Dimensional Transport Model Research Articles

Prediction of Heavy Metals Concentrations Profiles in Groundwater around Soluos Dumpsite in Lagos State, Nigeria

Water pollution is a threat to human life. Heavy metals in leachates from dumpsites pollute groundwater within the vicinity of the dumpsites. This work was carried out to predict the heavy metals concentration profiles in groundwater around Soluos dumpsite in Lagos State. A one dimensional transport model with a decay factor component was used to predict the concentration profiles of heavy metals in groundwater within the vicinity of Soluos dumpsite using finite difference techniques implemented in matrix laboratory (Matlab) 7.9. the concentration profiles for heavy metals considered in this work which include lead (Pb), copper (Cu), nickel (Ni), chromium (Cr) and Iron (Fe) were similar but different in term of concentrations values. The one dimensional transport model used predicted the experimental data from groundwater at the depth of 22 m within the vicinity of Soluos dumpsite up to 98 percent confidence level compare to a one dimensional transport model without a decay factor which predicted the experimental data up to 94 percent confidence level in the work of Salami and Susu. The concentration profiles of heavy metals in groundwater were also predicted at the depths of 38, 46, and 54 and 62 m. It was shown that the one dimensional transport model with a decay factor component yeilded a better prediction of heavy metals in groundwater around Solous dumpsite than the one dimensional transport model without a decay factor. The predicted concentration profiles at various depths can be used as a guide to determine the depth to which boreholes within the vicinity of Soluos dumpsite should be dug for the purpose of provision of good groundwater.

Micro atmospheric pressure plasma jets excited in He/O2 by voltage waveform tailoring: a study based on a numerical hybrid model and experiments

A hybrid simulation code is developed to treat electrons fully kinetically by the particle-in-cell/Monte Carlo collision (PIC/MCC) algorithm, while ions and neutral species are handled by a fluid model, including a time slicing technique to reduce the computational expenses caused by the responses of various species on different time scales. The code is used to investigate a capacitively coupled COST reference micro atmospheric pressure helium plasma jet with 0.1% oxygen admixture excited by a valley-type tailored voltage waveform with a fixed peak-to-peak voltage of 400 V, and a fundamental frequency of 13.56 MHz. The computational results are compared to experiments based on several sophisticated diagnostics, showing good agreement in the electron impact helium excitation rate, the helium metastable density, and the atomic oxygen density. The spatio-temporal electron heating dynamics, are found to be asymmetrical due to the specific shape of the driving voltage waveform. Tailoring the voltage waveform is shown to enable to control the electron energy probability function (EEPF) in distinct spatio-temporal regions of interest. As a consequence, the generation of reactive neutral species can be enhanced by increasing the number of consecutive harmonics. Based on a simplified two dimensional neutral transport model in the hybrid code, it is demonstrated that the transport between the electrodes, as well as the gas flow have different effects on various neutral species distributions due to the relevant chemical reaction rates for the generation and destruction of species.

Study of water renewal and sedimentation of a square harbor encapsulated in a coastal front with seawalls due to wind-induced hydrodynamic circulation

In the current study in the middle of a coastal zone, a harbor basin in the form of a square area recessed to the front is considered. A breakwater of variable length and position offers protection from waves. The water renewal time and the self-purification capacity of the harbor under the influence of alongshore currents due to wind-induced water circulation of varying intensities were examined. Furthermore, the transport of particulate matter released from the upstream side of the coastal zone and the possible influence (via sedimentation) on the lateral basin was investigated. The current study was based on the use of a two-dimensional depth-averaged hydrodynamic model and a quasi-three-, dimensional transport model while the effect of partial closing of the harbor's entrance was examined. The (1) adjustment and (2) validation of the reliability of the numerical model at a laboratory level were done using a recent research based on the use of a particle image velocimetry (PIV) measurements ensuring very good agreement between numerical and experimental results. The current study showed that the partial closing of the opening between the harbor basin and the extended coastal zone, with a breakwater of length equal to 1/3 of the opening, seems to be the most acceptable technical solution.

