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A vertical-to-horizontal (V/H) response spectral ratio of 2/3 is commonly adopted in earthquake engineering for assessing the magnitude of vertical motion. However, higher V/H ratios are found in some earthquake records. This study evaluates the factors that can influence the V/H ratio on the basis of vertical and horizontal site response analyses. Two sets of rock motions representing near-source and far-field conditions are propagated through four selected sites that vary in soil column thickness, groundwater table, soil type, and wave velocity profile. The V/H ratio on the ground surface is calculated and compared with that at the bedrock. Results show that the V/H ratio is amplified by the local site effect, and increases at low wave velocity and high intensity of input motion owing to the different nonlinearities presented in the vertical and horizontal directions. The groundwater table considerably varies the V/H ratio and should be considered in assessing the vertical motion or V/H ratio. [ABSTRACT FROM AUTHOR]

The aim of the article is to submit data about ground water table and soil salinity of the rice irrigated systems at the Sivash seashore in Nyzhnegorsky district of Crimea in 2017–2018 which is 4–5 years from irrigation cease. It was found that many soil cover patterns with salt-affected solonetz at the rice system were leached from salts to the depth about 3–3.5 m by flooding irrigation during half a century. In 2017–2018 ground water tables were deeper than the critical depth. Ground water mineralization is characterized by mosaic spatial distribution, varying from 1.9 to 7.4 g/l with a tendency to growth as ground water depth increases. Depression funnel of ground water table was formed at the seashore. The bottom water drive is up to 0.8–1.6 m relatively sea level. The first symptoms of the salinity returning in grounds of vadose zone were found: (1) appearance of calcium and magnesium chlorides in pore solutions of formally no saline or weakly saline horizons; (2) increasing trend of sodium and chloride ion activity measured in pastes with moisture 50% (w) at the dynamic plots in 2018 as compared with 2017; (3) frequency of grounds with clustered gypsum crystals is increased.

Selection of drainage equation with acceptable accuracy has always been a challenge for designers to design subsurface drainage systems. In this research, seven steady state drainage equations were used for predicting daily and cumulative drainage rate on a farmland of sugarcane in Imam agro-industrial Company. These drainage equation included Hooghoudt, Ernst, Kirkham and Dagan that have been developed in the past and Mishra and Singh, Henine and Yousfi et al that recently developed. The statistical indices consist of P-value, RMSE, R2 and Percentage Error of estimating cumulative drainage rate were calculated for Hooghoudt equation 0.9501, 1.49 (mm/day), 0.80 and -0.19%, respectively. For Ernst equation 0.0001, 2.46 (mm/day), 0.34 and 16.98%, respectively. The result of performance of drainage equations revealed that Hooghoudt and Ernst equation were as the equations with the highest and lowest accuracy in predicting drainage rate, respectively. Also from the newly developed equations, the Yousfi et al equation was found with relatively well accuracy to predict the drainage rate. This equation was placed in second rank after Hooghoudt equation and other equations showed poor performance. Thus, with selection of the appropriate drainage rate, the Hooghoudt equation is suggested for designing of drain spacing in medium to heavy textured soils such as sugarcane agro-industrial.

The slope instability is associated with increasing rate of rainfall infiltration which cause shear strength reduction and suction loss and the slope tend to failure. The influences of rainfall infiltration on the stability of clayey and sandy slopes have been analyzed but the effect of rainfall infiltration on the stability of unsaturated coal gangue accumulated slope was needed to study. Therefore, a coal gangue accumulated slope prone to failure in Fuxin area of Northeast China was considered to evaluate its failure mechanism under different rainfall events. The effects after five different rainfall events on slope stability were physically analyzed, numerically investigated and the results from both uncoupled (hydraulic) and coupled (hydromechanical) responses were compared using finite element analysis. It was observed that the decisive soaking and leaching under different rainfall conditions caused maximum deformation at the crest of slope due to maximum value of permeability coefficient of coal gangue. The critical duration of moderate intensity (147 mm/day) of rainfall for the instability of coal gangue accumulated slope is declared as five days. The results from finite element analysis in this paper further clarifies that increase in duration of rainfall infiltration process cause hysteretic change in positive pore-water pressure causing decrease in factor of safety and increase in deformation. It is concluded that the stability of unsaturated coal gangue accumulated slope is greatly influence by the coupled effect of stress and pore-water pressure in comparison of uncoupled (hydraulic) analysis as the obtained factor of safety values after five days of rainfall infiltration were 0.9 and 1.1 respectively. [ABSTRACT FROM AUTHOR]

