3D Hydrodynamic Model Development and Verification

A three-dimensional numerical model was developed to simulate hydrodynamic, temperature, and water quality distributions in rivers and lakes. In an attempt to get rid of the extra approximation and complexity, no coordinate transformation has been done and z-coordinate system has been employed. The governing equations are the continuity equation, free surface equation, momentum equations, and conservation equations of temperature and water quality. The model employs the time splitting technique which allows splitting the directions in which we end with two-dimensional governing equations and eventually the solution ends with a tri-diagonal matrix, which is easily solved by Thomas algorithm. The first step after developing a numerical model and before adding more features or applying the model to a real case, the model should be verified. The verification of the model was done by implementing the model to known solutions test cases in additional to evaluating whether the code preserves fluid mass. A series of test cases is performed by comparing the model results with the analytical solutions as proposed by many modelers. The model showed good agreement between the analytical and the numerical solution

Air Pollution Levels by Re-suspended and Airborne Dust Due to Traffic Movement at the Main High Traffic Crossroads of Hilla City, Iraq

يتضمن هذا البحث عمليه مراقبه وتقييم لمستويات تلوث الهواء الناتج عن الغبار المتصاعد والمحمول بالهواء بسبب حركه المرور في تقاطعات الطرق الأكثر ازدحاما في مدينه ألحله وهي تقاطع نادر وتقاطع ألثوره. إن الغبار المتصاعد هو واحد من أكثر مصادر تلوث الهواء المساهم في التلوث الجوي الكلي وخصوصا عندما تكون الطرق غير مبلطه أو تحت الصيانة وبحمل مروري عالي مثل مايحصل ألان في تقاطع نادر الذي هو تقاطع رئيسي غير مبلط حاليا كونه تحت عمليه صيانة لأقامه مجسر عليه. تم إيجاد تراكير الدقائق العالقة الكلية للموقعين بواسطة جهاز اخذ العينات المحمول خلال ساعة الازدحام المروري وفي جو مشمس ومعتدل ولأربعه شهور( كانون الأول 2011, شباط 2012, نيسان 2012, أيار 2012 ). قد أكدت النتائج مساهمه الطرق غير ألمبلطه في تلوث الهواء. بينت النتائج أن معدل مستويات الدقائق العالقة في تقاطع نادر أعلى من معدلاتها في تقاطع ألثوره طوال فتره الدراسة حيث كان اقل مستوى للدقائق العالقة في تقاطع نادر(5676,67 مايكرو غرام\م3 ) هو أعلى من أعلى مستوى للدقائق العالقة في تقاطع ألثوره (4096,41 مايكرو غرام\م3 ). كما بينت النتائج أن تركيز الغبار المتصاعد ألمقاسه في هذه الدراسة (426.06-9348.95) مايكرو غرام\م3 هي أعلى بكثير من الحدود المسموحه في المواصفات ألقياسيه لوكالة حماية البيئة الامريكيه.This research includes a monitoring and an evaluation of the air pollution levels generated by the re-suspended and airborne dust due to traffic movement at the main busy crossroads of Hilla City, Nader Crossroad and Al-Thowra Crossroad, Iraq. The re-suspended dust is one of the most important contributors towards overall atmospheric pollution, especially when the roads are unpaved or under maintenance with high traffic load such as Nader Crossroad, which was under maintenance to construct a bridge on it. The concentrations of the total suspended particulate matters were determined at the two locations using portable air sampler during traffic rush hour on sunny moderated weekdays for four months, December 2011, February 2012, April 2012, and May 2012. The results have confirmed the contribution of the unpaved roads in air pollution. The results showed that the average TSP levels at Nader Crossroad was higher than the average TSP levels at Al-Thowra Crossroad during the total period of the study in which the minimum TSP level at Nader Crossroad was 5676.67 μg/m3, which was higher than the maximum TSP level at Al-Thowra Crossroad, 4096.41 μg/m3. In addition, the re-suspended dust concentrations that were measured in this study and ranged from 426.06 to 9348.95 μg/m3 are much higher than the American Environmental Protection Agency acceptable limits of national ambient air quality standards for the particulate matter. &nbsp

Bigger tides, less flooding: Effects of dredging on barotropic dynamics in a highly modified estuary.

