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Overview of the CFMPs and the MDSF Rob Cheetham HR Wallingford LTD. INTRODUCTION The following presentation aims to give: a brief overview of Catchment Flood Management Planning (CFMPs) and the Modelling and Decision Support Framework (MDSF)
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Overview of the CFMPs and the MDSF Rob Cheetham HR Wallingford LTD HR Wallingford Ltd 2002
INTRODUCTION • The following presentation aims to give: • a brief overview of Catchment Flood Management Planning (CFMPs) and the Modelling and Decision Support Framework (MDSF) • show methods of developing catchment wide rainfall runoff and flow routing models • Demonstrate how to carry out socio-economic impact analysis within the MDSF • Show how “what-if” scenarios can be developed to address policies HR Wallingford Ltd 2002
PURPOSE OF CFMPs • To determine the socio-economic risks associated with flooding; • To investigate the efficacy of different flood management in reducing unacceptable risk at a catchment scale; • To provide the basis for sustainable flood management policies within each catchment over the next 50 years. • PURPOSE OF MDSF • To support implementation of CFMPs • To provide tools to aid socio-economic and uncertainty analysis • Manage data and results of “what if” scenario testing HR Wallingford Ltd 2002
MDSF system diagram HR Wallingford Ltd 2002
Import base data HR Wallingford Ltd 2002
Routeing modelling Upstream boundary Croal/Tonge confluence Farnworth GS Section 105 hydraulically modelled reaches HR Wallingford Ltd 2002 Downstream boundary
Linked with rainfall runoff model Sub-catchment 1-9 FEH lumped catchment Sub-catchment 1-6 Sub-catchment 1-9i (intermediate sub-catchment) HR Wallingford Ltd 2002
Import water levels and hydrographs HR Wallingford Ltd 2002
External model results HR Wallingford Ltd 2002
Economic damages HR Wallingford Ltd 2002
Social vulnerability HR Wallingford Ltd 2002
Policy development • Rainfall runoff - routing model generates water levels for present and future conditions • MDSF generates flood outlines and socio-economic impacts, thus defining the present and likely future flood risks • THESE ARE THE BASE CONDITIONS • Policies are developed to address flood risks • In the following example, the policy for the Croal catchment is ‘ensure River Tonge water levels do not increase in the future for the 100-year event’ HR Wallingford Ltd 2002
Flood management option appraisal Overview • Flood management options are developed to try to achieve the policy • Each option consists of a set of measures • Flood management measures include: • On-line/off-line storage • Flood diversion • Channel works/maintenance • Walls and embankments • Non-structural measures HR Wallingford Ltd 2002
Off-line Storage facility River Tonge HR Wallingford Ltd 2002
Flood management option appraisalConclusion • Model used to determine feasibility of options. Objective is to achieve “sufficient and robust” options • MDSF used to determine benefits of different options • Off-line storage facility for the River Tonge: • Requires modification to achieve stated policy for the Tonge • Difficult to locate within Bolton (consider upstream sites) • This is an example only - need to investigate other options HR Wallingford Ltd 2002
Overview of the CFMPs and the MDSF Rob Cheetham HR Wallingford LTD HR Wallingford Ltd 2002