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VIRGINIAVIRGINIAWORKSHOPWORKSHOP

Feb. 28 – Mar. 3, 2006Feb. 28 – Mar. 3, 2006

INTRODUCTION to SITESINTRODUCTION to SITESfor

WATER RESOURCE SITE ANALYSIS

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OBJECTIVEOBJECTIVEDescribe general

range of SITES model application

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HISTORYHISTORY• Program Developed Over Time by

NRCS

• Spillway Erosion Technology Developed Jointly by ARS and NRCS

• Interface, developed to provide a user-

friendly environment

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SITES ? ? ?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

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TYPICAL DAM TYPICAL DAM XSECTIONXSECTION

OUTLET STRUCTIRE

PSH

SDH

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SITES Model Spwy stability/Composed of sub models integrity

&Precipitation rain Loss runoff Transformation inflow Reservoir routingModel Model Model Modelsinput: input: input: input: -rainfall amount -CN as a -DA -given/proposed Outflow -rainfall distribution function of soils -Tc S-S-D and land use -UH -Spwy parameters

Reach routingModelinput: -x-sec data

SITES ModelSITES Model

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HISTORYHISTORY• Program Developed Over Time by NRCS

• Spillway Erosion Technology Developed

• Jointly by ARS and NRCS

• Interface, developed to provide a • user-friendly environment

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ERODED SPILLWAYERODED SPILLWAY

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LABORATORY SPILLWAY MODELLABORATORY SPILLWAY MODEL

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Auxiliary Spillway ProfileAuxiliary Spillway Profile

InletNaturalGround

ConstructedInlet Channel Constructed

Exit Channel

Exit Natural Ground

Tie

Sta

.

Flow

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SITES STABILITY SITES STABILITY ANALYSISANALYSIS

•TECHNOLOGY OPTIONSTECHNOLOGY OPTIONS• PERMISSIBLE VELOCITYPERMISSIBLE VELOCITY• ALLOWABLE STRESSALLOWABLE STRESS

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Old TR-60 Table 7-1 had corrections for Old TR-60 Table 7-1 had corrections for Permissible Velocities.Permissible Velocities.

10% for not more than once in 50 years 10% for not more than once in 50 years andand

25% for not more than once in 100 years.25% for not more than once in 100 years.

To make stress on an equal footing as To make stress on an equal footing as velocity the same type of correction velocity the same type of correction needs to be made. Stress is proportional needs to be made. Stress is proportional to the square of the velocity.to the square of the velocity.

1 in 50 (1.10)1 in 50 (1.10)2 2 = 1.21 say a 20% increase= 1.21 say a 20% increase

1 in 100 (1.25)1 in 100 (1.25)22 = 1.5625 say a 50% = 1.5625 say a 50% increaseincrease

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

Once in 50 years 20% increase in Once in 50 years 20% increase in stressstress

Once in 100 years 50% increase in Once in 100 years 50% increase in stressstress

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• BARE EARTH e=ds

EFFECTIVE STRESSEFFECTIVE STRESS

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EFFECTIVE STRESSEFFECTIVE STRESS

• VEGETATIONVEGETATION

e= ds (1-Cf) (ns/n)2

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Note:If Cf = 0.9 then (1-Cf) = 0.1andif Cf = 0.8 then (1-Cf) = 0.2 ===> this is a 100% increase in effective stress.From soil grain roughnessif ns = 0.0156 & n = 0.040 D75 = 0.05”(ns/n)2 = 0.1514A 100% increase from a change in soil roughness requires a D75 = 0.40”

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MAINTENANCE CODEMAINTENANCE CODE

1 - UNIFORM COVER OR 1 - UNIFORM COVER OR SURFACESURFACE

2 - MINOR DISCONTINUITIES2 - MINOR DISCONTINUITIES

3 - MAJOR DISCONTINUITIES3 - MAJOR DISCONTINUITIES

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SITES AUXILIARY SITES AUXILIARY SPILLWAYSPILLWAY

STABILITY ANALYSISSTABILITY ANALYSIS

• BASED ON PEAK OF SDHBASED ON PEAK OF SDH• APPLIED TO EXIT CHANNELAPPLIED TO EXIT CHANNEL• VELOCITY OR STRESS calculationsVELOCITY OR STRESS calculations

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MASS MOVEMENTMASS MOVEMENT

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SPILLWAY EROSION SPILLWAY EROSION PHASESPHASES

INTEGRITY ANALYSISINTEGRITY ANALYSIS

1. SURFACE EROSION 1. SURFACE EROSION (Cover Destruction)

2. CONCENTRATED FLOW EROSION2. CONCENTRATED FLOW EROSION

3. HEADCUT ADVANCE3. HEADCUT ADVANCE

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COVER FAILURE INITIATIONCOVER FAILURE INITIATION

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HEADCUTHEADCUT

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EXPANDING HEADCUTEXPANDING HEADCUT

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SPILLWAY GEOLOGYSPILLWAY GEOLOGY

STATION

EL

EV

AT

ION

, ft

, ft

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SPILLWAY SURFACESPILLWAY SURFACE

STATION

EL

EV

AT

ION

, ft

, ft

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ERODED PROFILEERODED PROFILEE

LE

VA

TIO

N

STATION, ft

, ft

ERODED AREA

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HISTORYHISTORY• Program Developed Over Time by NRCS

• Spillway Erosion Technology Developed • Jointly by ARS and NRCS

• Interface developed to provide a • user-friendly operating

environment

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How the Program How the Program WorksWorks

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History list

LAST 5 PROJECTS LAST 5 PROJECTS AVAILABLEAVAILABLE

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

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

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

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In this case just a single structure.

SYMBOL FOR STRUCTURE

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

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Watershed Watershed information screeninformation screen

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Structure Data Structure Data Table screenTable screen

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PSH Rainfall:

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Help is available by screen Help is available by screen for every data fieldfor every data field

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

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Auxiliary Spillway ProfileAuxiliary Spillway Profile

InletNaturalGround

ConstructedInlet Channel Constructed

Exit Channel

Exit Natural Ground

Tie

Sta

.

Flow

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130 ft upstm & 2 ft below crest

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INTERFACE CONCEPTSINTERFACE CONCEPTS

• File management

• Data entry

• Output viewing and interpretation

• Comparison of alternatives

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SUMMARY OUTPUTSUMMARY OUTPUT

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Integrity DistanceInteg. Dist.

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Checks IncludeChecks Include• Completeness - Is the data

there?• Consistency - Is the data

reasonable?

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ADDITIONAL CHECKSADDITIONAL CHECKS• Is the output reasonable?• Do the results make sense?

Sites is a

great

program

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CHANGES ON CDCHANGES ON CD• Correct Manual in manual directory

called DraftSITES.pdf.• New Chapter 52 and excel

spreadsheet on WEB to compute Kh.

• http://www.wcc.nrcs.usda.gov/http://www.wcc.nrcs.usda.gov/wcc.htmlwcc.html

• Any updates will be posted at the address above.

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The Water Resource Site The Water Resource Site Analysis (SITES) software is an Analysis (SITES) software is an

engineering tool.engineering tool.

Not a replacement for sound engineering.

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END OF PRESENTATION END OF PRESENTATION