Section 1 Introduction - Arizona State University...and erosion damage. Uses that are inadequately...

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Section 1 Introduction..................................... 4 1.1 Purpose...................................................................................................................... 4 1.2 Project Authority....................................................................................................... 4 1.3 Project Location ........................................................................................................ 5 1.4 Hydrologic and Hydraulic Methods.......................................................................... 6 1.5 Acknowledgments..................................................................................................... 6 1.6 Study Results ............................................................................................................ 6

Section 2 FEMA Forms ................................. 10 2.1 Study Documentation Abstract for FEMA submittals............................................ 10

2.1.1 Date Study Accepted: ___________________ ............................................... 10 2.1.2 Study Contractor: ............................................................................................. 10 2.1.3 Local Technical Reviewer: ............................................................................. 10 2.1.4 Reach Description............................................................................................ 10 2.1.5 USGS Quad Sheets .......................................................................................... 10 2.1.6 Unique Conditions and Problems .................................................................... 10 2.1.7 Coordination of Peak Discharges..................................................................... 11

2.2 FEMA Forms .......................................................................................................... 11

Section 3 Survey and Mapping Information 11 3.1 Field Survey Information........................................................................................ 11 3.2 Mapping .................................................................................................................. 11

Section 4 Hydrology...................................... 11 4.1 Method Description ................................................................................................ 11 4.2 Parameter Estimation .............................................................................................. 12

4.2.1 Drainage Area .................................................................................................. 12 4.2.2 Watershed Work Map...................................................................................... 12 4.2.3 Gage Data......................................................................................................... 12 4.2.4 Statistical Parameters ....................................................................................... 12 4.2.5 Precipitation ..................................................................................................... 12 4.2.6 Physical Parameters ......................................................................................... 13

4.3 Problems Encountered During the Study................................................................ 14 4.3.1 Special Problems and Solutions....................................................................... 14 4.3.2 Modeling Warning and Error Messages .......................................................... 14

4.4 Calibration............................................................................................................... 14 4.5 Final Results........................................................................................................ 15

4.5.1 Hydrologic Analysis Results........................................................................ 15 4.5.2 Verification of Results ................................................................................. 15

Section 5 Hydraulics ..................................... 16 5.1 Method Description ................................................................................................ 16 5.2 Work Study Maps ................................................................................................... 17 5.3 Parameter Estimation .............................................................................................. 17

5.3.1 Roughness Coefficients ................................................................................... 17 5.3.2 Expansion and Contraction Coefficients ......................................................... 19

5.4 Cross-Section Description ...................................................................................... 19

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5.5 Modeling Consideration.......................................................................................... 19 5.5.1 Hydraulic Jump and Drop Analysis................................................................. 19 5.5.2. Bridges and Culverts....................................................................................... 19 5.5.3 Levees and Dikes ............................................................................................. 19 5.5.4 Island and Flow Splits...................................................................................... 19 5.5.5 Ineffective Flow Areas..................................................................................... 19

5.6 Floodway Modeling................................................................................................ 19 5.7 Problems Encountered ............................................................................................ 20

5.7.1 Special Problems and Solutions....................................................................... 20 5.7.2 Model Warnings and Errors............................................................................. 20

5.8 Calibration............................................................................................................... 20 5.9 Final Results............................................................................................................ 20

5.9.1 Hydraulic Analysis Results.............................................................................. 20 5.9.2 Verification of Results ..................................................................................... 20

Section 6 Erosion and Sediment Transport 20

Section 7 Draft FIS Report Data ................... 21 7.1 Summary of Discharges.......................................................................................... 21 7.2 Floodway Data ........................................................................................................ 21 7.3 Annotated Flood Insurance Rate Map .................................................................... 21 7.4 Flood Profiles.......................................................................................................... 21

List of Tables Table 4. 1. Methods used for the HEC-HMS analysis...................................................... 13 Table 4. 2. Physical Parameters for the Sub-Basins. ........................................................ 14 Table 4.3. Summary of the Hydrologic Analysis Results for Sub-Basins........................ 15 Table 4.4. Comparison of the modeled peak discharges to the USGS Regional Regression Equation 13 peak discharges.......................................................................... 16 List of Figures Figure 1. 1. Watershed Map for the Picture Rocks Study Area......................................... 7 Figure 1.2. Study Limit Map of the Picture Rocks Study Area. ........................................ 8 Figure 1. 3. Soil Classification of the Picture Rocks Study Area ...................................... 9 Figure 5. 1. Picture Rocks Flow Path Photo 1. ................................................................ 18 Figure 5.2. Picture Rocks Flow Path Photo 2. ................................................................. 18 Appendix A: References Appendix B: General Documentation and Correspondence Appendix C: Survey Field Notes Appendix D: Hydrologic Analysis, Supporting Documents Appendix E: Hydraulic Analysis, Supporting Documents Appendix F: Erosion Analysis, Supporting Documents

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Exhibit Exhibit 1 Picture Rocks Maximum Flow Depth Exhibit 2 Picture Rocks Flood Hazard Areas Attached CD Picture Rocks TDN with supporting models and GIS data.

