Rise Of Groundwater Table Research Articles

Causes of landslide recurrence in a loess platform with respect to hydrological processes

Irrigation-induced landslide is a recurring problem in the Heifangtai loess platform of northwest China. The landslide sites are characterized by a concave topography. Numerical modeling indicates that the groundwater table at the past-landslide site rises more quickly than the other natural platform borders under irrigation conditions. This is consistent with the field observations that seepage of the groundwater appeared in the hollow is higher than that of lateral slopes. In order to investigate the response of soil behavior due to rise in groundwater table, stress-path tests were performed on undisturbed specimens. It has been observed that the increase in pore water pressure in loess can trigger soil liquefaction and eventually results in landslide. Hence, the concave past-landslide site is much more prone to landsliding, which contributed to the landslide recurrence.

WATERLOGGING AND FARMLAND SALINISATION: CAUSES AND REMEDIAL MEASURES IN AN IRRIGATED SEMI‐ARID REGION OF INDIA

ABSTRACTWaterlogging and secondary salinisation have become serious problems in canal irrigated areas of arid and semi‐arid regions. This study examined hydrology and estimated the seasonal net groundwater recharge of an irrigated semi‐arid region located in the Haryana State of India where about 500 000 ha area are waterlogged and unproductive, and the size of the waterlogged area is increasing, causing a threat to agricultural sustainability. Groundwater recharge analysis during the study period (1989–2010) revealed that percolation from irrigated fields was the main recharge component, with 48% contributing to total recharge. An annual groundwater table rise of 0.198 m was estimated for the study area. Since the groundwater table had been rising continuously, suitable water management strategies such as as conjunctive use of groundwater and canal water and changes in crop patterns by reducing rice crop areas against of other low‐water crops such as sorghum are suggested to bring the groundwater table down to a safe limit and prevent further rise of the groundwater table. Copyright © 2012 John Wiley & Sons, Ltd.

Two and three-dimensional slope stability reanalyses of Bukit Batok slope

A residual soil slope in Singapore that failed on two occasions, in 1989 and 1991, was reanalysed using two (2D) and three-dimensional (3D) slope stability analyses. The geometry of the slope in 1989 differed from that in 1991. The 2D and 3D slope stability analyses on the slope that failed in 1989 showed that the average shear strength parameters of the residual soils are representative of the slope and the factors of safety obtained from 2D slope stability analyses are not necessarily more conservative than 3D slope stability analyses. The analyses also showed that the slope failed in 1989 due to rising groundwater table. The analyses of the slope in 1991 showed that the slope experienced shallow failure due to the high groundwater table. Analyses of the slope after lowering of groundwater table by horizontal drains showed that the factor of safety of the slope has improved tremendously. The differences in factors of safety for 2D and 3D slope stability analyses are greater for low groundwater table as compared with those for high groundwater table. The results illustrated how 3D slope stability analyses have become less daunting to perform and can be incorporated into routine slope designs.

Estimating long-term regional groundwater recharge for the evaluation of potential solution alternatives to waterlogging and salinisation

Summary Accurate estimation of the groundwater recharge is essential for efficient and sustainable groundwater management in arid and semi-arid regions, as water resources are critical to economic development in these areas. Various techniques are available to quantify recharge. The hydrological budget model proposed herein is unique, simple, and easy to apply. It uses data on groundwater level, groundwater extraction, and distributed specific yield information for estimating groundwater recharge. The Model is employed to estimate the seasonal long-term (35 years, e.g., from 1974 to 2009) groundwater recharge of an irrigated semi-arid area located in Haryana State of India, where groundwater levels are rising, continuously. The results are analysed to provide an overview of the process dynamics that led to imbalance of the system. Groundwater recharge analysis during the study period reveals that percolation from irrigated fields is the main recharge component with 49% contribution to the total recharge. An annual groundwater table rise of 0.14 m has been estimated for the study area. Various potential solution alternatives are evaluated to mitigate the problems of waterlogging and salinisation, considering the socio-economic issues which have wider policy significance on sustainability. Several suitable water management strategies such as reduction in rice area, increase in pumping volume and using the groundwater conjunctively with higher quality canal water, and lining of canal networks are suggested to bring the watertable down to a safe limit and to prevent further rising of the watertable. Among the potential solution alternatives studied, the one which considers 10% reduction in rice area along with 2% increase in pumping volume and 20% canal lining, yields best result for mitigating the waterlogging problems.

