Table of Contents CHAPTER 1: INTRODUCTION .............................................................................................. 14 1.1 General .................................................................................................................................... 14 1.2 Status of Urban Drainage System in India ......................................................................... 14 1.3 Causes of urban flooding ...................................................................................................... 15 1.4 Need for Storm Water Drainage Manual ............................................................................ 16 1.5 Scope of Manual ..................................................................................................................... 17 1.6 Use of Manual ......................................................................................................................... 18 CHAPTER 2: PROJECT PLANNING AND INVESTIGATION .............................................. 19 2.1 General .................................................................................................................................... 19 2.2 Objectives of Planning & Investigation ................................................................................ 19 2.3 Data Collection, Survey and Investigation ......................................................................... 20 2.3.1 Data Collection ............................................................................................................... 20 2.3.2 Survey and Investigation ............................................................................................... 22 2.4 Other Considerations ............................................................................................................. 23 2.4.1 Permissions and Clearances ....................................................................................... 23 2.4.2 Environmental Consideration ....................................................................................... 23 2.5 Hydraulic Design of Storm Water Drainage Systems ....................................................... 24 2.5.1 Inlet locations .................................................................................................................. 25 2.5.2 Manholes (MHs) and its locations ................................................................................ 25 2.5.3 Pumping of storm runoff ................................................................................................ 25 2.5.4 Outfall Structures ............................................................................................................ 26 2.5.5 Natural Streams/ River .................................................................................................. 26 2.5.6 Augmentation and Rehabilitation of Existing Drainage system .............................. 26 2.6 Financing ................................................................................................................................. 27 2.7 Operation & Maintenance ..................................................................................................... 28 2.8 Citizen Awareness ................................................................................................................. 28 2.9 Institutional Arrangement and Capacity Building .............................................................. 28 2.10 Service Level Benchmark ..................................................................................................... 28 2.11 Checklist for DPR preparation ............................................................................................. 29 CHAPTER – 3: RAINFALL ANALYSIS .................................................................................. 30 3.1 General .................................................................................................................................... 30 3.2 Rainfall ..................................................................................................................................... 30 Page 1 of 272 3.2.1 Measurement of Rainfall ............................................................................................... 30 3.3 Rain Gauge Density ............................................................................................................... 33 3.4 Rainfall Analysis ..................................................................................................................... 33 3.4.1 Steps for Analysis of Rainfall ........................................................................................ 34 3.5 Alternative Method of Rainfall Analysis .............................................................................. 44 3.6 Probabilistic Method ............................................................................................................... 46 3.6.1 Normal Distribution and Log Normal Distribution ...................................................... 46 3.6.2 Gumbel Extreme Value Distribution ............................................................................ 46 3.6.3 Log Pearson Type III Distribution ................................................................................ 49 3.7 Translation of IDF curve into rainfall hyetograph .............................................................. 53 CHAPTER 4: RUNOFF ESTIMATION .................................................................................... 55 4.1 General .................................................................................................................................... 55 4.2 Storm Runoff ........................................................................................................................... 55 4.3 Estimation of runoff from rainfall .......................................................................................... 56 4.4 Methods of runoff estimation ................................................................................................ 56 4.4.1 Rational Method ............................................................................................................. 56 4.4.2 Time Area Method .......................................................................................................... 64 4.4.3 Unit Hydrograph Method ............................................................................................... 67 4.4.4 Rainfall- runoff process simulation .............................................................................. 68 4.5 Climate Change effects on Urban Storm Runoff ............................................................... 71 CHAPTER 5: HYDRAULIC DESIGN OF STORM WATER DRAINS .................................... 73 5.1 General .................................................................................................................................... 73 5.2 Storm water flows in Channels and Conduits .................................................................... 73 5.3 Design consideration for surface/ sub surface drains....................................................... 77 5.3.1 Permissible limit of Velocity in storm conduits ........................................................... 77 5.3.2 Freeboard in channel ..................................................................................................... 78 5.3.3 Curves / bends in drains................................................................................................ 78 5.3.4 Junction Sump for storm water drain intersection ..................................................... 79 5.3.5 Hydraulically Efficient Channel Section ...................................................................... 79 5.3.6 Partially Filled Circular Section .................................................................................... 81 5.4 Design Sheet ........................................................................................................................... 85 5.5 Gutters and Inlets ................................................................................................................... 91 5.5.1 Gutter ............................................................................................................................... 91 5.5.2 Design of Gutters............................................................................................................ 91 Page 2 of 272 5.5.3 Composite Gutter Sections ........................................................................................... 93 5.6 Storm water inlets ................................................................................................................... 95 5.6.1 Types of inlets ................................................................................................................. 95 5.6.2 Street Inlet ....................................................................................................................... 96 5.6.3 Location of inlets ............................................................................................................. 98 5.7 Gradually Varied Non-uniform Flow .................................................................................... 99 5.7.1 Basic equation for gradually varied flow ................................................................... 100 5.7.2 Method of solution of the gradually varied flow equation ......................................