Riemann solution for a class of morphodynamic shallow water dam-break problems

This paper investigates a family of dam-break problems over an erodible bed. The hydrodynamics are described by the shallow water equations, and the bed change by a sediment conservation equation, coupled to the hydrodynamics by a sediment transport (bed load) law. When the initial states ~Ul and ~Ur are sufficiently close to each other the resulting solutions are consistent with the theory proposed by Lax (1973), that for a Riemann problem of n equations there are n waves associated with the n characteristic families. However, for wet-dry dam-break problems over a mobile bed, there are 3 governing equations, but only 2 waves. One wave vanishes because of the presence of the dry bed. When initial left and right bed levels (Bl and Br) are far apart, it is shown that a semi-characteristic shock may occur, which happens because, unlike in shallow water flow on a fixed bed, the flux function is non-convex. In these circumstances it is shown that it is necessary to reconsider the usual shock conditions. Instead, we propose an implied internal shock structure the concept of which originates from the fact that the stationary shock over fixed bed discontinuity can be regarded as a limiting case of flow over a sloping fixed bed. The Needham & Hey (1991) approximation for the ambiguous integral term RhdB in the shock condition is improved based on this internal shock structure, such that mathematically valid solutions that incorporate a morphodynamic semi-characteristic shock are arrived at

Swash zone morphodynamic modelling including sediment entrained by bore-generated turbulence

In this paper we introduce a mathematical model of sediment entrainment due to bore-generated turbulence in a shallow water context. In this model, the entrainment is assumed to be proportional to the energy decay rate across a bore on a mobile bed. The energy decay rate across a bore on a mobile bed is derived analytically. This model is incorporated into the one dimensional morphodynamic model developed by Zhu and Dodd (2015), which includes bed- and suspended load transport. This results in new shock conditions, which allow for sediment entrainment at a shock. With it we investigate the effects of sediment entrainment due to bore-generated turbulence on beachface evolution under a single swash event driven by a solitary wave. The simulation results imply that sediment entrainment by bore turbulence at the incoming bore dominates over sediment mobilisation by bed shear stress. In contrast, the backwash bore is dominated by bed shear stress related processes. The morphodynamic impact of bore turbulence on this swash event is primarily erosion of the sea bed seaward of the initial shoreline. Any sediment remaining in the water column seaward of this point is then available to be transported by subsequent events. It is shown that the bed step is primarily a bed load related feature, with sediment entrained as suspended load counteracting the bed step growth

Development of the EU Green Public Procurement (GPP) Criteria for Paints, Varnishes and Road Markings. Technical Report with final criteria.

The Development of the Green Public Procurement (GPP) criteria for Paints, Varnishes and Road Markings is aimed at helping public authorities to ensure that paints, varnishes and road markings are procured in such a way that it delivers environmental improvements that contribute to European policy objectives for energy, chemical management and resource efficiency, as well as reducing life cycle costs. In order to identify the most significant improvement areas for criteria development an analysis has been carried out of the environmental and health impacts of manufacturing and using paints, varnishes and road markings. The most commonly used procurement processes have been also identified and are further addressed in the separate criteria document (published as a Staff Working Document of the Commission). Together these two documents aim to provide public authorities with orientation on how to effectively integrate these GPP criteria into their procurement processes.JRC.B.5-Circular Economy and Industrial Leadershi

Impact of a uniform bore on an erodible beach

AbstractThe impact of a uniform bore on an erodible beach is investigated using a shallow water description and a sediment conservation equation. The solution, which is obtained using the method of characteristics, employs a cubic bed-load formula and a crudely calibrated sediment transport coefficient. It is found that, as with the fixed bed case of Hibberd and Peregrine (1979), a backwash bore forms, which for the mobile bed also comprises a bed step. It is found that this bed step achieves a significant height. The volume of sand deposited above the final still water level is consistent with that observed under certain events on some sandy beaches

Coastal morphodynamical modelling in nonlinear shallow water framework using a coordinate transformation method

A 1D numerical model of Nonlinear Shallow Water Equations (NSWEs) coupled to an advection equation for suspended sediment and a bed evolution equation is developed. The moving boundary at the shoreline is treated by a coordinate transformation method (CTM). An absorbing-generating seaward boundary condition in the transformed variables is also developed. The purely hydrodynamic component (NSWEs) is verifed against analytical results. The NSWEs plus advection equation is verifed quasi-analytical results. The fully-coupled model with bed change due to bed-load is verifed against a single swash event and long-term numerical simulation. Excellent agreement is observed in all verifcations

Revision of the EU Green Public Procurement (GPP) Criteria for Textile Products and Services: Technical Report with final criteria.

