Applied Hydrometeorology

Transcription

1 Applied Hydrometeorology

2 Applied Hydrometeorology By Pukh Raj Rakhecha Formerly at Indian Institute of Tropical Meteorology, Pune, India and Vijay P. Singh Department of Biological and Agricultural Engineering and Department of Civil & Environmental Engineering Texas A & M University, College Station, USA

3 A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN ISBN (HB) (e-book) Copublished by Springer, P.O. Box 17, 3300 AA Dordrecht, The Netherlands with Capital Publishing Company, New Delhi, India. Sold and distributed in North, Central and South America by Springer, 233 Spring Street, New York 10013, USA. In all other countries, except India, sold and distributed by Springer, Haberstrasse 7, D Heidelberg, Germany. In India, sold and distributed by Capital Publishing Company, 7/28, Mahaveer Street, Ansari Road, Daryaganj, New Delhi, , India. Cover photos: Courtesy United States Bureau of Reclamation (USBR) Printed on acid-free paper All Rights Reserved 2009 Capital Publishing Company No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Printed in India.

4 Dedicated to Our families Wife Anusuya, sons Ashok Kumar and Ramesh Pukh Raj Rakhecha Wife Anita, son Vinay, daughter-in-law Sonali and daughter Arti Vijay P. Singh

5 About the Authors Dr. Pukh Raj Rakhecha, former Dy. Director (Hydrometeorology) with the Indian Institute of Tropical Meteorology in Pune has worked on a variety of hydrometeorological projects including studies of design rainfalls, rainfall statistics, river basin PMP analysis, IFD relations in engineering design, major rainstorms analysis, floods and drought studies, water balance studies and rainfall runoff relations. He has over 250 research papers to his credit and has been consultant on numerous hydrometeorolgical studies. Dr. Rakhecha has travelled widely visiting Australia, Sweden, Switzerland, England, Malaysia, Japan, Iceland and United States for research work and participation in international conferences. He is an internationally recognised hydrometeorologist on PMP studies and member of several scientific societies including International Association of Hydrological Sciences (IAHS). Dr. Vijay P. Singh holds the Caroline & William N Lehrer Distinguished Chair in Water Engineering, is Professor of Civil and Environmental Engineering, and Professor of Biological and Agricultural Engineering at Texas A & M University. He has published more than 450 journal articles, 70 book chapters, 240 conference proceeding papers, and 70 technical reports and bulletins; authored or co-authored fourteen books and has edited another forty-five texts. Prof. Singh has made pioneering contributions in the application of systems analysis, kinematic wave theory, and entropy theory to a range of problems in hydraulics, water quality engineering, irrigation, hydrology and water resources. Prof. Singh has been the recipient of the ASCE Arid Land Hydraulic Engineering Award (2002) and the Ven Te Chow Award (2005), and most recently the AIH Ray K. Linsley Award for outstanding contributions to surface water hydrology. He has served as Editorin-Chief of the Water Science and Technology (WST) series for Springer, and also currently serves as Editor-in-Chief of the ASCE Journal of Hydrologic Engineering and Editor-Chief of Water Science and Engineering. He has directed the organization of 17 international conferences, chaired more than 40 conference sessions, given more than 35 keynote addresses, and examined more than 40 PhD. candidates abroad.

6 Preface Water is vital for life. Since the dawn of civilization, much effort has been made to harness sources of fresh water. Recent years have raised global awareness of the need for increasing demand of water worldwide, largely because of growing population, rising standard of living, higher demand for energy, and greater appreciation for environmental quality. As an example, the world population has increased threefold in the past five decades. In order to meet the rising water demand, water resources are being developed by building large dams, reservoirs, barrages and weirs across rivers worldwide. The guiding principle for water resources development has been to ensure adequate supply of water for agriculture, domestic use (including fine drinking water), waste disposal, industries, and energy production, with due attention to maintain the ecosystem functions. This development, however, depends on a holistic, cooperative and scientific approach. The basic inputs in the assessment of water resources for a given region are from hydrological data and the subject of hydrology forms the core in achieving sustainable development of water resources. Barring a few exceptions, hydrological data for most river basins are sparse and therefore it is difficult to comprehensively assess their water resources. The major source of water is rainfall which occurs as a result of condensation of atmospheric moisture governed by the science of meteorology. Rainfall, therefore, is the principal meteorological element whose recording with other meteorological elements, such as temperature, humidity, wind, and so on, was initiated a long time ago. That is why good networks of raingauge stations have been in existence for several decades in many countries of the world, and long rainfall records are not uncommon these days. Meteorologists, hydrologists and engineers have long recognized the value of hydrometeorological data and more importantly the rainfall data for hydrologic analyses. Thus, application and analysis of meteorological data for the solution of hydrologic problems has precisely come to be known as the science of

