Section 1 Introduction ........................................................................................4 1.1 Propose...................................................................................................................... 4 1.2 Project Authority....................................................................................................... 4 1.3 Project Location ........................................................................................................ 5 1.3 Hydrologic and Hydraulic Methods.......................................................................... 5 1.4 Acknowledgment ...................................................................................................... 6 1.5 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 .........................................................................................12 4.1 Method Description ................................................................................................ 12 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 Spatial Parameters............................................................................................ 13 4.2.5 Precipitation ..................................................................................................... 13 4.2.6 Physical Parameters ......................................................................................... 13 4.3 Problems Encountered During the Study................................................................ 15 4.3.1 Special Problems and Solutions....................................................................... 15 4.3.2 Modeling Warning and Error Messages .......................................................... 15 4.4 Calibration............................................................................................................... 15 4.5 Final Results........................................................................................................ 15 4.5.1 Hydrologic Analysis Results........................................................................ 15 4.5.2 Verification results....................................................................................... 16 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 ......................................................... 17 5.4 Cross-Section Description ...................................................................................... 17 5.5 Modeling Consideration.......................................................................................... 17 5.5.1 Hydraulic Jump and Drop Analysis................................................................. 17 5.5.2. Bridges and Culverts....................................................................................... 18 2 5.5.3 Levees and Dikes ............................................................................................. 18 5.5.4 Island and Flow Splits...................................................................................... 18 5.5.5 Ineffective Flow Areas..................................................................................... 18 5.6 Floodway Modeling ................................................................................................ 18 5.7 Problems Encountered ............................................................................................ 18 5.7.1 Special Problems and Solutions....................................................................... 18 5.7.2 Model Warnings and Errors............................................................................. 19 5.8 Calibration............................................................................................................... 19 5.9 Final Results............................................................................................................ 19 5.9.1 Hydraulic Analysis Results.............................................................................. 19 5.9.2 Verification of Results ..................................................................................... 19 Section 6 Erosion and Sediment Transport ...................................................20 Section 7 Draft FIS Report Data.......................................................................20 7.1 Summary of Discharges.......................................................................................... 20 7.2 Floodway Data ........................................................................................................ 20 7.3 Annotated Flood Insurance Rate Map .................................................................... 