Development and lithogenesis of the palustrine and calcrete deposits of the Dibdibba Alluvial Fan, Kuwait

A model is proposed for the development of the Quaternary palustrine carbonate–calcrete association, which occurs as hard crust capping low hills at a distal flood plain of Al Dibdibba alluvial fan located at southwestern Kuwait. Field occurrence, detailed petrographic investigation and geochemical analysis revealed that a single cycle of groundwater calcrete with vertical gradational maturity pattern was developed. This represents a continuous sedimentological cycle during which flood sheet conditions prevailed with intermittent periods of humid and arid conditions. Subsequently, calcitic micrite was continuously precipitated from small, shallow, local, isolated and short lived ponds fringed by freshwater marshes with abundant charophyte meadows. The latter were developed as a result of flooding scattered depressions by groundwater supersaturated with respect to calcite due to rise of groundwater table. The deposition of two facies of carbonate muds, namely; biomicrite and pelintraclasts skeletal micrites was followed by a drought phase which witnessed desiccation of the fresh water ponds and significant drop in groundwater level. A sequence of pedogenic and diagenetic processes acted on the deposited carbonate muds are manifested by: (a) desiccation cracks, (b) micrite neomorphism, (c) infilling of root burrows and some cracks by aeolian siliciclastics, (d) karstification, (e) marmorization, (f) calcretization of root burrow infill and development of pseudo-rhizocrete, (g) calcite cementation and mineral authigenesis, and (h) silcretization. These processes are responsible for the development of hard palustrine carbonate crust. At the advent of aridity, the whole system of Al Dibdibba alluvial fan was subjected to deflation. This resulted in reversing the paleotopography of the hard crusted palustrine depressions into carbonate capped domal hills.

Determining optimal groundwater table depth for maximizing cotton production in the Sardarya province of Uzbekistan

AbstractPoor on‐farm irrigation practices and rising groundwater table depths are the major reasons for low cotton yields in the Sardarya province of Uzbekistan. To ensure sustainability of cotton production in the area, precise calculations of irrigation requirements are needed to optimize crop yields and to keep groundwater table depth below the root zone to avoid soil salinization. To determine optimal groundwater table depth and irrigation amounts for the Sardarya province of Uzbekistan, the Soil–Water–Atmosphere–Plant (SWAP) model was used. SWAP was calibrated and validated using measured data from an experimental cotton field during the agricultural year of 2006 and 2007. The calibrated SWAP model was then used to simulate optimal groundwater table depth and irrigation amounts. The simulation results show that for the existing conditions in the study area, a groundwater table depth of approximately 200 cm together with an irrigation application of 2500 m3 ha−1 will be the most appropriate combination for optimal cotton yields (≈ 3.0 t ha−1). However, to achieve maximum potential yields of cotton (5–6 t ha−1), leaching of excessive salts from the root zone through freshwater application would be imperative. This would require rehabilitation of the existing drainage network in the area. Copyright © 2010 John Wiley & Sons, Ltd.

