Nifty Copper Operation has three waste landforms with highly saline materials: tailings dam, heap leach facility and a PAF waste dump. Once rehabilitated, potential exists for salts from these wastes to rise via capillary action into the cover material. Two large-scale trial plots were installed on each of these landforms in June 2015 following preliminary water and solute balance modelling. The objectives of the cover trial are to measure the actual movement of water and salts within the cover layers and the underlying in situ materials.
Plots were established with different cover thicknesses on each landform. Specialised monitoring equipment was installed on each plot to monitor climate and soil moisture and salt movements through the cover profiles. Data was collected via wireless and cloud-based systems. Simulated rainfall was applied to the plots to expedite data collection and reduce the risk that insufficient rainfall events would occur during the short available trial period. Physical samples of the materials’ salinity and moisture (along with a suite of other measures) were taken to validate the data recorded by the electronic monitoring equipment.
These data provide a validation dataset used to complete long-term water and solute movement modelling, and in turn identify the cover design that would most effectively manage potential salt movement in the long term. Additionally, the data has been used to calibrate water-solute balance models, with outputs used to assess the long-term performance of the cover design. This case study details the initial modelling, cover trial set up, and a summary of the data collected.
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March 1960 · Journal of Agricultural Meteorology
Usually water losses by evaporation from a soil surface are replenished from below by 3 ways:(1) inflow of gravity water in a saturated state in soil; (2) upward movement of water by the action of capillary force; (3) diffusion of water vapor in soil crevices. The sampling ground of soil for use to measure the soil moisture is flat and bare so that the water supply by (1) may be disregarded
... [Show full abstract] except when raining. In (2) and (3), water moves in soil obeying the same law as heat. So the moisture distribution in soil partakes of the same function as the temperature in conductor.(1+k)∂c/∂t=(D+kD')∂2c/∂x2where D, D' are diffusion-coefficients of water in soil and of vapor through crevices and c is the water content per unit volume of soil (soil moisture) at the depth x and at the time t, k being the ratio of the vapor content g/cc in the crevice to the water content of soil g/cc of the boundary of the crevice. The above equation needs one more correction-term to get it complete if the vapor in the creviee is not of saturated state. It is proved not only by showing k being very small with physical experiments but also by taking into consideration of a well-known preventive method of water losses by sand-strewing over the soil that (3) plays no important part in evaporation from the soil. Therefore the evaporation from the soil surface is computed bywhere (D+kD')(1+k)∂c/∂k≈(D+kD')Δc/Δt/Δ2c/Δx2·Δc/Δx Δ2c/Δx2=(c1+c3-2c2)/(Δx)2Δc/Δt=(c2(t+Δt)-c2(t))/Δtand c1, c2, c4 are the soil moisture at the depth 0.5cm, 1.5cm and 2.5cm respectiviely and Δt is 15 minute-interval. The result of measurements by this method is presented in Table 3 which shows the amount of evaporation measured is of the reasonable order of magnitude. Read more Article Full-text available October 2001 · Journal of Contaminant Hydrology
Solute transport in soils is affected by soil layering and soil-specific morphological properties. We studied solute transport in two sandy Spodosols: a dry Spodosol developed under oxidizing conditions of relatively deep groundwater and a wet Spodosol under periodically reducing conditions above a shallow groundwater table. The wet Spodosol is characterized by a diffuse and heterogeneous
... [Show full abstract] humus-B-horizon (i.e., Spodic horizon), whereas the dry Spodosol has a sharp Spodic horizon. Drainage fluxes were moderately variable with a coefficient of variation (CV) of 25% in the wet Spodosol and 17% in the dry Spodosol. Solute transport in 1-m-long and 0.8-m-diameter soil columns was investigated using spatial averages of solute concentrations measured by a network of 36 Time Domain Reflectometry (TDR) probes. In the dry Spodosol, solute transport evolves from stochastic-convective to convective-dispersive at a depth of 0.25 m, coinciding with the depth of the Spodic horizon. Chloride breakthrough at the bottom of the soil columns was adequately well predicted by a convection-dispersion model. In the wet Spodosol, solute transport was heterogeneous over the entire depth of the column. Chloride breakthrough at 1 m depth was predicted best using a stochastic-convective transport model. The TDR sampling volume of 36 probes was too small to capture the heterogeneous flow and concomitant transport in the wet Spodosol. View full-text Presentation Full-text available April 2019