20 7.4 Flood Profiles.......................................................................................................... 20 List of Tables Table 1 Methods used for a HEC-HMS analysis.............................................................. 13 Table 2 Physical Parameters for the Sub-Basins .............................................................. 14 Table 3 Summary of the Hydrologic Analysis Results for Sub-Basins............................ 15 Table 4 Summary of the Hydrologic Analysis Results at the Concentration Points ........ 16 Table 5 Comparison of a peak discharge.......................................................................... 16 List of Figures Figure 1.1 Watershed Map.................................................................................................. 7 Figure 1.2 Study Limit........................................................................................................ 8 Figure 1.3 Soil Classification.............................................................................................. 9 Appendix A: References Appendix B: FEMA MT-2Forms, 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 Exhibit Exhibit 1 100-yr floodplain limit for the Roger Wash Exhibit 2 Annotated Flood Insurance Rate Map for the Roger Wash 3 Section 1 Introduction 1.1 Propose This Technical Data notebook (TDN) has been prepared for a Letter of Map Revision (LOMR) application for a portion of the Roger Wash (RGR) located in Pima County, Arizona. The objective of the TDN and LOMR submission is to provide regulatory discharge rates and floodplain limits along the Roger Wash using better topographic, hydrologic, and hydraulic data. 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 Guideline. FEMA LOMR forms are included in this TDN. 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. 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). 4 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: Akitsu Kimoto, Ph.D., C.F.M., Principal Hydrologist. Pima County Regional Flood Control District 97 East Congress, Tucson, AZ 85701 1.3 Project Location The study reach of the Roger Wash (RGR) is located within a Federal Emergency Management Agency (FEMA)-designated “Zone A” flood-hazard area, as depicted on FIRM Map Panel Numbers 04019C1616K and 1618K (February 8, 1999). No documented hydraulic analyses were found to determine the “Zone A”, and the existing “Zone A” depiction is not consistent with current topography. The objective of the TDN and LOMR submission is to provide regulatory discharge rates and floodplain limits along the Roger Wash using better topographic, hydrologic, and hydraulic data. The study reach of the Roger Wash is located primarily west of Silverbell Rd., Pima County, Arizona (Fig. 1.1). The Roger Wash enters the study limit from the west and flows east until it converges with the Santa Cruz River. The study limit for the Roger Wash is from approximately 4100 ft southwest of the intersection of Sweetwater Dr. and El Moraga Dr. to the confluence with the Santa Cruz River. 1.3 Hydrologic and Hydraulic Methods Hydrologic analysis was preformed to determine a proposed regulatory discharge rate at Silverbell Rd using U.S. Army Corps of Engineers Computer Hydrologic Modeling System, HEC-HMS. Parameterization followed guidelines developed by Pima County Regional Flood Control District and described in technical Policy 018 (Tech 018, Appendix A). The proposed regulatory discharges are flow rates that have a 1-percent chance of being equaled or exceeded each year (“100-year” discharge rates). Hydraulic analysis was performed to delineate floodplain limit along the study reach of the Roger Wash using U.S. Army Corps of Engineers Computer Backwater Model, HEC-RAS. . 5 1.4 Acknowledgment This study relied on assistance of RFCD GIS staff, who were integral to the development of the models and maps. 1.5 Study Results The regulatory peak discharge rate was calculated at Silverbell Rd (CP A; Fig. 1.3). The estimated regulatory discharge rate is 5563 cubic feet per second (cfs) with a drainage area of 5.36 square mile at CP A. 6 CP A ! ( Figure 1.1 Watershed Map Roger Wash CP B SWEETWATER ( ! EL MORAGA ( ! Discharge Point River 20 foot Contour Roger Wash Subbasins CP F CP C ( ! ( ! CP H ( CP I ! ( ! RGR A CP G RGR B ( ! RGR C GORET RGR D CP D RGR E ( ! RGR F RGR G RGR H RGR I Aerial Photo: 2008 Pima Associiation of Governments IRONWOOD HILL CP E ( ! CAMINO DE OESTE 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 databases provided and maintained by several governmental agencies. The