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Section 1 Introduction

1.1 Purpose This Technical Data notebook (TDN) has been prepared for the Picture Rocks (PCR) area located in Pima County, Arizona. The objective of the TDN is to provide regulatory discharge rates and identify floodplain hazard area along in the Picture Rocks study area using better topographic, hydrologic, and hydraulic data. The precision of the floodplain data resulting from this study is limited to 50 feet based on the grid resolution used in the FLO-2D models. Therefore, the results are appropriate for planning but may not be appropriate for detailed studies at the parcel or sub-division level. It is recommended that the results from this study are used as the inflow for performing more detailed studies at smaller scales. Floodplain cross sections from this study are intended to provide discharge values for future detailed studies. The purpose of the FLO-2D modeling was to delineate flood hazard areas for floodplain management. Larger flow depths and velocities were used to delineate the main flow corridors, and the shallow flow depths were identified as sheet flooding areas. Wash lines were created and are intended for use with erosion hazard setbacks. This TDN was prepared in accordance with the “Instructions for Organizing and Submitting Technical Documentation for Flood Studies” prepared by the Arizona Department of Water Resources, Flood Mitigation Section (Arizona State Standard, SSA 1-97) and FEMA Guidelines.

1.2 Project Authority The State of Arizona has delegated the responsibility to each county flood control district to adopt floodplain regulations designed to promote the public health, safety and general welfare of its citizenry as provided under the Arizona Revised Statutes, Title 48, Chapter 21, Article 1, Sections 48-3601 through 3627. More specifically, A.R.S. 3609 directs county flood control districts to adopt floodplain regulations that:

A. Regulate all development of land, construction of residential, commercial or industrial structures or uses of any kind which may divert, retard or obstruct flood water and threaten public health or safety or the general welfare; and B. Establish minimum flood protection elevations and flood damage prevention requirements for uses, structures and facilities which are vulnerable to flood damage; and C. Comply with state and local land use plans and ordinances, if any.

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In conformance with A.R.S. 3609, this ordinance provides for protection of the public health safety and welfare by regulation of flood and erosion hazard areas to control flood hazards and prevent repetitive loss from flood damage. D. The flood hazard areas of Pima County are subject to periodic inundation which may result in loss of life and property, create health and safety hazards, disrupt commerce and governmental services, require extraordinary public expenditures for flood protection and relief, and impair the tax base, all of which adversely affect the public health, safety, and general welfare. E. These flood losses are caused by the cumulative effect of obstructions in areas of special flood hazards which increase flood heights, flow velocities, and cause flood and erosion damage. Uses that are inadequately flood-proofed, elevated, or otherwise protected from flood damage, also contribute to the flood loss. (Ord. 2005 FC-2 § 2 (part), 2005).

Section 16 of the Pima County Ordinance describes the provisions for floodplain regulation in Pima County. This study has been prepared by the Pima County Regional Flood Control District (RFCD): Pima County Regional Flood Control District 97 East Congress, Tucson, AZ 85701 The project was prepared by: Dave Stewart, EIT, Civil Engineering Assistant. Pima County Regional Flood Control District 97 East Congress, Tucson, AZ 85701

1.3 Project Location The Picture Rocks study area currently has a Federal Emergency Management Agency (FEMA) undetermined flood hazard risk or “Zone D”, as depicted on FIRM Map Panel Numbers 04019C1600K (February 8, 1999). The study area is the region primarily East of the Central Arizona Project (CAP) canal, West of Golden Gate Rd., South of Magee Rd., and North of Sweetwater Dr. The region is located in the following Sections: E121132 E121133 E121134 E121135 E121136

E131101 E131102 E131103 E131104 E131105

E131108E131109E131110E131111E131112

E131113E131114E131115E131116E131117

E131120 E131121 E131122 E131206 E131207

E131218

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1.4 Hydrologic and Hydraulic Methods A hydrologic analysis was performed to determine proposed regulatory discharge rates at concentration points along the CAP canal using the U.S. Army Corps of Engineers Hydrologic Modeling System (HEC-HMS). The proposed regulatory discharges are flow rates that have a 1-percent chance of being equaled or exceeded each year (“100-year” discharge rates). The discharge values from the HEC-HMS were used in the hydraulic analysis using FLO-2D to determine the main flow corridor floodplains. A second hydrologic analysis was performed by using the 100-yr rainfall depth with a 3-hr SCS Type II distribution and SCS Curve Number infiltration in FLO-2D to determine the local flow or tributary floodplains. The hydraulic analysis was performed to delineate floodplain limits within the study area using FLO-2D.

1.5 Acknowledgments This study relied on assistance of RFCD staff, who were integral to the development of the models and maps.

1.6 Study Results The regulatory discharges for floodplain mapping were calculated along the CAP in HEC-HMS (Appendix D) and the flow depths within the study area were modeled using FLO-2D (Appendix E). Floodplain cross sections were used in FLO-2D to provide 100-yr discharge values on the floodplain map (Exhibit 1). Flood hazard areas were mapped as a flow corridor, shallow sheet flooding, or as a tributary wash line for erosion hazard setbacks (Exhibit 2).

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\\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Picture_Rocks\Picture_Rocks_Fig1_1.mxd

Figure 1.1Watershed Map

Picture Rocks Wash

Pima County Index Map

Index Map Scale 1:5,250,000

The information depicted on this display is the result of digital analyses performed on a variety of databasesprovided and maintained by several governmental agencies.The accuracy of the information presented is limited tothe collective accuracy of these databases on the dateof the analysis. The Pima County Regional Flood ControlDepartment makes no claims regarding the accuracy of theinformation depicted herein.This product is subject to the Department of TransportationTechnical Services Division's Use Restriction Agreement.

