Verification of Radiocarbon Transport Predicted by Numerical Modeling in the Porous Formation of NE Hungary Considering Paleo-Hydrogeology

Radiocarbon ◽  
2019 ◽  
Vol 62 (1) ◽  
pp. 219-233 ◽  
Author(s):  
Ferenc Székely ◽  
József Deák ◽  
Péter Szűcs ◽  
László Kompár ◽  
Balázs Zákányi ◽  
...  
Keyword(s):  
Steady State ◽  
Groundwater Flow ◽  
Flow Velocity ◽  
Land Surface ◽  
Flow Model ◽  
Radioactive Tracer ◽  
Reduction Factor ◽  
Average Flow Velocity ◽  
Velocity Reduction ◽  
Solute Transport Modeling

ABSTRACTVerification of a groundwater flow model by radiocarbon (14C) data are presented taking into consideration the paleo-hydrogeological changes. Northeastern area of the Great Hungarian Plain was a deep-lying flat area, and its central part (Nyírség) has been uplifted in the last 15,000 years. These geological events have drastically changed the hydrogeological conditions of Nyírség. The groundwater flow system is composed of the Quaternary-Pliocene-Upper Pannonian clastic sediments. Groundwater flow modeling has been performed to define the main lateral and vertical flow directions and velocities controlling the propagation of the environmental radioactive tracer 14C. Solute-transport modeling was used to calculate the 14C activity. The recent steady-state groundwater flow velocity was reduced to a reasonable value characterizing the average flow velocity over the 15 ka simulation period using “trial and error” method. The best fit between the simulated and measured 14C data was achieved by assuming 0.4 flow velocity reduction factor. Results indicate that the present steady-state flow model with this flow velocity reduction factor is capable of reproducing the observed 14C data taking into account the effect of the significant uplift of the part of the land surface in the last 15 ka in NE Hungary.

scholarly journals The Cascade device – In vitro tests to assess coil protrusion into the parent vessel

2020 ◽  
Vol 26 (4) ◽  
pp. 494-500 ◽  
Author(s):  
P Bhogal ◽  
K Wong ◽  
HLD Makalanda
Keyword(s):  
Flow Velocity ◽  
In Vitro Tests ◽  
Parent Vessel ◽  
Single Episode ◽  
Average Flow Velocity ◽  
Velocity Reduction ◽  
Temporary Support ◽  
Aneurysmal Neck ◽  
Aneurysm Model

Background Balloon and stent-assisted coiling of aneurysms have increased the number of aneurysms available for endovascular treatment. Newer devices that allow flow within the parent vessel but coverage at the neck have recently entered the market. The Cascade is a new non-occlusive fully retrievable neck-bridging support device that has been designed to provide temporary support during coil embolisation of intracranial aneurysms. Methods Using a silicone aneurysm model three different aneurysms were catheterised with the coiling microcatheter placed in three different positions within each aneurysm – at the neck, centrally, and looped within the aneurysm. Multiple different coils were then deployed within each aneurysm with the Cascade device deployed across the neck to provide protection. In total 480 attempted coilings were performed. Aneurysm flow was used to calculate the change in intra-aneurysmal flow with the Cascade device deployed across the neck of the aneurysm. Results We did not observe a single episode of coil protrusion through the Cascade mesh nor did we observe any coil protrusion into the parent vessel when the Cascade was deployed across the neck. There was an average flow velocity reduction of 23% with the Cascade device deployed across the neck of the aneurysm. Conclusion The Cascade device offers robust protection of the aneurysmal neck and parent vessel as well as inducing significant intra-aneurysmal flow velocity reduction.

scholarly journals A steady-state groundwater flow model for the Des Moines River alluvial aquifer near Prospect Park, Des Moines, Iowa

2022 ◽  
Author(s):  
Kendall M. FitzGerald ◽  
Wonsook S. Ha ◽  
Adel E. Haj ◽  
Lance R. Gruhn ◽  
Emilia L. Bristow ◽  
...  
Keyword(s):  
Steady State ◽  
Groundwater Flow ◽  
Flow Model ◽  
Alluvial Aquifer ◽  
Groundwater Flow Model ◽  
Des Moines ◽  
Prospect Park

scholarly journals Coupling a groundwater model with a land surface model to improve water and energy cycle simulation