Effects of flow-interruption on the bacteria transport behavior in porous media

Attachment is an important strategy for microorganisms to survive, grow, and perform biogeochemical functions in soil and groundwater systems. This study investigated the effect of flow-interruption (FI) that is common in subsurface environments on bacterial attachment/detachment using a metal-reducing bacterium Shewanella oneidensis strain (MR1) as an example. Column experiments and one dimensional bacterial transport models were performed by varying flow interruption duration, fluid ionic strength, and solid grain surface electrostatic properties with a goal to understand the effect of FI on bacterial attachment/detachment. The results indicated that MR1 generally behaved as colloidal particles in transport and attachment/detachment under continuous flow conditions. However, the FI events induced a significant release of MR1 in both injection and elution phases, showing a peak MR1 concentration, which was higher than that in the injecting solution, immediately after the FI events. The peak MR1 concentrations were higher in systems with lower adhesive forces between bacteria and solid grains, a lower attachment site capacity in porous media, and a longer FI duration. The diffusive release of the previously attached bacteria during the FI events and the momentum force when flow re-started immediately after the FI events were likely the mechanisms leading to bursting release of bacteria with the release concentrations higher than that in the influent solutions. The results have important implication for understanding bacterial migration and attachment, and their subsequent functions, especially in dynamic hydraulic environments such as in hyporheic zones or in soils subject to dynamic changes in infiltration rates under for example extreme precipitation and drought conditions.

Transitional Waters Typology in Turkey: Melen Estuary Case Study

Balas, L.; Genc, A.N., and Eser, E., 2020. Transitional waters typology in Turkey: Melen Estuary case study. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 18-22. Coconut Creek (Florida), ISSN 0749-0208.Transitional and coastal water bodies are dynamic and complex environments. Even though widespread typological descriptors have been defined for coastal waters, typology studies for transitional waters are still continuing in Turkey as in many European countries. Transitional waters include estuaries, lagoons, and deltas. In this manuscript, the typology study applied for the Melen estuary is presented. Melen Estuary located in the Western Black Sea Part of Turkey is one of the significant watersheds of Turkey as it supplies more than 50% of the drinking water to the city of Istanbul. In typology approach, System B is accepted, and the Guidance Document No 5 produced by the Common Implementation Strategy for the Water Framework Directive (2000/60/EC) Working Group 2.4 (COAST) is closely followed. In addition to the obligatory factors, current velocity, wave exposure, and mixing characteristics are investigated as the optional factors. Measurements and modeling studies are used together. The coastal processes in the Melen Estuary are modelled. The wind and wave climate, wind and wave-induced current patterns, and mixing zone are simulated by HYDROTAM-3D (Three dimensional hydrodynamic, transport and water quality model). In the long term directional wind analyses, six hourly predictions of the European Centre for Medium-Range Weather Forecasts (ECMWF) between 2000-2019 are analyzed. In the long term directional wave statistical analysis, six hourly wave predictions of ECMWF between 2000-2019 operational archive are used. The range of significant wave heights, with 12 hours/year exceedance probability, is estimated as 0.4m≤Hs,12≤3.2 m. The wave exposure index for Melen transitional water is calculated. The dominant wave direction interval is determined as North-Northeast. Based on the mixing studies, the degree of stratification is determined as partially stratified.

Analysis and design of a SiGe-HBT based terahertz detector for imaging arrays applications

In this paper, we will introduce a new designed direct conversion terahertz detector. Characteristics of this new detector have been compared with a prefabricated design in order to obtain better performance of our new proposed design. We have introduced an exponentially graded base SiGe-HBT instead of linearly graded ones, and have used a single transistor with two base contacts, which is equivalent to two transistors in common emitter configuration. New proposed detector has been analyzed by both compact circuit and two dimensional carrier transport models. Responsivity and minimum noise equivalent power of new detector are about 4.9 A/W and 6.5 pW/Hz1/2 at 700 GHz respectively, while these characteristics for the prefabricated detector, are about 1 A/W and 50 pW/Hz1/2. Also about 231μW/pixel decrement in power consumption for the same responsivity, and a same bandwidth have been achieved.