accuracy of the information presented is limited to the collective accuracy of these databases on the date of the analysis. The Pima County Regional Flood Control Department makes no claims regarding the accuracy of the information depicted herein. This product is subject to the Department of Transportation Technical Services Division's Use Restriction Agreement. Pima County Regional Flood Control District Scale 1:2000 SPEEDWAY S AS SP E T GA 2,000 1,000 0 AN 03/2010 2,000 Feet KLAM \\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Roger_wash_Watershed_Fig1_1.mxd CAMINO DE OESTE SA CA DE AN GR Figure 1.2 Study Limit Roger Wash RUTHRAUFF 0 I1 EX IT L EL RB VE SIL EL CAMINO DEL CERRO 25 2 ON M RA P I10 Study Limit I10 ( CP A ! ! ( I10 GE TA ON FR RGR A ( CP B ! SWEETWATER Discharge Point River Subbasins EL MORAGA Existing FEMA Floodplain RGR B RGR F CP H ( ! (( CP G ! CP I ! ( CP C ! CP F ZONE A ZONE AE Study Limit RGR G ZONE X - SHADED GORET Aerial Photo: 2008 Pima Associiation of Governments ( CP D ! RGR H RGR C RGR I IRONWOOD HILL RGR D CAMINO DE OESTE CP E ! ( S TE GA Index Map Scale 1:5,250,000 SPEEDWAY SS PA 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 to the collective accuracy of these databases on the date of the analysis. The Pima County Regional Flood Control Department makes no claims regarding the accuracy of the information depicted herein. This product is subject to the Department of Transportation Technical Services Division's Use Restriction Agreement. Pima County Regional Flood Control District Scale 1:3000 ANKLAM 3,000 1,500 0 3,000 Feet GREASEWOOD RGR E Pima County Index Map 03/2010 \\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Roger_wash_Watershed_Fig1_2.mxd CAMINO DE OESTE SA CA DE AN GR Figure 1.3 Soil Classification Roger Wash RUTHRAUFF 0 I1 EL CAMINO DEL CERRO EX IT 25 2 ON M RA P I10 L EL RB VE SIL I10 Subbasins Soil Classification I10 GE TA ON FR RGR A SWEETWATER Soil Group: B (100%), ANTHONY FINE SANDY LOAM, 0 TO 3 PERCENT SLOPES Soil Group: B (100%), PINALENO VERY COBBLY SANDY LOAM, 1 TO 8 PERCENT SLOPES Soil Group: B (100%), PINALENO-STAGECOACH COMPLEX, 5 TO 16 PERCENT SLOPES Soil Group: B (100%), STAGECOACH-SAHUARITA ASSOCIATION, 1 TO 8 PERCENT SLOPES Soil Group: B (82%) C (18%), PINALENO-STAGECOACH-PALOS VERDES COMPLEX, 10 TO 35 PERCENT SLOPE EL MORAGA Soil Group: C (47%) D (53%), PANTANO-GRANOLITE COMPLEX, 5 TO 25 PERCENT SLOPES RGR B Soil Group: C (53%) D (47%), PALOS VERDES-JAYNES COMPLEX, 2 TO 8 PERCENT SLOPES Soil Group: D (100%), ANKLAM-CELLAR-ROCK OUTCROP COMPLEX, 15 TO 55 PERCENT SLOPES 2008PAGclr04ft.ecw RGR F RGR G GORET RGR H RGR C RGR I IRONWOOD HILL RGR D CAMINO DE OESTE Pima County Index Map S TE GA Index Map Scale 1:5,250,000 SPEEDWAY SS PA 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 to the collective accuracy of these databases on the date of the analysis. The Pima County Regional Flood Control Department makes no claims regarding the accuracy of the information depicted herein. This product is subject to the Department of Transportation Technical Services Division's Use Restriction Agreement. Pima County Regional Flood Control District Scale 1:3000 ANKLAM 3,000 1,500 0 3,000 Feet GREASEWOOD RGR E 04/2010 \\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Campbell_wash_Watershed_Fig1_3.mxd 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 Akitsu Kimoto, Ph.D, C.F.M., Principal Hydrologist. 2.1.3 Local Technical Reviewer: Terry Hendricks, C.F.M, Chief Hydrologist 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 study reach of the Roger Wash is located within a Federal Emergency Management Agency (FEMA)-designated “Zone A”, as depicted on FIRM Map Panel Numbers 04019C1616K and 1618 K (February 8, 1999). The study reach of the Roger Wash is located primarily west of Silverbell Rd., Pima County, Arizona (Fig. 1.1). The study reach of the Roger Wash is primarily composed of sand and cobble channel, and the bottom of the reach is relatively clean with vegetation cover. The overbank of the reach is covered with desert brush. 2.1.5 USGS Quad Sheets Not available for this study 2.1.6 Unique Conditions and Problems None. 10 2.1.7 Coordination of Peak Discharges The 100-year regulatory discharge rate at the Silverbell Rd. was computed using HECHMS, assuming no base flow in the watersheds and no transmission loss within the reaches. The hydraulic data used to derive parameters for the HEC-HMS model was obtained using HEC-RAS. The discharge rate was acceptable per Suzanne Shield, Director of the Pima County Regional Flood Control District. 