in afflicted regions. The bio-drainage system helped in reducing the waterlogged areas and soil salinity by lowering the water table in the study area. Traditional knowledge and modern agricultural management good practices should be adopted for efficient and optimal use of water resources. This can be achieved by maintaining irrigation through the minimum pumping hours according to the minimum water requirements of the crop, as well as choosing more cost-effective planting methods. This research paper recommends policies to improve traditional and scientific knowledge into policies and improve mutual understanding, cooperation, and collaboration for better policy results for sustainable development and mitigate the emerging Issues and problems of soil Salinity and water logging in the area of Indira Gandhi Canal, Rajasthan.

Failure mechanism and movement process of three loess landslides due to freeze-thaw cycle in the Fangtai village, Yongjing County, Chinese Loess Plateau

In the seasonal freeze-thaw region of China, the long-term freeze-thaw cycle (FTC) weakens the strength of the soil's structure leading to a series of geohazard events such as landslides and collapses. In order to understand the formation mechanism of the landslide during periods of freeze-thaw in the Chinese Loess Plateau (CLP). In this study, we analyzed the evolution process of the microstructure and the strength combined with triaxial test, resistivity experiments and CT technology. Furthermore, we collected meteorological, irrigation, groundwater level and landslide data to discuss landslide inducing factors. The results show that (1) the FTC has a significant damage effect on the strength of the original loess. After 10 FTCs, the strength of the original loess with various moisture content (ωmc) is reduced by at least 50%. The higher the ωmc of the original loess sample, the greater the strength reduction and the more apparent the deterioration characteristics. (2) FTC causes the expansion of the pore structure, that gradually presents non-uniformity and complexity, resulting in the continuous increase of resistivity. The pore area of macropores and mesopores are the most significant feature after 10 FTCs, and the increase of pore structure leads to the gradual loosening of the soil structure, which reflects the essence of strength deterioration. (3) Fangtai 1# landslide has the typical characteristics of high-speed and long-distance. The primary movement period of the landslide was from 4 s to 30s, the maximum speed of the landslide was 20 m/s, and the apparent friction angle was 0.34. (4): The most direct inducing factor of the three consecutive landslides in the Fangtai village was a temperature change lasting >10 days. Through mechanical and microstructure analysis, we found that the increase of FTCs leading to soil strength damage is the trigger factor, especially in the slope softening zone, which promotes the frequent occurrence of landslides. The rise of groundwater level caused by irrigation is the fundamental condition for the formation of landslide, and the irrigation plan of the Heifangtai tableland needs to be paid reasonable attention.

Landslide mechanism and stability of an open-pit slope: The Manglai open-pit coal mine

A clear understanding of landslide mechanisms and stability analyses is of great significance for landslide monitoring, prediction, and control. A large-scale end wall landslide occurred and its area reached 47,752 m2 on August 7–20, 2020, in the Manglai open-pit coal mine, China. In this paper, the engineering geological survey, mechanical test, large-deformation finite element numerical method, limit equilibrium method and analytical formula are used to analyze how the groundwater level rise caused this end wall failure and landslide. The engineering geological conditions, hydrogeological conditions, landslide activity signs and physical and mechanical parameter calibration of the sliding mass are investigated in detail and tested. Three-dimensional and two-dimensional numerical models of slopes are established, and an analytical formula calculation method to calculate the factor of safety (FoS) is proposed when sliding cracks are located on the top and toe of a slope. The results indicate that the fault fracture zone, soft strata, continuous heavy rainfall, and groundwater were the main contributors to this landslide. The three-dimensional numerical calculation results are consistent with the deformation and failure process of the slope observed in the field, which shows a retrogressive progressive failure mode. The calculation results of SLOPE/W and the analytical formula are consistent; i.e., when the groundwater level rises to +950, the stability of the end wall reaches the critical stability state. With the passage of time, the creep of the sliding surface accelerates until the entire end wall landslide.

