Ion, Stelian

Ion S., Marinescu D., Cruceanu S.G.

Ion S., Marinescu D., Cruceanu S.

Hillslope hydrology is a very important part of research based on watershed hydrology. In this study, we focus on water flow over a soil surface with vegetation in a hydrographic basin. We introduce a partial-differential-equation model based on the general principles of fluid mechanics where the unknowns are the depth and velocity of water. The effect of vegetation on the dynamics of water is explained in terms of porosity (a quantity that is related to the density of vegetation) that is a function defined over the hydrological basin. Using a Finite Volume scheme for discretization in space, we introduce an ordinary-differential-equation system that constitutes the base of the discrete model that we are working with. We discuss and investigate several properties of this model that have a physical relevance. Finally, we perform different quantitative validation tests by comparing numerical results with exact solutions or with laboratory-measured data. We also consider some qualitative validation tests by numerically simulating the flow on a theoretical vegetated soil and on a real hydrographic basin.

Ion S., Marinescu D., Ion A.V., Cruceanu S.G.

One often deals with a large number of measurements of natural phenomena in environmental sciences. These data can be frequently irregularly distributed and affected by different type of errors. The problem of interest is to recover the variable field with certain regular properties and a reasonable computational effort. To solve this problem, we use block interpolation followed by a projection onto the wavelet space of cubic splines. In this article, we focus our attention on the block interpolation using Thin Plate and Kriging methods.

Ion S., Cruceanu S., Marinescu D.

Abstract We investigate the Riemann Problem for a shallow water model with porosity and terrain data. Based on recent results on the local existence, we build the solution in the large settings (the magnitude of the jump in the initial data is not supposed to be “small enough”). One di culty for the extended solution arises from the double degeneracy of the hyperbolic system describing the model. Another di culty is given by the fact that the construction of the solution assumes solving an equation which has no global solution. Finally, we present some cases to illustrate the existence and non-existence of the solution.

Constantinescu P., Neagoe A., Nicoară A., Grawunder A., Ion S., Onete M., Iordache V.

Phytostabilisation projects for tailing dams depend on processes occurring at spatial scales of 106 m2 and at decadal time scales. Most experiments supporting the design and monitoring of such projects have much smaller spatial and time scales. Usually, they are only designed for one single scale. Here, we report the results of three coupled experiments performed at pot, lysimeter and field plot scales using six sampling periodstimes from 3 to 20 months. The work explicitly accounts for the sampling times when evaluating the effects of amendments on the performance of plants grown in tailing substrates. Two treatments with potentially complementary roles were applied: zeolites to decrease availability of Cd, Cu, Pb and Zn and green fertilizer to increase the availability of nutrients. Zeolites have a positive influence on plant development, especially in the early stages. Analyses of the pooled datasets for all sampling times revealed the possibility of predicting plant physiological variables, such as protein concentrations, pigments and oxidative stress enzyme activities, as a function of the factors extracted by principal component analysis from the metal concentrations in plants, phosphorus concentrations in plants, and sampling times. Two potentially general methodological rules were extracted: account for the spatial geochemical variability of tailings, and cover the broadest possible range of time scales by experiments. The proposed experimental methodology can be of general use for the design of tailing dam remediation technologies with improvements involving the set of measured variables and sampling frequency and by carefully relating the costs to the institutional aspects of tailing dam management.

Ion S., Marinescu D., Cruceanu S.G.

The transfer information across scales is of great importance in environmental sciences. The data collection from direct observations is the only fundamental information that one can have about a natural phenomenon. Based on this direct information, the environmental scientists test hypothesis or make scenarios about how the natural systems work. The components of a natural system interact at different levels and in order to explain this, one needs models at different scales. In this paper, we address the problem of building up an interface that allows different scaled models to access a given set of data observations.

Ion S., Marinescu D., Cruceanu S.

Abstract We investigate the existence of the solution of the Riemann Problem for a simplified water ow model on a vegetated surface - system of shallow water type equations. It is known that the system with discontinuous topography is non-conservative even if the porosity is absent. A system with continuous topography and discontinuous porosity is also non-conservative. In order to define Riemann solution for such systems, it is necessary to introduce a family of paths that connects the states defining the Riemann Problem. We focus our attention towards choosing such a family based on physical arguments. We provide the structure of the solution for such Riemann Problems.

Ion S., Marinoschi G.

We introduce a new model to predict the spread of an epidemic, focusing on the contamination process and simulating the disease propagation by the means of a unique function viewed as a measure of the local infective energy. The model is intended to illustrate a map of the epidemic spread and not to compute the densities of various populations related to an epidemic, as in the classical models. First, the model is constructed as a cellular automaton exhibiting a self-organizing-type criticality process with two thresholds. This induces the consideration of an associate continuous model described by a nonlinear equation with two singularities, for whose solution we prove existence, uniqueness and certain properties. We provide numerical simulations to put into evidence the effect of some model parameters in various scenarios of the epidemic spread.

Neagoe A., Tenea G., Cucu N., Ion S., Iordache V.