2012 ◽  
Vol 9 (1) ◽  
pp. 1163-1205 ◽  
Author(s):  
W. Tian ◽  
X. Li ◽  
X.-S. Wang ◽  
B. X. Hu
Keyword(s):  
Groundwater Flow ◽  
Land Surface ◽  
Flow Model ◽  
Land Surface Model ◽  
Coupled Model ◽  
Subsurface Water ◽  
Surface Model ◽  
Groundwater Flow Model ◽  
Groundwater Model ◽  
Depth Zone

Abstract. The water and energy cycles interact, making them generally closely related. Land surface models (LSMs) can describe the water and energy cycles of the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs) well describe the dynamic movement of subsurface water flow, but they cannot depict the physical mechanism of the evapotranspiration (ET) process in detail. In this study, a coupled model of groundwater with simple biosphere (GWSiB) is developed based on the full coupling of a typical land surface model (SiB2) and a three-dimensional variably saturated groundwater model (AquiferFlow). In this model, the infiltration, ET and energy transfer are simulated by SiB2 via the soil moisture results given by the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. The developed model is then applied to study water cycle processes in the middle reaches of the Heihe River Basin in the northwest of China. The model is validated through data collected at three stations in the study area. The stations are located in a shallow groundwater depth zone, a deeper groundwater depth zone and an agricultural irrigation area. The study results show that the coupled model can well depict the land surface and groundwater interaction and can more comprehensively and accurately simulate the water and energy cycles compared with uncoupled models.

scholarly journals Coupling a groundwater model with a land surface model to improve water and energy cycle simulation

2012 ◽  
Vol 9 (9) ◽  
pp. 10917-10962 ◽  
Author(s):  
W. Tian ◽  
X. Li ◽  
G.-D. Cheng ◽  
X.-S. Wang ◽  
B. X. Hu
Keyword(s):  
Groundwater Flow ◽  
Land Surface ◽  
Flow Model ◽  
Land Surface Model ◽  
Coupled Model ◽  
Groundwater Depth ◽  
Subsurface Water ◽  
Surface Model ◽  
Groundwater Flow Model ◽  
Groundwater Model

Abstract. Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs) can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs) describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET) process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB) is developed based on the full coupling of a typical land surface model (SiB2) and a three-dimensional variably saturated groundwater model (AquiferFlow). In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reaches of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.

MODELING OXIDATION DITCHES USING THE IA WPRC ACTIVATED SLUDGE MODEL WITH HYDRODYNAMIC EFFECTS

1994 ◽  
Vol 30 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Anastasios I. Stamou
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Flow Velocity ◽  
Dispersion Coefficient ◽  
Aerobic Oxidation ◽  
Model Parameters ◽  
Activated Sludge Model ◽  
Average Flow Velocity ◽  
Oxygen Requirements ◽  
Hydrodynamic Effects

A mathematical model is presented to predict the concentrations of the active heterotrophic biomass, the readily biodegradable substrate (soluble COD) and the dissolved oxygen (DO) in a completely aerobic oxidation ditch. The model involves the one-dimensional convection-dispersion equations for biomass, COD and DO. Hydrodynamic effects are represented in the model by the values of the average flow velocity and the dispersion coefficient. Biological processes are described in the model according to the IA WPRC activated sludge model, using typical values for the model parameters at 10°C. The equations are solved with the finite volume method. The application of the model leads to the following conclusions: (i) Steady state biomass concentrations are almost constant throughout the ditch. (ii) Steady state COD concentrations in the ditch are very low, and COD removal efficiency is practically independent of the values of the flow velocity and the dispersion coefficient. The distribution of the COD concentration in the ditch is less uniform, when small values of the dispersion coefficient are used. (iii) The distribution of the DO concentration in the ditch is very sensitive to the values of the flow velocity, the dispersion coefficient and to the capacity of the rotors. DO concentrations increase when the dispersion coefficient decreases or the flow velocity increases. (v) Daily sludge production, oxygen requirements and sludge age are calculated equal to 0.44 g (g COD removed)‒1, 0.56 g (g incoming COD)‒1 and 6.3 days, respectively.