Pima County Regional Flood Control District

12/2010

Countour 50 ft

SubbasinsPCR1

PCR2

PCR3

PCR4

PCR5

PCR6

PCR7

PCR8

PCR9

PCR10

PCR11

Topo: 2008 Pima Association of GovernmentsAerial : 2009 Landiscor Aerial Imagery

Datum: NAVD 1988

1,000 0 1,000500 Feet

SILVERBELL

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

PCR5

PCR4

PCR7

PCR1

PCR3

PCR10PCR11

PCR9

PCR8

PCR6

PCR2

PCR9

PCR4

PCR3

PCR4

PCR7

PCR2

PCR8

PCR5

PCR6

PCR1

PCR11

PCR10

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\\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Picture Rocks\Picture_Rocks_Fig1_2.mxd

Figure 1.2Study Limit Map

Picture Rocks Wash





12/2010

1,000 0 1,000500 Feet

!( Discharge Point

Subbasin

Existing FEMA FloodplainZONE A

ZONE AE

ZONE X - SHADED

Aerial : 2009 Landiscor Aerial Imagery

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PCR5

PCR4

PCR7

PCR1

PCR3

PCR10PCR11

PCR9

PCR8

PCR6

PCR2

PCR9

PCR4

PCR3

PCR4

PCR7

PCR2

PCR8

PCR5

PCR6

PCR1

PCR11

PCR10

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MILE WIDEKINNEY

MANVILLE

PICTURE ROCKS

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\\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Picture Rocks\Picture_Rocks_Fig1_3.mxd

Figure 1.3Soil Classification

Picture Rocks Wash





12/2010

1,000 0 1,000500 Feet

Aerial : 2009 Landiscor Aerial Imagery

!( Discharge Point

Subbasin

Soil ClassificationSoil Group: B (100%), HAYHOOK SANDY LOAM,

Soil Group: B (100%), MOHAVE SOILS AND URBAN LAND,

Soil Group: B (100%), PINALENO VERY COBBLY SANDY

Soil Group: B (100%), PINALENO-STAGECOACH COMPLEX,

Soil Group: B (100%), SONOITA SANDY LOAM,

Soil Group: B (100%), VALENCIA-ANTHONY SANDY LOAMS,

Soil Group: B (100%), VALENCIA-SONOITA SANDY LOAMS,

Soil Group: B (43%) C (57%), NAHDA-PINALENO COMPLEX,

Soil Group: C (100%), TUBAC SANDY LOAM,

Soil Group: C (47%) D (53%), PANTANO-GRANOLITE

Soil Group: C (53%) D (47%), PALOS VERDES-JAYNES

Soil Group: D (100%), ANKLAM-CELLAR-ROCK OUTCROP

Soil Group: D (100%), CHIMENEA VERY GRAVELLY FINE

Soil Group: D (100%), CHIMENEA-CELLAR-ROCK OUTCROP

Soil Group: D (100%), PANTANO-ROCK OUTCROP

Soil Group: D (100%), SAGUARO-ROCK OUTCROP

1 TO 5 PERCENT SLOPES


LOAM, 1 TO 8 PERCENT SLOPES







COMPLEX, 5 TO 25 PERCENT SLOPES



SANDY LOAM, 5 TO 15 PERCENT SLOPES

COMPLEX, 15 TO 50 PERCENT SLOPE



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Section 2 FEMA Forms

2.1 Study Documentation Abstract for FEMA submittals 2.1.1 Date Study Accepted: ___________________ 2.1.2 Study Contractor: Planning and Development Division, Pima County Regional Flood Control District 97 East Congress, Tucson, AZ 85701 (520) 243-1800 Prepared by Dave Stewart, Civil Engineering Assistant. 2.1.3 Local Technical Reviewer: Planning and Development Division, Pima County Regional Flood Control District 97 East Congress, Tucson, AZ 85701 (520) 243-1800

2.1.4 Reach Description The washes of the PCR study area are braided channels that have residential development in some of the flow paths. The obstructions in the flow paths appear to increase the distributary flow conditions and sheet flooding hazard of the study area. The channels of the PCR study area contain coarse sand and cobble beds. Small shrubs and trees grow in some areas of the channel bed, and desert brush covers the overbanks.

2.1.5 USGS Quad Sheets The study area is better described by the FEMA maps, which are referenced in Section 2.1.7.

2.1.6 Unique Conditions and Problems There were no unique conditions or problems with the study.

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2.1.7 Coordination of Peak Discharges The 100-year regulatory discharge rates at the concentration points were calculated using HEC-HMS, assuming no base flow in the watersheds and no transmission loss within the reaches. The discharge rates were acceptable per Suzanne Shields, Director of the Pima County Regional Flood Control District.