Several studies have shown that hairy roots (HRs) can increase the phytoextraction of organic and inorganic pollutants. In addition, microorganisms colonizing the rhizosphere of hairy roots have demonstrated the efficacy of HRs either in removing or in stabilizing of pollutants. This growth chamber study aimed to determine the effect of colonization by the arbuscular mycorrhizal (AM) fungus (Rhizophagus irregularis) on the HRs of tobacco (Nicotiana tabaccum L. cv. Virginia gold) under heavy metals (Cu, Pb and Zn) conditions. Seedlings of N. tabacum were grown in contaminated substrate without infection caused by Agrobacterium rhizogenes expressed in the form of HRs disease, a second one with infection, and the third treatment contained AM fungus beside the A. rhizogenes infection. In the order they have been described, these treatments were coded with C, CT and CTM. The experiment demonstrated that HRs mutants resisted better in terms of higher biomass content in the contaminated soil than the normal plants. Even more, the transgenic plants also had a very strong interaction with mycorrhizal fungi. Thus, soil respiration, biomass and some biochemical variables such as assimilating pigments, protein content and lipid peroxidation indicate a decrease in stress due to the presence of heavy metals in the CTM treatment. Furthermore, CTM treatment significantly alleviated the concentration of toxic elements in plants, compared with the CT treatment, in which a significant increase was registered when compared to treatment C.

Ion S., Marinescu D., Cruceanu S.G.

The primary goal of our study is to model the plant cover influence on water and soil erosion dynamics. The mathematical model consists in Saint-Venant equations coupled with the multiple particle class Hairsine-Rose soil erosion model. The numerical solutions are obtained from a finite volume scheme used to discretize the continuum model, where a second order fractional time step is applied for time integration. The numerical scheme is well-balanced and preserves the positivity of water depth and sediment density functions. The presence of the soil erosion equations do not imposes any restriction on the magnitude of the time step. Secondarily, we apply the general model to study the sediment transport in a vegetative buffer.

Ion S., Marinescu D., Ion A.V., Cruceanu S.G., Iordache V.

Abstract A mathematical model for the water ow on a hill covered by variable distributed vegetation is proposed in this article. The model takes into account the variation of the geometrical properties of the terrain surface, but it assumes that the surface exhibits large curvature radius. After describing some theoretical properties for this model, we introduce a simplified model and a well-balanced numerical approximation scheme for it. Some mathematical properties with physical relevance are discussed and finally, some numerical results are presented.

Ion S., Marinescu D., Cruceanu S.G.

The erosion is a complex process determined by many physical, chemical, biological factors, affects the environment in a number of ways, and has a significant impact on the conservation and exploitation of natural resources, as well as on the quality of life. Due to its complexity, it is crucial to build a good erosion model in accordance with the envisaged main effects. The most determinant factors in the soil erosion - the process we focus in this article - are water dynamics, soil particle cohesion, and the cover plant presence. Our study focuses on the topography influence on water dynamics, the interactions plant cover - water flow, soil particle detachment - plant cover. We also analyze the model sensitivity to the variation of some soil parameters.

Ion S., Marinescu D., Cruceanu S.G., Iordache V.

The presented work is part of a larger research program dealing with developing tools for coupling biogeochemical models in contaminated landscapes. The specific objective of this article is to provide researchers with a data porting tool to build hexagonal raster using information from a rectangular raster data (e.g. GIS format). This tool involves a computational algorithm and an open source software (written in C). The method of extending the reticulated functions defined on 2D networks is an essential key of this algorithm and can also be used for other purposes than data porting. The algorithm allows one to build the hexagonal raster with a cell size independent from the geometry of the rectangular raster. The extended function is a bi-cubic spline which can exactly reconstruct polynomials up to degree three in each variable. We validate the method by analyzing errors in some theoretical case studies followed by other studies with real terrain elevation data. We also introduce and briefly present an iterative water routing method and use it for validation on a case with concrete terrain data. • We provide a method to resample piecewise constant functions. • The method recovers cubic polynomials and doesn't introduce spurious oscillations. • We construct a hexagonal cellular automaton model of flow routing. • The water flows from a cell to the neighbors pointed by the water velocity. • The velocity aligns to the projection of gravitational force on the water surface.

Iordache V., Ion S., Pohoaţă A.

We performed an analysis of a family of models relevant for the integrated modeling in metals biogeochemistry by two approaches: a hierarchical one and a disciplinary one. The hierarchical approach was performed in a theoretical framework accepting the existence of a hierarchy of ecological systems, and split the population of analyzed models into classes based on their relevance for various biological and ecological hierarchical levels. We identified two types of integrated models: between abiotic and biotic components at the same levels, and between biotic components across hierarchical levels. The complementary, disciplinary approach, focused on bioremediation models. The delineation of the class of bioremediation models proved that practically all biogeochemical models are relevant for this class, while only some of the analyzed models have been explicitly declared as ‘bioremediation models’. Based on these analyses we identified a set of research directions, and proposed an alternative, complementary theoretical framework for basic research problems. With regard to bioremediation models, we could identify three levels of potential for development. The strategic potential: if correctly evaluated, models in bioremediation are the most useful tools for rational decision making. The tactical potential, of reactive type: internalizing the future knowledge arising from systems biology, and many other fields such as cognitive sciences biogeochemistry, ecotoxicology, soil science or plant science. The tactical potential of proactive type: (a) combining physico-chemical mechanistic “in principle” approach with uncovering the mathematical laws directly at the bio-geo level by empirical research and use of the existing new mathematical tools and (b) empirical research for delineating in situ the elementary units of models application and the use of programming in geographic information systems (GIS) and new generation GIS software for up-scaling the models’ results from the elementary units of application to the site. And, finally, the operational potential: long-term research network for the study of contaminated sites as basic science experimental areas for implementing the proactive operational potential.

