Showing papers in "Journal of Applied Water Engineering and Research in 2018"

Simulation and control of sediment transport due to dam removal

Abstract: This paper presents two case studies of post-dam removal sedimentation in the United States. Two similar 1D channel evolution simulation models were used: CCHE1D and CONCEPTS. The first case is the model validation and application of CCHE1D to assess morphological response to the Marmot Dam removal in the Sandy River, Oregon. Simulation results showed a persistent erosion of sediments from the reservoir over the 10-year period. To minimize morphological changes downstream of the dam site, the CCHE1D-based optimization model is applied to find the optimal sediment diversion from the dam site. The optimization results show that the optimal diversion rate can significantly reduce the bed elevation changes downstream, which can be used as a guideline for planning best dam decommissioning management. The second case is a CONCEPTS study of the sediment dynamics over a 37-year period after removal of the Plainwell and Otsego City Dams along the Kalamazoo River, Michigan. Removing the dams would increase sediment...

Engineering and enviro-management value of radius of influence estimate from mining excavation

Abstract: In mining operations carried out below the water table, mine area could potentially affect the surrounding. With further deepening of the mine and quarry, the drawdown can impact on water supply wells and base flow. The variation in radius of influence under confined and unconfined aquifer condition is assessed using a hypothetical case study with three operational quarry sites. Average pit-wise radius of influence (R0) for the pit mine, under unconfined and confined aquifer conditions is 963 m and 61 km, respectively, whereas effective radius (Re) for total (cumulative) excavated mine area is 1.7 and 146 km, respectively. It means that the maximum and minimum value of overall impact/influence for the unconfined aquifer lies in-between 963 m and 1.7 km. Similarly that the maximum and minimum value of overall impact/influence for the confined aquifer lies in-between 61 and 146 km. Meanwhile, Re or effective radius for total (cumulative) excavated area seems more appropriate from evaluation viewpoint due to...

River bank stabilisation by bioengineering: potentials for ecological diversity

Abstract: Riverbanks hold a key position on functionality of floodplains as they constitute the gradual transition between aquatic and terrestrial ecosystems. However, due to technical constructions the majority of riverbanks in temperate regions are far from their ecological potential. This results in the loss of valuable habitats and biodiversity. The need for restoration is high but hardly compatible with economic interests. Bioengineering methods could help to increase the ecological potential of river banks. A comparative investigation on bioengineering bank protection techniques was conducted along two watercourses of different characters of navigation and hydrology (Rhine, Weser). We measured the response of four organism groups to different bioengineering methods. Our results indicate an ecological enhancement of riparian zones by re-establishing of valuable floodplain habitats. The number of terrestrial riparian species increased at both rivers. However, habitat quality for aquatic communities remained lim...

Flow field in a reservoir subject to pumped-storage operation – in situ measurement and numerical modeling

Abstract: In pumped-storage reservoirs, turbulent kinetic energy input from plant operation can be considerably high. Flow velocities were measured by Acoustic Doppler Current Profilers near the intake/outlet structure to describe flow patterns induced by pumped-storage operation in an Alpine reservoir. Recorded data allowed reproducing 1D and 2D velocity profiles along the water column. The comparison between the main frequencies of the velocity signal and the discharge series from the plant reveals correlation between recorded flow patterns and pumped-storage operation. Numerical modeling enhanced the understanding of flow patterns developing near the intake/outlet structure. Both results reveal that water withdrawal by pumping only marginally affects flow patterns in front of the intake, whereas water injected during turbine mode leads to backflow areas and large-scale recirculation cells. Numerical modeling further revealed that steady flow patterns are developing only after some 2.5 h of continuous turbine ope...

Pre-impoundment assessment of the limnological processes and eutrophication in a reservoir using three-dimensional modeling: Abolabbas reservoir, Iran

Abstract: Eutrophication in lakes and reservoirs plays a key role in aquatic environments and water quality management by affecting oxygen and nutrient cycles, especially in deep and large impoundments. Prior to reservoir construction, understanding the potential for eutrophication would provide valuable information to water resources planners on the critical factors affecting eutrophication and how reservoir operations might need to be limited or controlled. The pre-impoundment problem, by definition, can only be studied by numerical models, and herein a methodology for applying three-dimensional (3D) hydrodynamic and ecosystem models is proposed. In this paper, the 3D hydrodynamic Estuary, Lake, and Costal Ocean Model is coupled with the Computational Aquatic Ecosystem Dynamic Model to simulate the oxygen and nutrient cycles (eutrophication processes) in a planned deep reservoir in southwest Iran (Abolabbas reservoir). The effects of three scenarios (one normal and two drought conditions) on the reservoir’s eutro...