Electrochemical Modeling of HTPEM Fuel Cells Using Elementary Step Kinetics

High temperature polymer electrolyte fuel cells (HT-PEM) offer certain advantages over the low temperature polymer electrolyte membrane fuel cells (LT-PEM). Numerical modeling is a powerful tool to understand the thermo-chemical and physico-chemical processes that takes place within the gas diffusion layer (GDL) and the catalyst layer (CL) during the cell operation. The models reported in the literature varies from simple analytical expressions to 3D models. Most of these models are based on a general Butler-Volmer equation, without giving any importance to the underlying charge transfer mechanism, and therefore the exchange current densities are fitted to some arbitrary order with respect to hydrogen and oxygen concentrations. Furthermore, most of these models are validated by reproducing the IV curve often by a one dimensional model by resolving the electrode thickness. Whenever such as validation is done, the fuel and oxidant depletion along the cell length and hence the fuel utilization is not accounted for. To the best of our knowledge no attempt has been done to date to validate the experimentally measured axial current density profile. A predictive model should be capable of predicting the measured axial current density profile and the IV curves. The objective of the current work is to develop an electrochemical model based on elementary step charge transfer that occur at the anode and cathode of the HT-PEM fuel cell. In order to develop the mechanistic steps, dissociative adsorption of H2 and O2 is considered. In addition, to account for performance drop in presence of CO, adsorption of CO is also considered in the elementary step reactions. Assuming the protonation reaction to be rate limiting at the anode three phase interface and OH formation to be rate limiting at the cathode three phase interface, Butler-Volmer expressions are derived for the charge transfer reactions at the respective electrodes.The exchange current density at the anode follows i=ioa [exp (βafηa) - exp (-βcfη)], and at the cathode follows i=ioc [exp (-βcfηc) - exp ((1+βa)fηc)].Here, the exchange current densities at the anode and cathode are respectively given by i0a =i*x [(KH2pH2)1/4]/[1+(KCOpCO)+(KH2pH2)1/2)]andioc = i*x [(pH2/p0)1/4 (KO2pO2)3/8]/[1+(KO2pO2)1/2+(pH2/p0) exp (- ΔG*/RT)]. The equilibrium constants appearing the expression for the exchange current densities are evaluated from the adsorption desorption equilibrium of the reactant species (H2, O2, and CO). The adsorption rates are calculated from the sticking coefficients. The activation energy for the desorption reactions is calculated using Unity Bond Index Quadratic Exponential Potential method (UBI-QEP) and the frequency factor for the desorption reactions is calculated from transition state theory. The electrochemical model is incorporated into a quasi-two dimensional numerical transport model of the cell.The transport model accounts for the species transport in the flow channels and diffusive transport across the thickness of the electrode (GDL + CL). The diffusive transport in the porous electrode is modeled using Dusty Gas Model (DGM). The resulting governing equations for the species transport are solved using the ODE solver CVode. The electrochemical model, i.e., the Butler-Volmer equations and the cell voltage equation, forms a set of algebraic equations, which are solved using a damped Newton iteration for every call made by the CVode solver.The whole model is implemented in C++. The model developed can predict the current density and species profiles along the cell length and the thickness of the catalyst layer required to achieve best cell performance. The current density profile predicted by the model along the length is validated by comparing against the experimental measurements reported in the literature. For demonstrating the capability of the model, a comparison between the simulated IV curves and the experimental measurements (Li et. al, 2003 ECS) is given in the Figure. Figure 1

