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Hydraulic conductivity is very low in saline-sodic soil, which decreases water infiltration. For saline-sodic soil, increasing infiltration water has a special meaning. Increasing infiltration water not only increases the water in the soil profile but also decreases the salinity of the soil, thus making it suitable for growing crops. This study aims to examine the effect of sand pipes on soil water and salt distribution through laboratory tests with different depths and diameters of sand pipes.

The soil water and salt distribution responses to different sand pipe depths and diameters was investigated. Treatments included sand pipes with diameters of 4 cm, 5cm, 6 cm and the same depth of 4 cm; with depths of 2cm, 6 cm and the same diameter of 5 cm, and a control with no sand pipe (with the diameter of 0 cm and the depth of 0 cm).

The results suggested that the amount of cumulative infiltration water and transport distance of the wetting front could be increased by increasing the depth and diameter of sand pipes. The soil water content in the soil profile decreased under all treatments except for the control, whereas the value of EC increased with increasing distance from the film hole center. Positive relationships were also found among the sand pipe depth, diameter and the zone of low salt content. Furthermore, salt leaching depth increased with sand pipe depth and diameter. Overall, the treatments with and without sand pipes exhibited obvious differences.

The correlation analysis proved that increasing the infiltration area through sand pipes positively affected the amount of infiltration water, wetting scope and salt leaching depth.

The purpose of this paper is to perform the thermo-hydro-mechanical (THM) numerical analysis in order to study the thawing process for frozen soil and to predict the thawing settlement.

A new one-dimensional multi-field physical coupled model was proposed here to describe the thawing process of saturated frozen soil, whereby the void ratio varied linearly with effective stress (Eq. 10) and hydraulic conductivity (Eq. 27b). The thawing process was simulated with different initial and boundary conditions in an open system with temperature variations. The mechanical behavior and water migration of the representative cases were also investigated.

The comparisons of representative cases with experimental data demonstrated that the model predicts thawing settlement well. It was found that the larger temperature gradient, higher overburden pressure and higher water content could lead to larger thawing settlement. The temperature was observed that to distribute height linearly in both frozen zone and unfrozen zone of the sample. Water migration forced to a decrease in the water content of the unfrozen zone and an increase in water content at the thawing front.

In this study, only the one-directional thawing processes along the frozen soil samples were investigated numerically and compared with test results, which can be extended to two-dimensional analysis of thawing process in frozen soil.

This study helps to understand the thawing process of frozen soil by coupled thermo-hydro-mechanical numerical simulation.

Based on the survey data of 1,152 households in three provinces of Shaanxi, Gansu and Ningxia on the Loess Plateau, this paper aims to empirically analyze the impact of aging and off-farm employment on farmers’ adoption behavior of soil and water conservation technology. This paper analyzes the moderating effect of social network and the mediating effect of technological cognition in this impact relationship.

Based on the above analysis, the second part of this paper is based on relevant theories and constructs a theoretical model of the relationship of aging, off-farm employment, social network, technology cognition and farmers’ adoption behavior of soil and water conservation technology. The third part introduces research methods, variable selection and descriptive statistics analysis of variables. The fourth part, based on the data of Shaanxi, Gansu and Ningxia provinces in the Loess Plateau in 2016, empirically analyzes the impact of aging, off-farm employment and social network on the farmers’ adoption behavior of soil and water conservation technology. This paper further examines the moderating effect of social network and the mediating effect of technology cognition in this influence relationship. Finally, based on the findings of the empirical study, this paper puts forward countermeasures and suggestions.

First, aging and off-farm employment have a significant negative impact on farmers’ adoption behavior of soil and water conservation technology, while social network has a significant positive effect. Second, social network has alleviated the effect of aging and off-farm employment on restraining farmers’ adoption behavior of soil and water conservation technology. Third, aging and off-farm employment have restrained farmers’ cognition of soil and water conservation technology. Social network has promoted farmers’ cognition of soil and water conservation technology. Social network plays a moderating role in the impact of aging and off-farm employment on farmers’ cognition of soil and water conservation technology. Technology cognition plays a mediating role in the impact of social network on farmers’ adoption behavior of soil and water conservation technology.