Dumitrescu H., Ion S., Dumitrache A.

Ion S., Marinescu D., Cruceanu S.G.

Lam E.J., Keith B., Bech J., Herrera C., Urrutia J., Montofré Í.L.

Mine tailings require careful monitoring and management, but traditional geochemical characterization methods are costly and time-consuming. This study demonstrates that magnetic properties can serve as effective proxies for predicting copper concentrations in mine tailings through an innovative spatial modeling approach. Analysis of magnetic and geochemical measurements from a Chilean copper mine tailing showed that magnetic properties combined with spatial modeling techniques could predict copper concentrations with high accuracy (R2 = 0.873 ± 0.085). The spatial distribution of magnetic properties revealed coherent patterns that effectively predicted geochemical characteristics. This approach substantially reduces characterization costs compared to traditional methods while maintaining accuracy. Our findings establish magnetic properties as valuable screening tools for tailings characterization, offering mining operations a cost-effective approach to environmental monitoring and management.

Magdalena I., Haloho D.N., Adityawan M.B.

In this study, we examine numerous numerical approaches for solving the 1-Dimensional Boussinesq problem. The proposed methods to be discussed include Mohapatra and Chaudhry’s two-four finite difference scheme, the modified two-four finite difference scheme, and the staggered finite volume scheme. The modified two-four finite difference scheme and staggered finite volume scheme has a shorter computational time than the Mohapatra–Chaudhry scheme, which reduces the computational cost. We compare the performance of each numerical scheme against the analytical solutions and approximate solutions using different type of numerical method that is called the MUSCL4 scheme. Furthermore, the calculated results are compared and utilized to assess the contribution of each individual Boussinesq term. Each Boussinesq term was evaluated to examine its affect on the Boussinesq equation’s calculated result. Further, we also implement the numerical schemes that we formulate to investigate the undular bore phenomena in Kampar River. This finding may be useful to those who use the Boussinesq equation to study fluid or wave phenomena.

Mandal S., Saluja S., Vishwakarma K., Tripathi A., Tayal P.

The use of plants to remove toxins from the soil, water, and air, known as phytoremediation, is a significant and expanding field of study. Using arbuscular mycorrhizal fungi (AMFs) is one promising strategy for improving the efficiency of phytoremediation. With the help of these fungi, the roots of the plants can absorb more nutrients and are shielded from biotic and abiotic stress. AMF can progress the capacity of the plants to absorb and break down heavy metals like copper, by extending their hyphal network in the soil, expanding the area for copper absorption. Such fungi aid in the transportation of copper ions from soil to plants, making them available for the various metabolic events in plants. Effective sequestration of copper ions in the mycelium prevents the metal from leaching into the groundwater and spreading in the soil. It further activates various transporters, specifically chelators, rendering the ions less toxic to the plants. Copper concentrations that are too high impact the physiological and morphological aspects of plants, leading to oxidative stress and cell toxicity. Moreover, arbuscular mycorrhiza fungus (AMF) participation is critical in the field of copper phytoremediation. Through its impact on soil structure and water retention, AMF plays a crucial role in enhancing the soil ecosystem, leading to improved soil fertility and greater agricultural output. AMF’s potential for copper phytoremediation is further enhanced by its capacity to enhance plant nutrient uptake, stress tolerance, and root system development. AMF’s potential for cleaning up copper-contaminated areas will eventually result in more sustainable and clean farming methods. However, because of its possible advantages, this method is an intriguing one to investigate and improve further in the field of soil remediation.

Surrette A., Dobosz A., Lambiv Dzemua G., Falck H., Jamieson H.E.

Reprocessing tailings to recover minerals of economic interest and environmental concern can add value to a project and decrease environmental risk, but dealing with heterogeneity within tailings facilities is a challenge. This study investigates the heterogeneity of the Cantung Mine tailings to assess the potential for reprocessing for both value recovery and remediation purposes. The Cantung Mine, Northwest Territories, was a world-class tungsten (W) deposit that was mined periodically from 1962 to 2015. Geochemical analysis of 196 tailings samples shows substantial heterogeneity in the elements of value (tungsten and copper (Cu)) and elements of environmental concern for acid rock drainage (iron (Fe) and sulfur (S)). Tungsten and copper concentrations range from 0.06 to 1.06 wt% W (average 0.32 wt% W) and 0.05 to 0.48 wt% Cu (average 0.23 wt% Cu). Iron and sulfur concentrations range from 8.25 to 34.08 wt% Fe (average 17.14 wt% Fe) and 2.20 to 19.70 wt% S (average 6.7 wt% S). Characterization of 29 samples by scanning electron microscope with automated mineralogy software shows that geochemical heterogeneity corresponds to mineralogical heterogeneity with variability in the concentrations of scheelite (CaWO4), chalcopyrite (CuFeS2) and pyrrhotite (Fe(1-x)S). Liberation analyses indicate that additional grinding would be necessary to recover scheelite, chalcopyrite or pyrrhotite. Pyrrhotite with monoclinic and hexagonal-orthorhombic forms were identified. Overall, the Cantung tailings display considerable heterogeneity, which could lead to difficulties in reprocessing for economic or environmental benefit, but characterizing the heterogeneity allows for systems to be optimized.