Validation of large-scale particle image velocimetry to acquire free-surface flow fields in vegetated rivers

Abstract: The reliability of large-scale particle image velocimetry (LSPIV) methodology to measure a 2D surface velocity field in a vegetated lowland stream is evaluated. To this end, measurements of the free-surface flow field obtained with LSPIV are compared with measurements with an electromagnetic current meter (ECM) close to the surface at four different locations. The measurements were performed monthly, allowing the evaluation of the LSPIV measurements in relation to different vegetated conditions. The difference observed between the mean velocities measured with ECM and LSPIV remains low in winter, whereas an increase is observed in summer. Inappropriate particle seeding density and unsteadiness of the flow are the main sources of LSPIV reliability reduction. Nonetheless, the seasonal average frequency of reliable LSPIV measurements is 97%, 95% and 78% in winter, spring and summer, respectively. The results illustrate that LSPIV is an inexpensive methodology, which provides high-resolution and reliable data...

Experimental and computational comparison of baffled-culvert hydrodynamics for fish passage

Abstract: For some applications, fish passage through culverts may be enhanced by adding weir baffles along the culvert invert. In an effort to evaluate the effectiveness of computation techniques as a design tool for baffled-culvert design, turbulent free-surface flow conditions through a weir-baffled-lined culvert were simulated numerically using a three-dimensional numerical model utilizing three different turbulence models: k–, renormalized group k–, and large Eddy simulation. Experimental data from a small prototype-scale baffled-lined culvert, measured using particle image velocimetry, were used to assess the ability of these turbulence models to predict the turbulent flow characteristics for various culvert slopes and discharges. All computer simulations struggled in the regions of high shear and reverse flow, independent of the specific turbulence model used. Comparisons between the measured and computed flow field velocity and turbulent kinetic energy data, however, found that the renormalized group k– mod...

Data-driven stochastic modeling for multi-purpose reservoir simulation

Abstract: This paper presents an integration of data-driven modeling and stochastic models for simulation of reservoir operation. The simulation model developed in this study was applied to the Ruhr river reservoirs system in Germany. An adaptive neuro-fuzzy inference system, Thomas–Fiering model and hidden Markov model were integrated in a simulation model. The set of model input included the time of the year, reservoir storage, inflow and Standardized Precipitation Index; and the target output was the reservoir release. Predicted and observed release values were evaluated using several common evaluation criteria. Results of model performance showed that the proposed model is capable of simulating reservoir operation and provides reliable reservoir release prediction. Results showed also that the proposed approach could be a good tool at the real-time operation stage to quickly check operational alternatives due to emergency events or planning and real-time incongruence.

Hydraulic investigation and design of roof profile of an orifice spillway using experimental and numerical models

Abstract: The roof profile of an orifice spillway plays an important role in deciding its discharging capacity. The necessary requirement is that the profile should not experience excessive negative pressures and should be simple to construct. It is found from the literature that the flow through orifice spillway at the entrance does not follow an elliptical roof profile recommended by United States Bureau of Reclamation. During the regime of flow with high heads, flow separation takes place on the orifice roof profile resulting in reduced discharging capacity. It is also found that there is no specific design method available for design of orifice spillway roof profile with respect to the upstream head as well as other parameters. The main aim of the present study is to develop an equation for design of the roof profile of an orifice spillway. Computational fluid dynamics software FLUENT version 6.3.26 was used for the numerical simulations. The numerical model was verified and validated by comparing the results w...

Hydrological simulation using the SWAT model: the case of Kalamas River catchment

Abstract: The study aims to accurately simulate the hydrological regime of Kalamas River catchment, located at Epirus, NW Greece. To that end, the Soil and Water Assessment Tool was implemented, for the time...

Abrasion prediction at Asahi sediment bypass tunnel based on Ishibashi’s formula

Abstract: Abrasion in a concrete-lined sediment bypass tunnel is estimated using a Japanese state-of-the-art prediction model and validated by measured invert abrasion data at Asahi Reservoir, Japan. The model is described in detail, certain shortcomings are disclosed, and a revised version is proposed. The model consists of a kinetic energy term accounting for the impact by saltating particles, and a friction work term accounting for the grinding stress. It is found that the latter term yields concrete abrasion values being consistently a multiple compared to its kinetic term contradicting other research. Based on that, and a possible particle impact angle inconsistency, it is proposed to omit the friction work term. It is shown that the calculated abrasion is overestimated by 138% on average compared with that measured, if both terms are accounted for. However, promising results are obtained with only 30% overestimation by neglecting the friction work term.

