Waste Containment Systems Research Articles

Application of Termite Mound-Bentonite Mixture as Bottom Liner for Industrial Waste Containment

The indiscriminate disposal of waste into various dumpsites with noncompliance to the existing environmental laws and the inadequate provision for leachate containments had resulted in the degradation of environmental resources over the years. The research investigated the practicability of enhanced termite mound-bentonite mixture as an alternate landfill bottom liner. The percentage weight ratio of mound soil and bentonite used for the experimental study were (100:0), (95:5), (90:10) and (85:15) respectively. The study was conducted on a pilot scale artificial landfill (800 x 800 x 400 mm) with four sections AX, AY, BX and BY. Bottom liner was exposed to wastewater for 26 weeks retention period. The pilot scale experimental study revealed that liner mixtures in sections AX, AY and BX failed during the 6, 11 and 17th week retention periods respectively with a corresponding seepage amounting to , and mm3 respectively. However, no seepage was recorded for liner mixture in section BY which connotes that wastewater leakage was prevented throughout the experimental framework. Conclusively, the application of termite mound soil enhanced with 15% bentonite is recommended as a bottom liner in a waste containment system.

Investigation of Corrosion Behavior of Oxygen-Free Copper Canisters in Groundwater Chemistry of Deep Geological Repositories.

The disposal of nuclear waste represents a paramount concern for human safety, and the corrosion resistance of containers within the disposal environment stands as a critical factor in ensuring the integrity of such waste containment systems. In this report, the corrosion behavior of copper canisters was monitored in Olkiluoto-simulated/-procured groundwater (South Korea) with different temperatures. The exposure of copper in the procured groundwater at 70 °C revealed a 3.7-fold increase in corrosion vulnerability compared with room temperature conditions, with a current density of 12.7 μA/cm2. During a three-week immersion test in a controlled 70 °C chamber, the canister in the Korean groundwater maintained a constant weight. In contrast, its counterpart in the simulated groundwater revealed continuous weight loss, indicating heightened corrosion. An X-ray diffraction (XRD) analysis identified corrosion byproducts, specifically Cu2Cl3(OH) and calcite (CaCO3), in the simulated groundwater, confirming its corrosive nature. The initial impedance analysis revealed distinct differences: Korean groundwater exhibits high pore resistance and diffusion effects, while the simulated groundwater shows low pore resistance. Consequently, the corrosion of copper canisters in the Korean environment is deemed relatively stable because of significant differences in ion concentrations.

Assessment of engineering properties of slag mixtures as a bottom liner in landfills

This work examines the engineering properties and leachate characteristics of ground granulated blast-furnace slag (GGBS) blended with laterite soil–bentonite mixtures as a bottom landfill liner. In this study, laterite soil is considered a non-expansive and non-plastic clay; in contrast, bentonite is a highly expansive and highly plastic clay. Laboratory experiments were performed to quantify the effect of GGBS–laterite soil–bentonite mixtures on the liquid limit (LL), free swell index (FSI), compaction characteristics, unconfined compressive strength (UCS), hydraulic conductivity (k) and leachate characteristics tests. As the GGBS percentage in the mix blend increased, the LL, FSI, optimum moisture content, k determined with deionised water/diesel oil contaminants and leachate concentration decreased, whereas the maximum dry densities and UCS value increased. Furthermore, X-ray diffraction analysis and energy-dispersive X-ray spectroscopy were performed on UCS samples to determine the occurrence of a hydration reaction in mix blends at 0, 14 and 28 days of curing. The test results revealed that an increase in the calcium (Ca)/silicon (Si) ratio and a decrease in the aluminium (Al)/calcium ratio enhanced the UCS during the curing period. Consequently, 20% GGBS combined with laterite soil–bentonite mixes proved to be the ideal material for landfill bottom liners in waste containment systems.