Varra G., Pepe V., Della Morte R., Cozzolino L.

The technological advancements of the last few decades have fostered the use of two-dimensional (2D) Shallow water Equations (SWE) flood simulations not only in academic research but also in practical real-world applications and territorial planning. The evaluation of flow resistance due to friction is crucial as it plays a relevant role in a variety of flow conditions. However, problems arise in dam-break and overland flow applications involving very small water depth because the time scale connected to the friction term may be much smaller than the hydrodynamic time scale. To cope with this issue, known as source term stiffness, an implicit treatment of the friction term is frequently adopted in Finite Volume (FV) numerical schemes, but there are cases (null roughness coefficient or null flow velocity) where a division by zero may occur during calculations, leading to a crash of the algorithm. Herein, we propose a reformulation of the implicit friction term that is general, more stable and computationally efficient (with a speed-up of approximately 3 times for the routine running the friction computation) than currently available approaches. The novel implicit method allows to manage special conditions with null roughness or null discharge, without resorting to ad-hoc thresholds, and can be easily implemented in existing schemes with pointwise friction treatment. The novel friction approach is implemented in a purposely simple FV numerical scheme (hydrostatic reconstruction to account for the bed slope terms, first-order accuracy in time and space) - to better focus on the friction term treatment - and it is validated against analytical, synthetic, laboratory and real-world case studies, showing promising capabilities.

Chirilă Băbău A.M., Micle V., Damian G.E., Sur I.M.

AbstractIn Romania, huge quantities of gangue material from the mining activity practiced in the past were improperly stored and led to the pollution of the environment. Thus, this work is framed to manage the sterile dump of the “Radeș” mine (Alba, Romania) through a 12-week phytoremediation process. The efficient use of Robinia pseudoacacia was studied through the implementation, at the laboratory level, of a phytoremediation experiment based on various variants prepared by mixtures of gangue material, uncontaminated soil, and dehydrated sludge. The prepared variants, all planted with R. pseudoacacia, were watered with tap water, potassium monobasic phosphate, and enzyme solution. The bioconcentration and translocation factors for lead showed values ˂ 1, which indicates a potential presence of an exclusion system for Pb or a reduced Pb bioavailability since the R. pseudoacacia accumulates high concentrations of metals absorbed on and inside the roots. For copper, both factors had values > 1 indicating the suitability of R. pseudoacacia to readily translocate copper into the epigean organs. In the investigated experimental conditions, the highest efficiency in the removal of copper (93.0%) and lead (66.4%) by plants was obtained when gangue material was not mixed with other materials and wetted with enzymatic solution.

HNINI M., RABEH K., OUBOHSSAINE M.

In response to mounting concerns over heavy metal contamination in soils, this review explores the potential of beneficial soil microorganisms, particularly Plant Growth-Promoting Rhizobacteria (PGPR) and Arbuscular Mycorrhizal Fungi (AMF), as a sustainable solution. These microorganisms play a pivotal role in enhancing plant growth, development, and resilience against heavy metal stress. Effective phytoremediation strategies depend on selecting suitable plant families, including Fabaceae, Brassicaceae, and Poaceae, known for their unique attributes that contribute to heavy metal mitigation. Utilizing beneficial microbes and fostering plant-microbe interactions, commonly termed as 'green technology,' offers a compelling strategy to address heavy metal contamination and promote environmental restoration. AMF species like Glomus and Rhizophagus, and PGPR species belonging to Bacillus and Pseudomonas, significantly enhance phytoremediation. The synergistic interaction between (AMF) and (PGPR) represents a significant advancement, especially in heavy metal-contaminated soils. This interaction amplifies plant growth, enhances resistance to heavy metals, and holds promise for soil restoration and phytoremediation. Future research should focus on elucidating the underlying mechanisms, optimizing synergies, and translating findings into practical applications. Tailored, crop-specific approaches may revolutionize agriculture, considering long-term effects and multi-stress tolerance.

Karjoun H., Beljadid A.

In this study, we used the depth-averaged shallow water equations for modeling flows through vegetation field. The vegetation effects on flow are modeled using Morison’s equation taking into account drag and inertia forces which depend on both vegetation and flow properties. We compute and compare different formulations for the stem drag coefficient based on the Froude number or the vegetation volume fraction. Vegetation-induced turbulence is taken into account by adding diffusion terms in the momentum equations. The resulting system of equations is solved using a well-balanced and positivity preserving finite volume method to guarantee the balance between the flux and bed topography source terms, and the positivity of the computed water depth. In our approach, the drag force and bed friction source terms are combined into a unified form. We propose to discretize the obtained term using an implicit temporal method where an analytical technique is used. Special discretization techniques are used for the inertia force and turbulent diffusion terms. Numerical simulations are performed to validate the accuracy of the proposed numerical model. We investigate and compare different formulations for the stem drag coefficient in the vegetation model. Our results confirm the capability of the proposed numerical model for simulating overland flows under vegetation effects.

Varra G., Della Morte R., Cimorelli L., Cozzolino L.

