The purpose of the Bridge Hydraulics is to enable practising engineers to conduct a competent hydraulic analysis of the flow through a bridge waterway. This analysis may be part of the design of a new bridge or an analysis of an existing structure to determine the backwater to see if it significantly exacerbates flooding upstream. It may be necessary to produce a mathematical or computer model of the flow of the river. Most of the published work relating to bridge hydraulics is contained in relatively obscure research publications that are not readily available to practising engineers. Some general texts on hydraulics (e.g. Chow, Open-channel Hydraulics) summarize parts of this research, but because of the need for brevity, only cover one of about four possible methods of analysis. Frequently one of the other methods would be more suitable. None of the existing publications guide the reader as to which method to use under what circumstances, or bother to explain the factors involved in bridge hydraulics and why they are so important. Thus engineers who are not specialists in this field (and even those that are) struggle to analyse and design bridge waterways effectively. The aim of the book is to provide an introduction to bridge hydraulics by introducing and explaining the significance of the variables involved, and summarizing all of the available methods of analysing and designing bridge waterway openings. This will provide an authoritative guide to the strengths and weaknesses of the methods, which to use under various circumstances, and the accuracy to be expected. Numerical examples will be provided where appropriate. Details of how to improve the hydraulic efficiency of a bridge will also be included. The book will cover single and multispan bridges with either rectangular or arched openings. Arched openings have often been omitted in the past but there are thousands of arch bridges in the UK and thus this book is the first to consider them in detail. The book will provide practising engineers with the means to design more authoritatively bridge waterway openings, thus making their designs more appropriate and more acceptable to the agencies that have to approve the proposals.