scholarly journals Flow Topology in the Confluence of an Open Channel with Lateral Drainage Pipe

Hydrology ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 57
Author(s):  
Mohammad Nazari-Sharabian ◽  
Moses Karakouzian ◽  
Donald Hayes
Keyword(s):  
Water Surface ◽  
Flood Control ◽  
Open Channel ◽  
Surface Elevation ◽  
Control Channel ◽  
Flow Conditions ◽  
Flow Topology ◽  
Water Surface Elevation ◽  
Drainage Pipe ◽  
Lateral Drainage

The purpose of this paper is to develop design guidelines for flood control channel height in the vicinity of the confluence of a submerged drainage pipe and a flood control channel. The water exchange in the confluence of an open channel with a lateral drainage pipe produces unique hydraulic characteristics, ultimately affecting the water surface elevation in the channel. An accurate prediction of the water surface elevation is essential in the successful design of a high-velocity channel. By performing several experiments, and utilizing a numerical model (FLOW-3D), this study investigated the impact of submerged lateral drainage pipe discharges into rectangular open channels on flow topology in the confluence hydrodynamics zone (CHZ). The experiments were conducted in different flume and junction configurations and flow conditions. Moreover, the simulations were performed on actual size channels with different channel, pipe, and junction configurations and flow conditions. The flow topology in the CHZ was found to be highly influenced by the junction angle, as well as the momentum ratios of the channel flow and the pipe flow. The findings of this study were used to develop conservative design curves for channel confluences with lateral drainage pipe inlets. The curves can be used to estimate water surface elevation rise in different channel and pipe configurations with different flow conditions to determine the channel wall heights required to contain flows in the vicinity of laterals.

scholarly journals THE IMPACTS OF PELOSIKA AND AMERORO DAMS IN THE FLOOD CONTROL PERFORMANCE OF KONAWEEHA RIVER

2017 ◽  
Vol 2 (3) ◽  
pp. 215
Author(s):  
Arif Sidik
Keyword(s):  
Return Period ◽  
Water Surface ◽  
Flood Control ◽  
Hydraulic Modeling ◽  
Surface Elevation ◽  
Control Performance ◽  
Design Flood ◽  
Hydrologic Modelling ◽  
Water Surface Elevation ◽  
Maximum Water

Konaweeha watershed is the largest watershed in Southeast Sulawesi with Konaweeha River as the main river. The main issues in Konaweeha Watershed is floods that occur caused damage to infrastructure and public facilities, lowering agricultural production, and cause fatalities. One of the government's efforts to cope with the flooding problem in Konaweeha Watershed is planning the construction of multi-purpose dams in the upstream of Konaweeha Watershed that is Pelosika Dam and Ameroso Dam. Necessary to study the flood control performance of the two dams. Analyses were performed with hydrologic-hydraulic modeling using HEC-HMS software (Hydrologic Modelling System) version 4.0 and HEC-RAS (River Analysis System) version 4.1. The design rainfalls that were used as input to the model were 2 year, 5-year, 10-year and 25 year. Scenarios used in this study are: (1) Existing Scenario (2) Pelosika Dam Scenario; (3) Ameroro Dam Scenario; (4) Pelosika and Ameroro Dams Scenario. The results showed the maximum water surface elevation along the downstream of Konaweeha River in Scenario (2) and (4) were almost the same in the 2 and 5 years return period design flood. However, in case of 10 and 25 years return period, the difference of maximum water surface elevation at downstream of Konaweeha River was slightly significant. Furthermore, the damping efficiency of the peak discharge (at Probably Maximum Flood or PMF) was found to be 71.70% and 18.18% for the individual Pelosika Dam and Ameroro Dam respectively. Further discussion suggests the development of Pelosika Dam as the higher priority rather than that of the Ameroro Dam.

scholarly journals Effects of the bottom slope and guiding wall length on the performance of a vortex drop inlet

2018 ◽  
Vol 78 (6) ◽  
pp. 1287-1295 ◽  
Author(s):  
Dong Sop Rhee ◽  
Yong Sung Park ◽  
Inhwan Park
Keyword(s):  
Water Surface ◽  
Laboratory Experiments ◽  
Surface Elevation ◽  
Design Criteria ◽  
Bottom Slope ◽  
Flow Conditions ◽  
Water Surface Elevation ◽  
Approach Channel ◽  
Maximum Water ◽  
Intake Structure