scholarly journals Coupling a groundwater model with a land surface model to improve water and energy cycle simulation

2012 ◽  
Vol 16 (12) ◽  
pp. 4707-4723 ◽  
Author(s):  
W. Tian ◽  
X. Li ◽  
G.-D. Cheng ◽  
X.-S. Wang ◽  
B. X. Hu
Keyword(s):  
Groundwater Flow ◽  
Land Surface ◽  
Flow Model ◽  
Land Surface Model ◽  
Coupled Model ◽  
Groundwater Depth ◽  
Subsurface Water ◽  
Surface Model ◽  
Groundwater Flow Model ◽  
Groundwater Model

Abstract. Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs) can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs) describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET) process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB) is developed based on the full coupling of a typical land surface model (SiB2) and a 3-D variably saturated groundwater model (AquiferFlow). In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reach of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.

About time lag and some morphometric characteristics of streams of the forest zone

2016 ◽  
Author(s):  
Н.А. Белоногова ◽  
А.Ю. Виноградов ◽  
Т.А. Виноградова ◽  
Д.А. Догановский ◽  
А.Н. Кондратьев ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Average Rate ◽  
Time Lag ◽  
High Water ◽  
Spatial And Temporal Variability ◽  
Forest Zone ◽  
Average Flow Velocity ◽  
Small Watersheds ◽  
Maximum Water ◽  
General Movement

Расчет максимальных расходов воды дождевых паводков на малых водосборах, в целях эффективного проектирования лесохозяйственных инженерных дорожных сооружений, представляет собой весьма сложную задачу вследствие отсутствия достаточных наблюдений за характеристиками дождевого стока. Кроме того, характеристики дождевого стока и определяющие их факторы обладают большой пространственной и временной изменчивостью, что еще больше затрудняет их определение. Рекомендуемая действующими нормативами методика определения максимального дождевого стока, как показывает практический опыт, нуждается в незамедлительном редактировании с точки зрения сопоставления размерностей и правильности ссылок. Особое внимание в статье уделено определению времени добегания, включенного в расчетные формулы в качестве определяющего параметра. В настоящее время понятие «время добегания» однозначно не определено. В связи с тем, что наполненность русел рек имеет высокую пространственную и временную неоднородность и изменчивость, общее движение воды в створе проектируемого инженерного сооружения можно представить достаточно упорядоченным и единообразным, с практически постоянной паводковой средней скоростью. На основе натурных наблюдений известно, что во время паводка средняя по сечению скорость потока сохраняется постоянной в пределах верхней десятипроцентной части амплитуды уровней воды. Такие данные с конца 70-х годов не публикуются. Обработка имеющихся данных говорит о том, что существует незначительное увеличение скоростей течения с ростом площади бассейнов. Поэтому предлагается принять время добегания τi, определенное по характерным отрезкам руслового пути от исследуемого створа до истока с помощью интерполяции измеренных на гидрометрических постах данных по скоростям течения. The calculation of the maximum water flow during the high water, especially on small watersheds, in order to effectively design engineering of road structures, is a very difficult task due to the lack of sufficient observations. In addition, the characteristics of rainfall, and their determinants have a high spatial and temporal variability, which further complicates their definition. Currently recommended method of determining the characteristics of the maximum rainwater, as the experience, needs immediate clarification of dimensions and verify links. Particular attention is paid to the calculation of lag time, included in the formulas as the defining parameter. Fullness riverbeds has high spatial and temporal heterogeneity and variability. The general movement of water in the closing alignment ordered and uniform. The average rate of slightly increased or decreased depending on the dryness of the season. Each cross-section corresponds to the value of average flow velocity. These data are from the late 70-ies are not published. Processing of existing data suggests that there is a slight increase in the flow velocity with increasing basin areas. Therefore, as a constant time lag is invited to take the time determined by the characteristic segments of the channel path from the source to the alignment of the test.

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