Water-soil Interaction Research Articles

Field‐scale apparent soil electrical conductivity

AbstractSoils are notoriously spatially heterogeneous and many soil properties are temporally variable. Spatial variability of soil properties has a profound influence on agricultural and environmental processes, such as plant–water–soil interactions, water flow, and solute transport, resulting in within‐field plant yield variation and degradation of soil quality, to mention only a few. Field‐scale mapping of spatial variability and monitoring of temporally dynamic soil properties is necessary for a variety of edaphic activities, such as soil surveys, reclamation, crop selection, sitespecific management, and soil quality assessment. There are various approaches for characterizing soil spatial variability, but none of these has been as extensively investigated and is as reliable and cost effective as apparent soil electrical conductivity (ECa) directed soil sampling. Geospatial measurements of ECa are well suited for characterizing the spatial distribution of soil properties because they are reliable, quick, and easy to take with GPS‐based mobilized ECa measurement equipment. Directed soil sampling based on geo‐referenced measurements of ECa is a proven and robust means of characterizing the spatial variability of any soil property that influences ECa, including sol salinity, water content, texture, bulk density, organic matter, and cation exchange capacity. It is the goal of this methodology paper to provide an overview of the characterization of soil spatial variability across multiple scales using ECa–directed soil sampling with a focus on the field scale. Mobile ECa equipment, protocols, guidelines, special considerations, data reliability tests, and strengths and limitations are presented for characterizing spatial and temporal variation in soil properties using ECa–directed soil sampling.

Validation of Cryogenic Vacuum Extraction of Pore Water from Volcanic Soils for Isotopic Analysis

Andean headwater catchments are key components of the hydrological cycle, given that they capture moisture, store water and release it for Chilean cities, industry, agriculture, and cities in Chile. However, knowledge about within-Andean catchment processes is far from clear. Most soils in the Andes derive from volcanic ash Andosols and Arenosols presenting high organic matter, high-water retention capacity and fine pores; and are very dry during summer. Despite their importance, there is little research on the hillslope hydrology of Andosols. Environmental isotopes such as Deuterium and 18-O are direct tracers for water and useful on analyzing water-soil interactions. This work explores, for the first time, the efficiency of cryogenic vacuum extraction to remove water from two contrasting soil types (Arenosols, Andosols) at five soil water retention energies (from −1500 to −33 kPa). Two experiments were carried out to analyse the impact of extraction time, and initial water content on the amount of extracted water, while a third experiment tested whether the cryogenic vacuum extraction changed the isotopic ratios after extraction. Minimum extraction times to recover over 90% of water initially in the soil samples were 40–50 min and varied with soil texture. Minimum volume for very dry soils were 0.2 mL (loamy sand) and 1 mL (loam). After extraction, the difference between the isotope standard and the isotopic values after extraction was acceptable. Thus, we recommend this procedure for soils derived from volcanic ashes.

Simulating the Overtopping Failure of Homogeneous Embankment by a Double-Point Two-Phase MPM

Embankments are usually constructed along rivers as a defense structure against flooding. Overtopping failure can cause devastating and fatal consequences to life and property of surrounding areas. This motivates researchers to study the formation, propagation, and destructive consequences of such hazards in risk analysis of hydraulic engineering. This paper reports a numerical simulation of failure processes in homogeneous embankments due to flow overtopping. The employed numerical approach is based on a double-point two-phase material point method (MPM) considering water–soil interaction and seepage effects. The simulated results are compared to available laboratory experiments in the literature. It was shown that the proposed method can predict the overtopping failure process of embankments with good accuracy. Furthermore, the effects of the cohesion, internal fiction angle, initial porosity, and maximum porosity of soil on the embankment failure are investigated.