Investigation of Water and Soil Migration and Mud Pumping of Subgrades under Traffic Load

Atmospheric precipitation leads to the increase of moisture in the subgrade. The moisture and soil migration in subgrade is a key scientific problem in evaluating the service performance of the subgrade and resolving or preventing mud pumping. Using a self-developed testing system as well as a numerical simulation model, a detailed study of the dynamic hydraulic characteristics, water migration mechanism, fine soil migration mechanism, and mud pumping properties of the subgrade was conducted. The results showed that water migrated into the upper layer of the subgrade under traffic load. Meanwhile, a pressure gradient for the pore water was generated in the subgrade. This kind of pressure gradient is beneficial for the moisture and fine soil migration. With rising groundwater level and increasing traffic load, the porosity of the subgrade soil differs at different depths. The fine soil migration is caused by water migration, which causes new migration channel for water in the subgrade. Then, a circulating system of moisture and fine soil is formed in the subgrade under a traffic load. After that, the upper layer subgrade soil is nearly saturated under the action of traffic load. Then, the nearly saturated soil liquefies instantaneously, becoming mud, under the action of traffic load. However, as the loading time progresses, the moisture and fine soil in the subgrade continue to migrate upward, resulting in the mud being pumped into the ballast and the gradual disappearance of liquefied soils at different depths.

Valorisation of dune sand-tuff for Saharan pavement design

The current experimental research aims to valorise two Saharan soils (dune sand and tuff) for pavement purposes in arid zones. A mixture of 65 % tuff and 35 % dune sand (named TDSopt) was previously studied and exhibited optimum geotechnical characteristics that were suitable for low-traffic pavements. However, the rise of groundwater level with aggressive sulphate in the Ouargla region, Algeria, weakened the mechanical properties of this TDSopt. Further treatment with sulphate-resistant binders was therefore proposed to remedy this defect. In this research, laboratory testing was performed to define the optimum treatment for the TDSopt, followed by the hydromechanical characterisation of the treated TDSopt. Experimental results validated the following observations. First, the treatment of TDSopt with cement and/or lime resulted in decreased dry density, but an increased California Bearing Ratio (CBR) index. Also notably improved were unconfined compressive strength (UCS), secant modulus (E50) and resistance to immersion (Rimm). More specifically, the defined optimum recipe – TDSopt plus 1.33 % cement and 2.66 % lime – increased the CBR index by 75 % and 35 % for the soaked and unsoaked specimens, respectively. UCS, E50 and Rimm increased by 65 %, 75 % and 65 %, respectively. The optimum treatment also increases the shrinkage limit void ratio of compacted TDSopt from 0.39 to 0.46. Finally, the strength parameters (UCS, cohesion and friction angle) of optimum treated specimens were larger than those of untreated material regardless of water content. At Modified Proctor Optimum, the UCS, cohesion and friction angle increase from 0.54 to 2.46 MPa, 167 to 800 kPa and 23° to 40°, respectively.

MODELLING IMPACT OF CROPPING PATTERN AND URBAN AREAON GROUNDWATER RESOURSES OF NAGARJUNA SAGAR RIGHTCANAL COMMAND AREA USING VISUAL MODFLOW