Influence of pore fluid salinity on shrinkage and water retention characteristics of biochar amended kaolin for landfill liner application

Biochar amended clay layer has emerged as a sustainable hydraulic barrier for hazardous municipal waste containment system. The effects of pore fluid salinity on soil shrinkage and water retention characteristics of biochar amended clay are unknown. This study aims to investigate the behavior of soil shrinkage and water retention of biochar amended kaolin under different pore fluid salinity. A series of volumetric shrinkage and water retention tests were conducted on biochar amended kaolin in sodium chloride solution at initial concentrations of 1 %, 5 %, and 10 %. Biochar addition increased the shrinkage limit and minimum void ratio of kaolin by up to 17 % and 11 %, respectively. Air entry value of kaolin increased by 6–88 times with an increase in pore fluid salinity, caused by interparticle aggregation. Micrographs showed that biochar intrapore was filled by kaolin particles, partially hindering the interparticle aggregation of clay in the salt solution. Biochar addition lowered zeta potential on the surface of kaolin particles by 50–75 %, indicating that the immobilisation of excess sodium ions was achieved by biochar. Correspondingly, osmotic suction of pore fluid decreased by 21–64 % due to biochar's ion absorption. The findings highlighted that biochar addition to kaolin specimens minimises NaCl-induced soil shrinkage and reduces the pore fluid salinity. This study indicates that biochar could be potentially helpful for desalinisation and mitigating volumetric change issues for geo-environmental infrastructures.

Graphene kirigami membrane with superior theoretical permeability and adjustable selection capability

Membrane plays a central role in molecule separation and selection. However, most artificial membranes utilise a fixed passage size and only effective for limited molecule types. Here, via a large series of molecular and first-principles calculations, we reveal the potential of graphene kirigami (GK), a novel structure with nanoscale incisions on one-atom-thick graphene, which can transform into a three-dimensional structure under deformation, as an ultra-membrane for highly adjustable molecule selection and the practical fabrication feasibility of GK-like membranes using a novel selective tearing process on initially defected graphene. Facilitated by the high stretchability of GK-based membranes, we demonstrate a wide range of gas selection capability on a single membrane. The interaction energy of adsorbed gas molecule also shows that the unique geometry of the pores on GK enables a new adsorption channelling mechanism that enhances molecular separation. Compared with nanoporous graphene, the dynamic gas penetration test shows that various GK membranes are capable of 30 times higher pore-size adjustability and up to 1.5–3.4 times higher gas separation rate. The GK ultra-membrane opens new venues for numerous applications in CO2 capture and storage, water desalination, wastewater treatment, hazardous waste containment system, chemical processing, bionics, and pharmaceutical and medical devices.

Selected Geotechnical and Geoenvironmental Aspects of Landfills in Japan

This paper presents selected issues of geotechnical and geoenvironmental engineering in waste landfills in Japan. Due to the limited available land space, there have been efforts in constructing and operating the coastal and offshore landfills, which are expected to provide the opportunities of proper waste management as well as the new land space for urban facilities such as port and harbour. Regulatory aspects are summarised focusing on the future land use of closed landfills. Some technologies to expedite the land use, such as foundation over closed landfills and newly proposed waste containment system, are introduced.

Potential application of cement amended marine clay as liner material

One of the major problems being faced today in the society is solid waste disposal. Compacted clay soils are commonly used as liner materials in waste containment systems. As marine clay is abundant in the coastal belt of Kochi, this locally available soil was used in the study. Desiccation cracking of clay mass can lead to development of shrinkage cracks and also provide pathways for moisture migration into the landfill. In order to minimize the adverse effect of cracks, the behaviour of sun-dried marine clay amended with cement in different percentages of 1%, 2%, and 4% were studied. To stimulate the field conditions, the samples were subjected to alternate wetting and drying cycles. For different cement content, three cycles of alternate wetting and drying were performed. The study indicates that the extent of crack formation decreases with increase in cement content and the optimum percentage of cement amendment is 4%.

Effect of Rice Husk Ash on the Hydraulic Conductivity and Unconfined Compressive Strength of Compacted Bentonite Enhanced Waste Foundry Sand