Effects of catchment area and nutrient deposition regime on phytoplankton functionality in alpine lakes

High mountain lakes are a network of sentinels, sensitive to any events occurring within their waterbodies, their surrounding catchment and their airshed. In this paper, we investigate how catchments impact the taxonomic and functional composition of phytoplankton communities in high mountain lakes, and how this impact varies according to the atmospheric nutrient deposition regime. For two years, we sampled the post snow-melt and the late summer phytoplankton, with a set of biotic and abiotic parameters, in six French alpine lakes with differing catchments (size and vegetation cover) and contrasting nitrogen (N) and phosphorus (P) deposition regimes. Whatever the nutrient deposition regime, we found that the lakes with the smallest rocky catchments showed the lowest functional richness of phytoplankton communities. The lakes with larger vegetated catchments were characterized by the coexistence of phytoplankton taxa with more diverse strategies in the acquisition and utilization of nutrient resources. The nutrient deposition regime appeared to interact with catchment characteristics in determining which functional groups ultimately developed in lakes. Photoautotroph taxa dominated the phytoplankton assemblages under high NP deposition regime while mixotroph taxa were even more favored in lakes with large vegetated catchments under low NP deposition regime. Phytoplankton functional changes were likely related to the leaching of terrestrial organic matter from catchments evidenced by analyses of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in seston and zooplankton. Plankton δ15N values indicated greater water–soil interaction in lakes with larger vegetated catchments, while δ13C values indicated the effective mineralization of the organic matter in lakes. The role played by catchments should be considered when seeking to determine the vulnerability of high altitude lakes to future changes, as catchments' own properties will vary under changes related to climate and airborne contaminants.

Correlation between geochemical, mineralogical and physical characters of sediments and salinization phenomena in a pilot area in the ionian plain (Southern Italy)

Superficial and sub-superficial soils affected by salinization were studied on a pilot site on an Ionian coastal plain in Basilicata, Southern Italy. Grain-size, mineralogical, and geochemical features favouring soil degradation were analyzed. This study identifies the main mechanisms for triggering soil salinization, including electrical conductivity which provide a physical marker by measuring the level of salinization and silty grain component size and halite and/or chlorite percentages provided compositional markers. A critical depth of about 20 cm was identified, impacting the downward diffusion mechanism of the superficial salt and a possible chloritization of smectite from/by soluble magnesium relating to saline water-soil interaction from weathering processes.

Factors in developing salt balances in groundwater basins

This paper discusses criteria and methodology for developing Salt Balance Analysis in Groundwater Basins The project describes a basic approach to account for geological processes including water rock and water soil interactions and mineral dissolution as an in situ source of salt loading to groundwater basins Salt balance terms are summarized along with factors responsible for the variation of the respective loading terms Methods of determining total dissolved solids TDS are discussed to allow conformity between time series data in long term analysis of salt loading to aquifers using multiple historical data bases

Studying of the combined salts effect on the engineering properties of clayey soil

In recent years, a number of studies had been performed to investigate the effect of pore water chemistry on the strength and compressibility characteristics of soil. Although the effect of chloride and sulfates salts separately in pore fluids on the geotechnical properties of soil seems to be well understood, but the influence of combined effect of sulfates and chlorides in pore water on the behavior of soil is still unclear mostly due to the limited numbers of studies as well as the complexity of processes that may occur in soil (with the presence of salts) in pore water-soil interaction. Southern regions of Iraq, especially Basra suffers from low water levels in the summer season in addition to the lack of rain water, which causes a significant increase of salt in the Shatt al Arab. Water salinity continues to increase with time. To investigate the combined impacts of water salinity on the behavior of clayey soils, the basic characteristics of the soil brought from Al-Nahrawan site was studied. Chemical methods were done with three types of water (distilled, water of highly saline as Shatt Al-Arab water and water of Tarmiya as moderate saline water). The effect of water salinity on the geotechnical properties of fine grain soil was investigated. Different laboratory tests such as Atterberg limits, standard compaction, consolidation and shear strength of soil .Results showed that the presence of perceptible amounts of dissolved salts in water can lead to changes in the engineering properties of the soil.