Electrochemical Modeling of HTPEM Fuel Cells Using Elementary Step Kinetics

High temperature PEM fuel cells (HT-PEMFC) offer several advantages over low temperature PEM fuel cells (LT-PEMFC). Numerical modeling is a powerful tool to understand the thermo-chemical and physico-chemical processes that take place within the gas diffusion layer (GDL) and the catalyst layer (CL) during the cell operation. The objective of the current work is to develop an electrochemical model based on the elementary step charge transfer reactions that occur at the anode and cathode of the HT-PEMFC. Elementary step reaction for adsorption of CO is also incorporated to account for performance drop in presence of CO. The electrochemical model is incorporated into a quasi-two dimensional numerical transport model of the cell. The diffusive transport in the porous electrode (GDL + CL) is modeled using Dusty Gas Model (DGM). The resulting governing equations for the species transport are solved using the ODE solver CVode. The whole model is implemented in C++.

Effects of in-stream structures and channel flow rate variation on transient storage

In-stream structures can potentially enhance surface and subsurface solute retention. They form naturally in small streams and their installation has gained popularity in stream restoration for multiple purposes, including improved water quality. Yet few studies have quantified the cumulative effect of multiple structures on solute transport at the reach scale, nor how this varies with changing stream flow. We built a series of weirs in a small stream to simulate channel spanning structures such as natural debris dams and stream restoration log dams and boulder weirs. We conducted constant rate conservative (NaCl) tracer injections to quantify the effect of the weirs on solute transport at the reach scale. We used a one dimensional solute transport model with transient storage to quantify the change of solute transport parameters with increasing number of weirs. Results indicate that adding weirs significantly increased the cross-sectional area of the surface stream (A) and transient storage zones (As) while exchange with transient storage (α) decreased. The increase in A and As is due to backwater behind weirs and increased hydrostatically driven hyporheic exchange induced by the weirs, while we surmise that the reduction in α is due at least in part to reduced hydrodynamically driven hyporheic exchange in bed ripples drowned by the weir backwater. In order for weir installation to achieve net improvement in solute retention and thus water quality, cumulative reactions in weir backwater and enhanced hydrostatically driven hyporheic exchange would have to overcome the reduced hydrodynamically driven exchange. Analysis of channel flow variation over the course of the experiments indicated that weirs change the relationship between transient storage parameters and flow, for example the trend of increasing α with flow without weirs was reversed in the presence of weirs. Effects of flow variation were substantial, indicating that transient storage measurements at a single point in time typically cannot be extrapolated to estimate net annual effects. Thus, rigorous evaluation of water quality effects of stream restoration structures requires measurements at multiple channel flow rates.

Development a numerical model of flow and contaminant transport in layered soils

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

Assessing pollution-related effects of oil spills from ships in the Chinese Bohai Sea

An analysis of the effects of potential oil spills will provide data in support of decisions related to improving the response to oil spills and its emergency management. We selected the Chinese Bohai Sea, especially the Bohai Strait, as our investigation region to provide an assessment of the effects of pollution from ship-related oil spills on adjacent coastal zones. Ship-related accidents are one of the major factors causing potential oil spills in this area. A three dimensional oil transport and transformation model was developed using the Estuary, Coastal, and Ocean Model. This proposed model was run 90 times and each run lasted for 15days to simulate the spread and weathering processes of oil for each of four potential spill sites, which represented potential sites of ship collisions along heavy traffic lanes in the Bohai Sea. Ten neighboring coastal areas were also considered as target zones that potentially could receive pollutants once oil spilled in the study areas. The statistical simulations showed that spills in winter were much worse than those in summer; they resulted in very negative effects on several specific target zones coded Z7, Z8, Z9, and Z10 in this paper. In addition, sites S3 (near the Penglai city) and S4 (near the Yantai city) were the two most at-risk sites with a significantly high probability of pollution if spills occurred nearby during winter. The results thus provided practical guidelines for local oil spill prevention, as well as an emergency preparedness and response program.