2.2 FEMA Forms No FEMA MT-2 forms are included in this TDN.

Section 3 Survey and Mapping Information

3.1 Field Survey Information No field survey was performed for this study.

3.2 Mapping The topographic data for the hydrology was obtained using 2005 Pima Associations of Governments (PAG) Light Detection and Ranging (LiDAR). A raster was created from the 2005 LiDAR data with 5’ cells and used with ArcGIS and Geo-RAS. The following data was used in this TDN;

The aerial photo: 2010 PAG aerial photo Projection: NAD 1983 HARN State Plane Arizona Central Units: International feet The contour interval of the topographic map is 2 feet. Vertical Datum: NAVD 1988

Section 4 Hydrology

4.1 Method Description The 100-year peak discharges for the Picture Rocks study area were modeled at the CAP using the U.S. Army Corps of Engineers Computer Hydrologic Modeling System, (HEC-HMS) version 3.2. The HEC-HMS model requires parameters for rainfall, topography, soil, vegetation, and channel characteristics to determine runoff volume and peak discharge. Those parameters

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were determined according to the Pima County Regional Flood Control District Technical Policy 018 (Tech-018). Tech-018 is included in Appendix A. The HEC-HMS model is included in Appendix D. The second hydrologic analysis used the 100-yr rainfall depth with a 3-hr SCS Type II distribution and the SCS Curve Number infiltration method in FLO-2D to model the floodplains for the tributaries to the main flow corridors.

4.2 Parameter Estimation

4.2.1 Drainage Area The topographic data was obtained from a 5’ cell raster created from 2005 PAG LiDAR data. ArcGIS was used to delineate watersheds from the raster and determine the drainage area of each sub-basin. The composite watershed map is included in Figure 1.1.

4.2.2 Watershed Work Map Eleven sub-basins were delineated in ArcGIS for the Picture Rocks study area with the concentration points located at the Central Arizona Project canal. The locations of the sub-basins were chosen based on the major flow paths found using the flow accumulation ArcGIS hydrology functions with a 5-ft cell raster. Sub-basins were placed at the culverts leading over the CAP, and additional sub-basin points were placed where major flow paths reached the CAP to break up larger sub-basins

4.2.3 Gage Data No gage data were used in this TDN.

4.2.4 Statistical Parameters No recorded data was available for the washes in the Picture Rocks study area and therefore no Bulletin 17B analysis was used for this TDN.

4.2.5 Precipitation According to Tech-018, the design storm should be used that produces the higher discharge between the 100-yr 3-hour SCS Type II distribution and the 100-yr 24-hr SCS Type I distribution. The 100-yr 3-hour SCS Type II distribution was found to produce the higher discharges for the Picture Rocks study area. The PCR 2 sub-basin has a drainage

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area of less than 1 mi2 and therefore a PC-Hydro run was performed that uses a 1-hr rainfall depth. NOAA Atlas 14, upper 90% confidence interval precipitation frequency estimate values (NOAA 14 rainfall) were used to determine 3-hour and 24-hour point rainfall depths for the watershed. The point rainfall depth for the 3-hour storm was obtained for the coordinates of the watershed centroid. An areal reduction factor was applied to watersheds larger than 1 square mile as noted in Tech-018.

4.2.6 Physical Parameters The physical parameters for the sub-basins and reaches of the HEC-HMS model are summarized in Tables 4.1 and 4.2. As mentioned in Section 4.1, all the methods and parameters were determined based on Tech-018. Table 4.1 summarizes the method used for the HEC-HMS analysis. Table 4. 1. Methods used for the HEC-HMS analysis

Selected MethodRainfall Depth NOAA 14, upper 90% Confidence IntervalRainfall Distribution 3-hr SCS Type II StormRainfall Loss SCS Curve numberTime of Concentration SCS Segmental MethodTransform SCS Unit HydrographRouting Modified-Puls The SCS Curve Number (CN) method was utilized as a rainfall loss method in the HEC-HMS model. The CN was determined using the Curve Number tables and Hydrologic Soils Group maps associated with the PC Hydro User Guide (Arroyo Engineering, 2007). The CN was not adjusted for rainfall intensity or antecedent moisture conditions. The SCS Unit Hydrograph method was used as a transform method. Impervious cover was determined using 2010 PAG aerial photographs. The combination of the kinematic wave time of concentration method and the U.S. Natural Resources Conservation Service (NRCS) segmented Time of Concentration (Tc) calculation (USDA-NRCS, 1986) was used to determine Tc, based on the recommendation on Tech-018. The Tc was calculated by summing the travel time for sheet flow, shallow concentrated flow and channel flow. The Tc for sheet flow was estimated using the kinematic wave equation. The Manning’s roughness coefficient for sheet flow was obtained using Table 3-1 in Technical Release 55, Urban Hydrology for Small Watersheds (USDA-NRCS, 1986). The channel velocity of each sub-basin was calculated as the harmonic mean velocity from a HEC-RAS model of the longest flowpath. The Tc calculations are included in Appendix D.

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Table 4. 2. Physical Parameters for the Sub-Basins.

Sub-basin Area (sq mi) CN Impervious Area (%)

Vegetation Cover (%)

Lag Time (min)

PCR1 3.55 87.31 20 20 62.8PCR2 0.53 85.37 10 20 30.9PCR3 3.00 87.81 20 20 100.2PCR4 3.91 85.49 5 20 43.1PCR5 4.45 86.44 10 20 75.0PCR6 1.77 86.91 10 20 84.7PCR7 3.59 89.38 5 20 40.9PCR8 2.26 89.53 10 20 56.1PCR9 2.57 87.13 10 20 89.9

PCR10 3.18 87.79 10 20 76.9PCR11 2.99 87.94 10 20 76.7

The sub-basins were not subdivided above the concentration points at the CAP canal, and therefore no hydrologic routing was performed to determine the 100-yr peak discharge rates.