Particle Flow Code Method-Based Meso-scale Identification for Seepage Failure of Soil Levee

The long-term action of internal and external factors leads constantly to seepage failures of soil levee engineering such as soil flow failure and piping failure. It is very disadvantageous to the service safety of levee engineering. Most of disastrous accidents are induced directly or indirectly by seepage. It has been known that the water–soil interaction with particle migration determines the occurrence and development of seepage failure. In this paper, a particle flow code (PFC)-based approach is introduced to implement the numerical simulation for seepage behavior in soil levee and investigate the meso-scale seepage failures. Firstly, according to the granular properties and particle migration characteristics of soil levee, an implementation process is presented to construct the meso-scale soil particle model and analyze the levee failure. Then, considering the coupling action of soil and water, a numerical method combining PFC with computation fluid dynamics is developed to simulate the seepage failure of soil levee. The corresponding criteria on seepage failures of soil levee are given. Lastly, one actual levee engineering is taken as an example. The movements of soil and water in the soil flow and piping processes are investigated with meso-scale soil particle model of selected levee. The meso-scale mechanism of seepage failures is analyzed, and the seepage stability is evaluated. It is indicated that the proposed PFC-based approach can fulfill the real-time observation for the movement status of soil particles and water during seepage failure of soil levee. The seepage stability identification with the introduced meso-scale criteria shows good agreement with the experimental result.

Smoothed Particle Hydrodynamics Simulation of Water-Soil Mixture Flows

AbstractA two-phase smoothed particle hydrodynamics (SPH) mixture model to simulate water-soil interactions is presented. In this model, each phase of the mixture satisfies its own conservation equations of mass and momentum. The water is considered as a Newtonian fluid and the soil is modeled as an elastic-perfectly plastic material. Drucker-Prager criterion is employed to test the yielding of the soil and an associated flow rule is adopted to describe the soil behavior after yielding. Interactions between water and soil are modeled by the viscous drag force according to Darcy’s law. With this mixture model, it is possible to investigate the temporal and spatial evolutions of the volume fractions of both phases. This study first examines the proposed SPH mixture model for two single-phase flows, i.e., water dam break and sand column collapse, respectively. The drag force model is also tested using the problem of flow in porous media. Then its application to the problem of soil excavation by high-velocity...

Study on the subgrade deformation under high-speed train loading and water–soil interaction

It is important to study the subgrade characteristics of high-speed railways in consideration of the water–soil coupling dynamic problem, especially when high-speed trains operate in rainy regions. This study develops a nonlinear water–soil interaction dynamic model of slab track coupling with subgrade under high-speed train loading based on vehicle–track coupling dynamics. By using this model, the basic dynamic characteristics, including water–soil interaction and without water induced by the high-speed train loading, are studied. The main factors-the permeability coefficient and the porosity-influencing the subgrade deformation are investigated. The developed model can characterize the soil dynamic behaviour more realistically, especially when considering the influence of water-rich soil.

Cascading breaching of the Tangjiashan landslide dam and two smaller downstream landslide dams

The 2008 Mw 7.9 Wenchuan earthquake triggered at least 257 landslide dams, most of which formed in series along rivers. The failure of an upstream dam could cause the failure of dams downstream one after another. The cascading dam breaching may result in a sharp increase in the flood and more serious damage downstream. This paper aims to simulate the cascading breaching of landslide dams with a case study of the Tangjiashan landslide dam and two smaller dams downstream. A modified DABA model is applied for this purpose, in which the water–soil interactions are simulated with erosion and shallow water flow theory. This paper first introduces the methodology of the cascading dam breach simulation, emphasizing modifications to the DABA model. Then, the cascading breaching of the Tangjiashan landslide dam and two smaller downstream dams is simulated using the modified DABA model. Finally, the influences of several key factors (e.g., dam height, dam width, dam erodibility) on cascading dam breaching are analyzed to identify the critical conditions of overlapping effect in breaching floods. The modified DABA model is shown to be a reliable tool for simulating the cascading dam breaching. The flood from the Tangjiashan dam was not significantly amplified by the breaching of the two small dams downstream, because the two smaller dams breached before the Tangjiashan dam. Some parameters, such as dam crest width and initiation water level, may not influence the peak outflow rate and breach size of a single dam obviously, but may influence the cascading breaching of several dams significantly through the amplification effect. The cascading breaching of several dams is likely to generate multi-peak floods. A critical condition for the overlapping effects of cascading dam breaching is that large and increasing inflow erodes the dam breach downstream in the development phase. If cascade breaching of several landslide dams is inevitable, one principle to mitigate the risks is to lower the breach flood of the largest dam with engineering measures. If significant overlapping effect is predicted, engineering measures may also be taken to breach the smaller dams before the breaching of the large dam upstream or delay the breach of those downstream dams by reinforcement measures.