7 viii Preface hydrometeorology. In a broad sense, hydrometeorology is a border line science linking meteorology the science of atmosphere with hydrology the science of water of the earth and earth s atmosphere. In engineering hydrology dealing with design and operation of water resource projects, the subject of hydrometeorology occupies a central position. Obviously, the importance of the subject of hydrometeorology has become increasingly recognized and it is now studied not only by hydrologists and engineers but also by students from many different disciplines. Realizing the importance of the subject, there is a need for a textbook like the present one on applied hydrometeorology oriented towards the Asian environment, particularly to India, which can provide a complete set of tools to practicing engineers and hydrologists engaged in the planning, development and management of water resources. This constitutes the primary objective of this book. The emphasis in the book is on the practical applications of meteorology for water resources development and understanding of the needed meteorological concepts. The subject matter of the book follows this rationale. The book contains 15 chapters encompassing a wide spectrum of topics of hydrometeorology. Chapter 1 scopes out the area of hydrometeorology, and deals with meteorological variables and their use in hydrology, hydrological cycle, global distribution of land and water, and global water budget. Chapter 2 discusses the earth-atmospheric system. Included in the discussion are composition of the atmosphere, mass of atmosphere and hydrosphere, vertical structure of atmosphere, air density and its variation, hydrostatic equation, hydrostatics of special atmosphere, reduction of pressure to sea level, and atmospheric stability. The discussion of meteorological processes, constituting the subject matter of Chapter 3, includes compression and expansion of gases, forms of heat, equation of state for a perfect gas, isothermal and adiabatic changes, the first law of thermodynamics, adiabatic process, vertical motion in the atmosphere, mixture of gases, equation of state of moist air, and precipitable water. Chapter 4 deals with radiation and temperature. Beginning with a discussion of the source of heat and light, it goes on to discuss different aspects of radiation, mean annual heat balance, non-radiative heat exchange between the earth and the troposphere, heat balance, and temperature zones. Weather systems for precipitation are discussed in Chapter 5. Included in the discussion are pressure belts; wind systems of the earth; and scales of weather systems including planetary scale, synoptic scale, and meso scale of weather systems. Chapter 6 deals with weather and precipitation in India. The discussion in the chapter includes location and area, land forms, river basins, and seasons of India; climate controls; rainfall and runoff of continents; seasonal variation of pressure and temperature; onset and withdrawal of monsoons; weather systems affecting Indian rainfall; history of rainfall measurement in India; rainfall over India; assessment of rainwater resources; and present status of water utilization in India.