2.2 FEMA Forms The FEMA MT-2 forms are included in Appendix B. Section 3 Survey and Mapping Information 3.1 Field Survey Information The survey of the culverts was conducted Frank Abell under direct contract with the Pima County Regional Flood Control. A signed and sealed copy of the survey is included in Appendix C. The site survey was performed by: Frank Abell Arizona Registered Land Surveyor, Certificate Number. 18211 3.2 Mapping The topographic data was obtained using HEC-GeoRAS and ArcGIS. Digital Elevation Model (DEM) derived from 2008 Light Detection was and Ranging (LiDAR) data and Digital Terrain Model (DTM) derived from 2005 LiDAR data were used for the hydraulic analysis with HEC-RAS. The DTM derived from 2005 LiDAR data was used for the downstream area (approximately 1700 feet from the Silverbell Rd. to a confluence with the Santa Cruz River.), while the DEM derived from LiDAR 2008 was used for the upstream area (from the upstream end of the existing FEMA Zone A floodplain to approximately 1700 feet from the Silverbell Rd.). The DTM with the 2005 LiDAR was developed by HDR in the Silverbell Road, Grant Road to Ina Road Design Concept Report (2009). It includes break lines, which is considered to be more accurate topographic data set. The sealed document for the field survey of the break lines is included in Appendix C. The DTM is available in the downstream area of the Silverbell Wash. The DEM was used to create a 2-foot interval contour map for the entire watershed of the Roger Wash. 11 The following data was used in this TDN; The aerial photo: 2008 PAG aerial photo Projection: UTM, Zone 12 Units: International feet The contour interval of the topographic map is 2 feet. Section 4 Hydrology 4.1 Method Description The 100-year peak discharges for the nine subbasins of the Roger Wash (RGR A, B, C, D, E, F, G, H, and I; Fig. 1.3) were calculated using U.S. Army Corps of Engineers Computer Hydrologic Modeling System, (HEC-HMS) version 3.4. The HEC-HMS model requires parameters regarding rainfall, topography, soil, vegetation, and channel characteristics to determine runoff volume and peak discharge. Those parameters 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. 4.2 Parameter Estimation 4.2.1 Drainage Area Subbasin boundaries were delineated using the hydrology function of ArcGIS with 2008 Lidar Data. A 5-ft contour map was used to make sure if the subbasin delineation was reasonable. 4.2.2 Watershed Work Map A watershed work map is included in Exhibit 1. Nine subbasins were delineated for HEC-HMS hydrologic analysis. A 100-year peak discharge at Silverbell Rd. (CP A) was used for HEC-RAS hydraulic analysis. 4.2.3 Gage Data No gage data were used in this TDN. 12 4.2.4 Spatial Parameters No spatial parameters were used in this TDN. 4.2.5 Precipitation According to the Tech-018, the 3-hour storm shall be used as rainfall data in the HECHMS model in case that a time of concentration (Tc) is equal or less than three hours. A 3-hour storm was selected for a peak discharge calculation for the Roger Wash, since Tc was less than 3 hours in all the subbasins. A point 3-hour rainfall depth at the coordinates of the centroid of the watershed was obtained from NOAA Atlas 14, upper 90% confidence interval precipitation frequency estimate (NOAA 14 rainfall). Areal reduction factor was applied to watersheds larger than 1 square mile, as described in Tech-018. The 3-hour rainfall depth for the Roger Wash watershed is 2.70 inches. The areal reduction factor of 0.86 was applied to estimate peak discharge at CP A. 4.2.6 Physical Parameters The physical parameters for the subbasins and reaches of the HEC-HMS model were summarized in Tables 1 and 2. As mentioned in 4.1, all the methods and parameters were determined following Tech-018. Table 1 summarizes the method used for a HEC-HMS analysis. Table 1 Methods used for a HEC-HMS analysis Rainfall Depth Rainfall Distribution Rainfall Loss Time of Concentration Transform Routing Selected Method NOAA 14, upper 90% Confidence Interval 3-hr SCS Type II Storm SCS Curve number SCS Segmental Method SCS Unit Hydrograph Modified-Puls The SCS Curve Number (CN) method was utilized as a rainfall loss method in the HECHMS model. The CN was determined using the Curve Number table associated with the PC-Hydro User Guide (Arroyo Engineering, 2007) and a Hydrologic Soils Group map. 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 the 2008 PAG aerial photograph and Table 3 in the PC-Hydro User Guide (Arroyo Engineering, 2007). The combination of the kinematic wave method and 13 the U.S. Natural Resources Conservation Service (NRCS) segmented Time of Concentration (Tc) calculation method (USDA-NRCS, 1986) was used to determine Tc, following 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. 