Character Exploration for River Ecology Condition Based on Factor Analysis

The basis of analysis of the ecological health of the river is taken into account, including water quantity, water quality, riparian zone, the physical structure of organisms and other elements to explore a new method based on factor analysis of river ecosystem health. 21 typical reaches along villages of Tang River in Beijing are measured using the method of 17 indexes system to analyze the index relevance for Tang River ecosystem health. The results showed that midstream of Tang River ecological health relevant factors are riverbed, water and biological effects, water quality, water-soil interaction, the downstream river bank only have slope factor, and significantly related reaches are distributed in water and biological effects, heart beach shape, river curvature, slope degree more. The evaluation results raised the indexes and reach affecting river ecological condition, to provide scientific guidance for the ecological restoration of Tang River (Beijing Reach).

A three-dimensional vibroacoustic model for the prediction of underwater noise from offshore pile driving

Abstract Steel monopiles are nowadays widely used as foundations for a large number of offshore structures. The installation procedure commonly involves a pile driving process which can last up to several hours depending upon pile dimensions, soil conditions and input energy of the hydraulic hammer. In impact pile driving, a hydraulic hammer delivers a series of hammer blows at the head of the pile that drive the pile into the sediment. Each hammer strike results in pile vibrations that emit strong impulsive sounds into the water column which can be harmful for the marine ecosystem. With today's increasing concern regarding the environmental impact of such operations, engineering tools which will be able to provide reliable predictions of the underwater noise levels are required. In this study, a linear semi-analytical formulation of the coupled vibroacoustics of a complete pile–water–soil interaction model is addressed. The pile is described by a high order thin shell theory whereas both water and soil are modelled as three-dimensional continua. Results obtained with the developed model indicate that the near-field response in the water column consists mainly of pressure conical waves generated by the supersonic compressional waves in the pile excited by the impact hammer. The soil response is dominated by shear waves with almost vertical polarization. The Scholte waves are also generated at the water–seabed interface which can produce pressure fluctuations in the water column that are particularly significant close to the sea floor. The effects of soil elasticity and pile size are thoroughly investigated and their influence on the generated pressure levels is highlighted. The results are also compared with those ones of a similar model in which the soil is treated as an equivalent acoustic fluid. It is shown that the latter approximation can yield inaccurate results at low frequencies especially for harder soil sediments.

Research on Variation of Land Subsidence in Changzhou

Land subsidence as one of geological disasters, due to the characteristics and specificity hydrogeology, which results in the differences of subsidence in different regions. Changzhou City, in Jiangsu province, in China, underlain by a multi-layered aquifer system in Quaternary sediments in the Great Yangtze River Delta region. Take into account geological characteristics and mechanisms, the Changzhou layers can be divided respectively into four soil stratifications: phreatic aquifer, Part I aquifer ,Part II aquifer ,and substratum. According to the monitoring data of bedrock bench mark at Changzhou Qingliang primary school, get the mechanism of water-soil interaction and the law between land subsidence and water level change, and establishes numerical coupling model and simulates, that can evaluate and predict Changzhou land subsidence.

Experimental Study at Chloride Erosion in Laterite Dam

Laterite dams are chronically eroded by chloride in acidic reservoir water, and the fact is confirmed by dam safety checkups. Based on chemical analysis of water-soil interaction, accelerated life tests of dipping in HCl solution were designed for laterite. Multi-team engineering indices and microstructure characteristics of deteriorated laterite were compared and analyzed, changes of ion concentration in exudates were tested, and changes of laterite microstructure were observed. Interaction mechanism between water and laterite was opened out, so historical statistical data was further confirmed why service life of laterite dam is always too short.

