Bruce W. Melville

• University of Auckland

Digital twins are transforming the paradigm of water management and water hazard mitigation globally, facilitating more effective governance. However, comprehensive digitalisation at the basin scale still faces major challenges in data, modelling, policy incentives, and, most critically, widespread inequity. This article outlines a framework for bu...

Cyclic lateral vibrations on monopile foundations of offshore wind turbines throughout their service life may affect the local scour around the foundations. While previous studies have explored local scour around vibrating monopile foundations under current-only conditions, the local scour characteristics around these foundations under combined wav...

The investigation of the critical bed shear stress at the bed surface with negative slopes in the scour hole downstream of a submerged structure has primarily relied on experimental methods with limited theoretical exploration. This paper examined the distribution of near-bed flow velocity and turbulence intensity at theequilibrium stage based on p...

This paper applied the fuzzy function approach, combined with the ridge regression model, to produce daily rainfall projections from large-scale climate variables. This study developed a statistical downscaling model based on principal components, c-means fuzzy clustering, Volterra series, and ridge regression. The model is known, hereafter as SDC2...

Flooding water in extreme hydrometeorological events may be significantly contracted by bridge abutments and superstructures, leading to severe sediment scour and threatening structure stability. A series of large-scale laboratory experiments assessing flood-induced scour processes near bridge abutments are presented, with particular attention paid...

Cyclic lateral loads on monopile foundations of offshore wind turbines induce vibrations that affect the clear-water scour process around the foundations. Previous experimental studies showed that the current-induced equilibrium scour depths at vibrating monopiles may be less than those at static monopile foundations. However, this observation may...

Existing methods for estimating critical bed shear stress are limited and usually do not consider local scour processes; therefore, the accuracy of numerical modeling is usually compromised. This paper presents the results of physical experiments on scour downstream of low-head weirs and proposes new equations for estimating the critical bed shear...

Bed solidification methods are widely employed for mitigating local scour. This study primarily examines the geometric aspects that influence bed solidification protections, including protection thickness, angle, lateral extent, and placement depth. Scour topography and longitudinal scour profile across various test conditions have also been discus...

Monopile foundations have been widely used to support offshore wind turbines in shallow waters. Current-induced local scour at monopile foundations, as a universal problem threatening the structure safety and the operational efficiency of the turbines, has been extensively studied in recent decades by flume experiments and numerical models. Recent...

Atmospheric rivers (ARs) are an important component of the global water cycle, and AR-related hydrological hazards are across the midlatitudes, including New Zealand. The ability to classify the strength and potential impact of ARs has shown benefits to water resource management in western U.S. regions. In New Zealand, the topography means that the...

Monopile foundations of offshore wind turbines undergo continuous vibrations due to the cyclic lateral loads induced by waves and winds. To focus on the dynamics of sand behavior around vibrating foundations, researchers often conduct two-dimensional experiments using flat plates as representations of monopile foundations. This approach enables con...

Atmospheric rivers (ARs) are elongated channels of enhanced water vapour transport in midlatitudes and contribute significantly to annual rainfall in northern and western New Zealand. Based on data from 529 rain gauge sites and detected landfalling ARs over New Zealand from 1950 to 2020, this study indicates that the presence of ARs generally leads...

When estimating design local scour depths at structures where the design flows have short durations, equilibrium scour depths can be too conservative. Attempts to develop methods to accurately estimate scour rates and times to reach near equilibrium scour depths have only been moderately successful. The objective of the work reported here was to de...

Rock weirs are low-head river restoration structures. The present study comprised two sets of flume tests (i.e. fixed bed and moveable sand bed tests) to investigate the rock dislodgement process, which is a primary cause of the failure of rock weirs. The impacts of approach flow intensity, submergence, void ratio and scour of bed sediment on rock...

Migrating bedforms in alluvial rivers can exacerbate scour damage instream structures, leading to severe structure failures, which can cause large-scale and long-term issues with fluvial morphology and environment. This study investigates the interaction between scour fluctuation at instream structures and bedform migration based on large datasets...

This study aims to optimize the Yeywa Hydropower Reservoir (YHR) operation using the multi-step-ahead time-varying hedging (TVH) rule under climate change (CC) and land-use change (LUC) to improve summer power generation. Three multi-objective algorithms: the Multi-objective Salp Swarm Algorithm (MOSSA), the Multi-objective Antlion Optimizer (MOALO...

