Leading linear growth rates for steady uniform morphodynamic overland flows at different Froude numbers and grain diameters (NERC Grant NE/S00274X/1)

Shallow overland flows in steady state can become unstable and break up into destructive surges. The following data documents maximum growth rates for disturbances to uniform steady flows on a fixed slope in a one-dimensional shallow-layer model that incorporates the mechanics of erosion and deposition of monodisperse sediment, documented in sections 2 and 4 of the following freely available preprint: https://arxiv.org/abs/2007.15989. The data comprises the following 4 columns, separated by spaces: grain diameter, Froude number, solid fraction and maximum growth rate. Grain diameter refers to the characteristic diameter of erodible particles, non-dimensionalised by the steady flow depth h0. Froude number, Fr, is a dimensionless constant defined as Fr = u0 / sqrt (h0 * g'), where u0 is the velocity of the steady flow and g' is gravitational acceleration resolved perpendicular to the slope. Solid fraction is a number between 0 and 1 that describes the proportion of solid particles in the flowing mixture. A solid fraction of 0 denotes a purely fluid flow and a solid fraction of 1 denotes a saturated mixture containing a maximum packing of solid particles. Maximum growth rate refers to the largest linear growth rate for perturbations to a uniform flowing layer with the corresponding properties given in the prior 3 columns. The model formulation describes the dynamics of 4 unknown observables: flow height, flow velocity, solids concentration and bed height. By taking the 'maximum' in this case, we mean the maximum over these 4 flow fields that may be perturbed by an environmental disturbance and also the maximum over all possible wavelengths of disturbance. We note that in this dataset, flows with a maximum growth rate equal to zero or small positive values (e.g. up to machine precision) are stable; flows with strictly positive growth rate are unstable. Zero growth rate indicates that the maximum growth rate is given by a neutrally stable perturbation and such perturbations always exist for reasons of symmetry in the model. For each grain diameter and Froude number in the dataset, there exist two steady uniform states with different solid fractions. Therefore two files are supplied - one containing data for the more dilute states and the other containing data for the more concentrated states. These various technical details, as well as full documentation of the model and the parameters used are explained more fully in the aforementioned paper.

Date (Creation): 2020-12-01

Citation identifier: http://data.bgs.ac.uk/id/dataHolding/13607693

Point of contact

Organisation name	Individual name	Electronic mail address	Role
University of Bristol	Dr Jeremy Phillips	not available	Principal investigator
University of Bristol	Jake Langham	not available	Originator
British Geological Survey	Enquiries	not available	Distributor
British Geological Survey	Enquiries	not available	Point of contact

Maintenance and update frequency: notApplicable

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Geology

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Fluid dynamics

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Other constraints: Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

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Other constraints: The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused.

Other constraints: Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

Language: English

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Geoscientific information

Begin date: 2020-12-01

End date: 2020-12-01 Before

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Organisation name	Individual name	Electronic mail address	Role
British Geological Survey	Enquiries	not available	Distributor

OnLine resource

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	https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item139765	Data

Hierarchy level: Non geographic dataset

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Title: INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology

Date (Publication): 2011

Explanation: See the referenced specification

Pass: No

Conformance result

Title: Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services