Abstract Laboratory experiments were conducted to assess the performance of a vortex drop inlet with a spiral intake in subcritical and supercritical flow conditions. The water surface elevation at multiple locations was measured for different flowrates by varying the extent of the guiding wall and the longitudinal and radial bottom slopes. The measurements show that a steeper longitudinal bottom slope decreases the water surface elevation at the beginning of the intake, resulting in a transcritical flow in the intake structure. However, a steeper longitudinal bottom slope also causes the maximum water surface elevation to occur within the spiral intake. For an effective vortex drop inlet design, achieving a low water surface elevation throughout the entire spiral intake structure is required. Experimental results show that the two seemingly conflicting design criteria, namely, achieving a low water surface elevation in the approach channel and reducing the maximum water surface elevation in the intake structure, can be simultaneously achieved by adding a radial bottom slope.

Characterizing water surface elevation under different flow conditions for the upcoming SWOT mission

2018 ◽  
Vol 561 ◽  
pp. 848-861 ◽  
Author(s):  
A. Domeneghetti ◽  
G.J.-P. Schumann ◽  
R.P.M. Frasson ◽  
R. Wei ◽  
T.M. Pavelsky ◽  
...  
Keyword(s):  
Water Surface ◽  
Surface Elevation ◽  
Flow Conditions ◽  
Water Surface Elevation

scholarly journals The FLOod Probability Interpolation Tool (FLOPIT): A Simple Tool to Improve Spatial Flood Probability Quantification and Communication

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 666
Author(s):  
Mahkameh Zarekarizi ◽  
K. Joel Roop-Eckart ◽  
Sanjib Sharma ◽  
Klaus Keller
Keyword(s):  
Flood Risk ◽  
Water Surface ◽  
The United States ◽  
Surface Elevation ◽  
Exceedance Probability ◽  
Water Surface Elevation ◽  
Inundation Maps ◽  
Probability Maps ◽  
Flood Probability ◽  
Floodplain Development

Understanding flood probabilities is essential to making sound decisions about flood-risk management. Many people rely on flood probability maps to inform decisions about purchasing flood insurance, buying or selling real-estate, flood-proofing a house, or managing floodplain development. Current flood probability maps typically use flood zones (for example the 1 in 100 or 1 in 500-year flood zones) to communicate flooding probabilities. However, this choice of communication format can miss important details and lead to biased risk assessments. Here we develop, test, and demonstrate the FLOod Probability Interpolation Tool (FLOPIT). FLOPIT interpolates flood probabilities between water surface elevation to produce continuous flood-probability maps. FLOPIT uses water surface elevation inundation maps for at least two return periods and creates Annual Exceedance Probability (AEP) as well as inundation maps for new return levels. Potential advantages of FLOPIT include being open-source, relatively easy to implement, capable of creating inundation maps from agencies other than FEMA, and applicable to locations where FEMA published flood inundation maps but not flood probability. Using publicly available data from the Federal Emergency Management Agency (FEMA) flood risk databases as well as state and national datasets, we produce continuous flood-probability maps at three example locations in the United States: Houston (TX), Muncy (PA), and Selinsgrove (PA). We find that the discrete flood zones generally communicate substantially lower flood probabilities than the continuous estimates.

Morphodynamic stability and characteristic length scales of bifurcations and confluences loops

2021 ◽  
Author(s):  
Niccolò Ragno ◽  
Marco Redolfi ◽  
Marco Tubino
Keyword(s):  
Froude Number ◽  
Water Surface ◽  
Characteristic Length ◽  
Coupled Model ◽  
Surface Elevation ◽  
Momentum Balance ◽  
Water Surface Elevation ◽  
Control Volumes ◽  
Almost All ◽  
Fluvial Environments