8 Preface ix Defining and classifying tropical disturbances and hurricanes, Chapter 7 discusses major hurricanes and super typhoons, wind rotation, conversion of wind speeds, formation of tropical storms, frequency of hurricanes for oceanic regions, absence of hurricanes in South Atlantic Ocean, naming hurricanes, life cycle of hurricanes, structure of hurricanes, hurricane climatology, record hurricane, largest rainfall from tropical storms/hurricanes, longest lasting hurricanes, climatic effects of hurricane activity, global warming and hurricanes, hurricane threats, damages and destruction, seeding of hurricanes, and damage caused by cyclones. Greatest point and areal rainfalls constitute the subject matter of Chapter 8. It includes significant point rainfall occurrences over India, China, Australia, and Japan; world s greatest point rainfalls; importance of greatest areal rainfalls; and greatest areal rainfalls over India, USA, Japan, and China. Recognizing rainfall as an important source of input for water resources, Chapter 9 covers precipitation and its measurement. It also encompasses mechanisms of precipitation, forms of precipitation, types of precipitation, measurement of precipitation, network design, estimation of missing data, mean depth of rainfall over an area, consistency of rainfall records, extension and interpretation of rainfall data, intensity-duration relationships, and point rainfall and areal rainfall relationships. The physical evaluation of probable maximum precipitation (PMP) based on a hydrometeorological procedure is a topic of considerable importance in designing large dams, reservoirs, and spillways and for the derivation of probable maximum floods (PMF). Techniques for estimating the PMP constitute the subject matter of Chapter 9. They discuss rainstorm analysis, depth-area-duration analysis, design storm, data for design storm studies, methods of estimating design storms, probable maximum precipitation, and methods of estimating PMP. Chapter 10 deals with design storm estimation. The material contained in this chapter is of particular value to design engineers. The discussion includes rainstorm and its analysis, depth-area-duration analysis of a rainstorm, design storms, data for design storm studies, methods for estimating design storms, probable maximum precipitation, and methods of estimating PMP. Statistical analysis of precipitation is presented in Chapter 11. It deals with data series for frequency analysis, recurrence interval, calculated risk, frequency analysis, measures of central tendency, measures of variability, skewness, and kurtosis (flattening), moments of frequency distribution, standard frequency distributions, tests of significance, homogeneity of data series, and frequency analysis. Foreshadowing rainfall is covered in Chapter 12. It includes measures of variability, correlation analysis, global scale factors affecting rainfall, types of weather forecasts, techniques for long-range rainfall forecasting in India, Indian summer monsoon and southern oscillation index, statistical techniques used in long range forecasting, multiple regression analysis, and parameters in long-range forecasting of Indian summer monsoon rainfall.

9 x Preface Chapter 13 deals with evaporation. Beginning with a discussion of the physics of evaporation, it goes on to discuss factors affecting evaporation, measurement of evaporation, evaporation measurement in India, and estimation of evaporation by indirect methods. Extreme hydrometeorological events that arise from unusually high and low precipitation lead to floods and droughts, respectively. These events cause considerable loss of life and property. Droughts constitute the subject matter of Chapter 14. It discusses causes of droughts, evapotranspiration and potential evapotranspiration, types of droughts, droughts in India, El Nino factor relating to droughts, and absence of tropical disturbances and Indian rainfall. The concluding chapter, Chapter 15, is on floods. Defining floods and classifying them, the chapter goes on to discuss the kinds and causes of floods, effects of floods, flood measurements, flood control, estimation of peak floods, flood frequency analysis, floods in Indian rivers, highest floods in India, and comparison of highest floods in India with world s highest floods. The text material of each chapter contains illustrative examples, which are mostly based on actual, recorded data. It is hoped that the book will be of much use to the professionals engaged in water resources planning, development, and management. Also the book should be useful to university courses concerned with hydrometeorology and its application to water-related issues, as it caters to the requirement of the syllabi of various Indian and foreign universities. There is vast literature on the topics in this book. A comprehensive list of references has been advertently omitted, and only those studies that are deemed most pertinent have been cited. This is because the intended audience would be more interested in applications rather than advanced literature. This, however, in no way reflects a lack of appreciation for the literature. Indeed this book would not have been completed without reviewing the pertinent literature. We have tried to make our acknowledgments as specific as possible. We would be most grateful if readers discovering any discrepancies, errors, or misprints would bring them to our attention. Our families provided unwavering support and help, without which this book would not have been completed. As a small token of our appreciation for their love and support, we dedicate this book to them. January 2009 Pukh Raj Rakhecha Vijay P. Singh

10 Contents About the Authors Preface vi vii 1. Introduction Scope of Hydrometeorology Meteorological Variables Earth System Orbital Motion of Earth and Seasons Global Distribution of Land and Water Global Water Budget Hydrologic Cycle 20 References The Atmosphere Earth-atmosphere System Composition of the Atmosphere Mass of the Atmosphere and the Hydrosphere Average Vertical Structure of Atmosphere Hydrostatic Equation Hydrostatics of Special Atmosphere Reduction of Pressure to Sea Level Atmospheric Stability and Instability 37 References Atmospheric Processes Heat and Temperature Compression and Expansion of a Gas Forms of Heat Equation of State for a Gas: Perfect Gas 41