Groundwater models can be used for the assessment of the impact of the different cropping pattern andchange in urban area on groundwater resource and modeling is the best tool to optimize the differentcombinations or scenarios and to select the best combination or scenario for management of sustainablegroundwater resources. In this study, three-dimensional finite-difference groundwater model VisualMODFLOW 2.8.1 was used to simulate the groundwater dynamics in Nagarjuna Sagar Right CanalCommand area. The net area irrigated under Nagarjuna Sagar Right Canal is 4.75 lakh ha. Calibration andvalidation of the model has been carried out and used to predict the static groundwater storage availabilityin the study area for different cropping pattern scenarios and change in the urban area. The validatedVisual MODFLOW 2.8.1 was used to simulate the groundwater dynamics in the study area for the years2030 and 2040 with different cropping pattern scenarios and change in the urban area. Global climatemodel MarkSim, which is developed by the International Centre for Tropical Agriculture (CIAT) was usedto generate future weather data for the years 2030 and 2040. The impact of change in cropping pattern onstorage of static groundwater resource in the study area for the years 2030 and 2040 was assessed with twoscenarios of change in rice cropped area decreased by 50 per cent and 100 per cent with this cropped areacultivated equally by the ID crops. These results showed that the lesser storage of static groundwaterresources in future lesser. The change in the cropping pattern affects the net recharge of the groundwaterwhich influences the groundwater levels. Increase in paddy area increases the recharge and rise ingroundwater level has been identified. In the study area, cropping pattern could be changed from rice cropto other irrigated dry crops to prevent the increase of groundwater resources which leads the water loggingcondition in the study area. The urbanization is one of the most significant factor considering for assessmentof the response on the groundwater levels and availability of static groundwater resources. The groundwaterrecharge is very less in case of increase in urban area and generates more runoff rather than the intake ofrainfall in the ground surface as having the impervious nature. In view of increase in urban area in thestudy area, the four scenarios are proposed with the combination of 10 per cent and 20 per cent decrease inrecharge and 50 per cent and 100 per cent increase in groundwater draft and simulated the groundwater fluctuations for the years 2030 and 2040. The impact of change in the urban area on storage of availablestatic groundwater resource in the study area for the years 2030 and 2040 was assessed with four scenarioscombination of groundwater recharge and groundwater pumping. The storage of static groundwaterresources would be expected in future lesser than the present storage of static groundwater resources in allscenarios due to increase in urban area as increased in impervious nature of the ground surface. The declinein available static groundwater resources would be expected 6.38 per cent and 7.08 per cent during 2030and 2040 respectively. The rapid expansion in the urban area and their settlements is also one of the reasonsfor the depletion of groundwater resources with low recharge and high groundwater draft.

Natural factors influence on first rarely flooded soil salination of the river Volga delta

Soil degradation is one of the common types of which is soil salination, is a serious limited factor of food security and sustainable territory development. It is necessary to pay a special attention on the first soil salination of arid regions, as arid climate leads to the active salt accumulation in the upper rooting soil horizons and gives rise to withdrawal of large land areas from economic turnover. The purpose of the this work is defining of the watersoluble salts specific features in soils of the river Volga delta upper level natural boundaries under the influence of natural factors. Botanic natural sanctuary “Svinoroiny meadow (Meshkovsky)” was chosen as a research object, associated with the new Caspian coastal plain within distribution of the river Volga delta Baer knoll landscape. Water extract ions analysis and soil solution toxicity calculation on the area were carried out from 1979 till 2020. It was revealed that dynamics direction of salination types are defined by the ascent of water predominanceon over descending on the area in the conditions of the territory exudative water regime. Salination increase to a great extent depends on the great volumes of spring-summer floods and appropriate ground water level rise, area desalination is defined by atmospheric precipitations quantity.

Mechanism of Changes in Goaf Water Hydrogeochemistry: A Case Study of the Menkeqing Coal Mine.

Goaf water in mining areas is widely found in China's coal mines. To clarify the hydrogeochemical characteristics of goaf water and the influence mechanism of water-rock interaction and further reveal microbial action on the formation of goaf water quality, the goaf water in the Menkeqing coal mine was taken as the object, and physical modeling was used to simulate the process of the real goaf changing from an oxygen-sufficient environment to an anoxic environment with the rise of groundwater level in this work. The experimental results showed that the water-rock interaction in the goaf was mainly the dissolution-precipitation of minerals in the rocks of the caving zone and fracture zone, cation exchange, and oxidation of pyrite in the coal layer. The primary sources of Na+ and K+ in the goaf water were the dissolution and reverse ion exchange of silicate minerals such as albite and potassium feldspar, while Ca2+ and Mg2+ mainly from the dissolution of minerals such as calcium feldspar, calcite, and chlorite. The oxidation of pyrite in coal was the main reason for the increase in SO42- concentration, the enhancement of reduction, and the decrease in pH and DO (dissolved oxygen) in the goaf water. Relative abundance of sulfate-reducing bacteria (SRB) in goaf (e.g., Desulfosporosinus, Desulfobacterium, etc.) increased gradually, inhibiting the increase in SO42- concentration in goaf water through the devulcanization of SRB. The inverse hydrogeochemical modeling was performed using PHREEQC for two stages of the simulation experiment: 0-30 days and 30-300 days. The simulation results show that the water-rock action in the formation of goaf water mainly occurred in the simulation experiment's early stage (0-30 days), and the mineral dissolution is dominant throughout the experimental stage. The results of the study provide a theoretical reference for the prediction of highly mineralized water pollution in goaf and its prevention and control.