An instrumented smart sediment particle (SSP) is used to investigate the entrainment of coarse grains. The SSP contains electronic sensors facilitating the direct measurement of tri-axial accelerations. The instantaneous flow field is measured simultaneously using two-dimensional particle tracking velocimetry (PTV). Two different initial positions...

Channel degradation can expose river-crossing cylindrical structures (e.g., pipelines, canals, and tunnels) that are completely buried in the riverbed, altering their surrounding flow patterns to cause scour that threatens their structural safety. This paper reports a case study of scour at a river-crossing canal in a degrading river. Based on the...

Impacts of the global climate change in hydrology and water resources are accessed by downscaling of local daily rainfall from large-scale climate variables. This study developed a statistical downscaling model based on the Volterra series, principal components and ridge regression. This model is known, hereafter as SDCRR. The proposed model is app...

Pressure sewer networks offer a flexible alternative to more traditional gravity-based systems for the conveyance of wastewater. Some of the issues associated with pressure sewer networks (e.g., odor, septicity) arise from inappropriate design assumptions. Daily inflow volumes are a crucial part of the design of pressure sewer systems; gravity desi...

Statement of Removal The initial Accepted Manuscript Online (AMO) version of this article, as detailed below, was identified to have significant proofing errors after acceptance and therefore has been removed. The revised article can be found here: 10.1080/02626667.2023.2196427 Article title: Optimal reservoir operation using the improved multi-ste...

Laboratory experiments were performed to study the impact of relative particle protrusion P/D (P is the protrusion height and D is the diameter of the spherical target particle) on the entrainment of sediment particles from a rough bed of spherical grains. The target particle to be entrained was instrumented with electronic sensors, that measure th...

The Smart Sediment Particle (SSP) instrumented with multiple sensors to obtain tri-axial linear accelerations is used for studying the mechanism of coarse grain entrainment. Three bed arrangements are tested to examine their influences on entrainment processes and the threshold force and impulse conditions. The SSP shows satisfactory precision to c...

Sediment flux in rivers has dropped globally in the past decades due to the increasing anthropogenic stressors, leading to significant riverbed degradation that may endanger the instream structures, collapse the banks and affect the riverine environment. To stabilise riverbeds, grade control structures (GCSs) have been widely applied in degrading c...

Accurate estimation of local scour depths at piers is important since underestimation can result in structural failure and possibly loss of lives and overestimation the needless waste of structure cost, which can be significant for large structures. An improved mathematical model for estimating equilibrium structure-induced (local) sediment scour d...

This paper presents an investigation of near-bed hydrodynamics for a protruding coarse particle over a regular roughened bed. The laboratory experiments were undertaken at the threshold flow condition, which induced dislodgement of the protruding particle. Using different protrusion heights, the experimental results show that the protruding particl...

Backfilling, as a common remedial countermeasure, is widely used in ocean engineering to address the scour or subsidence problem around offshore-structure foundations. However, the performance of the backfilling in solving subsidence problems around vibrating monopiles has not been studied, and the mixing mechanisms of the backfilling sand with the...

Hydrodynamic forces, especially uplift forces, during a flood event are critical to the stability of bridge superstructures. This study focuses on the interaction between the migrating dunes, the scour depth beneath the deck, and the uplift force that fluctuates during bedform migration. Experimental results show that the fluctuation of uplift forc...

Previous studies have primarily focused on the estimation of equilibrium scour depths around weirs, while overlooking the details of the temporal evolution of the live bed scour process of submerged weirs at the equilibrium stage. This study aims to investigate the relationships between fluctuating frequencies of the approaching bedforms and live b...

Bridge abutment-induced sediment scour in compound river channels is time-sensitive during floods, and, thus, estimating the scour rate has significance in design. In the current study, large-scale laboratory experiments were done to examine the influence of multiple factors on scour evolution, including channel geometry, bed mobility (clear-water...

This study introduced a new riprap placement design for the purpose of reducing bridge pier scour. The design consisted of embedding a layer of the riprap around the pier, flush with the surrounding bed, with a depression to help guide the horseshoe vortex. The new countermeasure design was tested among other conventional riprap placement designs i...

Most tsunamis are triggered by seismic events, involving an underwater earthquake with a sharp vertical displacement of the seafloor. Generally, seabed deformations are not unipolar, but instead bipolar or even more complex. To model tsunamis generated by segmented seafloor deformations, an analytical model and a numerical model including source ki...