The use of classic two-dimensional (2D) shallow water equations (SWE) for flooding simulation in complex urban environments is computationally expensive, due to the need of refined meshes for the representation of obstacles and building. Aiming to reduce the computational burden, a class of sub-grid SWE models, where small-scale building features are preserved on relatively coarse meshes by means of macroscale porosity parameters, has been recently introduced in the literature. Among the other porosity-based models, the single porosity (SP) model is relevant because the corresponding one-dimensional (1D) Riemann problem is the building block for the construction of many porosity-based numerical schemes. Like the Riemann problem connected to mathematical models such as the SWE with variable bed elevation and the 1D Euler equations in contracting pipes, the SP Riemann problem may exhibit multiple solutions for certain initial conditions. This ambiguity can be solved by restoring the microscale information of the 2D SWE model that is lost at the SP macroscale. In the present paper, we disambiguate the solutions' multiplicity by systematically comparing the solution of the SP Riemann problem at local porosity discontinuities with the corresponding 2D SWE numerical solutions in contracting channels. An additional result of this comparison is that the SP Riemann problem should incorporate an adequate amount of head loss when strongly supercritical flows past sudden porosity reductions occur. An approximate Riemann solver, able to pick the physically congruent solution among the alternatives and equipped with the required head loss amount, shows promising results when implemented in a 1D single porosity finite volume scheme.

Jung J., Hwang J.H.

The present study constructed a path-conservative high-order positivity-preserving well-balanced finite volume Riemann solver for the one-dimensional porous shallow water equations with discontinuous porosity and bottom topography. First, the finite difference equations were formulated using the path-conservative approach to treat non-conservative products in source terms. As the solution depends on the paths, the family of paths was formulated for the solutions to satisfy the mass and energy conservations over the smooth paths connecting the discontinuous geometry (porosity and/or bottom topography). Such a property was achieved using the stationary wave, a stationary weak solution of the porous shallow water equations. Second, to increase computational accuracy, the weighted essentially non-oscillatory (WENO) and the Runge-Kutta methods were implemented for the spatiotemporal discretization of the porous shallow water equations, respectively. Third, a positivity-preserving limiter was employed to provide robustness and efficiency in handling wet and dry problems. Finally, all procedures in the present model were formulated to ensure the well-balanced property (i.e., the exact conservation of initial still water conditions over the irregular geometry). A set of numerical experiments was performed to verify that the present model exhibits positivity-preserving and well-balanced properties along with high-order accuracy and the shock-capturing ability for all types of Riemann problems, including eight wet cases and five dry cases. The numerical results of all cases agree with the analytical solutions.

Zulkernain N.H., Uvarajan T., Ng C.C.

Phytoremediation is a biological remediation technique known for low-cost technology and environmentally friendly approach, which employs plants to extract, stabilise, and transform various compounds, such as potentially toxic elements (PTEs), in the soil or water. Recent developments in utilising chelating agents soil remediation have led to a renewed interest in chelate-induced phytoremediation. This review article summarises the roles of various chelating agents and the mechanisms of chelate-induced phytoremediation. This paper also discusses the recent findings on the impacts of chelating agents on PTEs uptake and plant growth and development in phytoremediation. It was found that the chelating agents have increased the rate of metal absorption and translocation up to 45% from roots to the aboveground plant parts during PTEs phytoremediation. Besides, it was also explored that the plants may experience some phytotoxicity after adding chelating agents to the soil. However, due to the leaching potential of synthetic chelating agents, the use of organic chelants have been explored to be used in PTEs phytoremediation. Finally, this paper also presents comprehensive insights on the significance of using chelating agents through SWOT analysis to discuss the advantages and limitations of chelate-induced phytoremediation.

Cao Y., Zhou B., Chung C.Y., Shuai Z., Hua Z., Sun Y.

This paper proposes a watershed-electricity nexus model to unlock the flexibility of watershed networks (WSNs) for supporting the operation of power distribution networks (PDNs) under rainy climates. The proposed model exploits the spatio-tem-poral flexibility of geographically dispersed pump clusters to pro-vide reserve services to PDNs, and a hyperbolic partial differential function derived from Saint-Venant hydrodynamic equations is formed to describe the dynamic processes of river stream flows. Be-sides, a flexibility evaluation method based on a composite sensitiv-ity matrix of water levels with respect to power injections is pre-sented to quantify the time-varying adjustable power domain of pump loads. Then, a multi-stage interactive coordinated scheduling strategy is developed for the mutual operation of WSNs and PDNs, where drainage pumps are jointly optimized to provide flexible power reserves, while an optimal PDN economic dispatch is per-formed to improve the power supply voltage of pump loads. Fur-thermore, an equivalent mixed-integer linear programming refor-mulation method is derived to cope with the original nonlinear par-tial differential optimization problem for computational tractabil-ity improvements. Comparative results have validated the effective-ness of the proposed strategy in eliminating voltage violations and shaving peak loads.

Luo Y., Xing R., Wan Z., Chen Y.

Direct revegetation is an important measure to immobilize heavy metals and improve the microecological properties of metal smelting slag sites. However, the vertical distribution of nutrients, microecological properties, and heavy metals at a directly revegetated metal smelting slag site remains unclear. Here, the distribution characteristics of nutrients, enzyme activities, microbial properties, and heavy metals in the vertical profile at a zinc smelting slag site directly revegetated with two herb species (Lolium perenne and Trifolium repens) for 5 years were investigated. The results showed that the nutrient contents, enzyme activities, and microbial properties decreased with increasing slag depth after revegetation with the two herb species. The nutrient contents, enzyme activities, and microbial properties of the surface slag revegetated with Trifolium repens were better than those in the surface slag revegetated with Lolium perenne. The higher root activity in the surface slag (0-30 cm) resulted in relatively higher contents of pseudo-total and available heavy metals in the surface slag. Moreover, the contents of pseudo-total heavy metals (except for Zn) and available heavy metals in the slag revegetated with Trifolium repens were lower than those in the slag revegetated with Lolium perenne at most slag depths. Overall, the greater phytoremediation efficiency of the two herb species occurred mainly in the surface slag (0-30 cm), and the phytoremediation efficiency of Trifolium repens was higher than that of Lolium perenne. The findings are beneficial for understanding the phytoremediation efficiency of direct revegetation strategies for metal smelting slag sites.