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). HEC-GeoRAS and HEC RAS were used to estimate average velocity of channels. The detail of the Tc calculation is included in Appendix D. Table 2 Physical Parameters for the Sub-Basins Sub-Basin RGR A RGR B RGR C RGR D RGR E RGR F RGR G RGR H RGR I Area (sq mi) 0.32 0.45 0.66 0.81 1.15 0.18 0.10 0.84 0.85 CN 83.4 89.0 89.3 89.3 89.9 87.2 89.5 89.4 89.3 Impervious Area (%) 7.0 35.0 10.0 5.0 7.0 10.0 7.0 5.0 5.0 Vegetation Cover (%) 30 30 30 35 35 30 30 35 35 Lag Time (min) 28.7 27.2 17.8 18.8 12.5 13.2 8.9 21.8 22.0 Runoff from subbasins was routed using the Modified-Puls method. Storage discharge tables for the channel routing were developed using HEC-GeoRAS and HEC-RAS. Six different discharges were used for storage-discharge relations. The number of subreaches was calculated using the following method: Vw = 1.5 * Vave .........eq.1 K= L ...................eq.2 Vw Therefore, K N = ..................eq.3 Δt where Vave is average flow velocity, L is reach length, Vw is velocity of flood wave (a conversion factor of 1.5 is used for natural channels), K is hydrograph travel time, Δt is the time interval for computations in the model, and N is the number of steps in the reach routing. Eq.4 was obtained from eq.1, 2, and 3. The detail of the calculation of the number of subreach is included in Appendix D. 14 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. 4.4 Calibration No calibration was conducted in this study. 4.5 Final Results 4.5.1 Hydrologic Analysis Results The 100-year peak discharges at CP A (at Silverbell Rd.) and for the subbasins were determined using the HEC-HMS. The results are summarized Tables 3 and 4. Table 3 Summary of the Hydrologic Analysis Results for Sub-Basins Sub-Basin RGR A RGR B RGR C RGR D RGR E RGR F RGR G RGR H RGR I Area (sq mi) 0.32 0.45 0.66 0.81 1.15 0.18 0.10 0.84 0.85 Rainfall Depth (in) 3.16 3.16 3.16 3.16 3.16 3.16 3.16 3.16 3.16 Runoff Volume (in) 1.61 2.04 2.07 2.07 2.12 1.89 2.09 2.08 2.07 Peak Discharge (cfs) 342 647 1277 1511 2781 379 276 1429 1436 15 Table 4 Summary of the Hydrologic Analysis Results at the Concentration Points Concentration Point Location CP A at Silverbell Rd. Area (sq Rainfall Runoff Q100 Time to mile) Depth (in) Volume HMS (cfs) Peak (in) 5.36 2.70 1.64 5745 2:13 4.5.2 Verification results The HMS-derived peak discharge at CP A was compared with an existing 100-year regulatory discharge (Special Study 4, 1986) and the peak discharge derived from USGS Regression Equation 13 (RRE) (Thomas et al., 1997) (Table 5). The comparison shows that the HMS-derived peak discharge is lower than the existing regulatory discharge, while the HMS-derived peak discharge was higher than the RRE-derived discharge. The higher HMS-derived peak discharge than the RRE-derived peak discharge would be expected, because these steep watersheds could be expected to produce higher than average at the subbasin scale. Table 5 Comparison of a peak discharge Concentration Point Location CP A at Silverbell Rd. Area (sq Q100 Q100 Q100 Existing mile) HMS (cfs) RRE (cfs) Regulatory (cfs) 5.36 5563 3480 7072 Section 5 Hydraulics 5.1 Method Description The hydraulic modeling for the Roger Wash was performed using Hec-RAS, Version 4.0 (HEC-RAS), HEC-GeoRAS, Version 4.1.1 (HEC-GeoRAS), and ArcGIS, Version 9.3. Corrected model is proposed in this study. The model name is RGR, and the plan name is Plan 11. Hydraulic analysis was performed in the area currently mapped as FEMA Zone A. Steady flow analysis was performed to determine a 100-year floodplain limit for the Roger Wash by using HEC-RAS. Normal-depth with a slope of 0.018 was assumed for a downstream boundary condition. The locations of the stream centerline, cross-sections, and bank of the Roger Wash were determined using the 5-ft contour map and 2008 PAG aerial photos. The geometric data, including stream centerline, flow paths and cross-sections, were digitized in HECGeoRAS. The digitized data was exported to create geospatially referenced geometric data (cross section, reach profile) in HEC-RAS. As previously mentioned, the DTM derived from 2005 LiDAR data was used for the downstream area (approximately 1700 16 feet from the Silverbell Rd. to a confluence with the Santa Cruz River.), while the DEM derived from LiDAR 2008 was used for the downstream area (from the upstream end of the existing FEMA Zone A floodplain to approximately 1700 feet from the Silverbell Rd.). Other parameters for the steady-state analysis in HEC-RAS, such as Manning’s nvalues, expansion and contraction coefficients, boundary condition, and ineffective flow areas were manually input into HEC-RAS. The hydraulic data obtained from HEC-RAS were imported into HEC-GeoRAS to delineate a floodplain boundary for the Roger Wash. 5.2 Work Study Maps The work study map for the Roger Wash is included in Exhibit 2. 