Process of Micro-Simulation of Infilitration Clogging for Highland Reservoir Dam Foundation

Using of numerical models of particle flow are based on discrete element theory, combining with the indoor infiltration clogging tests in the region of south mountain in Tibet, the whole development process of the infiltration clogging of loose foundation is simulated. The loss volume, fluid velocity，osmotic coefficient, porosity and moving track of particle samples are recorded and traced in the analytical model, which reveals the water-soil interaction throughout the whole process of the infiltration clogging. The results show that clogging often occurs in the upper soil. Particle trajectory is random reveals the certain randomness of formation of pores. Results of simulation are consistent with the indoor test, to some extent, which validate the feasibility of numerical method in infiltration clogging research. These results provide certain useful data for the further study of infiltration clogging, and also provide a new way for interpretation and analysis of penetration clogging phenomenon in micro-scale .

Metal concentrations and metal mobility in unsaturated mine wastes in mining areas of Goa, India

To aid in evaluating the environmental impacts of mining activities in the State of Goa, India, this paper examines water–soil interactions occurring in the mining area. Using flame atomic absorption spectroscopy, mine and mineral processing wastes (tailings) from the Codli mining area were examined for their metal concentrations. And it was found that these wastes contain several metals such as Cr, Zn, Pb, Cd, Ni, Mn, Fe and Cu. Among the various metals present, iron and manganese were found to be very high in concentration. Groundwater samples collected from five dug-wells in the study area were tested for their metal concentrations during the pre-monsoon and monsoon periods. It was found that some metal concentrations in the pre-monsoon water samples were high compared to those in the post-monsoon water samples. Experiments were performed to ascertain the acid producing potential (APP) of the mine wastes and their potential influence on metal leaching into the surface and groundwater of the area. The APP of the wastes from Codli area was estimated to be of the order of 0.005 mole of H +/g. In addition, the metal leachability associated with these metal bearing wastes under the influence of acidic rainwater was examined through the synthetic precipitation leaching procedure tests and the results are discussed in detail. Thus, in general, it was found that ground and surface water in the mining area is highly vulnerable to heavy metal contamination.

Mobility and speciation of rare earth elements in acid minesoils and geochemical implications for river waters in the southwestern Iberian margin

This paper discusses the abundance, fractionation and chemical speciation of the rare earth elements (REE) released during two contrasting water–soil interactions, using acid sulfate and circumneutral soil samples from an abandoned mine land watershed in SW Spain. Our simulative experiment shows that the REE mobility is strongly dependent on the soil solution acidity. The acid solution extracts (pH = 3.1–3.7) extracted from the minesoils display overall REE concentrations much higher (up to three orders of magnitude) than those of the near-neutral soil extracts. The middle REE (MREE) were preferentially removed when compared to light REE (La N /Sm N = 0.07) and heavy REE (Gd N /Yb N = 2.49). The origin of this MREE-enriched signature is attributed to dissolution and/or solid–liquid exchange reactions involving iron oxy-hydroxides particles and surface coatings. The REE were found to behave conservatively under the strong acid conditions of the soil solutions, with sulfate complexes (mainly LnSO 4 +) being the largely dominant aqueous species (75–80%) despite the competitive effects of aluminium. Free metal ions (Ln 3+) accounted for most other species in solution (12–16%). All other ligands analysed (phosphate, nitrate, chloride, fluoride and bicarbonate) were not predicted to be significant complexers of REE, according to speciation calculations. The results of this study have implications for the REE geochemistry of the rivers draining the mine sites of the Iberian Pyrite Belt. The acid sulfate soils represent a major readily leachable MREE reservoir for the Tinto–Odiel fluvial system, which reflect the geochemical signature of the soil–water interaction in the mine lands watersheds.