Selenium Dynamics in Boreal Streams: The Role of Wetlands and Changing Groundwater Tables

The concentrations of selenium in 10 catchments of a stream network in northern Sweden were monitored over two years, yielding almost 350 observations of selenium concentrations in streamwater. The export of selenium was found to be systematically greater from forests than from mires. Accounting for atmospheric deposition, which was monitored over four years, there was a net accumulation of selenium in mires, while the export from forest soils was approximately equal to the atmospheric deposition. In forest dominated catchments the concentrations of selenium oscillated rapidly back and forth from high to low levels during spring floods. High selenium concentrations coincided with rising groundwater tables in the riparian forest soils, while low selenium concentrations were associated with receding groundwater. Thermodynamic modeling indicated that precipitation of elemental selenium would occur under reducing conditions in the riparian soils. Since changes in the redox conditions are likely to occur near the transition from the unsaturated to the saturated zone, it is hypothesized that the transport of selenium from forest soils to streams is controlled by redox reactions in riparian soils.

Soil salinity development in the yellow river delta in relation to groundwater dynamics

AbstractThe Yellow River Delta occupies an important position in the global ecosystem because of its valuable wetland habitat resources for migratory birds on the Eastern Pacific migration route. However, it has suffered from severe land degradation because of soil salinization. This paper assesses the distribution maps of saline soils during the past two decades, using field observations at three points in time using remote sensing images for the same periods, in combination with spatial models. Soil salinization appears to have expanded from the coastline to inland areas of the Yelow River Delta at a surprising speed during that period. The spatio‐temporal dynamics of the groundwater table and total dissolved solids (TDS) during the last 20 years were analyzed using maps based on Kriging interpolation. Kriging helped substantially to improve the accurateness of the predicted values of soil salt content, using a random subsample of the observation points as validation basis. Correlation analysis of the spatial data revealed that the distribution and evolution of saline soils are closely related to the dynamics of groundwater: the aggravation of soil salinization is associated with a rising groundwater table and increasing TDS. Insufficient recharge of the groundwater with fresh surface water due to reduced Yellow River discharge and subsequent seawater intrusion are therefore serious environmental problems in the Yellow River Delta ecosystem. Copyright © 2011 John Wiley & Sons, Ltd.

Rising water table: A threat to sustainable agriculture in an irrigated semi-arid region of Haryana, India

Abstract The sustainability of the rice–wheat cropping system in an irrigated semi-arid area of Haryana State (India) is under threat due to the continuous rise in the poor quality groundwater table, which is caused by the geo-hydrological condition and poor irrigation water management. About 500,000 ha in the State are waterlogged and unproductive and the size of the waterlogged area is increasing. We analyse the hydrology and estimate seasonal net groundwater recharge in the study area. Rainfall is quite variable, particularly in the monsoon season, and the mean monthly reference evapotranspiration shows a high inter-annual variation, with values between 2.45 and 8.47 mm/day in December and May. Groundwater recharge analysis during the study period (1989–2008) reveals that percolation from irrigated fields is the main recharge component with 57% contribution to the total recharge. An annual groundwater table rise of 0.137 m has been estimated for the study area. As the water table has been rising continuously, suitable water management strategies such as increasing groundwater abstraction by installing more tubewells, using the groundwater conjunctively with good quality canal water, changes in cropping patterns, adoption of salt tolerant crops, changes in water-pricing policy, and matching water supply more closely with demand, are suggested to bring the water table down to a safe limit and to prevent further rising of the water table.

Rise of ground water in the Ishim steppe

In the 1980–2000s, a rise of ground-water table within the Ishim-Irtysh steppe watershed was recorded. An effect of forest shelter belts, ditches, villages, and tilled microdepressions on the long-term dynamics of the ground-water level has been studied.