A laboratory study of the hydraulic conductivity, (HC), and unconfined compressive strength, (UCS), of compacted bentonite enhanced waste foundry sand (BEWFS) treated with rice husk ash, (RHA) for possible use as liner material is presented. The bentonite enhanced waste foundry sand, BEWFS, was obtained by blending waste foundry sand (WFS) with 12% bentonite by weight of the WFS and mixing the resulting blend thoroughly to obtain a homogenous mix. RHA was added to the BEWFS in increment of 2, 4, 6, 8 and 10% respectively of the dry weight of the BEWFS. The entire blended material was thoroughly mix together to obtain sample with different content of RHA. Index tests, compaction, UCS and HC tests were carried out on the blended materials to determine the effect of RHA on the behaviour of the BEWFS. HC as well as UCS of the materials were study using three compactive efforts of British standard light, (BSLC), West African standard, (WASC) and British standard heavy, (BSHC) compactive efforts respectively. The results obtained show that addition of RHA to BEWFS affected the index properties of the material marginally where the liquid limit increased to 35 from 32 %, plastic limit reduced from 12 to 11% and plasticity index increased from 20 to 25% respectively. The HC of the material was found to increase slightly from 6.28 x 10-08 to 3.90 x 10-08, 2.64 x 10-09 to 2.07 x 10-08 and 8.55 x 10-11 to 1.83 x 10-10 m/s with addition of up to 10 % RHA content and compacted at BSLC, WASC and BSHC respectively. Similarly, the UCS was found to increase to peak values of 177.22, 288.48 and 454.26 kN/m2 at same RHA content and compactive efforts. The implication of this result is that the addition of RHA up to 10% to BEWFS slightly increase the HC but does not compromise it while the strength gain in term of UCS can be said to compensate for the slight lost in HC. It is recommended that BEWFS treated with between 8 to 10% RHA content and compacted at BSHC compactive effort can be applied as liner in engineered waste containment system.

Effects of acidic attack on chemical, mineralogical, and morphological properties of geomaterials.

Exposure of geomaterials to acidic leachates may compromise their structure and functionality due to changes in physicochemical, mineralogical, and hydraulic behavior. The literature identifies the need to evaluate changes in a pure state and in conditions of extreme acidity. This study aimed to evaluate changes in the chemical, mineralogical, and morphological properties of Osorio fine uniform sand (OFS), basalt residual soil (BRS), kaolin (KAO), and bentonite (BEN) exposed to sulfuric acid in concentrations of 0.00mol/L (distilled water), 0.01mol/L, and 1.00mol/L. The tested samples were characterized using X-ray fluorescence spectrometry, X-ray diffraction, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. The acid attack on geomaterials by contact with the solution 1.00mol/L has resulted in the solubilization of some constituent minerals, as well as the formation of sulfate minerals, changes in the water dehydration peak in the pores, and mass loss. The morphology of the sand and bentonite particles did not change with exposure to sulfuric acid. The acidic attack resulted in changes in the morphology of the particles for BRS and KAO. The results of this study are important for determining operational parameters of waste containment systems and contaminated areas, as well as for applying geomaterials as founding materials.

Potentials of bentonite enhanced termite mound soil for bottom lining in waste containment system

The sole purpose of a compacted landfill liner is to contain and mitigate the impact of leachate on the environment. This research assessed the engineering properties of bentonite enhanced termite mound mixture to ascertain their suitability as an alternate landfill liner. The mixture of mound soil and bentonite was proportioned by percentage weight as (100:0), (95:5), (90:10) and (85:15) respectively. The compaction analysis reveals an optimum moisture content ranging from 13.80% to 18.52% and a maximum dry density that varied from 1.72 g/cm 3 to 1.88 g/cm 3 . The hydraulic conductivity result of 15% bentonite-mound soil mixture (0.23 x 10 -9 m/s) established hydraulic conductivity less than 1 x 10 -9 m/s, which satisfied the criteria for landfill liner. Hence, a mixture of 15% bentonite enhanced mound soil is found suitable as an alternate bottom liner.

Unconfined Compressive Strength of Lateritic Soil Treated with Bacillus Coagulans for use as Liner and Cover Material in Waste Containment System

The innovative and environmentally friendly Microbial Induced Calcite Precipitation (MICP) technique involves the use of micro-organisms to facilitate soil improvement. Urease positive bacteria in the company of urea and calcium sources formed dissolved ammonium and inorganic carbon, carbon dioxide and subsequent formation of calcite which is a pore filling material that stiffens the soil and improve its strength. The study involved assessing the potential of Bacillus coagulans(B.coagulans) to improve the unconfined compressive strength (UCS) of lateritic soil. The soil samples were treated with 1/3 pore volume B. coagulans suspension densities of 0, 1.5×108, 6 × 108, 1.2 × 109, 1.8× 109 and 2.4 × 109 cells/ml, respectively. Soil specimens were prepared at moulding water content (MWC) of -2, 0, +2 and +4 % relative to optimum moisture content (OMC) and compacted with the British Standard light (BSL) energy. Cementation reagent was allowed to percolate the compacted specimens until partial saturation was achieved. Results show that UCS values increased with rise in B. coagulans suspension density. UCS of natural soil prepared at -2 % OMC decreased from 278.3 kN/m2 to 141.45 kN/m2 at +4 % OMC. Similar trend were recorded for specimens treated with varying B. coagulans suspension densities when prepared at MWC of -2, 0, +2 and +4 % relative to OMC. Also, UCS values improved with rise in dry density. The UCS values of specimens prepared with B. coagulans suspension densities and compacted at MWC of -2, 0 and +2 OMC, respectively, satisfied the minimum requirement of 200 kN/m2 and can be apply as liner and cover materials in municipal solid waste containment system.