A study of solute transport of radiolysis products in crud and its effects on crud growth on PWR fuel pin

This research examines the concentration of radiolysis species (H2, O2, and H2O2) over the porous crud layer using a three dimensional time dependent solute transport model. A Monte Carlo random walk technique is adopted to simulate the transport behavior of the different species with various parametric studies of source term, crud thickness, and crud porosity. Particularly, this model employs a system of coupled mass transport and chemical interactions as the source term, which makes the problem non-linear. It is demonstrated that a negligible effect on radiolysis species concentrations change due to the consideration of source term. The crud thickness and porosity effect on the concentration distributions are notably observed. In general, higher concentration starts from the intersection of the heating surface with the chimney wall from the beginning and it reaches the equilibrium state within tens of seconds. The concentration profiles of the radiolysis species H2, O2, and H2O2 can be directly related to corrosion issues. The direct application of this study to nuclear engineering research is to aid in the design of reactors with higher performance without experiencing an Axial Offset Anomaly (AOA), an unexpected measured shift in axial power distribution from predicted values.

Simulating aerosols over Arabian Peninsula with CHIMERE: Sensitivity to soil, surface parameters and anthropogenic emission inventories

A three dimensional chemistry transport model, CHIMERE, was used to simulate the aerosol optical depths (AOD) over the Arabian Peninsula desert with an offline coupling of Weather Research and Forecasting (WRF) model. The simulations were undertaken with: (i) different horizontal and vertical configurations, (ii) new datasets derived for soil/surface properties, and (iii) EDGAR-HTAP anthropogenic emissions inventories. The model performance evaluations were assessed: (i) qualitatively using MODIS (Moderate-Resolution Imaging Spectroradiometer) deep blue (DB) AOD data for the two local dust events of August 6th and 23rd (2013), and (ii) quantitatively using AERONET (Aerosol Robotic Network) AOD observations, CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) aerosol extinction profiles, and AOD simulations from various forecast models. The model results were observed to be highly sensitive to erodibility and aerodynamic surface roughness length. The use of new datasets on soil erodibility, derived from the MODIS reflectance, and aerodynamic surface roughness length (z0), derived from the ERA-Interim datasets, significantly improved the simulation results. Simulations with the global EDGAR-HTAP anthropogenic emission inventories brought the simulated AOD values closer to the observations. Performance testing of the adapted model for the Arabian Peninsula domain with improved datasets showed good agreement between AERONET AOD measurements and CHIMERE simulations, where the correlation coefficient (R) is 0.6. Higher values of the correlation coefficients and slopes were observed for the dusty periods compared to the non-dusty periods.

Coastal erosion problem, modelling and protection

Goksu Delta, located in the south of Silifke County of Mersin on the coastal plain formed by Goksu River, is one of the Specially Protected Areas in Turkey. Along the coastal area of the Delta, coastline changes at significant rates are observed, concentrating especially at four regions; headland of Incekum, coast of Paradeniz Lagoon, river mouth of Goksu and coast of Altinkum. The coast of Paradeniz Lagoon is suffering significantly from erosion and the consequent coastal retreating problem. Therefore, the narrow barrier beach which separates Paradeniz Lagoon from the Mediterranean Sea is getting narrower, creating a risk of uniting with the sea, thus causing the disappearance of the Lagoon. The aim of this study was to understand the coastal transport processes along the coastal area of Goksu Delta to determine the coastal sediment transport rates, and accordingly, to propose solutions to prevent the loss of coastal lands in the Delta. To this end, field measurements of currents and sediment grain sizes were carried out, and wind climate, wave climate, circulation patterns and longshore sediment transport rates were numerically modeled by HYDROTAM-3D, which is a three dimensional hydrodynamic transport model. Finally, considering its special importance as an environmentally protected region, some coastal structures of gabions were proposed as solutions against the coastal erosion problems of the Delta. The effects of proposed structures on future coastline changes were also modeled, and the coastlines predicted for the year 2017 are presented and discussed in the paper.

