scholarly journals Roughness Effect of Submerged Groyne Fields with Varying Length, Groyne Distance, and Groyne Types

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1253 ◽  
Author(s):  
Ronald Möws ◽  
Katinka Koll
Keyword(s):  
Flow Resistance ◽  
Relative Increase ◽  
Design Guidelines ◽  
Water Levels ◽  
Constant Field ◽  
Initial Water ◽  
Mobile Bed ◽  
Wake Interference ◽  
Backwater Effect ◽  
Varying Length

Design guidelines were developed for a number of in-stream structures; however, the knowledge about their morphological and hydraulic function is still incomplete. A variant is submerged groynes, which aim to be applicable for bank protection especially in areas with restricted flood water levels due to their shallow height. Laboratory experiments were conducted to investigate the backwater effect and the flow resistance of submerged groyne fields with varying and constant field length and groyne distance. The effect of the shape of a groyne model was investigated using two types of groynes. The validity of different flow types, from “isolated roughness” to “quasi smooth”, was analyzed in relation to the roughness density of the groyne fields. The results show a higher backwater effect for simplified groynes made of multiplex plates, compared to groynes made of gravel. The relative increase of the upstream water level was lower at high initial water levels, for short length of the groyne field, and for larger distance between the single groynes. The highest roughness of the groyne fields was found at roughness densities, which indicated wake interference flow. Considering a mobile bed, the flow resistance was reduced significantly.

scholarly journals The geometric parameters of plants on the spur dykes in a selected section of the Odra River

2018 ◽  
Vol 45 ◽  
pp. 00110
Author(s):  
Magda Hudak
Keyword(s):  
Water Surface ◽  
Flow Resistance ◽  
Water Levels ◽  
Flow Conditions ◽  
Plant Structure ◽  
Central Section ◽  
Quantitative Characteristics ◽  
Odra River ◽  
The Impact ◽  
Resistance Coefficients

Spur dykes are structures for regulating rivers. They are designed for medium water levels, when spur dyke tops are above the water surface. In the central section of the Odra River the water level is changeable, and the spur dykes work in different hydrological conditions: as non-submerged and submerged. Correct recognition of the plant structure growing on the spur dykes is of great importance in the context of the subsequent allocation of its measure related to the hydraulic action, among others coefficients of resistance of plant zones and refers mainly to grasses. In hydraulic calculations, it is required to determine the value of flow resistance coefficients. In such a departure, the flow is omitted in the area occupied by vegetation. Therefore, it is necessary to know the quantitative characteristics of overgrowth. Vegetation should be presented in the form of a model reflecting the impact of plants growing on the spur dykes and their impact on the water flow conditions in the river. Literature data are not very numerous and are still awake unsatisfied. The paper presents the results of research on the density of vegetation on the Odra River in the Nowa Sól region.

scholarly journals Flow resistance of vegetated oblique weir-like obstacles during high water stages

2014 ◽  
Vol 18 (1) ◽  
pp. 1-14 ◽  
Author(s):  
S. Ali ◽  
W. S. J. Uijttewaal
Keyword(s):  
Flow Resistance ◽  
Research Work ◽  
High Water ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Water Levels ◽  
Sudden Expansion ◽  
Form Drag ◽  
Head Losses ◽  
The One

Abstract. At high water stages, obstacles (submerged and particularly emerged vegetation) in the flood plains of a river contribute to the flow resistance and hamper the conveyance capacity. In particular the elevated vegetated parts are expected to play an important role. The objective of this research work is to determine the form drag due to vegetated oblique weir-like obstacles. Experiments have been performed to measure the energy head losses for a range of subcritical flow conditions, varying discharges and downstream water levels. The energy head loss caused by the submerged vegetated weir-like obstacle has been modeled using an expansion loss form drag model that has been derived from the one-dimensional momentum conservation equation and accounts for the energy loss associated with a deceleration of the flow downstream of a sudden expansion. The results have been compared with the experimental data and showed an overall good agreement.

scholarly journals Proposed Swedish Spillway Design Guidelines Compared with Historical Flood Marks at Lake Siljan

1989 ◽  
Vol 20 (4-5) ◽  
pp. 293-304 ◽  
Author(s):  
Joakim Harlin
Keyword(s):  
Sensitivity Analysis ◽  
Water Level ◽  
Frequency Analysis ◽  
Return Period ◽  
Design Guidelines ◽  
Water Levels ◽  
Spring Flood ◽  
Design Flood ◽  
Design Floods ◽  
Modelling Assumptions

A comparison between the proposed Swedish spillway design floods and historic flood marks made at lake Siljan in central Sweden, is shown. Frequency analysis is performed incorporating pregauge information on water levels together with a sensitivity analysis of modelling assumptions. A water level of 0.42 to 0.75 metres above the highest historic flood mark (166.10 m.a.sl., 1659) was obtained when routing the design spring flood through lake Siljan. The design autumn flood lifted the lake to 1.56 to 1.52 metres below the highest flood mark. Return period for the design spring and autumn flood was estimated to about 1,000 years. The uncertainty in frequency analysis proved to have larger impact than modelling assumptions on estimating the risk of the design flood.