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124 (2019): 196-211, doi:10.1029/2018JC014313.Since the late nineteenth century, channel depths have more than doubled in parts of New York Harbor and the tidal Hudson River, wetlands have been reclaimed and navigational channels widened, and river flow has been regulated. To quantify the effects of these modifications, observations and numerical simulations using historical and modern bathymetry are used to analyze changes in the barotropic dynamics. Model results and water level records for Albany (1868 to present) and New York Harbor (1844 to present) recovered from archives show that the tidal amplitude has more than doubled near the head of tides, whereas increases in the lower estuary have been slight (<10%). Channel deepening has reduced the effective drag in the upper tidal river, shifting the system from hyposynchronous (tide decaying landward) to hypersynchronous (tide amplifying). Similarly, modeling shows that coastal storm effects propagate farther landward, with a 20% increase in amplitude for a major event. In contrast, the decrease in friction with channel deepening has lowered the tidally averaged water level during discharge events, more than compensating for increased surge amplitude. Combined with river regulation that reduced peak discharges, the overall risk of extreme water levels in the upper tidal river decreased after channel construction, reducing the water level for the 10‐year recurrence interval event by almost 3 m. Mean water level decreased sharply with channel modifications around 1930, and subsequent decadal variability has depended both on river discharge and sea level rise. Channel construction has only slightly altered tidal and storm surge amplitudes in the lower estuary.Funding for D. K. R., W. R. G., and C. K. S. was provided by NSF Coastal SEES awards OCE-1325136 and OCE-1325102. Funding for S.T. and H. Z. was provided by the U.S. Army Corps of Engineers (award W1927 N-14-2-0015), and NSF (Career Award 1455350). Data supporting this study are posted to Zenodo (https://doi.org/10.5281/zenodo.1298636).2019-06-1

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

3D Numerical Temperature Model Development and Calibration for Lakes and Reservoirs: A Case Study

A 3D hydrodynamic and temperature numerical model was developed and calibrated for Lake Chaplain, Washington, USA. The governing equations are the continuity equation, free surface equation, momentum equation, and conservation equation of transport. The model employs the semi-implicit finite difference scheme to solve the governing equations and higher order schemes (QUICK and Quickest) for mass and heat transport in contrast to simpler but more diffusive first order UPWIND scheme. A unique feature of the 3D numerical solution of the model free surface equation is that the solution uses a tri-diagonal matrix form rather than a more common pentadiagonal matrix. The surface heat exchange and turbulence structure were based on the CE-QUAL-W2 model. Comparisons in water surface levels and temperature vertical profiles between model predictions and data were performed using different advective transport schemes. The model matched data with good error statistics

Bigger Tides, Less Flooding: Effects of Dredging on Barotropic Dynamics in a Highly Modified Estuary

Since the late nineteenth century, channel depths have more than doubled in parts of New York Harbor and the tidal Hudson River, wetlands have been reclaimed and navigational channels widened, and river flow has been regulated. To quantify the effects of these modifications, observations and numerical simulations using historical and modern bathymetry are used to analyze changes in the barotropic dynamics. Model results and water level records for Albany (1868 to present) and New York Harbor (1844 to present) recovered from archives show that the tidal amplitude has more than doubled near the head of tides, whereas increases in the lower estuary have been slight

Application GIS Software to Determine the Distribution of T.D.S. Concentrations Along the Tigris River

Tigris River is a major source to supply water for a big part of Iraq. Lately, Iraq has experienced water shortage problems such as variability in climate and the building of huge dams in the upstream countries (Turkey and Iran). In this work, the total dissolved salts (T.D.S.) were measured at fourteen sites on the Tigris River in two periods of the year 2014. The first period consisted of six rainy-months (April–September) and the second period covered non-rainy-months (October-March). Interpolation technique of inverse-distance-weighting (I.D.W.) in ArcGIS was applied to create the prediction maps of the river for (T.D.S.) concentration in both periods. The findings revealed that the (T.D.S.) levels continued to the last site in Al-Qurnah-city (Basrah) from the first site in Fish-Khabur-city (S-1). In the first period, the (T.D.S.) levels at fourteen selected sites were over the levels in the second period. According to World-Health-Organization (2003), the (T.D.S.) concentration on the Tigris River in both periods in 2014 was graded into five classes, then, the prediction maps of the (T.D.S.) classifications were created