This paper aims to improve summer power generation of the Yeywa Hydropower Reservoir in Myanmar using the modified multi-step ahead time-varying hedging (TVH) rule as a case study. The results of the TVH rules were compared with the standard operation policy (SOP) rule, the binary standard operation policy (BSOP) rule, the discrete hedging (DH) rul...

To elucidate the tsunami-wharf interaction (e.g., flow field and pressure distribution), a numerical study was carried out to simulate a wharf subjected to a tsunami bore. A dam-break-like tsunami bore was simulated by modeling a gate-reservoir system. Five sections (reservoir, wet-bed, transitional, dry-bed and wharf model sections) were establish...

Many bridges that lie within possible tsunami inundation zones are critical links in transport networks. Some efforts have been made to determine the effects of tsunamis on bridges, but only a limited range of published design guidelines are available. Therefore, it is necessary to further investigate the effects of tsunamis on bridges. In the curr...

The effects of inlet configurations in sediment retention ponds (SRPs) have been widely investigated by several researchers. However, when considering temperature differentials in the ponds where density and buoyancy change with temperature the challenges associated with the proper inlet design still exist. The buoyancy forces are generated due to...

River mouths are often highly dynamic environments, fluctuating in location and depth with riverine and coastal processes. Where river training structures restrict the river to a fixed location, these structures must be protected against the effects of scour occurring within the main channel. One possible toe protection method is to construct a "fa...

Plain Language Summary When volcanoes erupt underwater, they can generate waves that are dangerous even at coastlines far away from the eruption itself. In this study, we investigated whether the wave heights changed when the underwater eruption lasted a different amount of time. Our experiments modeled an underwater eruption by releasing compresse...

Local scour is an important design factor for submerged weirs. This study conducted a clear-water scour experiment at a submerged weir, using the particle tracking velocimetry technique to measure the flow field in the developing scour hole. The mean flow patterns, turbulence intensities and near-bed Reynolds shear stresses in the scour hole at dif...

Local scour at pile-supported bridge foundations in coastal and offshore areas are an essential factor to engineering design and evaluation. This study experimentally investigates live-bed local scour at complex bridge piers under the influence of bed-form migration. The results show that the variation of the mean scour depth as a function of flow...

Statistical and dynamic downscaling approaches are commonly used to downscale large-scale climatic variables from global circulation (GCM) and regional circulation (RCM) model outputs to local precipitation. The performance of these two approaches may differ from each other for daily precipitation projections when applied in the same region. This i...

Erosion of sediments is of crucial significance to morphologic evolution, management of water quality and aquatic ecosystems. However, the prediction of the pickup rate of non-cohesive sediments is a challenging topic because of the complex interaction between the bed and the flow. This study reports the experimental results of the pickup rate of n...

Tsunamis in Indonesia (2004) and Japan (2011) severely affected communities bordering the Indian Ocean and Japan's east coast. Despite the plausible findings arising from the available studies, the research on the impact of tsunami bore forces applied to bridges of different designs is limited. This is because the estimation methods for tsunami-ind...

Fluvial morphology in compound river channels usually undergoes drastic variation during extreme floods due to scour and erosion processes. Those processes can be highly dynamic consisting of multiple elements (e.g. bed-form migration, bank erosion, riprap break-down, etc) that are inter-dependent. The existence of bridge abutments and embankments...

Since tsunamis pose a threat to many coastal areas, the mitigation of tsunami forces is important in saving lives and reducing damage when a tsunami comes. Barriers are generally constructed to protect coasts from extreme waves including tsunamis. Although extensive research has been conducted to investigate tsunami forces on coastal structures, th...

This study investigates the flood flow characteristics in a compound channel subject to both lateral contraction (caused by bridge abutment/embankment) and vertical contraction (caused by bridge deck submergence) at bridge sites. Three abutment setback distances and three pressure flow types (free surface (FS), submerged orifice (SO) and overtoppin...

Scour at bridge abutments usually consists of local and contraction scour that correlate because of the flow field that develops both scours. Flume experiments were conducted using simulated compound channels to investigate the effect of a setback vertical-wall abutment’s streamwise contraction length on the scour depth and pattern. The adequacy of...

Watershed hydrology changes are mostly influenced by changes in climate and land use and understanding of the interaction between these changes is required for the sustainable water management of water resources. In this study, an integrated approach of land-use modelling, downscaling climate data, and river flow simulation is carried out to detect...