This paper presents the results of a technical investigation on the causation of the landslide that occurred in Las Nieves quarry on October 26, 2016 in the municipality of Copacabana, located in the northern part of the Colombian Andes. This landslide caused the highest number of fatalities in Colombia in 2016, totalling 16 deaths. The study included field visits, soil sampling, study of the geology and geomorphology, as well as analysis of rainfall and groundwater flows presented in the area. The information collected in this study is consistent with the hypothesis that the regional groundwater flow which comes from recharge zones, generated an increase in water levels in the landslide zone thus triggering the landslide. Finally, a stability analysis (statistical analysis and sensitivity analysis) was performed using the limit equilibrium method, where the effect of the rise in the ground water table was modelled as the trigger. The results of the stability analysis showed a low safety factor for the slope, even when low water levels were considered.

Abstract The behavior of a slope reinforced by passive piles 15 years ago was studied during removal of some passive piles, additional steeper slope cutting, and reinforcement by soil nails and anchors. Through a comparison of the measured value and numerical analysis results, it was found that the maximum lateral displacement developed at bench No. 4, which was the nearest bench to the additional steep slope cutting, and it could be correlated with the groundwater table. In particular, the relaxation of the ground from past failure sliding could affect the slope stability.

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Aim. Ground water reserves in the floodplains that form during the spring flood is of great importance for the sustainable development of arid regions. They support the ecosystems and provide the population with fresh water. Monitoring and management of ground water is an important economic task. The authors develop a methodology for predicting ground water for the conditions of floodplains of the rivers in the arid zone of the South Russia. The proposed methodology allows you to minimize labor costs, improve the accuracy of research results. Methods. The methodology of the study covers three stages. On the first, geodetic profiling methods are applied to key areas that have a characteristic conditions for the study area. The second stage is the determination of the ground water table level by a geophysical method with the help of a georadiolocation. The third stage is the analysis and interpretation of the measured data, the construction of models for the distribution and dynamics of ground water in the ArcGis. Results. Preliminary data obtained from the georadiolocation profiling of the river floodplain contain more objective information on the depth of the ground water table than the data of the drilling. The results of continuous georadiolocation profiling when combined with the hypsometrical profile make it possible to construct a model of ground water dynamics by the seasons of the year. Main conclusions. Previous studies in the Volga-Akhtuba floodplain, using the proposed methods, showed their reliability and high information value. Interpretation and data processing through geoinformation systems allows to build a model of ground water dynamics by seasons of the year. The proposed method can be tested for river deltas of the Don basin.

Groundwater, as the key element of water resources, can play inevitably substantial role in managing groundwater aquafers. In fact, a ferocious demand for acquiring precise estimation of groundwater table is of remarkable significance for analyzing water resources systems. A wide range of artificial intelligence techniques were used to predict groundwater table with highly convincing level of precision. Hence, this investigation aims to present an integration of a neuro-fuzzy (NF) system and group method of data handling (GMDH) in order to forecast the ground water table (GWT). The NF-GMDH network has been improved by means of the particle swarm optimization (PSO) and gravitational search algorithm (GSA) as evolutionary algorithms. The proposed methods were developed using records of two wells in Illinois State, USA. For this purpose, datasets related to time series of GWT have been grouped into three sections: training, testing, and validation phases. Through training and testing phases, the efficiency of the NF-GMDH methods were studied. The performances of proposed techniques were compared to the performance of radial basis function-neural network (RBF-NN). Evaluation of statistical results indicated which NF-GMDH-PSO network (R = 0.973 and RMSE = 0.545) is capable of providing higher level of precision rather than the NF-GMDH-GSA network (R = 0.969 and RMSE = 0.618) and RBF-NN (R = 0.814 and RMSE = 1.41). Also, conducting an external validation for the improved NF-GMDH models showed the most permissible level of precision. [ABSTRACT FROM AUTHOR]