Natural-human driving factors of groundwater salinization in a long-term irrigation area

Salinization of groundwater is a major challenge for groundwater management in long-term irrigation areas, decoupling its complex influencing factors can provide insights for the sustainable development of irrigation areas. In this study, the natural-human driving factors of groundwater salinization in the Yinchuan Plain, a typical irrigated area, were identified using isotope analysis, information entropy, and self-organizing map. Results show that groundwater in the study area is seriously salinized with obvious spatial heterogeneity. Multiple natural conditions and frequent human activities complicate the salinization characteristics of groundwater. On this basis, four typical natural influence units of groundwater were identified, namely, an evaporation and upward leakage zone, a runoff zone, an evaporation zone, and a runoff and upward leakage zone. Information entropy was proposed to quantify the complexity of groundwater resulting from human activities: The complexity difference between densely populated areas and natural dominant areas is mainly reflected in Na+, SO42−, and Cl−. Multiple human-made drivers of complex water environment were further separated into three patterns by the SOM model: blockage-evaporation type, leakage-evaporation type, and irrigation type. The blockage of drainage ditches and obstruction of salt discharge has the highest impact on the salinization of groundwater, followed by irrigation activities and transportation losses. Water excessive stagnation caused by blockage or irrigation is the root cause of groundwater salinization in the irrigated area, and its impact is greater than that of the traditional understanding of groundwater level rise. Based on the evaluation of irrigation water quality, management initiatives for irrigated areas should prioritize dredging and maintaining a healthy soil and groundwater environment in tandem.

Reconstruction of the sedimentary environment of phytogenic deposits in the Tomisławice opencast mine (Konin Region, central Poland)

Palynological analysis of the Tomis³awice opencast mine deposits has allowed reconstruction of the plant communities and investigation of the evolution of sedimentary environments at various stages of lignite-forming marsh development, recorded in the composition of pollen assemblages from deposits of the 1st Mid-Polish lignite seam (MPLS-1). Rich pollen communities from an ~9 m thick section has enabled study of the succession of plant communities and of the evolution of phytogenic sedimentation. The pollen succession indicates that the assemblages in the whole lignite seam represent the VIII Celtipollenites verus pollen Zone. Slight differences in the composition of the communities reflect different stages of basin development, depending more on the variable water dynamics than on climatic oscillations. Lignite of the MPLS-1 developed in a continental regime on alluvial plains. Changes in the succession of plant communities in the Tomis³awice section record flooding-drainage cycles caused by groundwater level oscillations. Peat bog accumulation took place in river basins, in which the lack of siliciclastic intercalations within the massive lignite seams points to weak fluvial dynamics. A rise in groundwater level and/or surface water resulted in flooding of the marshes and the formation of an extensive shallow lake basin, as shown by the presence of freshwater algae and pollen of aquatic plants. The section as a whole does not record an increased contribution of thermophilic plant taxa. The flora was generally dominated by warm-temperate and thermophilic species, without the participation of strongly thermophilic vegetation, which indicates that the lignite seam in the Tomis³awice opencast mine was formed in the generally stable conditions of a warm temperate climate.