5.3 Parameter Estimation 5.3.1 Roughness Coefficients Manning’s n values were determined by a combination of a site visit and 2008 PAG aerial photo. Manning’s n value of 0.05-0.06 was assigned to overbank with desert brush along the Roger Wash, while 0.04-0.045 was assigned to a channel. 5.3.2 Expansion and Contraction Coefficients The channel of the Roger Wash is assumed to have generally gradual transitions with minimum curvature. The expansion coefficient of 0.30 and contraction coefficient of 0.10 were used for the study reach except immediately upstream or downstream of culverts. There are culverts located on the Sweetwater Dr. The expansion coefficient of 0.50 and contraction coefficient of 0.30 were used for the cross sections immediately upstream or downstream of the culverts. 5.4 Cross-Section Description A 2-foot interval contour map was used to select the location of cross sections. Crosssection locations were determined primarily based on the channel topography. The crosssection lines were drawn to be perpendicular to flow paths in Hec-GeoRAS. 5.5 Modeling Consideration 5.5.1 Hydraulic Jump and Drop Analysis 17 No hydraulic, drop analyses or adjustment of the floodplain was conducted in this study. 5.5.2. Bridges and Culverts There is one road crossing with nine arch culverts on the Sweetwater Dr. Survey data for the culverts are included in Appendix C. 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 were no islands or flow splits modeled. 5.5.5 Ineffective Flow Areas Ineffective flow option was modeled in the following situations; 1. disconnected overbank areas that would not convey flow to the next downstream cross-section, and 2. upstream or downstream of the arch culverts located on the Sweetwater Dr. Ineffective area was determined using a standard modeling guideline described in a HEC-RAS manual. 5.6 Floodway Modeling No floodway modeling was performed in this study. 5.7 Problems Encountered 5.7.1 Special Problems and Solutions This study assumed that El Moraga Rd. would not comply with the National Flood Insurance Program (NFIP) regulation for a levee. In other words, the road is not expected to provide a 100-year flood protection. A floodplain limit near the intersection of El Moraga Rd. and Sweetwater Dr. was determined by assuming that a levee system of El Moraga Rd. would be failed by 100-year flood. A 100-year flood hazard area proposed in this study shows a potential flood hazard area by a failure of the road. 18 Overtopping flows were found at the following cross sections: station # 1563.77, 1941.11, 5145.836, and 5231.996. The lateral weir was used to estimate the discharge potentially flows over the top of the banks for the following cross sections: 1563.77 and 1941.11. The potential loss of flow is 110 cfs at the right bank of the station 1563.77 and 34 cfs at the right bank of the station 1941.11. The right banks of the cross sections of 5145.836 and 5231.996 were too low to contain flow during 100-year events, which is caused by the Sweetwater Dr. Final mapping assumes no loss of flow at the right banks, which provides conservative water surface elevations. 5.7.2 Model Warnings and Errors No errors occurred. The following warning messages occurred: Divided flow Energy loss greater than 1.0 Energy equation could not be balanced and defaulted to critical. Cross-section extended vertically. Multiple critical depths calculated. Conveyance ratio is less than 0.7 or greater than 1.4. Inspection indicated that the modeling is accurate given the steep channel conditions. Most of these errors force a critical solution which is reasonable for these steep watercourses. 5.8 Calibration The model was not calibrated in this study. 5.9 Final Results 5.9.1 Hydraulic Analysis Results The HEC-RAS modeling results are included in Appendix E. 5.9.2 Verification of Results The floodplain limit proposed in this Roger Wash LOMR study was compared to the existing FEMA floodplain limit. The proposed floodplain limit tends to follow the existing floodplain limit. The results suggest that the proposed floodplain limit is reasonable based on the topography. 