Desiccation-Induced Volumetric Shrinkage Characteristics of Highly Expansive Tropical Black Clay Treated with Groundnut Shell Ash for Barrier Consideration

Contamination of underground water as a result of excessive crack on clay liner material is a prevalent phenomenon in an engineered landfill. Volumetric shrinkage strain (VSS) is one of the veritable properties considered for selection of materials suitable for liners and cover in waste containment systems. Material devoid of excessive shrinkage and cracking during climate change could possibly make a better barrier material that will eventually limit or control infiltration of leachate in an engineered landfill. Hence, to obtain a clay liner and covers system that are safe and robust, stabilization of such soil (expansive clay soils) becomes imperative. In order to stabilize or reduce excessive cracking and shrinkage of this soil, earlier researchers have employed cement, chemicals, and fibers. However, in recent times, the ill effects of these stabilizers on the environment have been realized, and hence their replacement with sustainable materials that are mostly agro and or industry by-products is becoming necessary. Tropical dark grey clay treated with up to 8 % Groundnut shell ash (GSA), was carried out. Specimen were compacted using British standard light (BSL) and British standard heavy (BSH) compactive efforts; at water contents between 2% dry and 4% wet of optimum. The compacted specimens were extruded and subjected to drying under laboratory conditions to evaluate its desiccation induced shrinkage and hence its suitability as a cover material in waste containment facilities. Results of this study show that changes in mass and volumetric shrinkage strain were large within the first five days of drying. Volumetric shrinkage strain increased with higher moulding water contents (MWC) and water contents relative to optimum (WRO). The effect of GSA treatment on VSS was not consistent from -2 to +2 % of optimum moisture content. For specimen prepared at +4 % of optimum moisture content, VSS decreased up to a threshold of 28% at 6 % GSA and 30% at 4% GSA for BSH and BSL compactive effort, respectively. Generally, lower compactive effort (BSL) with higher moulding water content and lower dry density produced higher VSS. A regression function was developed from the data to estimate VSS given the compaction water content relative to optimum (WRO), groundnut shell ash content (GSA), plasticity index (PI), percentage fine content (PF) and compactive effort (CE). Compaction water content relative to optimum significantly correlated with VSS, thus should be strictly regulated during field compaction to realize a durable hydraulic barrier. Keywords: Atterberg limit, compaction, desiccation, expansive soil, groundnut shell ash, statistical analysis DOI : 10.7176/CER/11-8-06 Publication date :September 30 th 2019

Soil water characteristic curves for laterite soil at different water contents and methods as lining system

Preventing groundwater contamination from the most common method of solid waste disposal technique i.e. landfilling is by proving hydraulic barriers. Accordingly, water movement in unsaturated soil is important in the analysis of leachate migration in soil material used as hydraulic barrier in waste containment systems. A full-scale experiment would be prohibitively costly and time consuming. The only feasible recourse therefore is to construct a model, which reasonably portray the behaviour of the full-scale system and simulate the relevant physical parameters and describes the overall significant characteristics of the transport phenomena. This paper presents the trends and patterns of soil water characteristic curves (SWCC) in terms of volumetric water content versus soil suction developed for compacted laterite soil specimens using data from pressure plate tests. Specimens were prepared at three different water contents corresponding to dry of optimum, optimum, and wet of optimum conditions. Models suggested by Brooks and Corey (BC), van Genuchten (VG), and Fredlund and Xing (FX) were used to obtain curve fitting parameters using the program “SWRC Fit” which performed nonlinear fitting of soil water retention curves. The SWRC Fit can simultaneously calculate the fitting parameters of these models with Root Mean Square Error values and draw the fitting curves. By comparing the results of the models using SWRC Fit, the model that best fits the laterite soil investigated will be chosen to be used for further analysis. The results show that the BC model represents the soil water retention curves better than the VG and FX models when the soil has distinct air entry suction. On the other hand, the VG and FX models can fit most soil water retention curves very well when discussion on the pore-size distribution is desired.