A simple numerical simulation method for unsaturated stratum under the water environmental load

A simple numerical simulation method is proposed to investigate the mechanical response of the unsaturated stratum under the water environmental load. The proposed numerical simulation method applies the water environmental load to the unsaturated stratum as the load condition, and adopts the developed non-orthogonal elastoplastic constitutive model for unsaturated soil to describe the mechanical behaviors at the material scale. The mechanical response of unsaturated stratum is obtained by solving the discretized governing equation of the mechanical equilibrium. The proposed numerical simulation method is implemented based on the commercial finite element software ABAQUS. The effectiveness of the proposed method is verified through the element tests on the Botkin silt, the element tests on the Pearl clay, and a model test of the rising water level on a sand column. The numerical simulations of the rising and decreasing groundwater level in the unsaturated stratum are conducted. During the rising groundwater level, the non-collapsible stratum produces rebound deformation, the collapsible stratum below the groundwater level occurs rebound deformation, and the collapsible stratum above the groundwater level mainly produces settlement deformation. During the decreasing groundwater level, both the collapsible stratum and the non-collapsible stratum produce the settlement deformation.

Failure Process Analysis of Landslide Triggered by Rainfall at Volcanic Area: Fangshan Landslide Case Study

The Fangshan landslide was a rainfall-induced landslide that occurred in a volcanic area in the Fangshan scenic spot, Nanjing, Jiangsu, China. On 25 October 2016, after approximately 10 days of continuous rainfall, a shallow landslide rapidly developed, which triggered slow movement of deep mudstone rock. According to the characteristics of the landslide body, measures such as anti-slide piles, anchor cables and drainage were used to reinforce the landslide. Active drainage measures included arranging plant growth zones at the trailing edge of the landslide, and passive drainage measures included arranging pumping wells at the trailing edge of the landslide. It is worth emphasizing that the Fangshan landslide was the first example of a landslide in Jiangsu Province, China that was treated by actively lowering the water pressure. After landslide treatment from 16 May 2017 to 21 January 2018, the Fangshan landslide tended to be stable. However, the stable landslide was reactivated by the rise in groundwater level caused by rainfall and pumping well damage and underwent accelerated downward sliding in July 2020. The Fangshan landslide has caused great damage to the roads and buildings of Fangshan scenic spot, with a direct loss of RMB 6 million and an indirect loss of RMB 95 million. This article discusses the development process of the shallow soil landslide and the underlying deep mudstone rock landslide. The influence of groundwater level variation on the deformation of the shallow soil landslide and deep mudstone rock landslide of the Fangshan landslide are also discussed.

Application of (SCS-CN) Method in Runoff Estimation in Qoratu Watershed Using (GIS & RS) Techniques

The method of Soil Conservation Service Curve Number (SCS-CN) was applied to assess runoff in Qoratu Watershed, Garmian Administration, (NE-Iraq). Digital Elevation Model (DEM-12.5m) and (Landsat OLI) were both utilized as the stuff of Geographic Information System (GIS) and Remote Sensing (RS) techniques analyzed to obtain accurate hydrological data. Qoratu watershed is a mutual (Iran-Iraq) watershed located within the Iraqi Kurdistan Region adjacent to the Sirwan River. Topographically, the study area is known as the sub-mountain area of the Kurdistan Region. At its sixth order, the watershed drains into the Sirwan River. The total area of the Qoratu watershed Was found to be (808.34 Km2); so, approximately (44.9%) of this area is located within the Iraqi Kurdistan Region. This study aimed to (i) Estimate the Runoff of the Qoratu watershed for dam construction purposes, (ii) estimate the water harvest of the Qoratu sub-watershed to achieve the best state of water management in the study area, (iii) estimate groundwater levels rise, and (iv) to control floods during the rainy season. The study concluded that the water inflow is high; thus, the possibility of constructing a dam and/or ponds in the area is beneficial.