Deconvolution of trace element (As, Cr, Mo, Th, U) sources and pathways to surface waters of a gold mining-influenced watershed

The Upper Isle River (SW France) drains the second most productive gold-mining district of France. A high resolution survey during one hydrological year of As, Cl(-), Cr, Fe, Mn, Mo, SO(4)(2-), Th and U dissolved concentrations in surface water aimed to better understand pathways of trace element export to the river system downstream from the mining district. Dissolved concentrations of As (up to 35000 ng/L) and Mo (up to 292 ng/L) were about 3-fold higher than the regional dissolved background and showed a negative logarithmic relation with discharge. Dissolved concentrations of Cr (up to 483 ng/L), Th (up to 48 ng/L) and U (up to 184 ng/L) increased with discharge. Geochemical relationships between molar ratios in surface water, geochemical background as well as rain- and groundwater data were combined. The contrasting behavior of distinct element groups was explained by a scenario involving three seasonal components: (i) The high flow component is poorly concentrated in As and Mo but highly concentrated in Cr, Th, U. This has been attributed to diffuse sources such as water-soil interactions, atmospheric inputs, bedrock and bed sediment weathering. Although this component probably also includes a contribution by weathering of sulfide veins, this signal is masked by dilution. (ii) One low flow component presents high SO(4)(2-), Fe, As and Mo and moderate Cr, Th and U concentrations. This component has been attributed to point sources such as mine gallery effluents, mining waste weathering and groundwater inputs from natural and/or mining-induced sulfide oxidation in the ore deposit. (iii) A second low flow component showing high As plus Mo concentrations associated with very low SO(4)(2-), Fe, Cr, Th and U concentrations, probably reflects trace element scavenging by ferric oxyhydroxide formation in the adjacent aquifer. This is supported by the decrease of Fe, Cr, Th and U in surface waters. Flux estimates suggest contrasting element-specific impacts on annual dissolved fluxes. Runoff may account for the major part of annual dissolved As, Mo, Th and U fluxes in the Upper Isle River. Inputs related to sulfide oxidation respectively contributed approximately 30% and approximately 24% to annual As and Mo fluxes. The formation of ferric oxyhydroxides strongly retained Cr, Th and U during the low flow, limiting their dissolved concentrations in surface waters. If this process may eventually decrease As mobility, its impact on dissolved As concentrations in surface water may be limited or/and counterbalanced by As release during sulfide oxidation.

Hydrogeochemical and bacteriological investigation of groundwater in Agbor area, southern Nigeria

Agbor, a town in southwestern Nigeria, is underlain by the Miocene to Recent Benin Formation. Groundwater occurrence within the formation has been investigated for its quality, from which inferences are drawn on its usability and the prevalent hydrogeochemical processes in the water systems. The results indicate a chemical attribute of low pH, low total dissolved solids (TDS) and salinity. Cationic concentrations including Na+, K+, Ca2+, Mg2+ have values ranging from 0.9 to 18.9 mg/l, 0.1 to 4.2 mg/l, 1.2 to 12.8 mg/l and 0.2 to 3.5 mg/ l respectively. Concentration values of Fe 2+ , Zn 2+ , Mn 2+ and Pb 2+ range from 0.08 to 1.92mg/l, 0.12 to 4.35 mg/l, 0.0 to 0.42 mg/l and 0.0 to 0.04 mg/l respectively. Anions including HCO3 , CO3 2, Cl , SO4 2, NO3 2, PO4 2have respective concentration values ranging from 1.0 to 10.0 mg/l, 0.1 to 0.9 mg/l, 3.2 to 24.0mg/l, 0.0 to 10.3 mg/l, 0.0 to 18.4 mg/l and 0.0 to 2.4 mg/ l. The bacteriological constituents of the water samples include Total aerobic bacteria counts (5 - 535cfu/ml) and Total coliform (10 - 70MPN/100ml). A comparison of these results with various quality guidelines, suggests that the groundwater may be suitable in its untreated state for crop irrigation, but will require pH remediation and microbial disinfection to upgrade its quality for potability and use in food processing industries. Factor analysis reveals three main hydrogeochemical activities operative within the groundwater system. Factor 1 is dominant and can be related to water-soil interaction and incorporation of leached formation water along the groundwater flow path. Factor 2 is related to pollution by biochemical related substances resulting from agricultural practices in the area. Factor 3 indicates fresh groundwater recharge. An inter-play of these processes, and base exchange reactions produced dominant chloride water types (Ca-Cl, Ca-Mg-Cl, Mg-Ca-Cl, Na-Ca-Cl and NaCl), and localized occurrences of bicarbonate types (NaHCO 3 and Na-Ca-HCO 3 .