4.3 Problems Encountered During the Study

4.3.1 Special Problems and Solutions There were no problems with the hydrologic modeling.

4.3.2 Modeling Warning and Error Messages The time interval of the rainfall data used in this study is 5 minutes, while the simulation time interval is 1 minute. The HEC-HMS model interpolated the 5-minute time interval of the rainfall data to 1-minute time interval. The following warnings were produced in HEC-HMS;

• The “3-hr SCS Type II” gage with data interval of 5 minutes was interpolated to a simulation time interval of 1 minute.

4.4 Calibration No calibration was conducted in this study.

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4.5 Final Results

4.5.1 Hydrologic Analysis Results The 100-yr peak discharges at the CAP canal are summarized in Tables 4.3. Table 4.3. Summary of the Hydrologic Analysis Results for Sub-Basins.

Sub-basin Area (sq mi) Rainfall Depth (in)

Runoff Volume (in)

Peak Discharge (cfs)

PCR1 3.55 2.70 1.50 1966.4PCR2* 0.53 972.0PCR3 3.00 2.76 1.59 1216.1PCR4 3.91 2.68 1.36 2596.4PCR5 4.45 2.64 1.39 1975.4PCR6 1.77 2.85 1.60 824.8PCR7 3.59 2.71 1.67 3091.9PCR8 2.26 2.81 1.77 1623.7PCR9 2.57 2.79 1.57 1122.5

PCR10 3.18 2.74 1.57 1575.6PCR11 2.99 2.76 1.60 1510.5

*PC-Hydro run. No rainfall or runoff volume is directly calculated.

4.5.2 Verification of Results The modeled 100-yr peak discharges are compared with the USGS Regional Regression Equation 13 (Thomas et al., 1997) peak discharges in Table 4.4. The Picture Rocks sub-basins have long flow paths due to their shape which causes a lower modeled peak discharge. However, the long flow paths do not change the hydrograph volume in the HEC-HMS modeling because no transmission losses are used and the hydrograph volume is the basis of the FLO-2D modeling. The modeled hydrographs at the sub-basin outlets at the CAP were entered at the top of the hydraulic modeling study area in FLO-2D and therefore the modeling produced a conservative floodplain.

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Table 4.4. Comparison of the modeled peak discharges to the USGS Regional Regression Equation 13 peak discharges.

Sub-basin Area (sq mi) Modeled Peak Discharge (cfs)

USGS RRE 13 Peak Discharge (cfs)

PCR1 3.55 1966.4 2761.8PCR2* 0.53 972.0 812.4PCR3 3.00 1216.1 2505.3PCR4 3.91 2596.4 2918.6PCR5 4.45 1975.4 3139.5PCR6 1.77 824.8 1819.5PCR7 3.59 3091.9 2778.6PCR8 2.26 1623.7 2116.0PCR9 2.57 1122.5 2288.6

PCR10 3.18 1575.6 2594.4PCR11 2.99 1510.5 2500.1

Section 5 Hydraulics

5.1 Method Description

The hydraulic modeling for the PCR was performed using FLO-2D Version 2009, and ArcGIS Version 9.3. The topographic data was obtained using a 5-ft cell raster developed in ArcGIS from the PAG 2005 LiDAR data and exporting it into FLO-2D. An initial “overview” model was created in FLO-2D that used 100-ft cells to identify areas for additional detail would be needed. The developed regions within the Picture Rocks study area were split into three areas and a detailed FLO-2D model with 50-ft cells was created for each area. A sample area in the Picture Rocks study area was used to measure the density of obstructions by development. A sample area of 17.3 ac was used, and approximately 1.3 acres was measured as obstructed by houses or other development. The blocked density was calculated as 7%, and a general value of 10% obstruction was assumed for all areas of development in the Picture Rocks study area. Therefore, the areas with development in the FLO-2D models were assumed to have a reduction in flow area of 10%. The HEC-HMS peak discharges at the CAP were entered into the FLO-2D model at the upstream boundaries of the major flow paths and routed through the study areas to obtain the main flow corridors. In addition, separate FLO-2D models were created for each area that used the rainfall distribution as an input and modeled the runoff using the weighted SCS Curve Numbers of each watershed to determine the tributary floodplains.

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The hydraulic data obtained from FLO-2D were exported to ArcGIS to delineate the floodplains in the study area. The tributary floodplains were then added to the main flow corridor floodplains. The FLO-2D data and shape files (maximum flow depths, flood hazard polygons, contour lines, flow paths, sub-basins, concentration points, hydrologic soil groups) used in the analysis are included in Appendix D.

5.2 Work Study Maps The work study map for the Picture Rocks study area is included as Exhibits 1 and 2. Exhibit 1 is the maximum flow depth data with the cross section discharges, and Exhibit 2 displays the flood hazard areas designated from the floodplain data.