11 xii Contents 3.5 Isothermal and Adiabatic Changes First Law of Thermodynamics Vertical Motion in the Atmosphere Mixture of Gases Equation of State of Moist Air Precipitable Water 50 References Radiation and Temperature Sun: The Source of Heat and Light Radiation Laws of Radiation Incoming Solar Radiation without Atmosphere at the Earth s Surface Passage of Solar Radiation through Average Atmospheric Condition Terrestrial Radiation Mean Annual Heat Balance of the Earth-Atmosphere System Non-radiative Heat Exchange between the Earth and the Troposphere Heat Balance Temperature Zones 68 References Weather Systems for Precipitation Pressure Belts and Wind Systems of the Earth Scale of Weather Systems Planetary Scale Weather Systems Synoptic Scale Weather Systems Meso Scale Weather Systems Oceanic Circulation 87 References Weather and Precipitation in India Location and Area of India Land Forms of India Climatic Control River Basins of India Rainfall and Runoff of Continents The Seasons of India Seasonal Variation of Pressure Mean Seasonal Variation of Air Temperature Onset and Withdrawal of Monsoons Main Weather Systems Affecting Indian Rainfall 111

12 Contents xiii 6.11 History of Rainfall Measurement in India Rainfall over India Assessment of Rainwater Resources of India Present Status of Water Utilization in India 122 References Tropical Storms and Hurricanes Definition Major Hurricanes and Super Typhoons Wind Rotation Formation of Tropical Storms Origin of Hurricanes Frequency of Hurricanes for Oceanic Regions Absence of Hurricanes in South Atlantic Ocean Naming of Hurricanes Life Cycle of Hurricanes Structure of Hurricanes Hurricane Climatology Most Intense Hurricanes on Record Largest Rainfall from Tropical Storms/Hurricanes Longest Lasting Hurricanes Climatic Effects of Hurricane Activity Global Warming and Hurricanes Hurricane Threats, Damage and Destruction 157 References Greatest Point and Areal Rainfalls Definitions Significant Rainfall Occurrences over India Significant Rainfall Occurrences over China Significant Rainfall Occurrences over Australia Significant Rainfall Occurrences over Japan World's Greatest Point Rainfalls Importance of the Greatest Areal Rainfalls Greatest Areal Rainfalls over India Greatest Areal Rainfalls over the USA Greatest Areal Rainfalls over China Greatest Areal Rainfalls over Australia 188 References Precipitation and Its Measurement Mechanisms of Precipitation Forms of Precipitation Types of Precipitation Measurement of Precipitation 194

13 xiv Contents 9.5 Network Design Estimation of Missing Rainfall Mean Depth of Rainfall Over an Area Consistency of Rainfall Records Extension and Interpretation of Rainfall Data Intensity-Duration Relationships Point Rainfall to Areal Rainfall Relationship 216 References Design Storm Estimation Rainstorm and its Analysis Depth-area-duration Analysis of a Rainstorm Design Storm Data for Design Storm Studies Methods for Estimating Design Storms Probable Maximum Precipitation Methods of Estimating PMP 230 References Statistical Analysis of Precipitation Data Series for Frequency Analysis Recurrence Interval Calculated Risk Frequency Analysis Measures of Central Tendency Measures of Variability Measures of Skewness Measure of Kurtosis (Flattening) Moments of Frequency Distribution Standard Frequency Distributions Homogeneity of Data Empirical Frequency Analysis Frequency Analysis by the Gumbel Method Frequency Factors 276 References Foreshadowing Precipitation Correlation Analysis Measure of Variability Global Scale Factors Affecting Rainfall Types of Weather Forecasts Development of Long Range Forecast of Rainfall in India Indian Summer Monsoon and Southern Oscillation Index Statistical Techniques in Long Range Forecast based on Improved Parameters 293

14 Contents xv 12.8 Multiple Regression Analysis Required Parameters in Long-range Forecasting of Indian Summer Monsoon Rainfall 297 References Evaporation Physics of Evaporation Factors Affecting Evaporation Measurement of Evaporation Evaporation Measurement in India Estimation of Evaporation by Indirect Methods 305 References Droughts Causes of Droughts Evapotranspiration and Potential Evapotranspiration Types of Droughts Droughts in India El Nino Factor Relating to Droughts Absence of Tropical Disturbances and Indian Rainfall 337 References Floods Definition of Flood Kinds of Floods Causes of Floods Effects of Floods Surface Runoff and Runoff Process Runoff Measurements Hydrograph Flood Control Estimation of Peak Flood Floods in Indian Rivers Highest Floods in India Comparison of the Highest Floods in India with World s Highest Floods 373 References 375 Appendix: World Weather Extremes 377 Index 379