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<br />e <br /> <br />~~ <br />. <br /> <br />'1' <br /> <br />e <br /> <br />( <br /> <br />if <br /> <br />e <br /> <br />Chapter 1 <br />Introduction <br /> <br />1.1. Purpose <br /> <br />This manual presents the techniques and procedures that <br />are used to investigate and resolve river engineering and <br />analysis issues and the associated data requirements. It <br />also provides guidance for the selection of appropriate <br />methods to be used for planning and conducting the <br />studies. Documented herein are past experiences that <br />provide valuable infonnation for detecting and avoiding <br />problems in planning, perfonning, and reporting future <br />studies. The resolution of river hydraulics issues always <br />requires prediction of one or more flow parnmeters; be it <br />stage (i.e., water surface elevation), velocity, or rate ~f <br />sediment transport. This manual presents pragmatic <br />methods for obtaining data and perfonning the necessary <br />computations; it also provides guidance for detennining <br />the components of various types of studies. <br /> <br />1.2, Scope <br /> <br />Procedures for conducting river hydraulic investigations <br />are presented herein with minimal theory. Details of the <br />theoretical principles of river hydraulics can be found in <br />standard textbooks and publications that are referenced <br />throughout this manual. Each chapter provides general <br />infonnation and guidance to assist and support decisions <br />regarding choice of the most appropriate analytical and/or <br />modeling methods and data acquisition for specific <br />circumstances. <br /> <br />1.3. Applicability <br /> <br />This guidance applies to HQUSACE elements, major <br />subordinate commands, laboratories, and field operating <br />activities having civil works responsibilities. <br /> <br />1.4, References <br /> <br />References are listed in Appendix A. <br /> <br />1.5, Needs for River Hydraulics Studies <br /> <br />Missions of the Corps of Engineers include the develop- <br />ment and maintenance of flood control and navigation <br />systems. It is the policy of the Corps of Engineers to <br />plan, design, construct, and provide for the maintenance <br />of safe, functional, cost,effective projects. River hydran, <br />lic analyses are an essential component of most riverine <br /> <br />EM 111()"2.1416 <br />15 0Cl93 <br /> <br />projects, and the results from these analyses are often <br />critical to project fonnulation, design, construction, and <br />operation throughout the project's life. River hydraulics <br />includes the evaluation of flow characteristics and goo- <br />mmphic (physical) behavior of rivers and changes in <br />these due to natura1 or man-made conditions. <br /> <br />As examples, determination of the elevations of dams, <br />spillways, levees, and floodwaIls requires both hydrologic <br />and hydraulic computations. A major component of <br />studies related to floodplain information, flood control <br />channel design, navigation, water quality assessment, <br />environmental impact and enhancement analysis, is the <br />prediction of stage, discharge, and velocity as functions <br />of time anywhere on a river. Environmental aspects of <br />river engineering often require the prediction of stage, <br />velocity distributions, sediment transport rates, and water <br />quality characteristics, to evaluate the impacts of pro- <br />posed actions on future river characteristics. Study of <br />any type of river project requires a thorough evaluation <br />of the possible impacts tbat it may have, both upstream <br />and downstream from the location of the project itself. <br />Prediction of the operation, maintenance, and repair or <br />replacement requirements of existing and proposed pro- <br />jects is another role that river hydraulics studies play in <br />the Corps' planning and design processes. <br /> <br />1.6. General Methods <br /> <br />Reliable assessment and resolution of river hydraulics <br />issues depend on the engineer's ability to understand and <br />describe, in both written and mathematical forms, the <br />physical processes that govern a river system. Provided <br />herein are background infonnation and technical proce- <br />dures necessary to perfonn river hydraulics engineering <br />studies. This manual provides river engineers at all <br />levels of experience with a wide range of practical field <br />examples, diagnostic advice. and guidance for perfonning <br />river hydraulics investigations. Three categories of <br />methods for predicting river hydraulic conditions were <br />identified by Rouse (1959). The first and oldest uses <br />engineering experience acquired from previous practice <br />by an individual. The second utilizes laboratory scale <br />models (physical models) to replicate river hydraulic <br />situations at a specific site or for general types of struc- <br />tures. Laboralory modeling has been in extensive and <br />successful use for at least the past 60 years. The third <br />category is application of analytical (mathematical) <br />procedures and numerical modeling. Recent use of phys, <br />ical and numerical modeling in combination, guided by <br />engineering experience, is tenned "hybrid modeling" and <br />has been very successful. <br /> <br />1.1 <br />