5.3 Parameter Estimation

5.3.1 Roughness Coefficients Manning’s n values were determined based on documentation in the FLO-2D User Manual, USGS publications for Manning’s n values in southern Arizona (Phillips and Tadayon, 2006), and field visits to the study area. The FLO-2D workshops and documentation recommend higher Manning’s n values for the floodplain grid in FLO-2D than is generally used for uniform flow in natural channels. A consistent Manning’s n value of 0.045 was assigned for the floodplain of the Picture Rocks study area based on the vegetation in the coarse sand channels (Figures 5.1). The models were calibrated by replacing the initial roughness values with any increased roughness values during the FLO-2D simulation. Grid elements that caused large numbers of time step reductions were assigned a Manning’s n value of 0.085.

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Figure 5. 1. Picture Rocks Flow Path Photo 1.

Figure 5.2. Picture Rocks Flow Path Photo 2.

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5.3.2 Expansion and Contraction Coefficients The expansion and contraction coefficients were not adjusted in the FLO-2D program.

5.4 Cross-Section Description The floodplain grid was used in FLO-2D and cross sections were not utilized in the hydraulic routing.

5.5 Modeling Consideration

5.5.1 Hydraulic Jump and Drop Analysis No hydraulic jumps or hydraulic drops were modeled in this study.

5.5.2. Bridges and Culverts No bridges or culverts were modeled in the Picture Rocks study.

5.5.3 Levees and Dikes There are no levees or dikes located within the study limit.

5.5.4 Island and Flow Splits There is distributary flow in much of the Picture Rocks study area, and the FLO-2D model was utilized to determine the two dimensional direction of the discharge.

5.5.5 Ineffective Flow Areas The developed areas were assumed to have a consistent blocked cell area of 10% based on the sample measurement. The major roads were digitized in FLO-2D and assumed to be 20 ft wide and have the minimum curb height of 0.1 ft.

5.6 Floodway Modeling No floodway modeling was performed in this study.

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5.7 Problems Encountered

5.7.1 Special Problems and Solutions The floodplain limiting Froude number in the FLO-2D model was set to 1.0 to force subcritical or critical flow. The dynamic wave stability coefficient was set to 1.0 for initial runs, and lowered to 0.25 for the final results of each FLO-2D model. There were no other special problems encountered in this study.

5.7.2 Model Warnings and Errors There were no warnings or errors on the final runs of the FLO-2D models. Volume conservation in all FLO-2D models remained negligible.

5.8 Calibration The roughness coefficients were calibrated when applicable by replacing the initial roughness values with the values adjusted by the FLO-2D program for each model. Additionally, grid elements that caused significant reduction in the time step were assigned a roughness value of 0.085.

5.9 Final Results

5.9.1 Hydraulic Analysis Results The FLO-2D modeling results are summarized in Appendix E.

5.9.2 Verification of Results The resulting floodplains fit the topographic data and the observed geologic floodplain from aerial photographs. Other verification of the floodplain results was not possible.

Section 6 Erosion and Sediment Transport No erosion or sediment transport analysis was conducted in this study.

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Section 7 Draft FIS Report Data

7.1 Summary of Discharges The discharge results are summarized in Table 4.3.

7.2 Floodway Data Not applicable.

7.3 Annotated Flood Insurance Rate Map No annotated Flood Insurance Rate Map is included.

7.4 Flood Profiles Flood profiles are included in Appendix E.

CA

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PICTURE ROCKS

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The information depicted on this display is the result of digital analyses performed on a variety of databases

provided and maintained by several governmental agencies.The accuracy of the information presented is limited tothe collective accuracy of these databases on the date

of the analysis. The Pima County Regional Flood Control District makes no claims regarding the accuracy of the information

depicted herein.This product is subject to the GIS Division Disclaimer

and Use Restrictions.Date: December 13, 2010

©Scale:

