Groundwater Nitrate Pollution Sources Assessment for Contaminated Wellfield

Nitrates are one of the most common groundwater contaminants and they come from different sources. The paper presents a study of groundwater quality at Varaždin wellfield in the north part of Croatia. The nitrate concentration at this location has been above the maximum allowed concentration for several decades, which has made the opening of new wellfields costly. Based on the previously developed groundwater flow model, a model that covers the narrow area of the wellfield is developed. The influential zone of the observed wellfield in working conditions is determined. Based on the developed model, the sources of nitrate pollution are located, which can be generally divided into non-point and point sources. Considering the time of groundwater retention in the horizontal flow, it is concluded that the water protection zones are marked following the applicable ordinance. Based on the developed groundwater flow model at the observed wellfield, a simulation of nitrate pollution propagation by advection and dispersion processes is performed. The simulation results point out the location of the poultry landfill as the largest source of nitrate pollution. However, poultry farms, which are located in the influence area of the wellfield, also contribute significantly to the nitrate concentration at the wellfield.

The Leading-Edge Structure Based on Geometric Bionics Affects the Transient Cavitating Flow and Vortex Evolution of Hydrofoils

A hydrofoil is a fundamental structure in fluid machinery, and it is widely applied to the fields of propellers, blades of axial flow pumps and underwater machinery. To reveal that the geometric structure of the leading-edge of a hydrofoil is the mechanism that affects the transient cavitating flow, we regard the three fish-type leading-edge structures of mackerel, sturgeon and small yellow croaker as the research objects and use high-precision non-contact 3D scanners to establish three bionic hydrofoils (Mac./Stu./Cro.). We use large eddy simulation to simulate the transient cavitating flow of hydrofoils numerically and compare and analyze their lift–drag characteristics, the transient behavior of unsteady cavitation and the vortex evolution. The numerical simulation results are in good agreement with the experimental results. The warping of leading-edge structure will cause a change in lift–drag characteristics, and the Cro. hydrofoil has a good lift-to-drag ratio. When the leading-edge structure is tilted upward (Cro. hydrofoil), the position of the attached cavity will move forward, which will accelerate the cavitation evolution and improve the velocity fluctuation of the trailing edge. When the leading-edge structure is tilted downward (Stu. hydrofoil), the change in the vortex stretching and dilatation terms will be complex, and the influence area of the vortex will widen.

A qualitative analysis on implementing the sewer system for an indigenous village in the influence area of Belo Monte Hydroelectric Plant (Brazil)

In this article, the project and implementation of the sewer system in the Paquiçamba Village, as a condition for environmental licensing, was investigated. This village is surrounded by the influence of the Belo Monte Hydroelectric Plant (Brazil). This research aimed to characterize the context of ethnodevelopment, thus recognizing the social participation of the indigenous people. The research within a qualitative approach between 2009 and 2018 was based on primary data sources (through structured interviews) and secondary data (electronic files related to the environmental licensing). Data were analysed according to descriptive, focused and selective observations until reaching theoretical saturation. The organization of the data was followed by the organization of the themes, which formed a spiral of interconnected activities based on Creswell's proposal (2014). It was detected that indigenous involvement occurred at some moments in the elaboration of the sewage system project. The maintenance of ancestral habits in the disposal of excreta by a portion of the indigenous people, even with the sewage system in place, makes it essential to broaden the debate on the projects proposed on the environmental licensing processes. The Indigenous can not only have a consultative role, but assume a deliberative participation, being protagonists in conducting their own development.

A wave-oriented variable cell transmission model in an urban road

To describe the dynamics of traffic flow in the urban link accurately, the waves which generate at intersections are adopted as the influencing factors of traffic flow. Based on the urban traffic waves, a wave-oriented variable cell transmission model (WVCTM) is proposed to illustrate the urban traffic flow. In this model, the average density and length are the state variables. The cells are divided by traffic waves. The upstream cell is the influence area of the waves at the upstream intersection, the downstream cell is the influence area of the waves at the downstream intersection, and the rest is the mediate cell. Consistent with the fundamental diagram and the cell division, the traffic states of urban links are divided into six modes. The variation of modes is explained by hybrid automata. Finally, an experiment is designed to verify the feasibility of WVCTM. The data in the experiment come from the actual scene. Compared with the cell transmission model (CTM) and variable-length CTM (VCTM), WVCTM possesses the valuable performance to predict the traffic states. Likewise, it is rational that WVCTM can correctly illustrate the urban traffic flow.

Elastic Settlement Analysis of Rigid Footings Relying On The “Characteristic Point” Concept

In the present paper, the problem of finding the location of the so-called “characteristic point” of flexible footings is revisited. As known, the settlement at the characteristic point, is equal to the uniform settlement of the respective rigid footing. The cases of infinitely long strips and circular footings are studied fully analytically. For the case of rectangular footings, analytical results (for flexible footings) are compared with the respective numerical results (for rigid footings) obtained from 3D finite element analysis (210 cases were examined). As shown, the location of the characteristic point may greatly deviate from the well-known values reported in the literature, as it strongly depends on the thickness and Poisson’s ratio value of the compressible medium. For rectangular footings this location also depends on their aspect ratio, L/B. The location of the characteristic point with respect to the center of footing for the various cases examined is given in tabular form. Strain influence area values (Aj=ρjEs/qB) are also given for the convenient calculation of the settlement (ρj) of footings, especially the rigid, rectangular ones; q is the uniform surcharge of footing and Es the soil modulus.