19 Section 6 Erosion and Sediment Transport No erosion or sediment transport analysis was conducted in this study. Section 7 Draft FIS Report Data 7.1 Summary of Discharges Peak discharge at CP A was used for the hydraulic analysis in this study. The estimated regulatory discharge rates are 5563 cubic feet per second (cfs) with a drainage area of 5.36 square mile. 7.2 Floodway Data Not applicable. 7.3 Annotated Flood Insurance Rate Map An annotated Flood Insurance Rate Map (FIRM) is included in Exhibit 2. 7.4 Flood Profiles Flood profiles are available in HECRAS model included in Appendix E. 20 22 5. 4 55 30 84 22 22 2290 2250 10 CP A V V U U SWEETWATER V VU U 5146 5232 480 5042 V U 6 19 0 2250 U V V U V U 20 23 .9 22 41 79 . 47 . 84 4 V U 248 30 110 CFS OUT OF SYSTEM 8 6 2 3 V U 264 85 .8 81 87 .1 35 Topo: 2008 Pima Association of Governments 40 42 31 23 .3 99 97 V U 32 95 2310 2300 70 22 0 5 71 22 2300 2350 22 6352 2350 V U 228 657 0 234 0 2330 2331.385 0 90 23 618 2 229 V U V U Pima County Index Map 6 600 7 47 2 2270 90 583 2270 2300 2290 U V V U V U 56 2290 231 2320 SWEETWATER 0 80 EL MORAGA 2320 5436 230 2300 22 60 91 V U . 69 9 553 4 551 4 V U 43 38 V U V U V U 00 43 3 87 23 V U 231 7. 4 10 40 12 V U 0 2300 2350 2 . 23 2328.837 0 2 V U 232 6. 466 44 19 2317.343 556 232 3 2317.073 V V U U 504 2 23 232 5486 52 9 70 . 78 2 49 7 . 15 5 7. 7 230 8 58 V U . 60 1. 2 CP B 2317.167 23 232 72 8 V U 98 . 84 35 34 .7 V U 37 9 Datum: NAVD 1988 V U .6 95 97 00 02 231 2. ! ( 231 7. 70 07 68 91 22 22 23 23 36 . 34 3 2314.56 236 230 5. 1 230 6 See Detail A 230 23 30 .5 93 Aerial : 2008 Pima Association of Governments V U 0 89 22 ZONE A 50 2280 78 22 22 230 22 2350 22 ZONE AE 4 V U 27 Existing FEMA Floodplain " ) EP V U 236 5 02 L EL 71 82 77 222 Proposed 100 year Floodplain 2250 RB 56 22 Detail A V U . 69 9 87 VE SIL V U 22 50 10 foot Contours 100 Feet 556 5 2 foot Contours 19 7 80 0 11 84 5 50 Discharge Point Cross Sections 4 22 211 100 111 3 5 22 V U 232 4. 2 ! ( 64 64 2 15 9 227 V U 14 5534 5. 9 2 V U U V V U 227 2. 68 9. 7 2270 5514 556 232 3 227 0. 61 8 17 1. 2 V U 87 2320 232 231 7. 4 227 2300 2 0 33 2317.343 9 .6 226 20 3 23 . 23 EL MORAGA 19 68 . 81 3 3 23 11 9 13 . 61 22 67 65 2 V U U V V U 3 14 14 56 7 35 22 2317.167 . 92 99 U V V U 3 88 6 . 48 2317.073 59 . 67 . 96 5 4 ! ( V U 18 22 2270 10 23 0 234 43 57 55 . 93 8 60 2340 6. 3 U V V U V U 38 25 62 ! ( . 78 2 9 65 52 22 22 7. 7 2310 CP B 72 8 22 90 . 22 22 30 231 231 2. 230 8 226 0 23 25 CFS OUT OF SYSTEM 54 52 V U . 75 V U 0 23 5436 59 79 22 46 225 V U 22 22 0 233 5 2340 1. 5 93 22 . 60 36 225 9. 2 00 22 230 40 0 02 224 22 7. 70 5 22 2300 2314.56 . 79 2240 228 23 230 5. 1 23 230 40 30 2260 2310 Exhibit 1 100-year Floodplain with cross sections Roger Wash Study Limits 50 224 2. 4 22 3 22 224 . 64 30 2260 38 22 2270 2240 235 0 0 V U 673 1 23 2334.063 70 23 80 2360 233 6. 0 233 2360 23 46 23 23 .1 40 35 .1 6. 82 38 . 13 44 Index Map Scale 1:1,500,000 V U 8 694 5 V U 4 704 0 23 234 00 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 to the collective accuracy of these databases on the date of the analysis. The Pima County Department of Transportation Technical Services Division makes no claims regarding the accuracy of the information depicted herein. 0 7 23 50 23 23 2370 90 22 50 90 23 V U 76 200 Feet Pima County Regional Flood Control District 23 60 .7 .6 V U 78 45 23 38 70 35 V U 05 83 240 0 V U 84 86 0 31 V U 80 232 0 .0 57 54 232 80 0 90 14 2330 23 23 100 2340 80 74 200 2350 23 41 V U 2350 23 This product is subject to the Department of Transportation Technical Services Division's Disclaimer and Use Restrictions. 98 50 0 90 23 62 0 2390 72 236 23 V U Study Limits 71 V U 52 86 23 86 239 71 0 2320 .5 .6 V U 08 40 51 .5 23 23 48 43 231 2350 2350 Pima County Regional Flood Control 97 East Congress Street - 3rd Floor Tucson. Arizona 85701-1207 (520)243-1800 - FAX (520)243-1821 http://www.rfcd.pima.gov 05/2010 \\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Roger_wash\Roger_watershed_100yr_exh1.mxd Exhibit 2 Annotated Flood Insurance Rate Map 04019C1618 K Roger Wash E131320 E131319 ER LV SI ZONE X - SHADED ZONE A SWEETWATER LL BE ZONE A EL MORAGA LOMR Case 10-09-2498P Effective Date 9/9/2010 ZONE X - SHADED ZONE A Streets FIRM X-Sections Proposed 100 year Floodplain ç ççç çç çç ççç çç ççç Base Flood Elevations Proposed Floodplain LOMR Case Studies FIRM - Flood Insurance Rate Map E131329 E131330 Floodways Sections Jurisdictions TUCSON Existing Floodplain Zone A ZONE X - SHADED AE AO X X - (SHADED) GORET PIMA COUNTY ZONE X - SHADED ççç2ç ç358 ççççç çç ç ççç ç ççççççççççç çççç çççç 23 çççç70 çççç ççç çç çççç " ) A ç ççççç çççç Pima County Index Map çç B " ) 74 23 78 ççç çççççç ç çççç çç çç2ç3ç ç8ç2çç ççç çççç 