<p>The morphodynamics of multi-thread fluvial environments like braided and anastomosing rivers is fundamentally driven by the continuous concatenation of channel bifurcations and confluences, which govern the distribution of flow and sediment among the different branches that are reconnecting further downstream. Almost all studies performed to date consider the two processes separately, although they frequently appear as closely interconnected. In this work, we tackle the problem of analyzing the coupled morphodynamics of such bifurcation-confluence systems by studying the equilibrium and stability conditions of a channel loop, where flow splits into two secondary anabranches that rejoin after a prescribed distance. Through the formulation of a novel theoretical model for erodible bed confluences based on the momentum balance on two distinct control volumes, we show that the dominating anabranch (i.e. that carrying more water and sediment) is subject to an increase of the water surface elevation that is proportional to the square of the Froude number. This increase in water surface elevation tends to reduce the slope of the dominating branch, which produces a negative feedback that tends to stabilize the bifurcation-confluence system. A linear analysis of the coupled model reveals that the stabilizing effect of the confluence depends on the ratio between the length of the connecting channels and the average water depth, independently of the channel slope and Froude number. Furthermore, the effect of the confluence is potentially able to stabilize the channel loop in conditions where the classic stabilizing mechanism at the bifurcation (i.e. the topographical effect related to the gravitational pull on the sediment transport) is very weak, as expected when most of the sediment is transported in suspension. The identification of a characteristic length scale that produces a coupling between the confluences and bifurcations opens intriguing possibilities for interpreting the self-adjustment of the planform scale of natural multi-thread rivers.</p>

scholarly journals Study on Backwater Effect Due to Polavaram Dam Project under Different Return Periods

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 576 ◽  
Author(s):  
Amarnath C R ◽  
Shashidhar Thatikonda
Keyword(s):  
Unsteady Flow ◽  
Water Surface ◽  
Water Levels ◽  
Surface Elevation ◽  
Flood Frequency Analysis ◽  
Discharge Data ◽  
Gate Operation ◽  
Water Surface Elevation ◽  
Flow Simulations ◽  
Flood Discharge

In this study, we present a scenario to evaluate the backwater impacts on upstream of the Polavaram dam during floods. For this purpose, annual peak discharges across the different gauge stations in river stretch considered for flood frequency analysis. Statistical analysis is carried out for discharge data to estimate probable flood discharge values for 1000 and 10,000 years return period along with 0.1 and 0.14 million m3/s discharge. Furthermore, the resulting flood discharge values are converted to water level forecasts using a steady and unsteady flow hydraulic model, such as HEC-RAS. The water surface elevation at Bhadrachalam river stations with and without dam was estimated for 1000 and 10,000 years discharge. Unsteady 2D flow simulations with and without the dam with full closure and partial closure modes of gate operation were analysed. The results showed that with half of the gates as open and all gates closed, water surface elevation of 62.34 m and 72.34 m was obtained at Bhadrachalam for 1000 and 10,000 years. The 2D unsteady flow simulations revealed that at improper gate operations, even with a flow of 0.1 million m3/s, water levels at Bhadrachalam town will be high enough to submerge built-up areas and nearby villages.

scholarly journals Case Study of Transient Dynamics in a Bypass Reach

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1585
Author(s):  
Anton J. Burman ◽  
Anders G. Andersson ◽  
J. Gunnar I. Hellström ◽  
Kristian Angele
Keyword(s):  
Water Surface ◽  
Operating Conditions ◽  
Surface Elevation ◽  
Water Surface Elevation ◽  
Positive Effects ◽  
Downstream Distance ◽  
Hydropower Plants ◽  
Wetted Area ◽  
Bed Stability

The operating conditions of Nordic hydropower plants are expected to change in the coming years to work more in conjunction with intermittent power production, causing more frequent hydropeaking events. Hydropeaking has been shown to be detrimental to wildlife in the river reaches downstream of hydropower plants. In this work, we investigate how different possible future hydropeaking scenarios affect the water surface elevation dynamics in a bypass reach in the Ume River in northern Sweden. The river dynamics has been modeled using the open-source solver Delft3D. The numerical model was validated and calibrated with water-surface-elevation measurements. A hysteresis effect on the water surface elevation, varying with the downstream distance from the spillways, was seen in both the simulated and the measured data. Increasing the hydropeaking rate is shown to dampen the variation in water surface elevation and wetted area in the most downstream parts of the reach, which could have positive effects on habitat and bed stability compared to slower rates in that region.

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