Selection of drainage equation with acceptable accuracy has always been a challenge for designers to design subsurface drainage systems. In this research, seven steady state drainage equations were used for predicting daily and cumulative drainage rate on a farmland of sugarcane in Imam agro-industrial Company. These drainage equation included Hooghoudt, Ernst, Kirkham and Dagan that have been developed in the past and Mishra and Singh, Henine and Yousfi et al that recently developed. The statistical indices consist of P-value, RMSE, R2 and Percentage Error of estimating cumulative drainage rate were calculated for Hooghoudt equation 0.9501, 1.49 (mm/day), 0.80 and -0.19%, respectively. For Ernst equation 0.0001, 2.46 (mm/day), 0.34 and 16.98%, respectively. The result of performance of drainage equations revealed that Hooghoudt and Ernst equation were as the equations with the highest and lowest accuracy in predicting drainage rate, respectively. Also from the newly developed equations, the Yousfi et al equation was found with relatively well accuracy to predict the drainage rate. This equation was placed in second rank after Hooghoudt equation and other equations showed poor performance. Thus, with selection of the appropriate drainage rate, the Hooghoudt equation is suggested for designing of drain spacing in medium to heavy textured soils such as sugarcane agro-industrial. [ABSTRACT FROM AUTHOR]

Peatland is a significant storage of carbon and nitrogen on the earth's surface. This paper reviews the impacts of changes in water table level and mineral nitrogen associated with human activities on greenhouse gases emissions in tropical peatland and northern boreal and temperate peatland, and evaluates the optimal water table level to minimize greenhouse gases emissions. CH4 emission increased significantly with the rise of ground water table level above -20 cm, and larger in northern peatland with plant mediated CH4 emission than tropical peatland with plant mediated oxygen supply. However, forest disturbance by fire in tropical peatland increased CH4 flux to the similar level in northern peatlands (8.3 mg C m-2 h-1) due to stagnant surface water associated with the peat subsidence. On the other hand, CO2 and N2O emissions were significantly lager in tropical peatland than in northern peatland especially due to nitrogen fertilization. CO2 and N2O emissions increased with falling ground water table level below -40 to -80 cm (19 Mg C ha-1 y-1 for CO2 and 700 kg N ha-1 y-1 for N2O). Total global warming potential was significantly low in the ground water table level from -20 and -40 cm. [ABSTRACT FROM AUTHOR]

Interpolation method is one of the most important techniques which have been used in zoning studies. In order to obtain the continuous and integrated maps and predict unknown values, the interpolation method has been used. Since measuring ground water levels is very difficult and costly, therefore the iso-water table maps are used. The main purpose of this research is to compare two geostatistical methods concluded Kriging and IDW methods in order to interpolation groundwater level of the West, South and South-West of the Urmia Lake. In the present study water level data of 634 piezometric wells located in the West, South and South-West of the Urmia Lake in the West Azerbaijan have been used in the period of 2010-2011. Stationary and independence of data were tested using Wald and Wolfowitz methods. Iso-water table maps were drawn using Kriging and Inverse Distance Weighted (IDW) methods. The result showed that the Kriging method has better results than Inverse Distance Weighted method.

Good drainage is the most important design consideration for a road, both to miniaturize road maintenance costs and maximize the time the road is operational. The lack of good drainage lead to the structural damages and costly repairs. Many of roads are built in intensively drained agricultural land. The effective way to drain subgrades is reconstruction of existing agricultural drainage. The impact of cross-subsurface drainage system on water level fluctuation was measured using Plane geofiltration mathematical model, one of 3D geofiltration modelling programs. The hydraulic permeability characteristics were determined in field of Pikeliai, close to local road in Kėdainiai district, Lithuania. This object is composed of clay and loamy soils. Subsurface cross drains trenches spacing of 20 m, 30 m and 40 m were simulated. The hydraulic permeability of cross drain trenches and lateral trenches modelled was from 0.006 m/a day to 6 m/a day. The simulation of cross drains trenches showed that the most effective distance between them are 20 m. The highest water depression occurs when the permeability of cross drain trenches and lateral trenches is ~ 6 m/day, at the distance of 20 m. The water recession is 20 cm lower compared to the drainage systems without cross drains trenches. By installing cross drains trenches every 30 m, water recession is 10 cm lower when the trench permeability is about 6 m/day. When increasing the distance between the cross drains up to 40 m their influence disappears.

