Title 210 – National Engineering Handbook Part 650 Engineering Field Handbook National Engineering Handbook Chapter 10 Gully Treatment (210-650-10, 2020 Ed., Feb 2021) Title 210 – National Engineering Handbook Issued February 2021 In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from discriminating based on race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident. Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the responsible Agency or USDA's TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA through the Federal Relay Service at (800) 877-8339. Additionally, program information may be made available in languages other than English. To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: [email protected]. USDA is an equal opportunity provider, employer, and lender. (210-650-10, 2020 Ed., Feb 2021) 650.10-i Title 210 – National Engineering Handbook Chapter 10 Gully Treatment Table of Contents 650.1000 Introduction .............................................................................................................. 10.1 (A) Purpose and Scope ....................................................................................................... 10.1 (B) Definition ..................................................................................................................... 10.1 (C) Impacts of Gullies ........................................................................................................ 10.2 (D) Causes of Gullies ......................................................................................................... 10.3 650.1001 Planning .................................................................................................................... 10.4 (A) Process Overview ........................................................................................................ 10.4 (B) General Planning Considerations ................................................................................. 10.4 (C) Channel Evolution Model ............................................................................................ 10.5 650.1002 Gully Treatments ...................................................................................................... 10.8 (A) Overview ..................................................................................................................... 10.8 (B) Gully Treatment by Vegetative Means ........................................................................ 10.8 (C) Gully Treatment by Filling and Shaping .................................................................... 10.10 (D) Gully Treatment by Water Diversion or Retention .................................................... 10.11 (i) Water Diversion .................................................................................................... 10.11 (ii) Water Retention ................................................................................................... 10.12 (E) Gully Treatment by Grade Stabilization Structures .................................................... 10.13 (i) Structural Measures .............................................................................................. 10.14 (ii) Earthfill Structures with Vegetated Spillway Only: ............................................. 10.16 (iii) Gully Plugs ......................................................................................................... 10.16 (iv) Gully Farming ..................................................................................................... 10.16 (F) Gully Treatment and Sediment Control with Water and Sediment Control Basins .... 10.16 (G) Gully Treatment by Structures for Water Control...................................................... 10.17 650.1003 Surveys ................................................................................................................... 10.19 650.1004 Design Guidelines................................................................................................... 10.19 650.1005 Installation of Measures .......................................................................................... 10.21 650.1006 Maintenance ........................................................................................................... 10.22 650.1007 References .............................................................................................................. 10.23 650.1008 Acknowledgments .................................................................................................. 10.24 (210-650-10, 2020 Ed., Feb 2021) 650.10-ii Title 210 – National Engineering Handbook Table of Figures Figure 10-1: Typical gully formation showing steep sides and upslope expansion ................. 10.1 Figure 10-2: Gullies can rapidly expand and adversely impact farmland ................................ 10.2 Figure 10-3: Floodwater storage in this watershed dam has been severely impacted by sedimentation ......................................................................................................................... 10.3 Figure 10-4: The Channel Evolution Model (from Figure 3-4a 210-NEH-654-3) ................... 10.6 Figure 10-5: A vegetated swale - CEM Type I without channel .............................................. 10.6 Figure 10-6: Newly formed gully advancing into a HGM Slope wetland ............................... 10.8 Figure 10-7: Gully site stabilized with shaping and vegetation ............................................... 10.9 Figure 10-8: Gully site stabilized with filling, shaping and planting to a grass waterway ..... 10.11 Figure 10-9: Gully forming by emptying terraces into an unprotected outlet ........................ 10.12 Figure 10-10: Terrace system protecting field from gully formation ..................................... 10.13 Figure 10-11: Concrete drop structures at outlet of grassed waterways ................................. 10.14 Figure 10-12: Gullies treated with aluminum drop structure, shaping, and critical area planting ............................................................................................................................................. 10.15 Figure 10-13: Gully treated with a pond structure ................................................................. 10.15 Figure 10-14: Gullies treated with low structures and gully farming ..................................... 10.16 Figure 10-15: Critical water flow profile ............................................................................... 10.17 Figure 10-16: Layout of Structures........................................................................................ 10.18 Figure 10-17: Stone water control structures used for stabilization of a slope wetland ......... 10.18 (210-650-10, 2020 Ed., Feb 2021) 650.10-iii Title 210 – National Engineering Handbook Part 650 – Engineering Field Handbook Chapter 10 – Gully Treatment 650.1000 Introduction (A) Purpose and Scope (1) Chapter 10 provides conservation professionals with a guide for the stabilization of active gullies by vegetative, structural measures or a combination thereof. The focus of this chapter is on gullies formed by precipitation runoff and seeps. (2) This chapter is national in scope and will often be supplemented with regional and local information. Additional background on specific designs and sample calculations are available in other sources such as Title 210, National Engineering Handbook, Part 654, “Stream Restoration Design Guide” (210-NEH-654)– Technical Supplement 14P, “Gullies and Their Control”. (B) Definition (1) One of the most severe erosion forms addressed by the Natural Resources Conservation Service (NRCS) measures are gullies. Gullies are entrenched channels extending into areas with previously undefined or weakly defined channels. Gullies can be thought of as extensions of a watershed drainage system up into the landscape. (2) If unchecked, gullies can erode and deliver sediment through a variety of processes that cause loss in soil productivity, channel entrenchment and headward expansion into the landscape. Under extreme conditions, gullies can expand into hillslopes extending up to the topographic watershed divide. Active gullies are recognized