Pima County Regional Flood Control District97 E Congress - 3rd Floor

Tucson, Arizona 85701-1207(520) 243-1800, FAX: (520)243-1821

http://www.rfcd.pima.gov

Exhibit 2Picture Rocks

Flood Hazard Areas

LegendWash Lines

Flow Corridor

Sheet Flow

Elevate 1 ft

Federal or State Land

Parcels

Limit of Study

0 2,000 4,000 6,000 8,0001,000 Feet

1 inch = 1,000 feet

E

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EE 230

0

2200

CA

P

761 c

fs

1006

cfs

922

cfs

2210

cfs

2289

cfs

2407

cfs

1393

cfs

490 c

fs

365 c

fs

413 c

fs

817 c

fs

1027

cfs

689 c

fs

1479

cfs

164 c

fs

1169

cfs

198

cfs

470 c

fs

960 c

fs

1965

cfs

475

cfs

1225

cfs

1256

cfs

2423

cfs

1366

cfs

563 c

fs

491

cfs

309

cfs

1616

cfs

378 c

fs 720 c

fs

636

cfs

1797

cfs

343 c

fs

228 c

fs

694 c

fs

243 c

fs

1387

cfs

88 c

fs

197

cfs

110 c

fs

199

cfs

150 c

fs

1301

cfs

124 c

fs

1290

cfs

599

cfs

385

cfs

52 c

fs

1011

cfs

487 c

fs

436 c

fs

861 c

fs

732

cfs

811 c

fs

606 c

fs

432 c

fs

137 c

fs

151 c

fs

406 c

fs

488 c

fs

91 cf

s

288

cfs

304

cfs

1220

cfs

4 cfs

116 c

fs

54 c

fs

215 c

fs

424 c

fs

397 c

fs

195 c

fs

564 c

fs

230

cfs

330

cfs

322

cfs

670

cfs

22 cf

s

38 c

fs

1046

cfs

187 c

fs

57 c

fs

1305

cfs

204

cfs

1062

cfs

73 cf

s

42 cf

s

65 cf

s

286 c

fs

104 c

fs

105 c

fs

155 c

fs

308

cfs

372

cfs

27 c

fs

55 c

fs

40 cf

s

292

cfs

92 cf

s

588

cfs

41 cf

s

272

cfs

313 c

fs

156 c

fs

258 c

fs

131 c

fs

163 c

fs

132 c

fs

449 c

fs

129

cfs

100

cfs

120

cfs

209

cfs

178

cfs

113 c

fs

222 c

fs

101 c

fs

479 c

fs

126 c

fs

633 c

fs

678 c

fs

34 cf

s

17 cf

s

36 cf

s

119 c

fs

99 cf

s

30 cf

s

419 c

fs

68 c

fs

166

cfs

47 c

fs

159 c

fs

63 c

fs

147 c

fs

294 c

fs

441 c

fs

681 cfs629 cfs

251

cfs

206

cfs

225 c

fs

125

cfs

70 cf

s

205

cfs

37 cf

s

64 cf

s

50 cf

s

26 cf

s

74 cf

s

23 cf

s

15 cf

s

25 cf

s

95 cf

s

13 cf

s

19 cf

s

28 cf

s

9 cfs

8 cfs

638 cfs

143

cfs

66 cf

s21

cfs

471 c

fs

220 c

fs

11 cf

s

29 cf

s

18 cf

s

14 cf

s

35 cf

s

44 cf

s

16 cf

s

33 cf

s

196

cfs

24 c

fs

10 c

fs

11 cf

s

40 cf

s

151 c

fs

23 cf

s

18 cf

s

25 c

fs

1393

cfs

378 c

fs

52 cf

s

164 c

fs

198 c

fs

42 cf

s

36 c

fs

13 cf

s

38 c

fs

195

cfs

199 c

fs

104

cfs

34 cf

s

150

cfs

23 c

fs

124 c

fs

91 c

fs

41 cf

s

215 c

fs

37 cf

s

150 c

fs

74 cf

s

8 cf

s

N SA

NDAR

IO R

D

W RUDASILL RD

W INA RD

W PICTURE ROCKS RD

W GOLD

EN GA

TE RD

W MANVILLE RD

W ANTHONY DR

W MAGEE RD

N RE

SERV

ATIO

N RD

N RI

VER

ROCK

LN

W MASSINGALE RD

W ORANGE GROVE RD

N AV

RA R

D

N TA

YLOR

LN

N TU

LA LN

N LY

DIA A

V

W MARS RD

N HOH

OKAM

RD

W LORD LN

N BL

UE B

L

N GU

THRI

E RD

N SA

NDER

S RD

N SC

ENIC

DR

W VAQUEROS RD

N LO

NE O

WL TR

N VA

N AR

K RD

W TRAIL DUST RD

W GARCIA RANCH RD

N CH

APAR

RAL R

D

N LA

K A Y

UCCA

RD

N OL

D WE

ST R

D

W SUNSET RD

W DALLY RD

N NO

EL LN

N OL

D RA

NCH

RD

N EL

LEXS

ON D

R

N ST

EELE

DR

W RANCHETTES DRW CURTIS RD

UNKNOWN

N BO

BCAT

LN

W BARNEY LN

W EL LOBO RD

N SU

NDOW

N RD

W VIRGIL DR

W AVRA VIEW RD

N GE

MSTO

NE R

D

N DE

SERT

VIEW

DR

N PR

AIRI

E DR

N MA

GGIES

FARM

LN

W TRIPLE J WY

N DE

SERT

TRAI

L RD

N PE

LTO

PH

W SWEETWATER DR

W WELL PUMP DR

N OU

R RD

W YANKEE RANCH RD

W CAMINO DE CONEJO N TA

RANT

ULA

TR

W SIGNAL HILL RD

N MA

VERI

CK R

D

W KIRK LN

N SH

ANE A

V

W TULA PL

N GL

ORY T

R

N DI

MITR

I LN

W BUSTERVILLE LN

N CA

LVIN

RD

W NOLEN RD

N DE

SERT

PASS

RD

N PR

AIRI

E WO

LF LN

W CRYSTAL ROSE LN

N DE

SERT

QUA

IL LN

N MO

UNTA

IN LI

ON LN

W HORSE MESA TR

W SUNSET DR

N SP

RING

WAG

ON D

R

N RO

XY R

D

W MCAFEE RD

N BU

FFAL