Although biodeterioration of building materials is a critical problem for maintenance of heritage constructions, lime and earth-based mortars have been poorly explored in this regard. This study examines the damage resulting from the biodeterioration of four different lime mortar novel formulations. Mortars of plaster, reintegration, joints and injection were prepared in 1:3 and 1:4 ratios of
... [Show full abstract] lime to sand, with different arid and additives (also hydraulic), using in all cases aerial lime in paste as binder. The microbial colonization on the mortars was assessed by colour spectrophotometry and PAM fluorometry non-destructive techniques in laboratory assays. Functional properties related to the wettability of the material (a factor controlling the movement of water on the surface or within the pore spaces of the material), including real and apparent density, open porosity, capillarity, wetting-drying kinetics and contact angle were determined. Biodeterioration processes were monitored and quantified. Also a bioreceptivity index (BI), related to the potential to host living organisms, was calculated for each material. View full-text April 2014 · Journal of Information Systems Management
The movement of water in soils occur mainly under the influence of a pressure gradient. Diffusion theory suggests that the flow of water is directed from wetter layers in less moist layers. In this case, the movement of moisture in the soil can be described by a nonlinear equation.
However, a sufficiently broad and repeatedly performed experiments show sometimes the opposite sign of the
... [Show full abstract] flow layers with small to layers with high moisture content. These facts are in conflict with the law of Darcy underlying diffusion theory. In order to keep the Darcy law and at the same time explain the presence of potential flows against moisture, apply the modified diffusion equation.
Disabled iteration method of moisture transfer in inhomogeneous medium. A mathematical model of a problem composes the nonlinear differential equation of the third order initial-boundary conditions. Compiled difference boundary value problem, the algorithm of calculation of moisture in a heterogeneous environment and a program is calculating. Numerical calculations show the stability of the solution of the approximate problem, and some results of numerical calculations.
1. Developed an approximate method for calculating the diffusion coefficient of soil moisture.
2. A program for solving nonlinear boundary value problems for the equation of moisture transfer.
3. The numerical calculations, taking into account evaporation and absorption of moisture in the soil. Read more December 2009 · Pest Management Science
Calibration by inverse modelling was performed with the MACRO transport and fate model using long-term (>10 years) drainflow and isoproturon (IPU) data from western France. Two lack-of-fit (LOF) indices were used to control the inverse modelling: sum of squares (SS) and an alternative statistic called the vertical-horizontal distance integrator (VHDI), which is designed to account for offsets in
... [Show full abstract] observed and predicted arrival times of peak IPU concentration. With these data, SS was artificially inflated because it is limited to comparison of predicted and observed IPU concentrations that are concurrent in time. The LOFs were used along with the index of agreement (d) and the correlation coefficient (r) to ascertain the fit of the calibrated models.
Predicted arrival times of peak IPU concentration differed somewhat from observed times. All four indices indicated better model fit for the second of two validation periods when inverse modelling was controlled by VHDI rather than SS (SS = 26.4, d = 0.660, r = 0.606 and VHDI = 1.25). The VHDI statistic was markedly lower compared with the uncalibrated model (38.0) and SS calibration results (24.5). The final maximum predicted IPU concentration (44.5 microg L(-1)) for the calibration period was very similar to the observed value (44 microg L(-1)).
VHDI is seen as an effective alternative to SS for calibration and validation of pesticide fate models applied to responsive systems. VHDI provided a more realistic assessment of model performance for the transient flows and short-lived concentrations observed here, and also effectively substituted for the objective function in inverse modelling. Read more Last Updated: 05 Jul 2022
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