Evaluation of hollow fiber-based direct contact and vacuum membrane distillation systems using aspen process simulation

Among four membrane distillation (MD) configurations, direct contact MD (DCMD) and vacuum MD (VMD) exhibit attractive characteristics from different perspectives and have great potential in treating reverse osmosis (RO) brine. Aiming at establishing a quick approach to predict the key output parameters associated with MD module performance and process efficiency, Aspen plus was employed to conduct systematic evaluation for both DCMD and VMD. Due to the lack of built-in MD operation models in Aspen Plus, one dimensional transport models were developed and complied as user customized units to simulate the hollow fiber-based DCMD and VMD modules. The corresponding programming was coded in FORTRAN language. The mathematical models for DCMD and VMD were verified by comparing the simulations results with the experimental and literature data, respectively.By incorporating the boundary-layer effect into the newly-established transport models, steady-state simulations of the respective DCMD and VMD flowsheets were carried out. The results showed that the DCMD presented much lower process efficiency than VMD in terms of permeation flux and specific energy consumption per kg distillate generated, even though it is considered as the simplest and most commonly employed configuration. With the same module specifications and operating conditions at equivalent energy cost, the VMD system demonstrated a minimal 2.5-fold higher average vapor flux (e.g., water recovery capacity) when compared to DCMD. The fundamental difference between the two configurations was revealed through MD mass- and heat-transfer analysis. Based on simulated temperature profiles, it was found that the VMD configuration presented a much higher driving force (transmembrane temperature difference) and negligible conductive heat loss to the membrane, which is a promising feature for achieving high thermal efficiency.

Using Unscented Kalman Filter in Subsurface Contaminant Transport Models

Using a traditional numerical approach in subsurface contaminant transport models generates unavoidable deviation due to unknown or uncertain sources, inaccurate transport and hydraulic parameters, and numeric scheme errors. As a result, stochastic data assimilation or filtering techniques have been employed in the subsurface simulation processes to improve the accuracy of model results. The Kalman Filter (KF) has been widely used for estimation and tracking of linear systems. In the subsurface transport model, even if the system dynamics are linear, it can become a nonlinear one because of the presence of the unknown parameters. The Unscented Kalman Filter (UKF) is one of the data assimilation filters that offer a potential solution to the problem of model development with noisy and incomplete data when the system is nonlinear. The objective of this study was to apply the UKF in subsurface contaminant transport models and to find the contaminant plume. The performance was then evaluated in comparison with the KF and numerical model. A two dimensional transport model with advection and dispersion was used as the deterministic model of a conservative contaminant transport in the subsurface. Random Gaussian noises were added to the numerical method result to simulate the true solution and the observation data. Then the UKF and KF filtering techniques were applied for the data assimilation. An Error Standard Deviation (ESD) of pollutant concentrations was used to examine the effectiveness. The UKF can reduce 6~75% and 2~52% of prediction errors when compared with the numerical and KF results, respectively.

Study of Protein Facilitated Water and Nutrient Transport in Plant Phloem

Biological systems use transporter proteins to create concentration gradients for a variety of purposes. In plant, sucrose transporter proteins play a vital role in driving fluid flow through the phloem by generating chemical potential. In this study, we investigate these nanoscale phenomena of protein directed active transport in a microscale biological system. We presented a mathematical model for protein facilitated sucrose loading considering six different states of the sucrose transporter protein. In addition, we developed a quasi-one dimensional transport model to study protein facilitated pumping mechanisms in plant phloem. Here we specifically study the influence of transporter protein reaction rates, apoplast proton concentration, membrane electrical potential, and cell membrane hydraulic permeability on flow through the phloem. This study reveals that increasing companion cell side deprotonation rate significantly enhances the sieve tube sugar concentrations, which results in much higher water transport. Lower apoplast pH increases the transport rate, but the flow control is less noticeable for a pH less than 5. A more negative membrane electrical potential difference will significantly accelerate the transporter proteins' ability to pump water and nutrients. Higher companion cell and sieve element membrane hydraulic permeability also promotes flows through the phloem; however, the flow difference is less noticeable at higher permeabilities when near typical plant cell membrane ranges.