An investigation of the chemical durability of hydrous and anhydrous rare-earth phosphates

Geological disposal of nuclear waste relies upon a multiple barrier approach in which canisters containing nuclear wasteforms are proposed to be stored in geological repositories. In the event of a failed container situation, the groundwater present near the repository may penetrate the waste containment system and eventually come in contact with the nuclear wasteform. Assessing the chemical durability of nuclear wasteforms is of utmost importance and in this study, leaching experiments were conducted on rare-earth phosphate materials adopting the monazite- (LaPO4), xenotime- (YbPO4), and rhabdophane- (GdPO4.H2O) type structures. Monazite and xenotime are abundant rare-earth minerals containing varying amounts of actinides incorporated within their crystal structure and are proposed as a potential host matrix for the immobilization of actinides. Rhabdophane is a hydrous rare-earth mineral that forms on the surface of chemically altered monazite mineral and is proposed to act as a protective barrier by preventing the release of actinides to the biosphere. The as-synthesized materials were exposed to deionized water for a total period of seven months and the concentration of the leached elements in the water solution were determined using inductively coupled plasma – mass spectrometry (ICP-MS). In this study, the normalized leach rates of LaPO4, YbPO4, and GdPO4.H2O materials were found to be low and indicate the chemical durability of these materials. Structural characterization of materials before and after leaching was performed using powder X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES). Analysis of the powder XRD diffractograms and XANES spectra has shown that the long-range and local structures of monazite-, xenotime-, and rhabdophane-type materials remain unaffected after exposure to water for seven months.

Thermo-elasto-plastic analysis of geosynthetic clay liners exposed to thermal dehydration

Geosynthetic clay liners (GCLs) are designed to minimise contaminant migration into subsoils in landfills and other waste containment systems. The so-called mixture theory has typically been chosen as a basis for numerical models describing the complicated behaviour of GCLs subjected to thermo-hydro-mechanical changes. Despite progress in this area in the past decade, some aspects of the response of GCLs have not been captured by these simulations. For example, a typical assumption of these analyses is that the mechanical response to thermal loads of GCLs can be described by linear or non-linear elastic constitutive equations. However, there is evidence that in many instances plastic deformation cannot be avoided. The primary aim of this study is to analyse the hydration and dehydration behaviour of GCLs within a thermo-elasto-plastic framework. First, a thermo-elasto-plastic constitutive model is introduced and numerically implemented. Next, the results of numerical simulations of the performance of GCLs are presented and discussed and the effects of deviations from elastic behaviour are identified. Finally, a parametric study is conducted to identify the influence of key parameters in the constitutive model on the horizontal stress in the GCL’s bentonite during restrained shrinkage driven by thermal dehydration.

Understanding the retention and fate prediction of copper ions in single and competitive system in two soils: An experimental and numerical investigation

The concept of sponge city has become very popular with major thrust on design of waste containment systems such as biofilter and green roofs. Factors that may influence pollutant ions retention in these systems will be soil type and also their interactions. The study investigated single and competitive interaction of copper in two soils and its influence on the fate prediction. Freundlich and Langmuir nonlinear isotherms were selected to quantify the retention results. Series of numerical simulations were conducted to model 1 D advection-dispersion transport for the two soils and analyse the role of isotherms. The results indicated that contaminant fate prediction of copper-soil interaction based on the two non-linear isotherms was different for both single and that in competition. Retardation factor obtained from Freundlich (RF) isotherm predicts more than Langmuir (RLa). This observation is more explicit at the higher range of equilibrium concentration. Fate prediction based on retardation value obtained from retention isotherms exhibited some anomalous trends contradicting the experimental findings due to inherent assumptions in governing equations. The necessity to have an approximate assessment of contaminant concentration in the field to effectively use contaminant retention results for accurate fate prediction is highlighted here. The study is important for modellers in design or analysis of biolfilter system (sponge city), where multiple ions tend to exist in waste water.