Characteristics of soil water retention curve at macro-scale

Scale adaptable hydrological models have attracted more and more attentions in the hydrological modeling research community, and the constitutive relationship at the macro-scale is one of the most important issues, upon which there are not enough research activities yet. Taking the constitutive relationships of soil water movement—soil water retention curve (SWRC) as an example, this study extends the definition of SWRC at the micro-scale to that at the macro-scale, and aided by Monte Carlo method we demonstrate that soil property and the spatial distribution of soil moisture will affect the features of SWRC greatly. Furthermore, we assume that the spatial distribution of soil moisture is the result of self-organization of climate, soil, ground water and soil water movement under the specific boundary conditions, and we also carry out numerical experiments of soil water movement at the vertical direction in order to explore the relationship between SWRC at the macro-scale and the combinations of climate, soil, and groundwater. The results show that SWRCs at the macro-scale and micro-scale presents totally different features, e.g., the essential hysteresis phenomenon which is exaggerated with increasing aridity index and rising groundwater table. Soil property plays an important role in the shape of SWRC which will even lead to a rectangular shape under drier conditions, and power function form of SWRC widely adopted in hydrological model might be revised for most situations at the macro-scale.

Micromorphology of solonetzic horizons as related to environmental events in the Caspian Lowland

Micromorphology of solonetz species with special attention to natric horizon was studied in microcatenas at the Dzhanybek Research Station (northwestern Caspian Lowland). The solonetzic (natric) horizon is easily identified, and it occurs at varying depths, which are the criteria for subdividing solonetzes into 4 species, namely, crusty, shallow, medium and deep. In this sequence, the depth of humus-accumulative horizons increases, and the upper boundary of salinity manifestations goes down. The following micromorphological features are assumed as typical for natric horizons: angular blocky microstructures with partially accommodated aggregates having sharp boundaries and narrow plane-like packing voids; b-fabric speckled in the aggregates' centers and monostriated at their peripheries merging into stress coatings; very few interpedal voids; organo-clay coatings; humusenriched infillings; no calcite and gypsum pedofeatures. A complete set of "natric" features was found only in the crusty solonetz; the shallow solonetz lacks only illuviation coatings, while the medium and deep species have several modifications of fabric elements: blocky aggregates have a rounded shape and are penetrated by biogenic channels favoring their further biogenic reworking; plant residues became more abundant and diverse, and blackened tissues occur; illuviation clay coatings evolved into papules; stress coatings gave birth to striated bfabrics, thus maintaining a high plasma orientation. The thin sections of natric horizons made 50 and 20 years ago were examined to study the influence of environmental changes (increase in precipitation and rise of ground water table) on micropedofeatures. The following processes took place: (i) in the topsoil: humus accumulation and biogenic structurization; (ii) in the natric horizon - re-arrangement of clay coatings into micromass b-fabrics; and (iii) in the lower part of the natric horizon - development of pseudosand fabric, calcite and gypsum formation. The trends revealed are in good agreement with the environmental events.

An embedded bond-slip model for finite element modelling of soil–nail interaction

Soil nailing has been widely used as a reinforcing technique to retain excavations and stabilise slopes. Proper assessment of the interaction between the nails and the surrounding soil is central to safe and economical design of the composite reinforced soil structure. In this note, a new interface model, denoted as “embedded bond-slip model”, is proposed to model the soil–nail interaction numerically in a simplified manner. Combining the key features of the embedded element technique and the conventional interface element method, the proposed plane–strain interface model has the advantages that no special considerations have to be given to the arrangement of the finite element mesh for the soil nails, and that possible tangential slippage along the interface can be modelled. The formulation also allows pore water flow across the soil nails to be incorporated into the analysis. The proposed model has been implemented into a finite element code and verified by simple element tests under different uni-direction loading conditions. Using the proposed interface model, back analyses of a field test involving a soil-nailed cut slope subjected to a rise in groundwater table have been conducted. This note presents the details of the embedded bond-slip model and the numerical results which demonstrate that the proposed model is capable of simulating soil–nail interaction conveniently and realistically.