Uptake of atmospheric hydrogen by soils: a case study from southern Poland

SummaryUptake of atmospheric hydrogen by soils constitutes the most important sink of this gas at the global scale. However, little is known about the strength and spatio‐temporal variability of this sink. We present the results of a systematic study aimed at characterizing hydrogen uptake by urban soils. The study was carried out at two field sites in Krakow, southern Poland. The measured fluxes of hydrogen to soils revealed distinct seasonality, with large values (up to 40 µmol hour−1 m−2) recorded during summer months and small values (between 5 and 10 µmol hour−1 m−2) during winter. Temperatures in the top 6 cm of the soil profile varied during the study from −9 to +24°C, while volumetric soil water content fluctuated between 15 and 50%. Measurable hydrogen fluxes were also observed when soil temperatures were less than zero. The results were interpreted in the context of seasonal changes of local climate and air and soil temperature, soil water content and amount of rainfall. Mixing conditions at the air–soil interface were also considered. Modelling of H2 uptake was performed with a two dimensional diffusion transport model, with contrasting assumptions about distribution and intensity of the hydrogen sink in the soil profile. The model results suggest that conditions in the uppermost soil layer exert a decisive control on measured hydrogen uptake rates. The measured hydrogen flux can be reproduced by the transport model only if significant reduction of the soil water content in the uppermost layer of the soil is postulated. This finding has important implications for the parameterization of hydrogen uptake rates in models of the global H2 budget.

Modeling of Erosion at Göksu Coasts

Numanoğlu Genç, A., İnan, A., Yılmaz, N. and Balas, L., 2013. Modeling of Erosion at Göksu Coasts.Göksu coastal area, located in the south of Silifke County of Mersin on the coastal plain formed by Göksu River, is one of the Specially Protected Areas with an area of almost 15000 hectares and at an altitude of 0–5 m. The Eastern and Western parts of the Göksu river mouth along the Mediterranean coast and the coast of Paradeniz Lagoon are suffering significantly from erosion. As a result of the coastal erosion and the consequent coastal recession problem along the coasts of Göksu, agricultural fields located near the coast are being lost, and especially the narrow barrier beach which separates Paradeniz Lagoon from the sea is getting narrower, creating a risk of uniting with the sea, thus disappearing of the Lagoon. In order to propose solutions for the problem, and to protect the coastal zone and the habitats of Göksu against coastal erosion, coastal dynamic processes and sediment transport characteristics of the region causing the erosion should be investigated and identified. Therefore, longshore sediment transport and suspended sediment transport in Göksu coastal area are examined. First of all, the wind and wave climate of the study area are determined. Then, current pattern, wave propagation, and longshore sediment movements are modeled numerically utilizing three dimensional hydrodynamic transport model HYDROTAM-3D. HYDROTAM-3D is a three (3) dimensional numerical Hydrodynamic and Transportation Model which simulates current patterns due to wind and wave actions, pollutant transport, wave propagation over mild slopes, and longshore sediment transport rates. Model includes hydrodynamics, transport, turbulence, wind and wave climate and wave propagation sub models. HYDROTAM 3D, is developed using “cloud computing” architecture and tightly integrated with Geographic Information System. The study outputs will be used for the determination of the coastal erosion.

Liman Yapılarının Tasarımı İçin Dalga Tahmini

Ports and marinas have a vital importance in sea transportation and boat tourism. In the design of these areas, one of the most important steps is the design of the coastal defence structure which provides the safe berthing of the ships and the boats calling ports and marinas. Wave climate providing information on the wave characteristics that will affect the design of the defence structure is the basic aspect of the design process. Modelling the wave climate is of great importance in reaching on sound coastal defence structure. Like the overall practice in the world, wave prediction studies in Turkey are based on either the data gained out of wave measurements or models. However, as there is no continuous wave measurement data along the Turkish coasts, models of wave climate are preferred in the design process. In this study, the wind and wave climate sub-models of HYDROTAM-3D, a three dimensional hydrodynamic transport model are used and and developed for Turkish coasts, and the results of a case study for Edremit, Balikesir are discussed