Exploring Potential of Fly Ash–Bentonite Mix as a Liner Material in Waste Containment Systems Under Concept of Sponge City

Abstract Many studies have been conducted to evaluate fly ash as an additive for the modification of hydraulic properties of soil. However, rarely are studies carried out that quantify physiochemical, strength, and hydraulic properties of fly ash–bentonite mix. Fly ash–bentonite mix may have the potential to be used as a landfill liner material instead of conventional sand in sand-bentonite landfills. Also, with the introduction of the new concept of sponge city, one of the aims of which is to minimize contamination and maximize the use of waste material, the exploration of fly ash–bentonite mix as a cover material in retention systems is highly crucial. The main objective of this study is to explore physicochemical, strength, and hydraulic properties as well as sorption characteristics of fly ash–bentonite mix. The sorption characteristics of the fly ash–bentonite mix for two heavy metals, lead ions (Pb+2) and nickel ions (Ni+2), were investigated. A criterion based on cation exchange capacity (CEC) and specific surface area (SSA) has been proposed. The study also developed correlations for estimating the CEC of soils with SSA and other soil parameters. Hydraulic conductivity decreases approximately four orders of magnitude with an increase in 30 % of bentonite. Unconfined compressive strength (UCS) is found to increase first (up to 40 % fly ash) and then reduces with further increase in fly ash. Furthermore, the curing time is also found to affect UCS significantly. The findings stated that the mix of 70 % or lower fly ash content (in fly ash–bentonite mix) is able to meet standard requirements for hydraulic conductivity and UCS. The Langmuir isotherm is found to better represent sorption behavior of fly ash–expansive soil, with nickel and lead as model contaminants. All the mixes considered in this study exhibited maximum uptake of Pb+2. Sorption decreases very mildly for mixes that have some expansive soil content, whereas it reduces drastically for only fly ash content.

Development of a numerical model for performance-based design of geosynthetic liner systems

A numerical model for performance-based design of the geosynthetic elements of waste containment systems has been developed. The model offers a rational alternative to the current state of practice for design of geosynthetic containment system elements in which neither the strains nor the forces in liner system elements are explicitly calculated. To explicitly assess the ability of the geosynthetic elements of a containment system to maintain their integrity under both static and seismic loads, a large strain finite difference model of waste-liner system interaction was developed. Modular features within the model allow the user to select the appropriate features required for any particular problem. A beam element with zero moment of inertia and with interface elements on both sides is employed in the model to represent a geosynthetic element in the liner system. This enables explicit calculation of the axial forces and strains within the liner system element. Non-linear constitutive models were developed to represent the stress-strain behavior of geomembrane and geosynthetic clay liner beam elements and the load-displacement behavior of the beam interfaces. The use of the various features on the model is illustrated using available experimental data, including shaking table test data on rigid and compliant blocks sliding on geomembranes. Analysis of geomembranes subject to waste settlement and subject to seismic loading demonstrate applications of the model and provide insight into the behavior of geosynthetic liner system elements subject to tensile loads.

Combinations of soil materials for granular capillary barriers for minimizing rainfall infiltration and gas emission

This paper presents a coupled air–water flow analysis to evaluate the performance of a three-layer capillary barrier for controlling water infiltration into and gas emission from a waste containment system in a high precipitation environment, and to optimize combinations of local soil layers for barrier construction. A multi-phase flow model is proposed considering the movements of the gas and water phases simultaneously. The governing partial differential equations are solved in COMSOL Multiphysics software. Several combinations of lean clay with sand (CL), clayey sand with gravel (SC), silty sand with gravel (SM), sandy silt (ML), and well-graded gravel with silt (GW–GM) are examined. The rates of percolation water and gas emission are used as indicators to compare the performance of different combinations. A fine-grained surface soil layer reduces both water infiltration and gas emission due to its low desaturation rate and high water-retention capacity. The coarse middle layer plays a critical role, promoting capillary effects and hindering water infiltration during rainfall as well as draining any infiltrated water or percolated gas.

Using Surrogate Meteorological Data to Predict the Hydrology of a Water Balance Cover

AbstractThe objective of this study was to evaluate strategies for addressing missing meteorological (MET) data when predicting the hydrology of a water balance cover for a waste-containment system using a variably-saturated flow code. Predicting the hydrology of water balance covers typically requires site-specific daily MET data, which may be only partially available (e.g., dew point temperature (Tdew), solar radiation (Rs), wind speed, and cloud cover frequently are only partly available). Thus, some of the input data may need to be estimated or surrogate data employed for hydrologic modeling. The influence of replacing missing MET data with estimates on hydrologic predictions was evaluated for a water balance cover in a semiarid climate. Substitution of single or multiple MET variables with long-term averages led to statistically similar predictions of annual percolation relative to percolation predicted using actual data. Replacing all MET variables (Tdew, Rs, wind speed, and cloud cover) with long-t...