Poghosyan S., Alaverdyan Y., Poghosyan V., Abrahamyan S., Atashyan A., Astsatryan H., Shoukourian Y.

Varra G., Cozzolino L., Della Morte R., Soares-Frazão S.

Climate change and urbanization, among various factors, are expected to exacerbate the risk of flood disasters in urban areas. This prompts the construction of appropriate modeling tools capable of addressing full-scale urban floods for hazard and risk assessment. In this view, sub-grid porosity models based on the classic shallow water equations (SWE) appear to be a promising approach for full-scale applications in urban environments with reduced computational cost with respect to classic SWE models on high-resolution grids. The present work focuses on the recently proposed two-dimensional binary single porosity (BSP) model, which is a porosity flooding model written in differential form and based on the use of a binary indicator function to locate obstacles and buildings. Several applications (synthetic, experimental, and real-world cases) show that (i) the BSP results tend to the classic SWE solution for sufficiently refined mesh and that (ii) the BSP model can be successfully applied to realistic conditions with complicated terrain and obstacle distribution on coarser grids. Clearly, the adoption of medium/coarse grids makes the BSP model inherently less accurate than the classic SWE model on high-resolution grids, but the corresponding reduction of computational cost makes the use of the BSP model promising in full-scale urban flood applications when (i) multiple simulations are needed to perform stochastic or scenario analysis, (ii) no detailed information of local flow characteristics is required, and/or (iii) for complementing classic SWE models in a nesting cascade.

Brendel C., Capell R., Bartosova A.

The open-source HYPEtools R package aims to address current challenges in hydrological modeling and data analysis by providing a suite of tools for data management, visualization, interpretation, and exploration. Originally developed as a supporting toolbox for the HYPE hydrological model, HYPEtools has since evolved into a standalone package with features ranging from diverse aggregation and evaluation routines to interactive apps and mapping. Specifically, functions are included for data manipulation and conversion, data summarization, plotting and mapping, and interactive data exploration. Two case studies are provided to highlight how HYPEtools can simplify hydrological workflows and analyses both independently of and within HYPE modeling contexts. First, HYPEtools is used for data exploration and mapping of water transfers in South Africa. Then, a case study for the Baltic Sea region of a pan-European HYPE model setup illustrates how HYPEtools can assist model calibration and validation.

García-Alén G., Montalvo C., Cea L., Puertas J.

Calibrating physically based hydrological models manually is time-consuming and challenging. Automatic calibration tools have become prevalent in these models; however, its effective use requires not only a deep knowledge of the calibration procedure itself, but also understanding the structure of the model input and output files. In this study, we introduce Iber-PEST, a novel framework combining the parameter estimation and uncertainty analysis package, PEST, with Iber, a 2D model based on the shallow water equations. We demonstrate its capabilities by successfully calibrating eight storm events in northwestern Spain's basins, achieving promising results (mean NSE equal to 0.84). Furthermore, by applying the iterative ensemble smoother included in PEST, we demonstrate the feasibility to use the calibration data generated by Iber-PEST with alternative PEST algorithms not directly integrated in the Iber-PEST framework. This work successfully addresses the significant implementation barrier associated with the automatic calibration of Iber hydrological models with PEST.

Kim D.D., Johnson J.M., Clarke K.C., McMillan H.K.

Accurate land cover information is essential for hydrometeorological modeling, as it defines parameters governing land-atmosphere-vegetation interactions, water partitioning, and routing. This study presents a controlled sensitivity analysis that evaluated the impact of land cover resampling methods on hydrologic simulations within the WRF-Hydro/NWM framework. The choice of resampling algorithms affected simulations but was generally limited to arid environments, catchments featuring minor land cover classes with high hydrologic impact, or low-flow predictions. We tested two distinct spatial aspects: areal proportions of land cover classes and spatial patterns in land cover. Areal proportions influenced vertical hydrologic fluxes at the catchment scale and subsequently affected streamflow characteristics. In contrast, spatial arrangement alone had a marginal impact on vertical fluxes but could still induce limited alterations in streamflow characteristics through routing processes. These results suggest that spatially distributed land cover, as used in physics-based model structures, has a limited impact on watershed-scale hydrologic simulations.

Ion S., Marinescu D., Cruceanu S.

Hillslope hydrology is a very important part of research based on watershed hydrology. In this study, we focus on water flow over a soil surface with vegetation in a hydrographic basin. We introduce a partial-differential-equation model based on the general principles of fluid mechanics where the unknowns are the depth and velocity of water. The effect of vegetation on the dynamics of water is explained in terms of porosity (a quantity that is related to the density of vegetation) that is a function defined over the hydrological basin. Using a Finite Volume scheme for discretization in space, we introduce an ordinary-differential-equation system that constitutes the base of the discrete model that we are working with. We discuss and investigate several properties of this model that have a physical relevance. Finally, we perform different quantitative validation tests by comparing numerical results with exact solutions or with laboratory-measured data. We also consider some qualitative validation tests by numerically simulating the flow on a theoretical vegetated soil and on a real hydrographic basin.

