Modelling uncertainty for flash floods in coastal plains using adjoint methods

Hossam Elhanafy, Graham J.M. Copeland

Research output: Contribution to conferencePaper

Abstract

This paper shows the application of adjoint sensitivity analysis to flash flood wave propagation in a river channel. The adjoint sensitivity analysis is used to assess flood hazard in a coastal area caused by river discharge. The numerical model determines the sensitivities of predicted water levels to uncertainties in key controls such as inflow hydrograph, channel topography, frictional resistance and infiltration rate. Sensitivities are calculated using the adjoint equations and are specified in terms of water levels being greater than certain safe threshold levels along the channel. The flood propagation model is based on the St. Venant equations while the propagation of sensitivity information is based on the corresponding adjoint equations. This analysis is achieved using a numerical model that integrates The St. Venant equations forward in time using a staggered finite difference scheme. An enhanced method of characteristics at the downstream boundary provides open boundary conditions and overcomes the problem of reflections from the boundaries. Then, the adjoint model is integrated backwards in time to trace the sensitivity information back through the model domain towards the inflow control boundary. The adjoint model has been verified by means of an identical twin experiment.

Conference

ConferenceSecond International Conference and Exhibition Water Resources, Technologies and Services
CitySofia, Bulgaria
Period6/06/077/06/07

Fingerprint

adjoint method
flash flood
coastal plain
modeling
sensitivity analysis
inflow
water level
flood wave
river channel
river discharge
hydrograph
wave propagation
infiltration
boundary condition
hazard
topography
experiment

Keywords

  • flooding
  • flash floods
  • modelling
  • wave propagationad
  • adjoint equations
  • civil engineering
  • ocean engineering

Cite this

Elhanafy, H., & Copeland, G. J. M. (2007). Modelling uncertainty for flash floods in coastal plains using adjoint methods. Paper presented at Second International Conference and Exhibition Water Resources, Technologies and Services, Sofia, Bulgaria, .
Elhanafy, Hossam ; Copeland, Graham J.M. / Modelling uncertainty for flash floods in coastal plains using adjoint methods. Paper presented at Second International Conference and Exhibition Water Resources, Technologies and Services, Sofia, Bulgaria, .11 p.
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title = "Modelling uncertainty for flash floods in coastal plains using adjoint methods",
abstract = "This paper shows the application of adjoint sensitivity analysis to flash flood wave propagation in a river channel. The adjoint sensitivity analysis is used to assess flood hazard in a coastal area caused by river discharge. The numerical model determines the sensitivities of predicted water levels to uncertainties in key controls such as inflow hydrograph, channel topography, frictional resistance and infiltration rate. Sensitivities are calculated using the adjoint equations and are specified in terms of water levels being greater than certain safe threshold levels along the channel. The flood propagation model is based on the St. Venant equations while the propagation of sensitivity information is based on the corresponding adjoint equations. This analysis is achieved using a numerical model that integrates The St. Venant equations forward in time using a staggered finite difference scheme. An enhanced method of characteristics at the downstream boundary provides open boundary conditions and overcomes the problem of reflections from the boundaries. Then, the adjoint model is integrated backwards in time to trace the sensitivity information back through the model domain towards the inflow control boundary. The adjoint model has been verified by means of an identical twin experiment.",
keywords = "flooding, flash floods, modelling, wave propagationad, adjoint equations, civil engineering, ocean engineering",
author = "Hossam Elhanafy and Copeland, {Graham J.M.}",
year = "2007",
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note = "Second International Conference and Exhibition Water Resources, Technologies and Services ; Conference date: 06-06-2007 Through 07-06-2007",

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Elhanafy, H & Copeland, GJM 2007, 'Modelling uncertainty for flash floods in coastal plains using adjoint methods' Paper presented at Second International Conference and Exhibition Water Resources, Technologies and Services, Sofia, Bulgaria, 6/06/07 - 7/06/07, .

Modelling uncertainty for flash floods in coastal plains using adjoint methods. / Elhanafy, Hossam; Copeland, Graham J.M.

2007. Paper presented at Second International Conference and Exhibition Water Resources, Technologies and Services, Sofia, Bulgaria, .

Research output: Contribution to conferencePaper

TY - CONF

T1 - Modelling uncertainty for flash floods in coastal plains using adjoint methods

AU - Elhanafy, Hossam

AU - Copeland, Graham J.M.

PY - 2007/6/7

Y1 - 2007/6/7

N2 - This paper shows the application of adjoint sensitivity analysis to flash flood wave propagation in a river channel. The adjoint sensitivity analysis is used to assess flood hazard in a coastal area caused by river discharge. The numerical model determines the sensitivities of predicted water levels to uncertainties in key controls such as inflow hydrograph, channel topography, frictional resistance and infiltration rate. Sensitivities are calculated using the adjoint equations and are specified in terms of water levels being greater than certain safe threshold levels along the channel. The flood propagation model is based on the St. Venant equations while the propagation of sensitivity information is based on the corresponding adjoint equations. This analysis is achieved using a numerical model that integrates The St. Venant equations forward in time using a staggered finite difference scheme. An enhanced method of characteristics at the downstream boundary provides open boundary conditions and overcomes the problem of reflections from the boundaries. Then, the adjoint model is integrated backwards in time to trace the sensitivity information back through the model domain towards the inflow control boundary. The adjoint model has been verified by means of an identical twin experiment.

AB - This paper shows the application of adjoint sensitivity analysis to flash flood wave propagation in a river channel. The adjoint sensitivity analysis is used to assess flood hazard in a coastal area caused by river discharge. The numerical model determines the sensitivities of predicted water levels to uncertainties in key controls such as inflow hydrograph, channel topography, frictional resistance and infiltration rate. Sensitivities are calculated using the adjoint equations and are specified in terms of water levels being greater than certain safe threshold levels along the channel. The flood propagation model is based on the St. Venant equations while the propagation of sensitivity information is based on the corresponding adjoint equations. This analysis is achieved using a numerical model that integrates The St. Venant equations forward in time using a staggered finite difference scheme. An enhanced method of characteristics at the downstream boundary provides open boundary conditions and overcomes the problem of reflections from the boundaries. Then, the adjoint model is integrated backwards in time to trace the sensitivity information back through the model domain towards the inflow control boundary. The adjoint model has been verified by means of an identical twin experiment.

KW - flooding

KW - flash floods

KW - modelling

KW - wave propagationad

KW - adjoint equations

KW - civil engineering

KW - ocean engineering

M3 - Paper

ER -

Elhanafy H, Copeland GJM. Modelling uncertainty for flash floods in coastal plains using adjoint methods. 2007. Paper presented at Second International Conference and Exhibition Water Resources, Technologies and Services, Sofia, Bulgaria, .