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Chapter 19 Hydrology Tools for Wetland Identification and Analysis Part 650 Engineering Field Handbook National Engineering Handbook Chapter 19 Hydrology Tools for Wetland Identification and Analysis (210–VI–NEH, September 2015) Chapter 19 Hydrology Tools for Wetland Identifica- Part 650 Engineering Field Handbook tion and Analysis National Engineering Handbook Issued September 2015 The U.S. Department of Agriculture (USDA) prohibits discrimination against its customers. If you believe you experienced discrimination when obtaining services from USDA, participating in a USDA program, or partici- pating in a program that receives financial assistance from USDA, you may file a complaint with USDA. Information about how to file a discrimination complaint is available from the Office of the Assistant Secretary for Civil Rights. USDA prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applica- ble, sex (including gender identity and expression), marital status, familial status, parental status, religion, sexual orientation, political beliefs, genetic information, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) To file a complaint of discrimination, complete, sign, and mail a program discrimination complaint form, available at any USDA office location or online at www.ascr.usda.gov, or write to: USDA Office of the Assistant Secretary for Civil Rights 1400 Independence Avenue, SW. Washington, DC 20250-9410 Or call toll free at (866) 632-9992 (voice) to obtain additional information, the appropriate office or to request documents. Individuals who are deaf, hard of hearing, or have speech disabilities may contact USDA through the Federal Relay service at (800) 877-8339 or (800) 845-6136 (in Spanish). USDA is an equal opportunity provider, employer, and lender. Persons with disabilities who require alternative means for communication of program information (e.g., Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). (210–VI–NEH, Amend. 75, September 2015) Acknowledgments Chapter 19, Hydrology Tools for Wetland Identification, is one of the 19 chapters of the U.S. Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) National Engineering Handbook (NEH), Part 650. This chapter is designated Engineering Field Handbook (EFH), Part 650.19. Other chapters that are pertinent to and should be referenced in use with chapter 19 are: Part 650.01 Engineering Surveys Part 650.02 Estimating Runoff Part 650.03 Hydraulics Part 650.04 Elementary Soils Engineering Part 650.05 Preparation of Engineering Plans Part 650.06 Structures Part 650.07 Grassed Waterways and Outlets Part 650.08 Terraces Part 650.09 Diversions Part 650.10 Gully Treatment Part 650.11 Ponds and Reservoirs Part 650.12 Springs and Wells Part 650.13 Wetland Restoration, Enhancement, or Creation Part 650.14 Drainage Part 650.15 Irrigation Part 650.16 Streambank and Shoreline Protection Part 650.17 Construction and Construction Materials Part 650.18 Soil Bioengineering for Upland Slope Protection and Erosion Reduction Part 650.19 was first issued in August 1997. This revision was done to incor- porate significant advances in the science and practice of wetland hydrolo- gy. It maintains the significant work done by the original task group, whose efforts were maintained and built upon to produce this update. This chapter was edited by Richard A. Weber, wetland hydraulic engineer, Wetland Team, Central National Technical Service Center. The revision team provided content, editorial assistance, and valuable review: Pat Willey, drainage/wetland engineer, NRCS, Portland, OR Sonia Jacobsen, hydraulic engineer, NRCS, St. Paul, MN Bill Reck, environmental engineer, NRCS, Greensboro, NC Jerry Walker, water management engineer, NRCS, Fort Worth, TX The editors and contributors acknowledge valuable contributions provided by: Chris Ritz, civil engineer, NRCS, Indianapolis, IN Karl Visser, hydraulic engineer, NRCS, Fort Worth, TX Dr. Marcel Schaap, assistant professor in environmental physics, the Uni- versity of Arizona (210–VI–NEH, Amend. 75, September 2015) Chapter 19 Hydrology Tools for Wetland Identifica- Part 650 Engineering Field Handbook tion and Analysis National Engineering Handbook Editorial assistance was provided by Wendy Pierce, illustrator, and Suzi Self, editorial assistant, NRCS, Technical Publications, National Geospatial Center of Excelence,Fort Worth, TX. 19–ii (210–VI–NEH, Amend. 75, September 2015) Chapter 19 Hydrology Tools for Wetland Determination and Analysis Contents 650.1900 Introduction 19–1 650.1901 Normal environmental conditions 19–2 (a) Definition of normal environmental conditions .......................................19–2 (b) Current conditions and long-term conditions ...........................................19–2 (c) Data sources ..................................................................................................19–2 650.1902 Soil survey information 19–6 (a) Introduction ...................................................................................................19–6 (b) Flooding and ponding ...................................................................................19–6 (c) Depth to water table ....................................................................................19–7 (d) Limitations .....................................................................................................19–7 (e) Example ..........................................................................................................19–7 650.1903 Hydrogeomorphic wetland classes 19–9 (a) Introduction to hydrogeomorphic wetland classification ........................19–9 (b) The HGM wetland classes ..........................................................................19–10 (c) Soil taxonomy, descriptive terms, and HGM ...........................................19–10 (d) Description of HGM wetland classes ........................................................19–12 650.1904 Probability-duration analysis using daily data 19–19 (a) Introduction .................................................................................................19–19 (b) Example ........................................................................................................19–20 650.1905 The wetland water budget and data sources 19–22 (a) Introduction .................................................................................................19–22 (b) Water budget parameters ...........................................................................19–22 (c) The water budget .........................................................................................19–22 (d) Data sources ................................................................................................19–22 (e) Water budget applications ..........................................................................19–27 (f) The time step ...............................................................................................19–27 (g) Simplified water budget applications .......................................................19–28 (i) Applicability to HGM classes .....................................................................19–28 650.1906 Tidal—estuarine applications 19–31 (a) Introduction .................................................................................................19–31 (b) Tide data .......................................................................................................19–31 (c) The tidal cycle ..............................................................................................19–32 (d) Tidal inlet hydraulics ..................................................................................19–32 (e) Hydrologic Engineering Center River Analysis System ........................19–33 (HEC-RAS) analysis (210–VI–NEH, Amend. 75, September 2015) Chapter 19 Hydrology Tools for Wetland Identifica- Part 650 Engineering Field Handbook tion and Analysis National Engineering Handbook 650.1907 Lake data applications 19–36 (a) Introduction .................................................................................................19–36 (b) Lake level data .............................................................................................19–36 (c) Other information ........................................................................................19–37 650.1908 Floodplain applications 19–37 (a) Introduction .................................................................................................19–37 (b) Limitations ...................................................................................................19–37 (c) Cases ............................................................................................................19–38 650.1909 Drainage equations for lateral effect determination 19–54 (a) Introduction .................................................................................................19–54 (b) Applicability to HGM Classes ....................................................................19–55 (c) Drainage theory and methods ....................................................................19–55 (d) Soil physics ..................................................................................................19–57 (e) Drainage equations ......................................................................................19–64
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