Guo K., Guan M., Yu D.

Abstract. Urbanisation is an irreversible trend as a result of social and economic development. Urban areas, with high concentration of population, key infrastructure, and businesses, are extremely vulnerable to flooding and may suffer severe socio-economic losses due to climate change. Urban flood modelling tools are in demand to predict surface water inundation caused by intense rainfall and to manage associated flood risks in urban areas. These tools have been rapidly developing in recent decades. In this study, we present a comprehensive review of the advanced urban flood models and emerging approaches for predicting urban surface water flooding driven by intense rainfall. The study explores the advantages and limitations of existing model types, highlights the most recent advances, and identifies major challenges. Issues of model complexities, scale effects, and computational efficiency are also analysed. The results will inform scientists, engineers, and decision-makers of the latest developments and guide the model selection based on desired objectives.

Huysegoms L., Rousseau S., Cappuyns V.

Soil contamination poses a global problem. To address this a lot of scientific progress has been made. However, the development of the economic aspect has been lacking even though the total cost of soil remediation in Europe is estimated to be 119 billion euro. Frameworks and tools are available (for example SuRF-UK framework) to address economic aspects of soil remediation, but an established set of well-defined indicators is currently not available. The introduction of a basic set of indicators for the investment analysis of a soil remediation project, based on an international survey, aims to fill this gap. The basic indicator set contains those indicators that were considered most relevant for an investment analysis by the respondents and includes, among other things, cost description, potential land use after remediation and estimation of human risk. In addition to this basic indicator set, three other indicator sets are defined to address the different needs for information of three large stakeholder groups (research, policy and practice) within the soil remediation sector. An indicator set for practitioners that includes, complementary to the basic indicator set, additional indicators concerning the practical issues of soil remediation projects (e.g. a BATNEEC analysis). For people working in policy, site valuation turned out to be a significant additional theme for an investment analysis, including indicators such as future land value. The indicator set designed to address the preferences of researchers included additional indicators related to financial support, local residents and neighbourhood, and boundaries and uncertainties allowing for a broader but also more detailed overview of the soil remediation project.

Matskevich N.A., Chubarov L.B.

We present some approaches to solving a problem of shallow water oscillations in a parabolic basin (including an extra case of a horizontal plane). Some requirements on the form of the solutions and effects of Earth’s rotation and bottom friction are made. The resulting solutions are obtained by solving ODE systems. The corresponding free surfaces are first- or second-order ones. Some conditions of finiteness and localization of the flow are analyzed. The solutions are used to verify the numerical algorithm of the large-particle method. The efficiency of the method is discussed in tests on wave run-up on shore structures.

Glavan M., Ojstršek Zorčič P., Pintar M.

Erosion processes in the watershed and sediment transport cause hydro-morphological changes, eutrophication, and the loss of storage capacity in reservoirs. This study examines the tool for the optimal selection and implementation (TSI) of eco-remediation measures (ERM) in the river basin area to improve water quality and to reduce storage loss in the reservoir in question. The main purpose of this tool is to support decisions and measures taken to correct defined problems and to improve water quality and storage capacity in the watershed while minimising sediment transport. This tool enables the effective and necessary implementation of these measures to the most critical source areas (CSAs). In order to verify its operability, we selected the Ledava reservoir with a transboundary area of 105.25 km2 in NE Slovenia and SE Austria. With the use of the Soil and Water Assessment Tool (SWAT), critical source areas were determined and the effects of eight different scenarios on sediment yield and load transport were simulated. The results showed that CSAs occupy 12% of the watershed and that sediment inflow into the Ledavsko jezero reservoir could be reduced by up to 30%. After determining the CSAs and which measures would be most effective, the implementation plan could be defined. Within this framework, the TSI enabled the selection of effective measures and contributed to the long-term improvement of the ecological status of surface waters required by Water Framework Directive (2000/60/EC), improving the quality of water bodies of all types to safeguard water ecosystems from harmful consequences.

Rincheval M., Cohen D.R., Hemmings F.A.

Trace and major element composition of selected plant species and parts may be used to map geochemical dispersion from mineral deposits and contaminated areas. This study examines the application of field-portable X-ray fluorescence spectrometry (fpXRF) in obtaining real-time biogeochemical data. In situ analysis of parts of black and silver wattle (Acacia mearnsii De Wild. and Acacia dealbata Link) was conducted to map the extent of contamination surrounding the former Woodlawn base metal mine. High levels of ore-related elements were detected in the bark of these species in a zone extending up to 1 km down-drainage from the tailing ponds. Major elements are more elevated in bark on the side of the trees facing the tailings ponds and correlations between trace and major elements indicate dust contamination. The penetration distance for X-rays is dependent on the energy of the secondary X-rays measured, with the maximum depth of penetration in bark and leaf material

Saltelli A., Aleksankina K., Becker W., Fennell P., Ferretti F., Holst N., Li S., Wu Q.