This paper integrates the aging, off-farm employment and social network into the same analytical framework and reveals their impact on farmers’ adoption behavior of soil and water conservation technology and its action mechanism, which enriches the impact of human capital and social network on farmers’ adoption behavior of soil and water conservation technology. Then taking the social network as a moderator variable, the paper verifies its moderating effect on the relationship of aging, off-farm employment and farmers’ adoption behavior of soil and water conservation technology. Farmers’ technology cognition should be included in the analysis framework to examine the impact of aging, off-farm employment and social network on farmers’ cognition of soil and water conservation technology. Taking the technology cognition as a mediator variable, the paper verifies its mediating effect on the relationship of aging, off-farm employment and farmers’ adoption behavior of soil and water conservation technology.

This paper aims to build a theoretical model of the impact of farmers’ adoption behavior of soil and water conservation measures on the agricultural output to analyze the impact of farmers’ adoption behavior of soil and water conservation measures on agricultural output.

Based on the field survey data of 808 farmers households in three provinces (regions) of the Loess Plateau, this paper using the endogenous switching regression model to analyze the effect of farmers’ adoption behavior of soil and water conservation measures on agricultural output.

Soil erosion has a significant negative impact on agricultural output, and soil erosion has a significant positive impact on farmers’ adoption of soil and water conservation measures. Farmers adopt soil and water conservation measures such as engineering measures, biological measures and tillage measures to cope with soil erosion, which can increase agricultural output. Based on the counterfactual hypothesis, if farmers who adopt soil and water conservation measures do not adopt the corresponding soil and water conservation measures, their average output per ha output will decrease by 2.01%. Then, if farmers who do not adopt soil and water conservation measures adopt the corresponding soil and water conservation measures, their average output per ha output will increase by 12.12%. Government support and cultivated land area have a significant positive impact on farmers’ adoption behavior of soil and water conservation measures.

The research limitation is the lack of panel data.

Soil erosion has a significant negative impact on agricultural output, and soil erosion has a significant positive impact on farmers’ adoption of soil and water conservation measures. Farmers adopt soil and water conservation measures such as engineering measures, biological measures and tillage measures to cope with soil erosion, which can increase agricultural output.

The conclusion provides a reliable empirical basis for the government to formulate and implement relevant policies.

The contributions of this paper are as follows: the adoption behavior of soil and water conservation measures and agricultural output are included into the same analytical framework for empirical analysis, revealing the influencing factors of farmers’ adoption behavior of soil and water conservation measures and their output effects, enriching existing research. Using endogenous switching regression model and introducing instrumental variables to overcome the endogenous problem between the adoption behavior of soil and water conservation measures and agricultural output, and to analyze the influencing factors of farmers’ adoption behavior of soil and water conservation measures and its impact on agricultural output. Using the counter-factual idea to ensure that the two matched individuals have the same or similar attributes, to evaluate the average treatment effect of the behavior of soil and water conservation measures, to estimate the real impact of adaptation measures on agricultural output as accurately as possible and to avoid misleading policy recommendations.

Introduction Although the soil as a corrosive environment is probably of greater complexity than any other environment, it is possible to make some generalisations regarding soil types and corrosion. It is necessary to emphasise that corrosion in soils is extremely variable and can range from the rapid to the negligible. This can be illustrated by the fact that buried pipes have become perforated within one year, while archaeological specimens of ancient iron have probably remained in the soil for hundreds of years without significant attack.

This study aims to predict the volume changes and collapse potential (CP) associated with the changes in soil suction by using the pressure cell and the effect of initial load on soil suction. Three types of gypseous soils have been experimented in this study, sandy gypseous soil from different parts of Iraq. A series of collapse tests were carried out using the oedometer device [single oedometer test (SOT) and double oedometer test (DOT)]. In addition, large-scale model with soil dimensions 700 × 700 × 600 mm was used to show the effect of water content changes in different relations (collapse with time, stress with time, suction with time, etc.).

