1 VIRGINIAWORKSHOP Feb. 28 – Mar. 3, 2006 INTRODUCTION to SITES for WATER RESOURCE SITE ANALYSIS

2 OBJECTIVE Describe general range of SITES model application

3 HISTORY Program Developed Over Time by NRCS Spillway Erosion Technology Developed Jointly by ARS and NRCS Interface, developed to provide a user- friendly environment

4 SITES ? ? ? Watershed Rainfall-Runoff Reservoir Routing –Principal spillway rating –Auxiliary spillway rating –NRCS dam design features Earth Spillway Analysis Complex Watersheds – Upstream sites and subwatersheds – Reach routing

5 TYPICAL DAM XSECTION OUTLET STRUCTIRE PSH SDH

6 SITES Model

7 HISTORY Program Developed Over Time by NRCS Spillway Erosion Technology Developed Jointly by ARS and NRCS Interface, developed to provide a user-friendly environment

8 ERODED SPILLWAY

9 LABORATORY SPILLWAY MODEL

10 Auxiliary Spillway Profile Inlet Natural Ground Constructed Inlet Channel Constructed Exit Channel Exit Natural Ground Tie Sta. Flow

11 SITES STABILITY ANALYSIS TECHNOLOGY OPTIONSTECHNOLOGY OPTIONS PERMISSIBLE VELOCITYPERMISSIBLE VELOCITY ALLOWABLE STRESS ALLOWABLE STRESS

12 Old TR-60 Table 7-1 had corrections for Permissible Velocities. 10% for not more than once in 50 years and 25% for not more than once in 100 years. To make stress on an equal footing as velocity the same type of correction needs to be made. Stress is proportional to the square of the velocity. 1 in 50 (1.10) 2 = 1.21 say a 20% increase 1 in 100 (1.25) 2 = say a 50% increase

13 The new TR-60 p 7-3 (2005) stability requirements for vegetated spillways has been revised. The allowable velocity table has been removed and allowable stress is now required. The stress is to be determined by the use of AH-667 with the following adjustments: Once in 50 years 20% increase in stress Once in 100 years 50% increase in stress

14 BARE EARTH  e =  ds EFFECTIVE STRESS

15 EFFECTIVE STRESS VEGETATION VEGETATION  e =  ds (1-C f ) (n s /n) 2

16 Note: If C f = 0.9 then (1-C f ) = 0.1 and if C f = 0.8 then (1-C f ) = 0.2 ===> this is a 100% increase in effective stress. From soil grain roughness if n s = & n = D 75 = 0.05” (n s /n) 2 = A 100% increase from a change in soil roughness requires a D 75 = 0.40”

17 MAINTENANCE CODE 1 - UNIFORM COVER OR SURFACE 2 - MINOR DISCONTINUITIES 3 - MAJOR DISCONTINUITIES

18 SITES AUXILIARY SPILLWAY STABILITY ANALYSIS BASED ON PEAK OF SDH BASED ON PEAK OF SDH APPLIED TO EXIT CHANNEL APPLIED TO EXIT CHANNEL VELOCITY OR STRESS calculations VELOCITY OR STRESS calculations

19 MASS MOVEMENT

20 SPILLWAY EROSION PHASES INTEGRITY ANALYSIS 1. SURFACE EROSION 1. SURFACE EROSION (Cover Destruction) 2. CONCENTRATED FLOW EROSION 3. HEADCUT ADVANCE

21 COVER FAILURE INITIATION

22 HEADCUT

23 EXPANDING HEADCUT

24 SPILLWAY GEOLOGY STATION ELEVATION, ft

25 SPILLWAY SURFACE STATION ELEVATION, ft

26 ERODED PROFILE ELEVATION STATION, ft ERODED AREA

27 HISTORY Program Developed Over Time by NRCS Spillway Erosion Technology Developed Jointly by ARS and NRCS Interface developed to provide a user-friendly operating environment

28 How the Program Works

29 History list LAST 5 PROJECTS AVAILABLE The last 5 projects that the user has worked on are displayed and are available for the user to open. This would be in place of making a new project.

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31 After you are in your project directory you choose to make a new file, import a file, or open an existing file.

32 Here we choose the type of site or hydrologic data options we want to use to design or analyze the site. In this case a 378 site.

33 User selects elements to develop a watershed schematic. We will just be using a single site.

34 In this case just a single structure. SYMBOL FOR STRUCTURE

35 All of the watershed elements are shown for an example series model.

36 Watershed information screen

37 Structure Data Table screen

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39 PSH Rainfall:

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42 Help is available by screen for every data field

43 An explanation of the Entrance Coefficient is shown for example.

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47 Auxiliary Spillway Profile Inlet Natural Ground Constructed Inlet Channel Constructed Exit Channel Exit Natural Ground Tie Sta. Flow

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ft upstm & 2 ft below crest

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54 INTERFACE CONCEPTS File management Data entry Output viewing and interpretation Comparison of alternatives

55 SUMMARY OUTPUT

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60 Integrity Distance Integ. Dist.

61 Checks Include Completeness - Is the data there? Consistency - Is the data reasonable?

62 ADDITIONAL CHECKS Is the output reasonable? Do the results make sense? Sites is a great program

63 CHANGES ON CD Correct Manual in manual directory called DraftSITES.pdf. New Chapter 52 and excel spreadsheet on WEB to compute K h. Any updates will be posted at the address above.

64 The Water Resource Site Analysis (SITES) software is an engineering tool. Not a replacement for sound engineering.

65 END OF PRESENTATION