Sensitivity analysis provides information on the relative importance of model input parameters and assumptions. It is distinct from uncertainty analysis, which addresses the question ‘How uncertain is the prediction?’ Uncertainty analysis needs to map what a model does when selected input assumptions and parameters are left free to vary over their range of existence, and this is equally true of a sensitivity analysis. Despite this, many uncertainty and sensitivity analyses still explore the input space moving along one-dimensional corridors leaving space of the input factors mostly unexplored. Our extensive systematic literature review shows that many highly cited papers (42% in the present analysis) fail the elementary requirement to properly explore the space of the input factors. The results, while discipline-dependent, point to a worrying lack of standards and recognized good practices. We end by exploring possible reasons for this problem, and suggest some guidelines for proper use of the methods.

Ion S., Marinescu D., Cruceanu S.G.

The transfer information across scales is of great importance in environmental sciences. The data collection from direct observations is the only fundamental information that one can have about a natural phenomenon. Based on this direct information, the environmental scientists test hypothesis or make scenarios about how the natural systems work. The components of a natural system interact at different levels and in order to explain this, one needs models at different scales. In this paper, we address the problem of building up an interface that allows different scaled models to access a given set of data observations.

Wu S., Liu Y., Southam G., Robertson L., Chiu T.H., Cross A.T., Dixon K.W., Stevens J.C., Zhong H., Chan T., Lu Y., Huang L.

The present study aimed to characterize key physico-chemical and mineralogical attributes of magnetite iron (Fe) ore tailings to identify potential constraints limiting in situ soil formation and direct phytostabilization. Tailings of different age, together with undisturbed local native soils, were sampled from a magnetite mine in Western Australia. Tailings were extremely alkaline (pH > 9.0), with a lack of water stable aggregate and organic matter, and contained abundant primary minerals including mica (e.g., biotite), with low specific surface area (N 2 -BET around 1.2 m 2 g −1 ). These conditions remained relatively unchanged after four years' aging under field conditions. Chemical extraction and spectroscopic analysis [e.g., X-ray diffraction (XRD) and synchrotron-based Fe K edge X-ray absorption fine structure spectroscopy (XAFS) analysis] revealed that the aging process decreased biotite-like minerals, but increased hematite and magnetite in the tailings. However, the aged tailings lacked goethite, a compound abundant in natural soils. Examination using backscattered-scanning electron microscope - energy dispersive X-ray spectrometry (BSE-SEM-EDS) revealed that aged tailings contained discrete sharp edged Fe-bearing minerals that did not physically integrate with other minerals (e.g., Si/Al bearing minerals). In contrast, Fe minerals in native soils appeared randomly distributed and closely amassed with Si/Al rich phyllosilicates, with highly eroded edges. The lack of labile organic matter and the persistence of alkaline-saline conditions may have significantly hindered the bioweathering of Fe-minerals and the biogenic formation of secondary Fe-minerals in tailings. However, there is signature that a native pioneer plant, Maireana brevifolia can facilitate the bioweathering of Fe-bearing minerals in tailings. We propose that eco-engineering inputs like organic carbon accumulation, together with the introduction of functional microbes and pioneer plants, should be adopted to accelerate bioweathering of Fe-bearing minerals as a priority for initiating in situ soil formation in the Fe ore tailings. • Magnetite Fe ore tailings were strongly alkaline and lack of organic carbon. • Biotite weathering in the tailings without amendments were very slow. • Fe oxides in the tailings lacked association with Al-/Si- minerals for aggregation. • Natural weathering of the tailings resulted in little physicochemical improvements. • Pioneer plants and microbes would be required to accelerate tailings weathering.

Kumpiene J., Antelo J., Brännvall E., Carabante I., Ek K., Komárek M., Söderberg C., Wårell L.

The chemical stabilization, or immobilization, of trace elements (metals and metalloids; TE) in contaminated soil has been studied for decades. A vast number of scientific publications are available on the method performance in laboratory settings, reporting that the application of various soil amendments to contaminated soil reduces TE mobility, bioavailability and toxicity. The most commonly used soil amendments include organic matter, iron oxides, phosphates, ashes, and lately biochar, alone or in combination with each other and/or lime. Most of the implemented field studies show a certain degree of improvement in soil and/or vegetation status following amendment. Regardless the positive performance of the technique in the laboratory, field validations and demonstrations remain scarce. The establishment of a field experiment often involves permits from authorities and agreements with site owners, both of which are considerably more time-consuming than laboratory tests. Due to conservative institutional structures, public authorities have been slow to adopt alternative remediation technologies, especially when the total TE concentration in soil remains the same and all of the associated risks are not yet convincingly described. For this reason, researchers should also focus on enhancing public knowledge of alternative remediation techniques so that future projects which aim to demonstrate the effectiveness of in situ immobilization techniques under natural conditions will be supported.

Gong Y., Zhao D., Wang Q.

Soil contamination by heavy metals and metalloids has been a major concern to human health and environmental quality. While many remediation technologies have been tested at the bench scale, there have been only limited reports at the field scale. This paper aimed to provide a comprehensive overview on the field applications of various soil remediation technologies performed over the last decade or so. Under the general categories of physical, chemical, and biological approaches, ten remediation techniques were critically reviewed. The technical feasibility and economic effectiveness were evaluated, and the pros and cons were appraised. In addition, attention was placed to the environmental impacts of the remediation practices and long-term stability of the contaminants, which should be taken into account in the establishment of remediation goals and environmental criteria. Moreover, key knowledge gaps and practical challenges are identified.