LAND USE CHANGE AND DETERIORATION OF PHARAONIC MONUMENTS IN UPPER EGYPT

Pharaonic monuments in Upper Egypt are currently threatened by environmental impacts including the rise of groundwater table, seepage of drainage and sewage water from cultivated lands and surrounding houses as well as salinity problems. These problems are mainly due to change of land use since construction of High Dam in 1968. land use changes include expansion of old cultivated lands, expansion of urban areas, as well as change of irrigation. The present paper uses techniques of geographic information systems and remotely sensed data for determination of land use change in Upper Egypt since construction of High Dam. The study depends on using Landsat imagery covering the period 1972 – 2000. Results of this study revealed that agriculture and urbanization were changed considerably during the studied period of time. Agriculture decreased from 1984 to 2000, whereas urbanization increased considerably from 1972 to 2000. These changes are accompanied by changes in environmental hazards including seepage of drainage water as well as sewage water. Management alternatives are required to make a balance between the land use changes and accompanied risks.

Centimetre-scale digital representations of terrain and impacts on depression storage and runoff

The microscale topography of a 20 × 10 m hillslope in a burned portion of Kootenay National Park, British Columbia, Canada was determined through laser scanning at a sub-centimetre scale. Digital terrain models (DTM) were developed for this hillslope at the 0.75 cm, 10 cm, 25 cm, 50 cm, 75 cm and 1 m scales. Random Roughness, Tortuosity and Mean Upslope Depression were computed for bare and vegetated surfaces created at each resolution to determine mean depression storage as a function of resolution. Results for these various roughness parameters and associated depression storage values are not found to change appreciably between the vegetated and bare surface DTMs, and moreover do not change notably with increasing grid cell resolution. Depression storage was also computed using a GIS-based method, the values of which are considered to be, at the highest resolution of 0.75 cm, the most realistic for comparative purposes. Mean depression storage using this latter approach decreases significantly with an increase in grid cell size, in contrast to the values based on Random Roughness which remain stable with increasing grid cell size. The generation of Hortonian overland flow was modelled at different scales using the GIS-derived DTMs. The values of depression storage for the various scales of DTM are demonstrated to have significant influences on overland flow generation. The scale of the DTM affects the changes over time between the proportion of water going into depression storage and that contributing to overland flow, with more water being retained as depression storage at a particular value of rainfall excess after infiltration for the smaller DTM scalings. When overland flow develops from a rising groundwater table in a simulation exercise, water depths are initially lower than the primary roughness elements on the land surface and water is relatively disconnected. As water depths increase, more integrated connections form.

Monitoring the Performance of Unsaturated Soil Slopes

Field monitoring is necessary for the geotechnical engineer to verify design assumptions. More importantly, the field data may also be assembled into a comprehensive case record that is available for use when checking validity of any analytical and numerical models. The ongoing process of back-analysis in unsaturated soil engineering can help to refine and improve our understanding, providing guidance for future designs, where the effects of soil suction and hydraulic hysteresis are still being explored. A range of recent field studies of the mechanisms of rainfall infiltration into slopes is presented. In addition, some physical simulations of unsaturated soil slopes subjected to rainfall, rising ground water table and changes of moisture in centrifuge model tests are reported.

Numerical modeling of rainstorm-induced shallow landslides in saturated and unsaturated soils

For the assessment of shallow landslides triggered by rainfall, the physically based model coupling the infinite slope stability analysis with the hydrological modeling in nearly saturated soil has commonly been used due to its simplicity. However, in that model the rainfall infiltration in unsaturated soil could not be reliably simulated because a linear diffusion-type Richards’ equation rather than the complete Richards’ equation was used. In addition, the effect of matric suction on the shear strength of soil was not actually considered. Therefore, except the shallow landslide in saturated soil due to groundwater table rise, the shallow landslide induced by the loss in unsaturated shear strength due to the dissipation of matric suction could not be reliably assessed. In this study, a physically based model capable of assessing shallow landslides in variably saturated soils is developed by adopting the complete Richards’ equation with the effect of slope angle in the rainfall infiltration modeling and using the extended Mohr–Coulomb failure criterion to describe the unsaturated shear strength in the soil failure modeling. The influence of rainfall intensity and duration on shallow landslide is investigated using the developed model. The result shows that the rainfall intensity and duration seem to have similar influence on shallow landslides respectively triggered by the increase of positive pore water pressure in saturated soil and induced by the dissipation of matric suction in unsaturated soil. The rainfall duration threshold decreases with the increase in rainfall intensity, but remains constant for large rainfall intensity.