A series of collapse tests were carried out using the oedometer device (SOT and DOT). In addition, a large-scale model with soil dimensions 700 × 700 × 600 mm was used to show the effect of water content changes in different relations (collapse with time, stress with time, suction with time, etc.).

The CP increases with the increasing of the void ratio for each soil. For each soil, the CP decreased when the initial degree of saturation increased. Kerbala soil with gypsum content (30%) revealed collapse value higher than Tikrit soil with gypsum content (55%) under the same initial conditions of water content and density, this is because the higher the Cu value of Kerbala soil is, the more well-graded the soil will be. Upon wetting, the smaller particles or fractions of the well-graded soil tend to fill in the existing voids, resulting in a lower void ratio as compared to the poorly graded one. Consequently, soils with high Cu value tend to collapse more than poorly graded ones. The compressibility of the soil is low when loaded under unsaturated condition, the CP for samples tested in the DOTs under stress level 800 kPa are greater than those obtained from collapse test at a stress level of 200 kPa.

The initial value of suction for all soils increases with initial water content decreases.

Traditional laboratory measurements of soil water diffusivity (D) and soil water retention curve (SWRC) are always time-consuming and labor-intensive. Therefore, this paper aims to present a simple and robust test method for determining D and SWRC without reducing accuracy.

In this study, a D model of unsaturated soil was established based on Gardner–Russo model and then a combination of Gardner–Russo model with one-dimensional horizontal absorption method to obtain n and a parameters of Gardner–Russo model. One-dimensional horizontal absorption experiments on loam, silt loam and sandy clay loam were conducted to obtain the relationships between measured infiltration rate and cumulative infiltration with wetting front distance. Based on the obtained relationships, the measured infiltration data from the one-dimensional horizontal absorption tests were used to calculate n and a parameters and further constructing D and SWRC.

Both the calculated D and SWRC inversed from the infiltration data were in good agreement with the measured ones that obtained from the traditional horizontal absorption method and the centrifuge method, respectively. Error analysis indicated that only the infiltration data are enough to reliably synchronously determine D and SWRC.

A simple and robust method is proposed for synchronous determination of soil water diffusivity and water retention curve.

The present study aims to determine the residue levels in the soil and water prior to, and after fertilization, as previous soil investigations in Kuwait indicated that different types of fertilizers are used leaving residues in the soil, in order to assist the prospective farmers in choosing environmental sound chemicals for each crop. The importance of the following is to determine the geologic conditions of the soil in such a productive farm area and the effect of the use of fertilizers.

To achieve the study purpose soil and water samples were collected over a wide area and chemical parameters (pH, electrical conductivity (ECe), cations (Ca⁺², Mg⁺²), and anions (CO₃⁻²,HCO₃⁻,Cl⁻)) were obtained via the suitable and most appropriate chemical analyses.

The soils have several levels of calcareous contents along with varying salinity and alkalinity. Before fertilization on average, soil ECe ranges from 0.93 to 4.37 mS/cm, pH from 7.4 to 7.60, cations 8.00 to 36.00 meq/l, and anions from 4.85 to 29.61 meq/l. After fertilization pH ranges from 7.09 to 7.47, ECe ranged from 3.79 to 12.85 mS/cm, cations ranges from 29.75 to 66.36 meq/l, and anions ranges from 15.18 to 63.32 meq/l; showing that ECe, cations and anions average values has increased by almost three to four orders of magnitude. Furthermore, ECe, pH, cations, and anions values have sharply increased with depth. The evidence from this study shows that vertical leaching adversely contributes to the deterioration of the groundwater quality and rate.

The output of this study is intended to be the building block or the nuclei for a data bank on the prevailed agricultural practices in different aspects, and upon which further studies on the southern area of Kuwait will depend.