O TR

W SANDY PEAK LN

W BERNICE LN

W LARIAT DR

N CO

LTSF

OOT D

R

W CAMEO MARY LN

W RAIN LILY LN

W MUSTANG RD

N FE

ATHE

RSTO

NE TR

N AN

NIES

LN

W KIRACHAMACA ST

N PIC

TURE

PL

N PE

AR TR

EE R

D

N BR

USHT

AIL L

N

N CA

RLES

S LN

W LE CONTES TR

W KEOGH RD

N MI

STY L

N

N WH

ITE D

EER

LN

N HO

T DES

ERT T

R

N PA

LE M

OON

TR

W LITTLE WILLIAM DR

N TA

YLOR

RAY

LN

N TE

AM R

OPER

RD

N AL

OE G

REEN

DR

W SHIDONI LN

N MI

XER

WY

W DALTON RAY TR

N DE

SERT

POS

T LN

N BL

AZIN

G ST

AR TR

W ROYALTY DR

N HO

WLIN

G MO

ON P

L

N WA

LTER

DR

W WINDCHIME DR

W SAGUARO PARK LN

W VAN ARK PL

N CH

EROK

EE P

ONY T

R

W PEDEN LN

N VE

RA W

Y

W NAJO LN

N PA

LE S

TONE

PL

W DESERT WREN DR

W VIA DICHOSA

W CAMPER RD

W ROCKY DESERT TR

W RAINING STARS LN

W HIDEAWAYS EMERALD LN

N KR

ILINA

RD

W PAYTON PL

N DI

AMON

D HI

LLS L

N

W FOURWAY DR

W DESERT LIGHTS TR

W CRITTY LN

W MONSOON TR

N WA

TER

WITC

H LN

N SH

AGGY

TREE

LN

W DESERT GRASS LN

N BO

SWEL

L LN

N GE

CKO

RUN

TR

N PL

EASA

NT LN

W ARCHER DR

W YEOMAN DR

W DESTINY WY

N VIR

GIL P

L

W BLUE QUAIL PL

W GR

EY S

TONE

LP

W SUNSET VALLEY TR

N BE

RNIC

E PL

UNKN

OWN

N AV

RA R

D

UNKNOWN

N TU

LA LN

N CA

LVIN

RD

N SA

NDER

S RD

N AV

RA R

D

UNKNOWN

UNKNOWN

UNKN

OWN

W ORANGE GROVE RD

W NAJO LN

N AV

RA R

D

W ORANGE GROVE RD

N BL

UE B

L

W GARCIA RANCH RD

N DE

SERT

VIEW

DR

N DE

SERT

VIEW

DR

N GE

MSTO

NE R

D

N SA

NDER

S RD

W INA RD

UNKNOWN

W CAMPER RD

UNKN

OWN

UNKN

OWN

N SA

NDER

S RD

UNKNOWN

W MAGEE RD

N BO

BCAT

LN

UNKN

OWN

N PE

AR TR

EE R

D

N GE

MSTO

NE R

D

UNKN

OWN

N AV

RA R

D

W MAGEE RD

N PE

LTO

PHUN

KNOW

N

W WINDCHIME DR

N GE

MSTO

NE R

D

UNKNOWN

N DE

SERT

VIEW

DR

N DI

AMON

D HI

LLS L

N

N RO

XY R

D

UNKN

OWN

UNKNOWN

W DESERT WREN DR

W KEOGH RD

N VA

N AR

K RD

N TU

LA LN

W DESERT WREN DR

2300

2400

2200

2500

2600

2700

2800

2100

2900

3000

3100

32003300

34003500

3600

3700

3800

3900

4000

4100 4200

3200

2500

3400

2800

2800

2700

2800

3100

3100

3400

3100

2700

3300

2600

2800

2900

3000

3000

3300

3000

2600

2700

3000

2600

3200

2900

3100

2900

2800 3000

3000

3100

2300

3000

2600

2400

2700

3200

2500

2700

2600

28002900

3100

2700

3300

2800

2500

3100

2600

3100

2500

2700

2600

3100310

0

2800

3300 32003200

2700

283

cfs

59 cf

s

431

cfs

1266

cfs

166

cfs

217

cfs

66 c

fs

52 cf

s

137

cfs

204

cfs

The information depicted on this display is the result of digital analyses performed on a variety of databases

provided and maintained by several governmental agencies.The accuracy of the information presented is limited tothe collective accuracy of these databases on the date

of the analysis. The Pima County Regional Flood Control District makes no claims regarding the accuracy of the information

depicted herein.This product is subject to the GIS Division Disclaimer

and Use Restrictions.Date: August 27, 2009

©Scale:

Pima County Regional Flood Control District97 E Congress - 3rd Floor

Tucson, Arizona 85701-1207(520) 243-1800, FAX: (520)243-1821

http://www.rfcd.pima.govR:\templates\48x36_portrait_template_rfcd_exhibit.mxd

Picture Rocks Draft Max Flow Depth

0 2,000 4,000 6,000 8,0001,000 Feet

1 inch = 1,000 feet

LegendDV Squared > 18

Max Flow Depth (ft)0 - 0.2

0.2 - 0.5

0.5 - 1.0

1.0 - 2.5

2.5 - 5.0

Wash Lines

Federal or State Land

Parcels

Limit of Study

100-ft ContourFloodplain Cross Sections

E

E

E

E

E

E

100-yr Peak Discharge

(Cross Section line thickness varies with discharge per unit width)

Section 1 Introduction - Arizona State University...and erosion damage. Uses that are inadequately...

Documents

Transcript of Section 1 Introduction - Arizona State University...and erosion damage. Uses that are inadequately...