Optimal contour mapping of groundwater levels using universal kriging—a case study

Universal kriging is applied to the command area of a set of canal irrigation projects in north-western India to show its applicability for optimal contour mapping of groundwater levels. This command area faces the problem of a rising groundwater table and manifestation of waterlogging over the years at many places. With the use of measured elevations of the water table in September 1990 at 143 observation sites in an area of 4500 km2, an omni-directional experimental semivariogram was constructed. The concave upward shape of omni-directional experimental semivariogram indicated the non-stationarity of the data and so the need for universal kriging. Directional semivariograms were calculated to find out the direction along which there is least drift. This directional semivariogram was considered as the underlying semivariogram and various theoretical semivariogram models were fitted to it. The drift order was estimated from the cross-validation procedure. The model and drift order finally selected were used to estimate the groundwater levels and corresponding estimation variances at the nodes of a square grid of 2 km × 2 km, and to develop the corresponding contour map.

Soil salinity evolution and its relationship with dynamics of groundwater in the oasis of inland river basins: case study from the Fubei region of Xinjiang Province, China

Soil salinization is an important worldwide environmental problem, especially in arid and semi-arid regions. Knowledge of its temporal and spatial variability is crucial for the management of oasis agriculture. The study area has experienced dramatic change in the shallow groundwater table and soil salinization during the 20th century, especially in the past two decades. Classical statistics, geostatistics and geographic information system (GIS) were applied to estimate the spatial variability of the soil salt content in relation to the shallow groundwater table and land use from 1983 to 2005. Consumption of reservoir water for agricultural irrigation was the main cause of a rise in the shallow groundwater table under intense evapotranspiration conditions, and this led indirectly to soil salinization. The area of soil salt accumulation was greater in irrigated than in non-irrigated landscape types with an increasing of 40.04% from 1983 to 2005 in cropland at approximately 0.43 t ha(-1) year(-1), and an increase at approximately 0.68 t ha(-1) year(-1) in saline alkaline land. Maps of the shallow groundwater table in 1985 and 2000 were used to deduce maps for 1983 and 1999, respectively, and the registration accuracy was 99%.

Nature and origin of the hematite‐bearing plains of Terra Meridiani based on analyses of orbital and Mars Exploration rover data sets

The ∼5 km of traverses and observations completed by the Opportunity rover from Endurance crater to the Fruitbasket outcrop show that the Meridiani plains consist of sulfate‐rich sedimentary rocks that are largely covered by poorly‐sorted basaltic aeolian sands and a lag of granule‐sized hematitic concretions. Orbital reflectance spectra obtained by Mars Express OMEGA over this region are dominated by pyroxene, plagioclase feldspar, crystalline hematite (i.e., concretions), and nano‐phase iron oxide dust signatures, consistent with Pancam and Mini‐TES observations. Mössbauer Spectrometer observations indicate more olivine than observed with the other instruments, consistent with preferential optical obscuration of olivine features in mixtures with pyroxene and dust. Orbital data covering bright plains located several kilometers to the south of the landing site expose a smaller areal abundance of hematite, more dust, and a larger areal extent of outcrop compared to plains proximal to the landing site. Low‐albedo, low‐thermal‐inertia, windswept plains located several hundred kilometers to the south of the landing site are predicted from OMEGA data to have more hematite and fine‐grained olivine grains exposed as compared to the landing site. Low calcium pyroxene dominates spectral signatures from the cratered highlands to the south of Opportunity. A regional‐scale model is presented for the formation of the plains explored by Opportunity, based on a rising ground water table late in the Noachian Era that trapped and altered local materials and aeolian basaltic sands. Cessation of this aqueous process led to dominance of aeolian processes and formation of the current configuration of the plains.