This paper presents an experimental study on scour at complex bridge piers exposed to combined waves and current. Regular waves were produced with various strength and superimposed on co-directional current with constant velocity. The key parameters tested and discussed include Keulegan-Carpenter () number, relative current strength , pile-cap elev...

Breakwaters are effective structures for mitigating tsunami-induced damage. However, pieces of the breakwater can be displaced by the turbulent tsunami flow, which undermines the stability of the breakwater and reduces its mitigation effectiveness. Assessing the damage to breakwaters in tsunami-prone coasts is, therefore, valuable for the port auth...

Equilibrium clear-water scour depths predicted by existing equations based on the peak flow rate of a flood hydrograph can be overly conservative for submerged weirs in mild-slope sandy rivers, because the equilibrium timescale normally is much larger than the timescale of a flood event. Therefore it is important to understand the clear-water scour...

This paper describes the laboratory experimental investigations undertaken to analyse the influence of floating treatment wetlands (FTWs) on the hydraulic performance of a stormwater retention pond. Two experimental series were conducted, each focussed on investigating the influence of placing an FTW in a pond with firstly the inflow entering the r...

Scour at bridge piers is time-dependent. In this paper, temporal evolution of clear-water scour at complex bridge piers is studied experimentally. The pier model has a typical form comprising three components, viz. a rectangular column, a rectangular pile-cap, and a group of vertical piles underneath. Various relative pile-cap positions and skew an...

New laboratory data of local scour at submerged weirs are presented. The dimensionless scour depth downstream of a submerged weir in a uniform sediment bed is expressed as a function of dimensionless weir height, flow intensity, sediment coarseness, and weir slope. The existing and newly presented data are combined to evaluate the dependencies of d...

The Ngongotaha Stream was used as a case study to assess the applicability of fibre optic distributed temperature sensing (FODTS) to identify the location of springs and quantify their discharge.Thirteen springs were identified, mostly located within a 115 m reach, five discharged from the right bank and eight from the left bank. To quantify ground...

In this study, we investigated the characteristics of scour at complex bridge piers in close proximity. The experiments were performed under both clear-water and live-bed flow regimes. We compare our results with those for a single complex pier. Further, the performance of existing predictors is discussed. In this study, four typical pier arrangeme...

An investigation of the characteristics of live-bed scour at circular and skewed rectangular (slab) piers in comparatively shallow flows is presented. The 110 experiments were undertaken in a 2.4-m flume using two circular piers and a slab (long) pier. Based on flow shallowness, that is, the ratio of approaching flow depth (y0) to pier diameter (D)...

Book Review - Experimental Hydraulics: Methods, Instrumentation, Data Processing and Management. Marian Muste (Editor in Chief). IAHR Monographs, two volumes, CRC Press, 2017. 906 pp. ISBN: 9781138027534. £190.00. - Volume 855 - Hubert Chanson, Bruce Melville, Hang Wang, Xinqian Leng, Colin Whittaker

Monopile foundations are the most common foundation type of offshore wind turbines. In the ocean environment, in addition to threats related to scour of the foundation, offshore monopiles of wind turbines also are subjected to lateral vibrations induced by waves and winds. Over the past decades, the scour process induced by flow and pile-soil inter...

Scour at bridge pier under live-bed regime represents the existence of sediment motion on the bed both upstream and downstream of the pier. The bed mobility leads to the formation of bed-forms, thereby bringing fluctuations to the scour depth at the pier due to the passing bed-forms entering and leaving the scour hole. Because of the difficulties o...

Research on erosion behavior of sediments usually treats sand and mud separately. However, natural soil often occurs as a sand- mud mixture. An expression for cohesive forces in sand-mud mixtures, which considers the effect of the sand component on the mud component, is first proposed. Then the balance of forces under the initial motion condition i...

This study used a new approach in data integration to fully evaluate water consumption across different housing types, income groups and seasons in Auckland, New Zealand. Using urban GIS-based databases, we developed a sample of 60,000 dwellings through integration of water consumption, land use and census microdata. We find that household size is...

This paper aims at deriving velocity potential for the regular wave passing through a concentric porous cylinder system, which has an arbitrary smooth section. The wave interaction with the structures, for instance wave force on them and wave elevation, are discussed with different sections and wave properties in this study. The efficiency and accu...

