This manual presents procedures for the design analysis and criteria of design for improved channels that carry rapid and/or tranquil flows.

Procedures are presented without details of the theory of the hydraulics involved since these details can be found in any of various hydraulic textbooks and publications available to the design engineer. Theories and procedures in design, such as flow in curved channels, flow at bridge piers, flow at confluences, and side drainage inlet structures, that are not covered fully in textbooks are discussed in detail with the aid of Hydraulic Design Criteria (HDC) charts published by the US Army Engineer Waterways Experiment Station (USAEWES).

The charts and other illustrations are included in Appendix B to aid the designer. References to HDC are by HDC chart number. The use of models to develop and verify design details is discussed briefly. Typical calculations are presented to illustrate the principles of design for channels under various conditions of flow. Electronic computer programming techniques are not treated in this manual. However, most of the basic hydraulics presented herein can be adapted for computer use as illustrated in Appendix D.

This manual describes methods for evaluating flood-runoff characteristics of watersheds. Guidance is provided in selecting and applying such methods to support the various investigations required for U.S. Army Corps of Engineers (USACE) civil works activities. The manual references publications that contain the theoretical basis of the methods and detailed information on their use. The manual is organized into four parts.

The first, Problem Definition and Selection of Methodology, describes the products of flood-runoff analysis and the types of investigation for which these products are required. Aspects of flood hydrology are discussed, including physical processes, data availability, and broad approaches to analysis. Guidance in formulating study procedures is provided, which includes criteria for method selection and recommended content for a hydrologic engineering management plan (HEMP). The reporting of study results is the focus of the last chapter in Part I.

Part II, Hydrologic Analysis, provides information on techniques for simulating various components of the hydrologic cycle, including rainfall, snow, infiltration (loss), surface and subsurface runoff, and flow in channels and reservoirs. Multisubbasin modeling and design storm definition are discussed.

Part III, Methods for Flood-Runoff Analysis, addresses the application of simplified techniques, frequency analysis of streamflow data, precipitation-runoff simulation of storm events, and period-of-record precipitation-runoff simulation. Data requirements and calibration / verification of simulation models are considered.

Part IV, Engineering Applications, deals with several issues associated with the application of methods from Part III. The processing of data can be time-consuming and costly; techniques for efficient data handling are addressed. The lack of historical streamflow data is the source of much difficulty and uncertainty in flood runoff analysis. Aspects of dealing with “ungauged” basins are discussed. Issues associated with the development of frequency-based estimates are covered, including the concept of calibration to “known” frequency information. Various aspects of modeling land use change, as well as the effects of reservoir and other projects, are discussed. Finally, three examples illustrate some of the principles presented in this manual.

Following Part IV, Appendices A and B provide references, a generic HEMP, and a set of example applications.

This engineer manual (EM) relies on references and/or technical information in several other guidance documents. Some of those documents are part of this current guidance effort and others are older documents. The most relevant documents are EM 1110-2-1416, River Hydraulics, EM 1110-2-1415, Hydrologic Frequency Analysis, and EM 1110-2-1413, Hydrologic Analysis of Interior Areas.

This Engineer Manual provides guidance to Corps of Engineers (CE) personnel who are responsible for groundwater-related projects. This manual was written with special attention to groundwater-related applications prevalent within the CE. Thus, sections addressing site investigation procedures and the performance of modeling studies are included. Additionally, a chapter focusing on the interaction between surface water and groundwater is included.

This manual applies to all USACE Commands having civil works responsibilities. This manual provides information for application to common Corps groundwater-related studies, including:

1. Site characterization for contaminant remediation.
2. Computer modeling of groundwater flow.
3. Groundwater and surface water interaction studies.
4. Reservoir operations.
5. Groundwater flow to adjacent locks and dams.
6. Remediation of reservoir leakage.
7. Infiltration of runoff to the subsurface.
8. Baseflow between aquifers and fixed bodies including streams and reservoirs.
9. Effects of aquifer pumping on adjacent lakes and streams.
10. Well installation involved with seawater infiltration barriers.
11. Dewatering of an excavation for construction purposes.
12. General regional and local applications.