The Scottish Government

Contents |

Listen

David Bassett, Angus Pettit, Caroline Anderton and Paul Grace
JBA Consulting

ISBN 978 0 7559 1563 7

This document is also available in pdf format (2.9MB)

Contents

ACKNOWLEDGEMENTS
EXECUTIVE SUMMARY
ABBREVIATIONS
DEFINITIONS

CHAPTER 1: INTRODUCTION
OBJECTIVES
STUDY APPROACH

CHAPTER 2: EXISTING ASSET INFORMATION
FLOOD PREVENTION SCHEMES
INFORMATION SUPPLIED BY THE SCOTTISH EXECUTIVE
INFORMATION SUPPLIED BY THE LOCAL AUTHORITIES
FLOOD EXTENTS
LOCAL AUTHORITY BIENNIAL REPORTS

CHAPTER 3: DATA COLLECTION
PROJECT OVERVIEW
SCHEME CATEGORISATION
'ON SITE' CONDITION ASSESSMENT
SURVEY
INFORMATION FROM DETAILED STUDY

CHAPTER 4: FLOOD ESTIMATION
INTRODUCTION
METHODS USED
REVIEW AND COMPARISON WITH DESIGN HYDROLOGY AND AUTOFEH
REVIEW AND COMPARISON WITH DESIGN HYDROLOGY AND SCHEME HYDROLOGY
CLIMATE CHANGE

CHAPTER 5: HYDRAULIC MODELLING
CHOICE OF MODEL
MODEL CONSTRUCTION
JOINT PROBABILITY
MODEL RESULTS

CHAPTER 6: FLOOD MAPPING
METHODOLOGY
NEXTMAP DTM
NEXTMAP AND SURVEY LEVELS
DELINEATION OF FLOOD EXTENTS
DESCRIPTION OF FLOOD OUTLINES

CHAPTER 7: STANDARD OF PROTECTION
GENERAL/METHODOLOGY
DISCUSSION ON METHODOLOGY
COMPARISON OF SURVEYED AND DESIGNED LEVELS
RESULTS
CLIMATE CHANGE

CHAPTER 8: ECONOMIC ASSESSMENT METHODOLOGY
INTRODUCTION
MDSF METHODOLOGY
PROJECT APPRAISAL METHODOLOGY
SCHEME COSTS
SCHEME COST EVALUATION

CHAPTER 9: RESULTS OF ECONOMIC ASSESSMENT
INTRODUCTION
HISTORY OF ECONOMIC APPRAISALS
RESULTS OF PROJECT APPRAISAL
DISCUSSION

CHAPTER 10: SCOTTISH FLOOD DEFENCE ASSET DATABASE
ASSET DATABASE
INFORMATION IN THE ASSET DATABASE

CHAPTER 11: FINDINGS AND RECOMMENDATIONS
INFORMATION ON FLOOD PREVENTION SCHEMES
BIENNIAL REPORT
COASTAL SCHEMES
ASSET CONDITION
REASSESSMENT OF PEAK FLOOD FLOWS
HYDRAULIC MODELLING
FLOOD MAPPING
STANDARD OF PROTECTION
NUMBER OF DEFENDED PROPERTIES
ECONOMIC ASSESSMENT
MANAGEMENT OF INFORMATION

APPENDIX A: SCHEME LISTS
APPENDIX B: HYDROLOGY
APPENDIX B: EXTREME SEA LEVEL ESTIMATION
APPENDIX C: SUMMARY OF ECONOMIC APPRAISAL RESULTS
APPENDIX D: ASSET DATABASE
APPENDIX D: DATABASE STRUCTURE
APPENDIX D: DATABASE TABLES
APPENDIX D: LOOKUP TABLES
APPENDIX D: PROFORMA FOR NEW FLOOD ASSET DATABASE INFORMATION

LIST OF FIGURES

FIGURE 2 1: LOCATION OF FLOOD PREVENTION SCHEMES IN SCOTLAND
FIGURE 3 1: METHODOLOGY FLOWCHART
FIGURE 3 2: EXAMPLE DEFENCE FAULTS
FIGURE 3 3: ALIGNMENT OF SURVEYED ASSETS AND OS BACKGROUND
FIGURE 5 1: HYDRAULIC MODEL SUMMARY SHEET
FIGURE 6 1: EXAMPLE FLOOD OUTLINES FORT AUGUSTUS
FIGURE 6 2: TYPICAL HEC-RAS OUTPUT SHOWING THE DIFFERENCE BETWEEN THE NEXTMAP DTM AND SURVEY CROSS SECTIONS
FIGURE 7 1: FREEBOARD DEFINITION
FIGURE 8 1: SCHEMES CONSTRUCTED AND TOTAL COST OF SCHEME BY FIVE YEAR PERIOD
FIGURE 9 1: CUMULATIVE SERIES OF CONSTRUCTION COSTS AGAINST PROPERTIES PROTECTED
FIGURE 9 2: TOTAL DAMAGES, DAMAGE AVOIDED AND RESIDUAL DAMAGE
FIGURE 9 3: CUMULATIVE SERIES OF CONSTRUCTION COSTS AGAINST DAMAGES AVOIDED
FIGURE 9 4: BENEFIT COST RATIOS FOR SCHEMES ASSESSED

LIST OF TABLES

TABLE 2 1: FLOOD DEFENCES REPORTED BY LOCAL AUTHORITIES NOT PROMOTED UNDER THE 1961 ACT
TABLE 2 2: FPS WITH FLOOD OUTLINES
TABLE 3 1: SEA AND RIVER DEFENCE CONDITION ASSESSMENT
TABLE 4 1: RETURN PERIOD AND PROBABILITY
TABLE 4 2: SUMMARY OF FLOOD ESTIMATION METHODS USED
TABLE 4 3: % DIFFERENCE BETWEEN CURRENT FLOW ESTIMATES AND SEPA / AUTOFEH FLOW GRID
TABLE 4 4: COMPARISON OF CURRENT AND PREVIOUS ESTIMATES
TABLE 4 5: CLIMATE CHANGE % INCREASES IN PEAK FLOWS BY THE 2080S
TABLE 5 1: EXAMPLE OF JOINT PROBABILITY MARGINAL RETURN PERIOD
TABLE 7 1: COMPARISON OF SCHEME DESIGN AS RETURN PERIOD
TABLE 7 2: COMPARISON OF SCHEME STANDARD OF PROTECTION
TABLE 7 3: COMPARISON OF SCHEME STANDARD OF PROTECTION UNDER CLIMATE CHANGE SCENARIO
TABLE 8 1: OUTTURN COSTS UPDATED TO PRESENT DAY (2004) VALUE BY LOCAL AUTHORITY
TABLE 8 2: COMPARISON OF SCHEME COSTS FOR SITES STUDIED
TABLE 9 1: NUMBER OF PROPERTIES PROTECTED BY LOCAL AUTHORITY
TABLE 9 2: DAMAGES AVOIDED BY LOCAL AUTHORITY
TABLE 11 1: WORK UNDERTAKEN SINCE DRAFT REPORTS
TABLE 12 1: INFORMATION STORED IN THE ASSET DATABASE

Contents |