The water budget and discharge processes in a seasonal tropical watershed were analyzed. The watershed has very stable base stream flows even in the late dry season and very quick direct runoff during rains. A tentative runoff error correction method applying an existing lumped runoff model was proposed in this paper and showed good agreement with the correct runoff error. After correcting runoff data, the annual average rainfall and runoff during the 11 years of 1998-2008 were calculated respectively as 1870.4 mm and 1229.2 mm. The average annual water loss was 641.2 mm. Distribution measurements of topsoil depth taken using a knocking cone penetration meter showed that this watershed has a deep topsoil layer (5.3 m average). Groundwater tables are apparent only in the lower area of the watershed. A saturated swamp area is a permanent feature near the weir. Results suggest that the stable base flow in this watershed was generated by return flow of soilwater infiltration into the thick topsoil and fractured bedrock. [ABSTRACT FROM AUTHOR]

India covers 147.75 mha degraded area, whereas 6.41 mha area confined to waterlogging problem in Bihar, Maharashtra, Gujarat, Uttar Pradesh, Orissa, West Bengal, Punjab, Tamil Nadu, Andhra Pradesh, Haryana, Kerala, Rajasthan and few other states. The transpiration principle of plants is used in bio-drainage treatment to reclaim such problematic areas sustainably. Evergreen broad leaved species recorded high transpiration rate and contribute highly in reclamation of waterlogged saline soils. Short rotation fast growing tree species like Salix, Eucalypt, Acacia, Albizia, Terminalia, Prosopis, Populus were the suitable species for such areas. Agri-silviculture, agri-horti-silviculture, silvi-pasture, multipurpose woodlots, strip plantation and boundary plantations were widely used for reclamation of saline-waterlogged conditions of India. In agri-silviculture system, Eucalypt based agroforestry systems are widely used for reclamation of waterlogged areas as compared to other woody plant based systems. 0.84-0.86 m total drawdown of ground water in 3 years Eucalypt tree species. The vertical and horizontal root spreading of tree species is one important character for capturing and transpiration of excess water from waterlogged area. From the present investigation, longest root system was recorded from Prosopis cineraria (20-60 m) species. [ABSTRACT FROM AUTHOR]

In residential areas where liquefaction occurred during the 2011 Great East Japan Earthquake, houses, roads, water pipes, sewage pipes and gas pipes were damaged, interrupting daily life. Though settled and tilted houses were repaired by uplifting, the ground in the whole area, including around lifelines and roads, must be treated by special measures to prevent liquefaction-induced damage. A project to improve the liquefiable soil of an entire area by lowering the ground water table started in November 2011. Based on case studies at sites of damaged and undamaged houses, a water table of about GL-3m was judged to be appropriate to prevent damage due to liquefaction. In-situ tests clarified that the pore water pressure decreased due to dewatering only at shallow depths and that subsidence was small. [ABSTRACT FROM AUTHOR]

Good drainage is the most important design consideration for a road, both to miniaturize road maintenance costs and maximize the time the road is operational. The lack of good drainage lead to the structural damages and costly repairs. Many of roads are built in intensively drained agricultural land. The effective way to drain subgrades is reconstruction of existing agricultural drainage. The impact of cross-subsurface drainage system on water level fluctuation was measured using Plane geofiltration mathematical model, one of 3D geofiltration modelling programs. The hydraulic permeability characteristics were determined in field of Pikeliai, close to local road in Kėdainiai district, Lithuania. This object is composed of clay and loamy soils. Subsurface cross drains trenches spacing of 20 m, 30 m and 40 m were simulated. The hydraulic permeability of cross drain trenches and lateral trenches modelled was from 0.006 m/a day to 6 m/a day. The simulation of cross drains trenches showed that the most effective distance between them are 20 m. The highest water depression occurs when the permeability of cross drain trenches and lateral trenches is ~ 6 m/day, at the distance of 20 m. The water recession is 20 cm lower compared to the drainage systems without cross drains trenches. By installing cross drains trenches every 30 m, water recession is 10 cm lower when the trench permeability is about 6 m/day. When increasing the distance between the cross drains up to 40 m their influence disappears. [ABSTRACT FROM AUTHOR]

