Abstract
The linkage between sewer pipe flow and floodplain flow is recognised to induce an important source of uncertainty within two-dimensional (2D) urban flood models. This uncertainty is often attributed to the use of empirical hydraulic formulae (the one-dimensional (1D) weir and orifice steady flow equations) to achieve data-connectivity at the linking interface, which require the determination of discharge coefficients. Because of the paucity of high resolution localised data for this type of flows, the current understanding and quantification of a suitable range for those discharge coefficients is somewhat lacking. To fulfil this gap, this work presents the results acquired from an instrumented physical model designed to study the interaction between a pipe network flow and a floodplain flow. The full range of sewer-to-surface and surface-to-sewer flow conditions at the exchange zone are experimentally analysed in both steady and unsteady flow regimes. Steady state measured discharges are first analysed considering the relationship between the energy heads from the sewer flow and the floodplain flow; these results show that existing weir and orifice formulae are valid for describing the flow exchange for the present physical model, and yield new calibrated discharge coefficients for each of the flow conditions. The measured exchange discharges are also integrated (as a source term) within a 2D numerical flood model (a finite volume solver to the 2D Shallow Water Equations (SWE)), which is shown to reproduce the observed coefficients. This calibrated numerical model is then used to simulate a series of unsteady flow tests reproduced within the experimental facility. Results show that the numerical model overestimated the values of mean surcharge flow rate. This suggests the occurrence of additional head losses in unsteady conditions which are not currently accounted for within flood models calibrated in steady flow conditions.
Highlights
In environmental governance, there is a growing tension between the pursuit of scientific and political consensus, and the recognised need to open up governance processes to diverse participants and worldviews
This paper examines the case of the Intergovernmental Platform on Biodiversity and Ecosystem Services, which is an international expert panel for
In Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), the pursuit of closure became a collective venture that was underpinned by a lively operational discourse: consensus was described as a problem to be ‘solved’; expert groups were given ‘marching orders’; ‘time-bound’ activities were delegated to ‘task forces’; and the Multidisciplinary Expert Panel was ‘mandated’ to complete ‘work programme deliverables’
Summary
There is a growing tension between the pursuit of scientific and political consensus, and the recognised need to open up governance processes to diverse participants and worldviews. The need to account for the rights and agency of indigenous peoples and local communities, which had been raised in the Convention on Biological Diversity (see for example, Reimerson, 2013), prefigured new approaches to knowledge production (Turnhout et al, 2012) These emergent perspectives were by no means universally held amongst the architects of IPBES, but were none the less integral to a call for greater inclusivity, in which a wider group of voices were to be welcomed into the process. To examine how the pursuit of consensus and diversity were converted into practice in the case of IPBES, this paper draws on theoretical and methodological approaches from science and technology studies (STS) This field of scholarship has drawn attention to how science shapes, and is shaped by, the settings in which it is produced (Jasanoff, 2004). When inclusion in a typology is dependent on being involved in their negotiation, the questions of who participates and how in environmental knowledge production becomes increasingly important
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