United States Department of National Agriculture Engineering Soil Conservation Handbook Service Section 3 Sedimentation Table of Contents Chapter 1 -- Introduction Chapter 2 -- Sediment Properties Chapter 3 -- Erosion Chapter 4 -- Transmission of Sediment by Water Chapter 5 -- Deposition of Sediment Chapter 6 -- Sediment Sources, Yields, and Delivery Ratios Chapter 7 -- Field Investigations and Surveys Chapter 8 -- Sediment-Storage Design Criteria Chapter 9 -- Units and Equivalents United States Soil P.O. Box 2890 Department of Consewation W shington, D.C. Agriculture Service 2&13 December 12,1983 NATIONAL ENGINEERING HANDBOOK, SECTION 3 (Second Editipn) 210-VI SUBJECT: ENG - SECTION 3, SEDIMENTATION Purpose. To replace Section 3. Effective Date. Effective uhen received. Explanation. All the old chapters have been revised, some chapters renumbered, and some new chapters added. Filing Instructions. Remove and discard existing Section 3 and replace with enclosed Section 3, Second Edition. Ordering Instructions. Additional copies may be ordered from Central Supply using order number NEH-003, Second Edition. PAUL M. HOWARD Deputy Chief for Technology Development and Application Enclosure DIST: NEH-003 The Soil Conservation Service is an agency of the Department of Agriculture U.S. DEPARTMENT OF A(3RICULTURE SOIL CONSERVATION SERVICE' DISTRIBUTION AND CHECK LIST OTHER 1m Central SUDD~V- 4420 Robert Shelton - 500 1 -- - , *d OR41 I 10 PA42 I 10 PR-72 i 5 R144 5 sc45 I 10 SO46 I 10 TN47 10 TX48 15 1 UT49 10 Srand Total I VT.50 5 VA-51 10 5500 WA-53 10 REMARKS WV.54 1 10 ~1.55 i lo WY.56 1 10 Total States 1 I Contents Page Purpose and scope. ........................................................................1-1 Responsibilities of SCS geologists. ...........................................................1-2 Chapter 1 Introduction Purpose and Scope i This section of the National Engineering Hand- in training SCS geologists and in maintaining \J' book presents in brief and usable form applications uniform procedures and standards for SCS work. of the principles of geology and hydraulic engineer- Knowledge of sedimentation and its application ing to the solution of sedimentation problems en- to the planning and operation of SCS programs is countered in programs of the Soil Conservation relatively new. Insufficient research contributes to Service (SCS). These programs and the sedimenta- uncertainty about approaches to some problems. tion investigations that serve them require a versa- Although specific examples are not included, pos- tile approach. sible approaches to these problems are outlined to Section 3 is necessarily limited to aspects of assist geologists in reaching reasonable solutions. sedimentation that pertain directly to SCS pro- Procedures found to be adequate for use nationally grams. Emphasis is, therefore, given to problems are outlined in detail and can be considered stan- affecting the evaluation of erosion and sediment- dard for SCS work. storage damages, formulation of programs for reducing these damages, and sediment-storage design criteria for structural works of improvement for the beneficial use, control, and conservation of soil and water resources. References at the end of each chapter list some of the more important literature related to the topic of that chapter. To help geologists acquire a complete understand- ing of a problem and make the investigations and computations necessary for a technically sound solution, this section describes typical problems arising in sedimentation investigations and outlines basic considerations and step-by-step pro- i cedures for solving them. These examples will help ~ Responsibilities of SCS Geologists The primary responsibilities of geologists in SCS programs are sedimentation investigations, damsite explorations, and ground-water investigations. General information, methods, and procedures to be used by geologists are presented in three sections of the National Engineering Handbook: Section 3, Sedimentation; Section 8, Engineering Geology; and Section 18, Ground Water. Section 3 is designed to help geologists select and follow procedures for making sedimentation in- vestigations. Geologists are responsible for making the required investigations in enough detail to pro- vide sound and factual information that supports their recommendations. Depending on the serious- ness of the problem, the degree of investigation can range from a brief reconnaissance of the area to detailed measurements of erosion and the effects of sediment. The objective of this section is to provide general guidance for making sedimentation investigations. Geologists must assemble information through observation, experience, and comparison with similar areas in the vicinity. No fixed method of investigation should be substituted for thinking. When there is doubt about the proper methods of solving sedimentation problems, the advice of the national technical center (NTC) sedimentation geologist should be sought. Contents Page i General ................................................................................. 2-1 Derivation of sediments .................................................................... 2-2 Disintegration .......................................................................... 2-2 Decomposition .......................................................................... 2-2 Carbonation ........................................................................... 2-3 Hydration ............................................................................. 2-3 Oxidation ............................................................................. 2-3 Solution .............................................................................. 2-3 Soilformation ........................................................................... 2-3 Particle characteristics ..................................................................... 2-5 Size ................................................................................... 2-5 Shape ..................................................................................2-5 Specificgravity ........................................................................ 2-5 Size distribution of sediments ............................................................... 2-8 Fine-grainseparation .................................................................... 2-8 Sieveseparation ......................................................................... 2-8 Fallvelocity ............................................................................ 2-8 Bulk properties ........................................................................... 2-11 Sorting ................................................................................ 2-11 Glacial and other ice-action deposits ...................................................... 2-11 Alluvialfans .......................................................................... 2-11 Alluvial deposits ....................................................................... 2-11 Beach deposits ......................................................................... 2-11 Colluvial deposits ...................................................................... 2-11 Marine sediments ...................................................................... 2-11 Eoliandeposits ........................................................................ 2-12 Lacustrine deposits ..................................................................... 2-12 Chemical deposits and evaporites ......................................................... 2-12 Texture ................................................................................2-12 Volume-weight ........................................................................ 2-13 Stability of sediment deposits ............................................................ 2-13 Porosity .............................................................................. 2-13 Permeability .......................................................................... 2-14 References ............................................................................... 2-17 Figures Page 2-1. Dimensions required for sphericity and roundness calculations . 2-7 2-2. Grain-size distribution graph . 2-9 2-3. Settling rates of sediment particles . 2-10 Page 2-1. Chemical weathering products of common rock-forming silicate minerals . 2-4 2-2. Common minerals: their hardness, specific gravity, and frequency of occurrence in average igneous rocks and sediments. 2-6 2-3. Sediment grade scales . 2-7 2-4. Volume-weight of reservoir sediment . 2-14 2-5. Approximate average porosity of various formations . 2-14 2-6. Permeability and porosity as related to grain-size distribution . 2-15 Chapter 2 Sediment Properties General Sediments are the products of disintegration and Small grains of certain minerals resistant to decomposition of rocks. Material becomes detached chemical weathering, such as zircon, quartz, rutile, and is transported to a deposition site where it tourmaline, topaz, and ilmenite, remain in sedi- may be affected by solution, cementation, consolida- ment relatively unchanged. These detrital mineral tion, or biological action. suites may reveal the source rock type (Krumbein The physical properties of sediments depend on a and Sloss 1963, p. 108). Feldspars, the most com- number of factors, including composition, texture, mon minerals in igneous rock (Pettijohn 1957, p. and structure of the