Physical Model Study of Chicago's New Calumet Influent Pumping Station

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
D. Brocard ◽  
M. Garcia ◽  
T. Kunetz ◽  
J. Sobanski ◽  
A. Waratuke ◽  
...  
Keyword(s):  
Physical Model ◽  
Air Entrainment ◽  
Design Guidelines ◽  
Water Levels ◽  
Maintenance Cost ◽  
Optimized Design ◽  
Original Design ◽  
Pumping Station ◽  
Model Study ◽  
Wide Range

A new raw wastewater influent pumping station was designed for the Calumet Water Reclamation Plant in Chicago. The new station could not be designed to be in full compliance with design guidelines of the Hydraulic Institute due to site constraints. Proper operation of the pumping station and optimum operational flexibility are goals for the successful long term performance of the new station. A physical model study was used to identify deficiencies in the original design relative to flow characteristics. The model enabled development of design modifications to address hydraulic flow deficiencies. The optimized design resulted in pump approach flow conditions that provide proper pump performance under a wide range of varying water levels and different combinations of operating pumps and screen channels. Other benefits of the model included improvement in pump efficiency, lack of air entrainment, decreased pump wear, and decreased scour of concrete surfaces. Optimized design also results in operation and maintenance cost savings which, in the long run, will greatly surpass the cost of the physical model study. The required elements to optimize the performance were integrated with the design of the facility, thereby avoiding potentially costly retrofits if the deficiencies had not been mitigated prior to construction.

Sloshing of Fluid Between Rotating Inner Vertical Shaft and Stationary Outer Casing

2021 ◽  
Author(s):  
Koichi Yonezawa ◽  
Kosuke Nishimura ◽  
Takeshi Sano ◽  
Kazuyoshi Miyagawa ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Free Surface ◽  
Theoretical Model ◽  
Angular Velocity ◽  
Rotational Speed ◽  
Water Levels ◽  
Vertical Shaft ◽  
Surface Oscillation ◽  
Rotating Shaft ◽  
Initial Water ◽  
Sloshing Mode

Abstract Unsteady behaviors of free surface around a rotating vertical shaft in cylindrical stationary casing were investigated. Experiments were carried out with various rotating frequency of the shaft at two initial water levels. An axi-symmetrical free surface oscillation took place when the rotational speed of the shaft became larger than a certain value. The frequency of the free surface oscillation decreased as the rotating frequency increased. A theoretical model was developed, and the mechanisms of the free surface oscillation were clarified. The oscillation was found to be a sloshing mode excited by the change of fluid angular velocity, caused by the change of wetted areas on the inner rotating shaft and outer stationary casing, associated with the change in free surface height.

An Experimental Study of Liquid Entrainment by Rapid Surface Swelling of Two-Phase Mixture in a Vessel

2001 ◽  
Author(s):  
Moon-Hyun Chun ◽  
Kyong-Won Seo ◽  
Hyeng-Kuk Kim
Keyword(s):  
Experimental Study ◽  
Water Level ◽  
Air Flow ◽  
Water Levels ◽  
Working Fluid ◽  
Entrainment Rate ◽  
Two Phase ◽  
Initial Water ◽  
Liquid Entrainment ◽  
Phase Mixture

Abstract An experimental study of liquid entrainment by rapid surface swelling of a two-phase mixture in a vessel has been performed. To investigate the effects of air flow rate and initial water level on the liquid entrainment, a series of experiments have been performed using air and water as working fluid. A total of 64 experimental liquid entrainment rate data have been obtained for various combinations of the test parameters (i.e., for six different initial water levels and various air flow rates) using two test vessels that have the same height but different inner diameters (0.15 and 0.3m, respectively) for vertical bubbly and churn-turbulent flow conditions. An empirical correlation for the liquid entrainment rate, E has been developed in terms of the superficial velocity of air, the initial water level, the density of gas, the surface tension, and the gravity. This correlation shows a good agreement with the present experimental data within ±30% over a wide range of flow parameters.

scholarly journals Water Level Prediction of Emergency Groundwater Source and Its Impact on the Surrounding Environment in Nantong City, China

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3529
Author(s):  
Jinbang Cai ◽  
Ping Wang ◽  
Huan Shen ◽  
Yue Su ◽  
Yong Huang
Keyword(s):  
Water Level ◽  
Small Deviation ◽  
Water Levels ◽  
Initial Water ◽  
Surrounding Environment ◽  
Pumping Wells ◽  
Using Data ◽  
Depression Cone ◽  
Groundwater Source ◽  
Short Time

Based on the geological and hydrogeological conditions, and in situ hydrogeological tests of the emergency groundwater source in Nantong City, China, a 3D numerical model of the heterogeneous anisotropy in the study area was established and calibrated using data from pumping and recovery tests. The calibrated model was used to simulate and predict the water level of the depression cone during the emergency pumping and water level recovery. The results showed that after seven days of pumping, the water level in the center of the depression cone ranged from −51 m to −55 m, and compared with the initial water level, the water level dropped by 29 m to 32 m. The calculated water level has a small deviation compared with that of the analytical solution, which indicates the reliability and rationality of the numerical solution. Furthermore, during water level recovery, the water level of pumping wells and its surroundings rose rapidly, which was a difference of about 0.28 m from the initial water level after 30 days, indicating that the groundwater level had recovered to the state before pumping. Due to the emergency pumping time is not long, the water levels of Tonglu Canal, surrounding residential wells, and other aquifers will not be affected. After stopping pumping, the water level recovers quickly, so the change of water level in a short time will not lead to large land subsidence and has little impact on the surrounding environment.