Reynolds stress modelling of flow in compound channels with vegetated floodplains

Abstract: Flow in compound channel with vegetated floodplain is complex and efficient modelling should include the effects of vegetation on velocity, secondary flow and shear stress. In the present study, the Volume-averaged Reynolds-averaged Navier–Stokes equations, in conjunction with a Reynolds Stress turbulence model, are solved numerically for a non-symmetrical compound channel of a trapezoidal main channel and a vegetated floodplain. The numerical results agree well with available experimental data, while the model is capable to reproduce the evolution of vortices. The cross-sectional flow characteristics reveal the momentum exchange mechanism between main channel and floodplain due to increased shear stresses and turbulence anisotropy near the vegetation interface. Also, the recently improved analytical Shiono and Knight method [1991. Turbulent open-channel flows with variable depth across the channel. J Fluid Mech. 222:617–646] is applied for the determination of the depth-averaged velocity and shear stress...

Impacts of climate change on the water quality of the Elbe Estuary (Germany)

Abstract: To simulate and quantify the impacts of climate change on phytoplankton dynamics and oxygen budget, a model-based approach is chosen. The 1D hydraulic model HYDRAX is coupled to the water quality model QSim (Quality Simulation). The coupled models are applied to the German section of the Elbe River and its estuary. A long-term run (1998–2010) has been performed to represent the phytoplankton dynamics and the oxygen concentrations for the reference state. The impacts of altered river discharge and air temperature on the water quality have been calculated by a model-based sensitivity analysis. A range of feasible projections of river discharge and air temperature for near (years 2021–2050) and far future (years 2071–2100) has been related to the results of the sensitivity analysis. A decrease in river discharge enhances oxygen deficits in the Elbe Estuary, while an increase in air temperature has a less pronounced and partly reverse effect.

Impact of rubber plantation age on erosive potential studied with USLE model

Abstract: Rubber (Hevea brasiliensis) plantations have a lifespan in the range of 25–40 years. We aimed at assessing soil losses in rubber plantations of different ages (4, 12, 18, 25 and 36 years old) and r...

Application of HEC-ResSim® in the study of new water sources in the Panama Canal

Abstract: This paper presents an evaluation of different projects for new water sources in the Panama Canal using the HEC-ResSim® program for simulating the reservoir systems. The HEC-ResSim® models of the reservoir systems were used to evaluate the discharges in spillways during the rainy months, hydroelectric generation at Gatun and Alhajuela Lakes, volumes available for navigation, municipal and industrial consumption at Gatun Lake and volumes supplied at Alhajuela Lake for municipal and industrial use. For each project analyzed, additional equivalent lockages were determined that could deliver 99.6% water reliability or 97.5% draft reliability. The results were validated using the storage–yield relationships of the reservoir systems. The storage–yield curves of the analyzed systems are highly similar to the storage–yield curve of White River [Vogel RM, Lane M, Ravindiran RS, Kirshen P. (1999). Storage reservoir behaviour in the United States. J Water Resour Plann Manag. 125:245–254], which was obtained to deliv...

German guidelines for designing alternative bank protection measures

Abstract: Prompted by the European Water Framework Directive, more environmental friendly bank protection measures will be demanded both for small waters and for inland waterways. These measures should conta...

Risk-based analysis of a detention basin for urban runoff control

Abstract: Various uncertainties exist in detention basin design which contribute to the potential failure or unsatisfactory performance of the system. Risk-based analysis provides a systematic framework to e...

Concept of the Integrated Hydrological Ensemble Prediction System applied for the Nattai River Catchment, Australia

Abstract: Reservoir inflow predictions are essential to ensure effective operations of Sydney’s main drinking water reservoir. The reservoir’s forecast system is based on empirical rainfall forecast scenario...

Modifying the downstream hydrograph with staged labyrinth weirs

Abstract: Labyrinth and piano key weirs are hydraulically more efficient than linear weirs of common width. As the spillway discharge efficiency increases, the required reservoir detention volume reserved for flood routing reduces and the maximum base-flow operating reservoir pool elevation can subsequently be increased (additional water storage) without a reduction in dam safety. Increased spillway discharge efficiency also causes the reservoir outflow hydrograph to compress temporally and increases the peak outflow discharge, potentially increasing downstream flooding impacts. The influence of linear, labyrinth, and staged labyrinth weir (i.e. cycles with different crest elevations) head-discharge characteristics on the outflow hydrograph behavior were evaluated by numerically routing various flood discharges through a reservoir; peak outflow discharges, the maximum water surface elevation, and the required detention volumes were quantified for each weir alternative. In addition to the benefit of isolating base f...

More bed load in rivers. Achieving a sediment balance close to the natural state

Abstract: A revised Water Protection Act has been in force in Switzerland since 2011. The act states that rivers are to be restored and that negative effects on the ecosystem, caused by installations such as...