The revision of the Green Public Procurement (GPP) criteria for Textile products and Services is aimed at helping public authorities to ensure that textiles products and services are procured in such a way that it delivers environmental improvements that contribute to European policy objectives for energy, chemical management and resource efficiency, as well as reducing life cycle costs. In order to identify the most significant improvement areas for criteria development an analysis has been carried out of the environmental impacts of manufacturing and using textile products and providing textile services. The most commonly used procurement processes have been also identified and are further addressed in the separate criteria document (published as a Staff Working Document of the Commission). Together these two documents aim to provide public authorities with orientation on how to effectively integrate these GPP criteria into their procurement processes.JRC.B.5-Circular Economy and Industrial Leadershi

Level(s) – A common EU framework of core sustainability indicators for office and residential buildings: Parts 1 and 2: Introduction to Level(s) and how it works (Beta v1.0)

Developed as a common EU framework of core indicators for the sustainability of office and residential buildings, Level(s) provides a set of indicators and common metrics for measuring the performance of buildings along their life cycle. As well as environmental performance, which is the main focus, it also enables other important related performance aspects to be assessed using indicators and tools for health and comfort, life cycle cost and potential future risks to performance. Level(s) aims to provide a general language of sustainability for buildings. This common language should enable actions to be taken at building level that can make a clear contribution to broader European environmental policy objectives. It is structured as follows: 1. Macro-objectives: An overarching set of six macro-objectives for the Level(s) framework that contribute to EU and Member State policy objectives in areas such as energy, material use and waste, water and indoor air quality. 2. Core Indicators: A set of 9 common indicators for measuring the performance of buildings which contribute to achieving each macro-objective. 3. Life cycle tools: A set of 4 scenario tools and 1 data collection tool, together with a simplified Life Cycle Assessment (LCA) methodology, that are designed to support a more holistic analysis of the performance of buildings based on whole life cycle thinking. 4. Value and risk rating: A checklist and rating system provides information on the potential positive contribution to a property valuation and the underlying reliability of performance assessments made using the Level(s) framework. In addition, the Level(s) framework aims to promote life cycle thinking. It guides users from an initial focus on individual aspects of building performance towards a more holistic perspective, with the aim of wider European use of Life Cycle Assessment (LCA) and Life Cycle Cost Assessment (LCCA). Part 1 provides a general introduction to Level(s). In Part 2 potential users are provided with a basic introduction to all of the elements of the framework, and how it can be used as a whole, or in part, to report on the performance of building projects.JRC.B.5-Circular Economy and Industrial Leadershi

Level(s) – A common EU framework of core sustainability indicators for office and residential buildings: Part 3: How to make performance assessments using Level(s) (Beta v1.0)

Developed as a common EU framework of core indicators for the sustainability of office and residential buildings, Level(s) provides a set of indicators and common metrics for measuring the performance of buildings along their life cycle. As well as environmental performance, which is the main focus, it also enables other important related performance aspects to be assessed using indicators and tools for health and comfort, life cycle cost and potential future risks to performance. Level(s) aims to provide a general language of sustainability for buildings. This common language should enable actions to be taken at building level that can make a clear contribution to broader European environmental policy objectives. It is structured as follows: 1. Macro-objectives: An overarching set of six macro-objectives for the Level(s) framework that contribute to EU and Member State policy objectives in areas such as energy, material use and waste, water and indoor air quality. 2. Core Indicators: A set of 9 common indicators for measuring the performance of buildings which contribute to achieving each macro-objective. 3. Life cycle tools: A set of 4 scenario tools and 1 data collection tool, together with a simplified Life Cycle Assessment (LCA) methodology, that are designed to support a more holistic analysis of the performance of buildings based on whole life cycle thinking. 4. Value and risk rating: A checklist and rating system provides information on the potential positive contribution to a property valuation and the underlying reliability of performance assessments made using the Level(s) framework. In addition, the Level(s) framework aims to promote life cycle thinking. It guides users from an initial focus on individual aspects of building performance towards a more holistic perspective, with the aim of wider European use of Life Cycle Assessment (LCA) and Life Cycle Cost Assessment (LCCA). Part 3 of the Level(s) documentation provides a complete set of technical guidance on how to make performance assessments at each of the three different Levels, and then to report on the results.JRC.B.5-Circular Economy and Industrial Leadershi

Numerical modelling of the flow and bed evolution of a single bore-driven swash event on a coarse sand beach

This paper examines the numerical prediction of the sediment transport and bed evolution for a single swash event on a coarse sediment beach. In these conditions bed load is the dominant mode of sediment transport. Laboratory experiments of a single bore-driven swash event are simulated numerically using a fully-coupled model that solves the system of Non Linear Shallow Water Equations and the Exner sediment conservation formula. The analysis focuses on two aspects: the optimal choice of parameters for the Meyer-Peter and Müller sediment transport formula and the model used for computing the shear stress. The methods tested for the bed shear stress are the momentum integral method and the Chezy formulation in which the friction factor is computed using two different formulae. Infiltration into the beach and its effects on the shear stress and sediment transport are also modelled. Results show that the basic Meyer-Peter and Müller sediment transport formula provides good results in the run-up. On the other hand, the sediment transport in the early stage of the backwash is overestimated. A reduction of the sediment mobility constant in the formula in the backwash marginally improves the results. However, the causes of the overestimation of the sediment transport at the early stage of the backwash is the overestimation of the shear stress, while at later stages there are several contributions that are identified, i.e. modelling of the sediment transport and infiltration. It is also suggested that the Meyer-Peter and Müller sediment transport formula might not capture the complexity of the processes involved during the backwash. The comparison of the methods for the estimate of the bed shear stress show that comparable results can be obtained using the momentum integral method and the Chezy formulation with time and space varying friction factor. The resulting bed evolution is also described. In the predicted final profile, deposition is found in the upper part of the beach and erosion in the lower part. A bed step is formed just below the position of the initial shoreline. This feature is determined by the onset of a hydraulic jump during the backwash

On the physics behind coastal morphodynamic patterns

Peer ReviewedPostprint (published version