The farm areas in the southern region of Kuwait state (case study: Al‐Wafrah farms) suffer from misuse and mismanagement of the agricultural lands in different aspects. This paper provides new source of information on the historical record of farm development and the nature, performance and results of the associated agricultural practices in such areas, as so to be the base or the starting point form which further studies can go forth.

This paper aims to construct a simplified distributed hydrological model based on the surveyed watershed soil properties database.

The new established model requires fewer parameters to be adjusted than needed by former hydrological models. However, the achieved stream-flow simulation results are similar and comparable to the classic hydrological models, such as the Xinanjiang model and the TOPMODEL.

Good results show that the discharge and the top surface soil moisture can be simultaneously simulated, and that is the exclusive character of this new model. The stream-flow simulation results from two moderate hydrological watershed models show that the daily stream-flow simulation achieved the classic hydrological results shown in the TOPMODEL and Xinanjiang model. The soil moisture validation results show that the modeled watershed scale surface soil moisture has general agreement with the obtained measurements, with a root-mean-square error (RMSE) value of 0.04 (m³/m³) for one of the one-measurement sites and an averaged RMSE of 0.08 (m³/m³) over all measurements.

In this paper, a new simplified distributed hydrological model was constructed.

The purpose of this paper is to show impacts of household wastes handling on some physicochemical parameters of surface water, soil, sediments and borehole water samples in Port Harcourt. Waste generated from the households are indiscriminately dumped on roads, stream channels, bush lands and open spaces thus defacing the landscape of the city, flooding and spreading vector-borne diseases. As a result there is unsustainable and wasteful utilisation of resources which gives rise to pollution of the environment. The research determines the pollution profile of some dumpsites, surface water bodies that act as recipients of household waste from result of analysis of physicochemical parameters.

Major dumpsites in the city were selected for sampling. Three sampling stations at upstream, discharge point and downstream were selected for water and sediments. Water samples were collected in one-litre plastic containers, and then labelled and transported to laboratory for analysis. Sediment samples were collected at a depth of 5-10 m under water and preservation, handling and analysis were based on standard principles and procedures. Soil samples were dug with auger at both top (0-15 cm) and bottom (15-30 cm) in radial coordinates. The soil and sediment samples were first digested using the wet oxidation method before analysis with atomic absorption spectrophotometry.

The physicochemical analysis of surface water samples showed that conductivity, salinity, turbidity, sulphate, phosphate, magnesium, total hardness and lead exceeded the World Health Organization and Nigerian Industrial Standard limits for drinking water qualities at the sampled areas. The same parameters in addition to pH and manganese also exceeded the limits for sediment samples. The soil pH showed acidity at the sampling stations for both top and bottom depths. Conductivity, sulphate, iron, manganese, phosphate and lead also exceeded the FMEnv Guidelines and standards for soil quality. The continuous discharge of household wastes on water and soil resulted in elevated levels of some measured parameters.

The research was limited by funds. The cost of sampling and analysis was enormous and limited the study to parameters that available funds could carry. This factor also stretched the period of study. The non-availability of sponsorship made it difficult to extend the research to soil particle size distribution and the underground water movement of the study areas. Another limitation was logistics as the study covered vast areas of the metropolis demanding steady means of mobility that was not available. Epileptic supply of power delayed the timely delivery of result of analysis.

The results of the analysed physicochemical parameters of water, sediments, soil and borehole water samples indicated spatial variations in their values at the study area, with higher values at the discharge points and downstream than the upstream, while for the borehole water analysis, the effect was more pronounced at stations with appreciable quantity of degradable household wastes. The levels of some physicochemical variables exceeded standard limits as a result of continuous discharge of household wastes .The implication is that household waste handling influenced the physicochemical variables negatively and constant monitoring serves as a useful tool of abatement.

This work is original and has not been published before in any book or journal article locally or internationally. The research related waste handling lifestyles with concentrations of measurable parameters, which is an additional work to what other authors have done. The value is that data generated will be a reference material to other researchers, city planners, government agencies and institutions that are involved with environmental management. Furthermore it has added a new dimension to the discipline of waste management in terms of scope and contribution to knowledge.