Flood Modeling, Prediction, and Mitigation

Transcription

1 Flood Modeling, Prediction, and Mitigation

2 Zekâi Şen Flood Modeling, Prediction, and Mitigation 123

3 Zekâi Şen Faculty of Engineering and Natural Sciences, Department of Civil Engineering Istanbul Medipol University Beykoz, Istanbul Turkey ISBN ISBN (ebook) Library of Congress Control Number: Springer International Publishing AG 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer International Publishing AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

4 NOAH PHENOMENON (GREAT FLOOD, WET SPELL) JOSEPH PHENOMENON (DROUGHT, DRY SPELL) There is sensitive balance in nature as a sequence of dry and wet periods, which needs care for their preservations without destroying the balance in the environment. This book is dedicated to those who care for such a balance by logical, rational, scientific and ethical applications for the sake of other living creatures rights.

5 Preface Floods are among the natural extreme events that occur after intensive storm rainfall events as excessive water volumes over the earth surface more than the capacity of surface natural or artificial conveyance systems (stream and river basins, creeks, estuaries, wadis, valleys, canals, channels, culverts, dams, cities). Apart from the rainfall causative floods, there are others as consequences of snowmelt, sea surge and tides, tsunamis, ground water level rise, urban sewer capacity overflow, dam breaks in addition to confined aquifer overflows. Since the start of human history, societies have been exposed to the danger of natural events such as earthquakes, droughts, and floods that could not be avoided completely even with the modern-day scientific and technological facilities, preparedness, mitigation, and early warning systems. The most hazardous extreme natural event is the flood occurrence not only due to the intensive rainfall effects, but more significantly due to human settlement along flood dangerous areas such as floodplains, adjacent to riverbanks, and valleys. The floods are extremely beneficial events in arid regions, because they are the main source of groundwater recharge along drainage basins (wadis), where there are no human settlements or urban area exposed to flood danger. For this purpose, there are even runoff harvesting works in many arid regions of the world. However, flood beneficial aspects are outside the scope of this book, which is concentrated on floods and flash floods. In order to achieve successful works to reduce flood danger and hazard, it is necessary to know scientific fundamental aspects of flood definition and generation processes, which pave way for methodological procedures to predict their future behaviors and to take precautions by means of hardware through the engineering water structures and software by means of early warning systems and also public awareness through educative training. The main purpose of this book is to bring together all the layman, technicians, engineers, and scientists methodological procedures that have been developed for flood peak discharge prediction during the last 150 years. Early approaches are rather logical and empirical, but later on, more systematic and analytical approaches are developed on the basis of rational, probabilistic, statistical, and stochastic vii

6 viii Preface uncertain methodologies in a better objective manner. Empirical formulations are location dependent and cannot be applied to other parts of the world with satisfaction. Their old versions, prior to the rainfall recording, are dependent on the drainage basin area, but later versions include the rainfall amount or intensity. Today, the evolution of the flood peak discharge calculation methodology has reached to the employment of remote sensing and satellite image procedures coupled with digital elevation model (DEM) in the electronic media as for the surface morphological feature description, which is an essential ingredient in flood discharge prediction. This book after the introductory chapter explaining the flood definition, types, physical causes, relationship to the overall hydrological cycle, and hazard types enters the domain of methodological procedures starting with the precipitation characteristics that take role in flood occurrence in addition to the surface features of drainage basin in terms of geomorphological variables. In two of the chapters, the hydrographs and flood discharge estimation empirical methodologies are presented with basic and fundamental explanations. The uncertainty aspects are presented through the probabilistic and statistical procedures including risk concept and return periods, which correspond to life of an engineering water structure. In the mean time, the sedimentation and debris expositions of various engineering structures are presented with some innovative recommendations for the first time in this book. In the last two chapters, climate change impact relationship to floods and also the flood hazard and mitigation procedures and approaches are exposed with the latest developments. In each chapter, some criticism and new suggestions are proposed for future better methodological advancements. The content of this book is based on the vast experience of the author especially in arid region of the Arabian Peninsula through his academic work at the King Abdulaziz University, Faculty of Earth Sciences, Kingdom of Saudi Arabia; at the application establishment of the Saudi Geological Survey, Jeddah; and also at the Meteorology and Civil Engineering Faculties at the Istanbul Technical University, Istanbul, Turkey. I hope that this book will support to those interested in flood discharge estimation with risk attachments, climate change relationships, hazard and mitigation aspects, and their applications in flood prevention works. I thank my colleagues who have encouraged me to write a book on floods and especially my wife Mr. Fatma Şen, who had kept silence, endurance, and patience during my extensive hourly, daily, monthly, and yearly works for the preparation of this book. Çubuklu, Istanbul, Turkey 2016 Zekâi Şen

7 Contents 1 Introduction General Flood and Hazard Definition Hydro-meteorological Events Global Environment and Cycle Hydrological Cycle Flood Definition Ordinary Floods Flash Floods Triggering Mechanism Types Physical Causes of Flood Flood Plains Flood Hazards Human Causes Water Disasters Various Definitions References Rainfall and Floods General Causative Reasons for Rainfall Occurrence Water Vapor Cooling Condensation Precipitation Types Elevation Difference (Orographic) Temperature Difference (Convective) Pressure Difference (Frontal) Rainfall Measurement Non-recording Raingauges Recording Raingauges ix