Riparian Microtopography Affects Event‐Driven Stream DOC Concentrations and DOM Quality in a Forested Headwater Catchment

AbstractThe transport of dissolved organic carbon (DOC) from the soils to inland waters plays an important role in the global carbon cycle. Widespread increases in DOC concentrations have been observed in surface waters over the last few decades, affecting carbon balances, ecosystem functioning and drinking water treatment. However, the primary hydrological controls on DOC mobilization are still uncertain. The aim of this study was to investigate the role of microtopography in the riparian zone for DOC export and DOM quality. DOC concentration and DOM quality in the shallow groundwater of a riparian zone and in streamflow in a forested headwater catchment was investigated using fluorescence and absorbance characteristics. We found higher DOC concentrations with a higher aromaticity in the microtopographical depressions, which were influenced by highly dynamic shallow groundwater levels, than in the flat forest soil. As a result of the frequent wet‐dry cycles in the upper soil layers, aromatic DOC accumulated in the shallow groundwater within and below the microtopographical depressions. Rising groundwater levels during precipitation events led to the connection of the microtopographical depressions to the stream, resulting in a change toward more aromatic DOC in the stream. Increasing stream DOC concentrations were accompanied by increasing concentrations of iron and aluminum, suggesting the coupled release of these metals with DOC from the riparian zone. Our results highlight the importance of the interplay between microtopography and groundwater level dynamics in the riparian zone for DOC export from headwater catchments.

Evaluation of the impact of natural conditions on the sprinkler irrigation system

Abstract Natural conditions highly predict further use of the locality. Current climate change, population growth and other crises open questions of better use and design of existing and new irrigation systems. Government of Uzbekistan currently highly invest in the water-saving irrigation systems which should correspond to natural conditions of the locality. Therefore, deep study of each area of interest is necessary. Based on the available information of natural conditions of Uzbekistan, the crop production localities overlap localities with low precipitation, high temperature rise in last years and middle groundwater level. Also, part of them lays on the soils with low water holding capacity and high salinity. Especially in those areas the proper design should be done.

Evolution of groundwater salinity and fluoride in the deep confined aquifers of Cangzhou in the North China plain after the South-to-North Water Diversion Project

The South-to-North Water Diversion Project (SNWDP) has greatly improved the water shortage in the North China Plain. However, the impact of the SNWDP on the evolution of groundwater chemistry, especially fluoride and salinity, was still unknown. Cangzhou, one of the recipient cities of SNWDP and suffered from severe land subsidence, was selected to collect the deep confined groundwater samples before and after the SNWDP. The results showed that groundwater fluoride concentration decreased after the SNWDP, with a median value of 4.39 mg/L in 2017 and 3.00 mg/L in 2021, respectively. This trend was more clearly observed in the land subsidence area, which could be related to the reduction of land subsidence, due to the stopping pumping of deep groundwater. The pore water in clayey sediments contains fluoride up to 7.02 mg/L, which can be released into groundwater due to the sediment compaction before the SNWDP. The extensive exploitation during last decades changed the groundwater recharge patterns, resulting in over 60% deep groundwater being recharged by the pore water released from clayey sediment. The results of the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) suggested that land subsidence has slowed down after the SNWDP, especially in the central area of land subsidence, thereby restricting the release of fluoride-rich pore water. However, groundwater salinity increased after the SNWDP, and the number of samples exceeding the drinking standard (TDS <1000 mg/L) increased by 26.4%. The rising groundwater level favors the water-rock interaction, promoting the dissolution of soluble minerals, for instance, halite, which was reflected by the results of inverse and forward modeling using the PHREEQC. Groundwater salinization after the SNWDP potentially induces the fluorite dissolution and causes the elevation of groundwater fluoride concentration. However, the calculated results indicate that the amount of F elevation related to groundwater salinization is significantly lower than the contribution of fluoride-rich pore water from clay sediment compaction. The findings of this study provide a comprehensive assessment of the influence of the SNWDP on the groundwater quality and some new insights for the management of groundwater resources.