Status, sources, and composition of fine sediments in Upper Austrian streams

Abstract: High loads of fine sediments are considered one of the most important causes of river ecosystem degradation worldwide. Especially in intensively used catchment areas changes in the sediment regime ...

Flow duration curve regionalization with enhanced selection of donor basins

Abstract: A non-parametric regionalization procedure for the assessment of flow duration curve (FDC) at ungauged basins is presented. This modeling approach is fundamentally based on the quantification of di...

Coupling flow with nutrient dynamics via BioChemFOAM in the Mississippi River

Abstract: An enhanced three-dimensional unsteady hydrodynamic, multispecies transport fate model called BioChemFOAM was developed in OpenFOAM-free computational fluid dynamic platform for understanding and predicting nutrient dynamics, namely, transport and transformation, in aquatic ecosystems. The study motivation was to better quantify transport and distribution of nutrient species in the Upper Mississippi River Basin (UMRB), a major source of nutrient contributor from intense agriculture. The study is unique in examining the transport and reactivity rates under complex hydrologic conditions where main conveyance channels and backwaters co-exist. The model has two main components: a new coupling of turbulent flow processes with multiple species to modulate transport and reaction rates simulations at channel/backwater areas and a complex chemical and biological transformation module suited for species reaction rates in backwaters. The coupled model was first tested for an idealistic domain/case borrowed from the ...

Large-eddy simulations of a sediment plume released by a dredger using overflow

Abstract: Sediment plume predictions are part of the assessment of environmental impacts of dredging. The main source of turbidity while employing Trailer Suction Hopper Dredgers is the release of excess water through the overflow shaft. The near-field plume dynamics below and directly behind the sailing hopper dredgers are traditionally unknown during predictions of far-field plume dispersion. Indeed, an accurate input of the vertical and horizontal distributions of sediment at the source location is important to obtain reliable results at environmentally sensitive areas further away. In this paper, a computational fluid dynamics model is presented as a tool to determine the three-dimensional flows of water, sediment and air bubbles directly after release from the overflow shaft. The full dredger hull geometry and an actuator disc accounting for propeller action are included. It is shown that the model can reproduce two different cases of overflow plumes measured in the field with fair accuracy.

Numerical simulation of laminar water hammer flow in a pipe with varying cross-section

Abstract: Numerical simulation of water hammer effect in a pipe with varying cross-section is presented for an initial laminar flow by solving Navier–Stokes equations in time, using Ansys Fluent software. Results for pressure variation with time are compared to available literature to validate the numerical method. The pressure signal is presented at various locations in the pipe and compared with existing studies qualitatively. Pressure and velocity profiles are shown at various times during the pressure wave along the length of the domain, which indicates fluctuation of these variables as the wave passes through the changing geometry. Attenuation of the pressure amplitude was found to be slower in the current geometry compared with experimental results from the literature due to a more gradual change in cross-sectional area. The pressure wave generated by valve closure and its interaction with the geometry is discussed in detail and comparisons are made with existing literature.

Evaluation of the PG method for modeling unsteady flows in complex bathymetries

Abstract: The performance graph (PG) hydraulic routing method has been shown to be accurate, numerically efficient, and robust for unsteady flow routing. However, up to present, the PGs are constructed using one-dimensional (1D) steady flow models only, which are often questioned when simulating flows through complex bathymetries. This paper investigates whether the PG method can still be used when utilizing two-dimensional (2D) models for the construction of PGs. The test case is a stretch around an island in the Fraser River in British Columbia. The results show that the PG method is still applicable when utilizing a 2D steady flow model. The results also show that once the PGs are constructed, the PG routing method (1D and 2D) is computationally more efficient than the unsteady HEC-RAS model and can be several orders of magnitude faster than TELEMAC-2D.

Application of multidisciplinary water resources planning tools for two of the largest rivers of Iran

Abstract: Two tailor-made spatial decision support systems (SDSSs) were developed for integrated water resources planning in the biggest basins of Iran named Karun and Karkheh. The decision support systems have many modules for simulating and screening scenarios in the planning stage. A spatial multi-criteria decision-making model was also developed to screen the scenarios. Planning scenarios were mainly defined for under-study hydropower projects including run-of-river and storage schemes. The results show that the run-of-river scheme in Karun and the storage scheme in Karkheh are the best scenarios. The optimization module was used in determining the height of dams and capacity of hydropower plants and water convey systems. Install capacity of Karkheh runoff HPP changed from 255 to 271 MW by using an optimization module. Integrated water resources planning results showed that total active volume of reservoirs would increase from 6595 to 8056 mcm (18%) in Karekheh when comparing individual studies.

The Kinetic Energy method revisited

Abstract: The Kinetic Energy method has been adopted by several standards and guidelines. While, on the one hand, this approach is to some extent subject to the subjective judgement of the designer, on the o...