Improving GSMaP V06 Precipitation Products Over the Upper Tocantins River Basin in the Brazilian Cerrado, Based on Local Rain-Gauge Network

This study aimed to evaluate the performance of GSMaP (Global Satellite Mapping of Precipitation) in estimating rainfall in central Brazil, using the Upper Tocantins River sub-basin as a specific area of ​​analysis. GSMaP data were compared with data from a rain gauge network between 2000 and 2019. Evaluations were made at daily and monthly temporal scales. In general, GSMaP products show an overestimate bias for drizzle (0.1~1 mm day−1) and underestimate for rainfalls above 10 mm day−1. The use of monthly scale data significantly reduces the bias observed in the daily scale, but with an underestimation trend of -28.3% and -39.7% for the dry and rainy periods, respectively. Categorical indices showed that the GSMaP system had better hit rates for rain detection in the rainy season (October-April) than in the dry season (May-September). For the studied region, the use of GSMaP data on daily and monthly scales should be preceded by a bias analysis as a function of rain gauge network data. The use of bias coefficient corrected observed rainfall data underestimation on daily and monthly scales, improved correlation between GSMaP and observed rainfall data and reduced errors associated with rainfall network data within the basin influence area.

Problems of Development and Implementation of Personal Protection Equipment for Personnel of Radiation and Chemical Hazardous Facilities, Emergency and Rescue Teams and Population

The article presents a brief review of the activities of the laboratory "Personal protection equipment for the personnel of hazardous production facilities" for creation of the regulatory-legal and regulatory-methodological support system for personal protection of the personnel of radiation and chemical hazardous facilities, of regular and non-staff emergency rescue teams of Rosatom State Corporation and of FMBA of Russia as well as of the population living in the influence area of the mentioned facilities. The issues of standardization and certification of personal protective equipment at NPPs and in the field of atomic energy use — both in the normal operation mode of dangerous objects, and in emergency situations of peace and war time are considered. The problems arising in the implementation of innovative personal protective equipment, primarily due to international obligations, are shown.

Combined integral and particle model for describing the dispersion, dilution, terminal layer formation and influence area from a point source discharge into a water body

Contamination of coastal water is a persistent threat to ecosystems around the world. In this study, a novel model for describing the dispersion, dilution, terminal layer formation and influence area from a point source discharge into a water body is presented and compared with field measured data. The model is a Combined Integral and Particle model (CIPMO). In the initial stage, the motion, dispersion and dilution of a buoyant jet are calculated. The output from the buoyant jet model is then coupled with a Lagrangian Advection and Diffusion model describing the far-field. CIPMO ensures that both the near- and far-field processes are adequately resolved. The model either uses empirical data or collects environmental forcing data from open source hydrodynamic models with high spatial and temporal resolution. The method for coupling the near-field buoyant jet and the particle tracking model is described and the output is discussed. The model shows good results when compared with measurements from a field study.

Avian extinctions induced by the oldest Amazonian hydropower mega dam: evidence from museum collections and sighting data spanning 172 years

Hydroelectric dams represent an emergent threat to lowland tropical forest biodiversity. Despite the large number of operational, under-construction, and planned hydroelectric dams, their long-term effects on biodiversity loss are still poorly documented. Here, we investigate avian extinctions resulting from the Tucuruí Hydroelectric Reservoir (THR), the oldest Amazonian mega dam, which impounded the Tocantins River in 1984. Our avian inventory—based on several sampling methods (mist-netting, point-counts, boat census and qualitative surveys) during 280 days of fieldwork from 2005 to 2007—was combined with an exhaustive search of museum vouchers and digital online databases of citizen science from the lower Tocantins River to identify long-term trends in species persistence and extinction in the THR influence area. The regional avifauna was comprised of 479 species, 404 of which were recorded during our fieldwork. Based on recent and historical records spanning 172 years, we found evidence for likely extinctions at THR influence area for 53 (11.06%) species that have remained entirely unreported since 1984. We were further able to estimate extinction probabilities for 20 species; 15 species were considered to be extinct, including Psophia interjecta and Pyrilia vulturina that are red-listed by IUCN. Our study serves as a baseline for avifaunal monitoring in the THR influence area and shows that degree of habitat specialization is a key factor in determining species extinctions caused by nonrandom habitat loss from either inundation or deforestation. Avian species extinctions will most likely continue across the area affected by the reservoir as a direct impact of alluvial forest loss and ongoing habitat degradation of upland forests.

Designing a supply chain network under a dynamic discounting-based credit payment program

This study examines the effects of dynamic discounting based credit payment on a supply chain network design problem. Dynamic discounting based credit payment is a supply chain finance policy wherein the supplier provides a credit period to a distribution center (DC) with a discount applied if the DC pays the supplier before the end of the credit period. This study also considers the time value of money and applies discounted cash flows to formulate a model that determines the DC’s optimal replenishment cycle, selling price, and influence area while maximizing the present value of the total profit. The continuous approximation approach is applied to formulate a mathematical model of the problems, and an algorithm based on non-linear optimization is established to solve the problem. A numerical example and a sensitivity analysis are provided to present the proposed model and solution approach and to illustrate the effect of each cost on the decisions and profit.