This article examines the capability of Gaussian Process Regression (GPR), Generalized Regression Neural Network (GRNN) and Relevance Vector Machine (RVM) for prediction of Ground Water Table (dw) at Vellore (India). RVM, GRNN and GPR have been adopted as regression techniques. RVM is a probabilistic model. GRNN approximates any arbitrary function between input and output variables. GPR is a non-parametric model. The developed GPR, RVM and GRNN give the spatial variability of dw at Vellore. Map of dw has been also produced by the GPR, RVM and GRNN models. The results show that the developed RVM gives the best model for prediction of dw at Vellore. [ABSTRACT FROM AUTHOR]

Abstract: Using seismic noise based monitoring techniques we find that seismic velocity variations ( ) observed with the borehole array of the Taiwan Chelungpu-fault Drilling Project (TCDP) are controlled by strong precipitation events associated with the Madden–Julian Oscillation (MJO), a dynamic intraseasonal atmospheric pattern in the tropical atmosphere. High-frequency noise (>1 Hz) excited by steady anthropogenic activity in the vicinity of the TCDP allows daily resolution of time series. Relatively large fluid discharge properties control the equilibration of the ground water table and hence seismic velocities on time scales smaller than the average precipitation recurrence interval. This leads to the observed synchronous 50–80 day periodicity in and rainfall records in addition to the dominant annual component. Further evidence for the governing role of hydraulic properties is inferred from the similarity of observed timing, amplitude, and recovery properties with synthetics generated by a combined model of ground water table changes and diffusive propagation of seismic energy. The lapse time (τ) dependent increase of amplitudes is controlled by the sensitivity of the diffuse wave field sampled at 1100 m depth to shallower water level fluctuations. The significant vertical offset between stations and water level explains the direct τ dependence which is opposite to the trend previously inferred from measurements at the surface. [Copyright &y& Elsevier]

In order to relate phenological responses of trees to environmental variables we recorded the phenological patterns and select morphological and physiological traits (wood density and water potentials) of five tree species ( Acacia gaumeri, Apoplanesia paniculata, Bursera simaruba, Gymnopodium floribundum, and Diospyros cuneata) in the tropical dry deciduous forest of the National Park of Dzibilchaltún, Yucatan, Mexico, over a period of 2 years (2004 and 2005). We chose two sites: one close to a permanent water source, locally known as ‘cenote’ (the CC site, ground water table was found at 2 m) and the other far from the cenote (FC site ground water table was at a depth of 10 m). Sites mainly differed in soil depth (FC site having greater soil depth) and soil nutrient characteristics (FC site more potassium, CC site more phosphorous). Our results indicated significant differences in phenology within species between sites and years, with leaf, flower and fruit production tending to be higher at the CC site and in the year 2004. Wood density and xylem water potentials were negatively related to each other, and midday water potentials were higher at the CC site. Differences in phenology found among years suggest that the timing of rainfall as well as the duration of periods without rain may play a more important role in phenology than total annual precipitation. Also differences inter-sites suggest a strong effect of site on tree phenology. Proximity to superficial bodies of water, such as cenotes, coupled with a greater concentration of available phosphorus in the soil may modify the effect of drought in this tropical dry deciduous forest. [ABSTRACT FROM AUTHOR]

A model for the alkaline grassland ecosystems, MAGE, was applied to plant communities dominated by three species. Field observations on two communities dominated respectively by Puccinellia tenuiflora and Suaeda corniculata were used to parameterize the model for multiple species interaction. The model behaves reasonably in following the seasonal variations of water content, soluble sodium cation and calcium cation in surface soil, as well as biomass of the plant communities. Simulations were run to investigate the effects of ground water quality, ground water table depth, maximum non-capillary porosity in surface soil and harvest intensity, on ecosystem dynamics. The results indicated that ground water sodium concentration and ground water table depth had primary control on soil alkalization and vegetation status. The improvement of soil conditions by vegetation is limited to an extent with moderate ground water depth and sodium concentration. Non-capillary pores are critical for vegetation to affect the soil alkalization/de-alkalization process, but the effect of non-capillary pores tends to saturate when maximum non-capillary porosity is greater than 0.1. [ABSTRACT FROM AUTHOR]