8 x Contents 2.5 Rainfall Measurement Errors Arid Region Rainfall Rainfall Duration Missing Data Filling Arithmetic Average Ratio Method Inverse Distance Square Method Correlation Method Double Mass Curve Method Rainfall Intensity Hyetograph Hydrograph Relationship Intensity Duration Frequency (IDF) Curves Dimensionless Intensity Duration (DID) Curve Intensity Duration Frequency (IDF) Curve Generation Probably Maximum Precipitation (PMP) Definitions of PMP and PMF Statistical Estimates Area Reduction Curves PMP and PMF Estimations Application of Procedure Probable Maximum Flood (PMF) Precipitable Water Calculation Application Principles Areal Average Rainfall Calculation Arithmetic Average Weighted Average References Floods and Drainage Basin Features General Topographic Map Presence Elevation Features Field Survey Digital Elevation Model (DEM) Flood Map Derivation Ingredients Drainage Basin (Catchment) Features Water Divide Point Water Divide Line Drainage Basin (Catchment) Drainage Basin Quantities Drainage Area Main Channel Length

9 Contents xi Main Channel Slope Drainage Density Shape Factor Stream Order Bifurcation Ratio Elongation Ratio Drainage Frequency Centroid Length Cross Sections Cross Section Slope Cross Sections Area and Rating Curve Cross Section Wetted Perimeter and Hydraulic Radius Cross Section Discharge Floods and Basic Concepts Flash Floods Flood Hazard Map Preparation Drainage Basin Flood System Standard Hypsographic Curves (HC) Direct Hydrograph Catchment Feature Relationships Drainage Area Discharge Approaches References Hydrograph and Unit Hydrograph Analysis General Hydrograph Theoretical Storm Hydrographs Hydrograph Properties Unit Hydrograph Definition (UH) UH Limitations S-Hydrograph and Decimal-Fold Duration UH Instantaneous Unit Hydrograph (IUH) IUH Derivation Dimensionless Unit Hydrograph (DUH) Synthetic Hydrographs (SH) Snyder Method Soil Conservation Service (SCS) Method The Geomorphologic Instantaneous Unit Hydrograph Santa Barbara Hydrograph Conceptual UH Models Nash Conceptual Model References

10 xii Contents 5 Rational Flood Methodologies General Early Methodologies Talbot Method Lacey Formulation Reliability of Early Methods Flood Discharge Envelope Curves Discharge-Area-Rainfall Intensity Rational Method Runoff Coefficient Seasonal Variation Runoff Coefficient Polygons Application Arid Zone Runoff Coefficient Area Relationship Arid Region Flood Calculations Irrationality of Rational Method and Some Rectification Criticisms Modified Rational Method (MRM) Application Ungauged Site Monthly Flow Estimation Standardizing Flows by Drainage Area Standardizing Flows by Mean Streamflow Standardizing Flows by Mean and Standard Deviation References Probability and Statistical Methods General Flood Frequency Calculations Plotting Positions Probability Distribution Functions (PDFs) Flood Data Preparation Annual Flood Discharge Partial Flood Discharges Hybrid Flood Discharges Flood Risk Calculations Annual Flood Discharge Calculations Probability Paper Plot Method Safety Risk on PDF Curve Frequency Factor Practical Flood Calculation Application Flood Analysis Regional Skewness Characteristics Relationship Between Extreme Values and Run-Lengths Extreme Values Run Properties

11 Contents xiii Extreme Values of Small Samples Application Simple Flood Risk Calculations in Dependent Time Series Flood Application Extreme Values in Small Sample-Dependent Processes Innovative Approach Application References Flood Design Discharge and Case Studies General Design Discharge Definition Design Discharge Choice Discharge Magnitude Classification Design Flood Prediction Flood Design Discharge Calculation Drainage Area- and Shape-Based Formulations Rainfall and Drainage Area-Based Formulation Total Runoff and Drainage Area-Based Formulation Rainfall Intensity and Drainage Area-Based Formulation Envelope Curves Engineering Water Structure Design Debris Flow Rock Falls Canals Groundwater Velocity Calculation Culverts Culvert Hydraulics Gully Sediment Yield Calculation Sediment Yield Models Highway Safety Assessment and Recommendations Flood Hazard Reduction Hydrological Flood Assessments First Stage Second Stage Third Stage References Climate Change Impact on Floods General Global Warming, Climate Change, and Water Resources Climate Change Vulnerability Climate Change Effects on Floods Climate Change and Dams

12 xiv Contents 8.5 Risk Management Frameworks Methods of Climate Risk Management Impacts, Adaptation, and Vulnerability Assessments Vulnerability Reduction in Climatic Variability Risk Assessment Under Climate Change Effects Modified Engineering Risk Assessment Due to Global Warming Applications Climate Change Impacts on Water Structures in Arid Regions Hydrometeorological Variables and Rainfall Records Climate Change Identification Methodologies Application References Flood Safety and Hazard General Flood Safety Defense Against Floods Flood Control Measures Flood Proofing Planning Control Emergency Plans Flood Hazard Risk Assessment Risks and Uncertainties at All Levels Risk Analysis Probability Distribution Functions of Flood Data Hazard and Safety Calculation Risk Calculations Flood Control Structures Land-Use Planning Public Awareness About Floods Integrated Flood Management (IFM) Flood Resilience References Index