Impact of vegetation on flow in a lowland stream during the growing season

Biologia ◽  
2017 ◽  
Vol 72 (8) ◽  
Author(s):  
Yvetta Velísková ◽  
Renáta Dulovičová ◽  
Radoslav Schügerl
Keyword(s):  
Water Depth ◽  
Flow Resistance ◽  
Aquatic Vegetation ◽  
Growing Season ◽  
Water Levels ◽  
Roughness Coefficient ◽  
Flow Conditions ◽  
Channel Network ◽  
Vegetation Impact ◽  
The Subject

AbstractVegetation growing in the water along watercourses has been the subject of several studies since it was recognized that it could have a significant impact on the water flow. It may increase resistance to flow and cause higher water levels. Also, it has an effect on the velocity profiles. Previous investigations on the flow of water through emergent vegetation have shown different results. The purpose of this paper is to investigate, and determine how aquatic vegetation influences flow resistance, water depth and discharge in the Chotárny channel at the Žitný Ostrov area. This area is part of the Danube Lowland (south-west of Slovakia). The channel network at the Žitný Ostrov region was built up for drainage and also to provide irrigation water. The Chotárny channel is one of three main channels of this network. Measurements performed during six years at this channel were used for an evaluation of vegetation impact on flow conditions. The roughness coefficient was used as one way of quantifying this impact. The results show variation of this parameter during the growing season. Vegetation causes resistance to flow; it reduces flow velocities, discharge and increases water depth.

Evaluation of the impacts of deep open drains on groundwater levels in the wheatbelt of Western Australia

2004 ◽  
Vol 55 (11) ◽  
pp. 1159 ◽  
Author(s):  
Riasat Ali ◽  
Tom Hatton ◽  
Richard George ◽  
John Byrne ◽  
Geoff Hodgson
Keyword(s):  
Western Australia ◽  
Discharge Rate ◽  
Soil Surface ◽  
Extreme Rainfall ◽  
Water Levels ◽  
Extreme Rainfall Event ◽  
Wet Season ◽  
Initial Water ◽  
Groundwater Levels ◽  
The Impact

Abstract. Over one million hectares of the wheatbelt of Western Australia (WA) are affected by secondary salinisation and this area is expected to increase to between 3 and 5 million hectares if current trends continue. Deep open drains, as an engineering solution to dryland salinity, have been promoted over the past few decades; however, the results of initial experiments were variable and no thorough analysis has been done. This research quantifies the effects of deep open drains on shallow and deep groundwater at farm and subcatchment level. Analysis of rainfall data showed that the only dry year (below average rainfall) after the construction of drainage in the Narembeen area of WA (in 1998 and 1999) was 2002. The dry year caused some decline in groundwater levels in the undrained areas but had no significant impact in the drained areas. The study found that the effect of drains on the groundwater levels was particularly significant if the initial water levels were well above the drain bed level, permeable materials were encountered, and drain depth was adequate (2.0–3.0 m). Visual observations and evidence derived from this study area suggested that if the drain depth cut through more permeable, macropore-dominated siliceous and ferruginous hardpans, which exist 1.5–3 m from the soil surface, its efficiency exceeded that predicted by simple drainage theory based on bulk soil texture. The effect of drains often extended to distances away (>200 m) from the drain. Immediately following construction, drains had a high discharge rate until a new hydrologic equilibrium was reached. After equilibrium, flow largely comprised regional groundwater discharge and was supplemented by quick responses driven by rainfall recharge. Comparison between the hydrology of the drained and undrained areas in the Wakeman subcatchment showed that, in the valley floors of the drained areas, the water levels fluctuated mainly between 1.5 and 2.5 m of the soil surface during most of the year. In the valley floors of the undrained areas, they fluctuated between 0 and 1 m of the soil surface. The impact of an extreme rainfall event (or unusual wet season) on drain performance was predicted to vary with distance from the drain. Within 100 m from the drain, water levels declined relatively quickly, whereas it took a year before the water levels at 200–300 m away from the drain responded. The main guidelines that can be recommended based on the results from this study are the drain depth and importance of ferricrete layer. In order to be effective, a drain should be more than 2 m deep and it should cut through the ferricrete layer that exists in many landscapes in the wheatbelt.

Testing slope effect on flow resistance equation for mobile bed rills

2018 ◽  
Vol 32 (5) ◽  
pp. 664-671 ◽  
Author(s):  
Costanza Di Stefano ◽  
Vito Ferro ◽  
Vincenzo Palmeri ◽  
Vincenzo Pampalone
Keyword(s):  
Flow Resistance ◽  
Mobile Bed ◽  
Resistance Equation
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