Existing studies on sediment retention ponds (SRPs) have examined the effects of pond layout, inlet and outlet geometry and the installation of baffles on the performance of the SRPs. However, the effects of a temperature difference between the ambient water in the pond and the inflow are often neglected, and the buoyancy forces arising from these...

An experimental study on flow-induced clear-water local scour at complex bridge piers was conducted using two typical pier models, nine pile-cap elevations, and seven pier skew angles from 0° to 90° with a 15° interval. Results show that a slight skew angle α imposed on an originally aligned pier can significantly increase the equilibrium scour dep...

This paper presents an experimental study of local scour at submerged weirs with different downstream slopes. Thirty-three tests of coarse sand (d50=0.85 mm) and 24 tests of fine sand (d50=0.26 mm) were carried out in a sand-recirculating flume. The tests for each sand type used four weirs with different downstream weir slopes (π/6, π/4, π/3, and π...

This paper discusses the scale-effects of flow-field and relative sediment size of scour at bridge pier, which are usually met and considered in laboratory experiments. Both the situations with simple and complex pier geometry are discussed. The flow-flow scale can be divided into three categories by the flow shallowness ratio y_0/D: narrow-pier (y...

For a preliminary investigation of the impact of a tsunami surge on wharf piles, a tsunami flume was built in a laboratory, and a dam break flow was generated by a gate-reservoir system to simulate a tsunami surge. In addition, a vertical wall was installed in front of the wharf model so that its effect in reducing tsunami load could be studied. Fi...

Previous investigations indicate that scour around bridge piers is one of the most important factors for the failure of waterway bridges. Hence, it is essential to determine the accurate scour depth around the bridge piers. Most of the previous studies were based on scour around a single pier; however, in practice, new bridges are usually wide and...

The variation of upstream slope of a submerged weir could significantly alter the local flow pattern and sediment transport. This paper presents an experimental investigation into local scour at submerged weirs with different upstream weir slope angles. In this study, 62 tests are carried out in a tilting recirculating flume, including 38 tests usi...

This study investigates tsunami bore impact on a cylindrical structure. A physical study was carried out in a large wave flume with a horizontal floor. Experiments covered a range of bore heights (140–210 mm) and bore velocities (1.98–2.45 m/s). The vertical and angular distributions of the applied pressure were measured using a vertical array of p...

Over the past decades rapid population growth in urban areas has promoted the development of high-density housing such as high-rise apartments. In order to properly supply water to this growing sector, it is essential to understand the determinants of its water use. However, this task has largely remained unexplored through the empirical study of w...

Many research have been carried out and formulas derived to estimate wide pier scour equation. However, many of these formulas were derived using data from laboratory and very limited equation that had been developed were tested using data from field. The purpose of this paper is to evaluate the laboratory wide pier scour equation that proposed fro...

The rainfall–runoff modelling being a stochastic process in nature is dependent on various climatological variables and catchment characteristics and therefore numerous hydrological models have been developed to simulate this complex process. One approach to modelling this complex non-linear rainfall–runoff process is to combine the outputs of vari...

Considering network topologies and structures of the artificial neural network (ANN) used in the field of hydrology, one can categorize them into two different generic types: feedforward and feedback (recurrent) networks. Different types of feedforward and recurrent ANNs are available, but multilayer perceptron type of feedforward ANN is most commo...

Estimation of bridge scour depth is a common problem encountered by hydraulic engineers involved in the design of major transport infrastructure. While there are standard scour depth estimation methods available, most of them were developed based on uniform pier configurations. Typical floodplain bridge structures in many of the recently constructe...

Raingardens are one of several versatile low impact design (LID) approaches; they have a significant effect on controlling runoff, groundwater recharge, and water quality. Much research has been done on the performance of raingardens (laboratory and field scale). However, most studies have focused on pollutant removal, and there is relatively littl...

As a result of rapid urbanization, installation of complex infrastructure and variations in rainfall, anthropogenic climate change is making cities increasingly vulnerable to flooding. Downscaling of climate change results from Global Circulation Models (GCM) to urban catchment scales are needed because these models are not able to describe accurat...

Results of a physical modelling study of clear-water scour at a tripod obstacle in uniform bed sediment under steady flow conditions are presented. 4 flow depths, 2 flow velocities and 3 angles of attack were considered. Maximum scour depth increased with increase in flow depth or velocity. For deep flows and high flow rate, the maximum value of th...