23 ç ççç64 ççç ççç23ççççççççççç ççççç çç ç ççç çççç çççççç çççç çç 23 85 çç ççç ççççççççççççççççç2ç 395 ççççççç ç çççççç ççç çççç ç çççç 23 çççç 90 çççç ççç ç çç ç ç ç ç ççç çççççç ç ZONE X - SHADED ççç çç2çç3ç9ç 9 çç çççççç ç E131332 E131331 ç ç çç ç 12 çç ç 24ç çç ç çççççççç ç ç çç 2 24ç2çççççççç ççççççç " ) C çç ç " ) D ZONE A ç ççç çç ççççççççççççççççççççççççççç 0 ç 2ç4ç4çç çç ç ç çç çç LOMR Case 10-09-2567P Effective Date 9/8/2010 E çç çççç " ) ç çç çç ç 46 çç ç 24çç ç çç ç çççç ç çççç çç çççç F " ) çç çççç 23ç3çç4çççç ççç çççççççç çççç ç ç çççç ç 50 ç ç ç 24 ççç çççç çççç ççç2çç4ç5ç ç6 ç ZONE A çççç240 çççç6 ç çç çççç ç ççç LOMR Case 99-09-434P Effective Date 4/26/2000 24 28 CAMINO DE OESTE ZONE A ZONE X - SHADED 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 to the collective accuracy of these databases on the date of the analysis. The Pima County Department of Transportation Technical Services Division makes no claims regarding the accuracy of the information depicted herein. This product is subject to the Department of Transportation Technical Services Division's Disclaimer and Use Restrictions. 500 2462 çç çç ççç çç ççç çç ççç çç ççç çççç ççççç ç2468 ççççç ççççç ççççç IRONWOOD HILL ççç 2 ççç 47 ççç 4 ççç ççç ççç ç E141306 250 0 " ) G E141305 çççç ççç çççç Pima County Regional Flood Control 97 East Congress Street - 3rd Floor Tucson. Arizona 85701-1207 (520)243-1800 - FAX (520)243-1821 http://www.rfcd.pima.gov çççç çççç çççç gislib\rfcd\projects\imd\xavi\mdx\AKITSU\Roger\Roger_watershed_Anno_FIRM28x40.mxd 500 Feet çççç çç A.1 Data Collection Summary Aldridge, B. and J. Garrett. 1973. Roughness Coefficients for Stream Channels in Arizona. US Department of the Interior Geological Survey. Tucson, AZ. Arizona Department of Water Resources, Flood Mitigation Section “Instruction for Organization and Submitting Technical Document for Flood Studies” SSA1-97, November 1997 Arizona Department of Water Resources, Flood Mitigation Section “Requirements for Flood Study Technical Documentation” SS1-97, November 1997 Arroyo Engineering. 2007. PC-Hydro User Guide. Pima County Regional Flood Control District City of Tucson (COT), Department of Transportation, 1989. Standards Manual for Drainage Design and Floodplain Management in Tucson, Arizona. Revised in 1998. National Weather Service. 1984. Depth-Area Ratios in the Semi-Arid Southwest United States, NOAA Technical Memorandum NWS Hydro-40 Phillips, J., and S. Tadayon. 2006. Selection of Manning’s roughness coefficient for natural and constructed vegetated and non-vegetated channels, and vegetation maintenance plan guidelines for vegetated channels in central Arizona: U.S. Geological Survey Scientific Investigations Report 2006–5108, 41 p. Phillips, J., and T. Ingersoll. 1998. Verification of Roughness Coefficients for Selected Natural and Constructed Stream Channels in Arizona. U.S. Geological Survey Professional Paper 1584. Pima County Regional Flood Control District “Pima County Mapguide Map”, 2008 U.S. Army Corps of Engineers (COE). 1998. HEC-1 Flood Hydrograph Package, Users Manual, CPD-1A, Hydraulic Engineering Center, Davis, CA. U.S. Army Corps of Engineers (COE). 2001. HEC-RAS, River Analysis System, Hydraulic Reference Manual, CPD-69, Hydraulic Engineering Center, Davis, CA. U.S. Army Corps of Engineers (COE). 2003. Geospatial Hydrologic Modeling Extension HEC-GeoHMS, (v 1.1) CPD-77, Hydraulic Engineering Center, Davis, CA. U.S. Army Corps of Engineers (COE). 2006. HEC-HMS, Hydrologic Modeling System User’s Manual, (v. 3.1.0) CPD-74A, Hydraulic Engineering Center, Davis, CA. U.S. Department of Agriculture Natural Resources Conservation Service (NRCS), 1986. Urban Hydrology for Small Watersheds, Technical Release 55. Washington, DC. A 2. Referenced Documents Arroyo Engineering. 2007. PC-Hydro User Guide. Pima County Regional Flood Control District Eychaner, J.H., 1984. Estimation of magnitude and frequency of floods in Pima County, Arizona, with comparisons of alternative methods: U.S. Geological Survey WaterResources Investigations Report 84-4142, 69 p. Haan, C.T., Barfield, B.J., Hayes, J.C. 1994. Design Hydrology and Sedimentology for Small Catchments, Academic Press. Thomas, B.E., H.W. Hjalmarson, and S.D. Waltemeyer. 1997. Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States. USGS Water Supply Paper 2433. 195 p. U.S. Department of Agriculture Natural Resources Conservation Service (NRCS), 1986. Urban Hydrology for Small Watersheds, Technical Release 55. Washington, DC. Appendix C: Survey Field Notes Page 1 of 1 Terry Hendricks From: Curtis, Edward [mailto:Edward.Curtis@dhs.gov] Sent: Tuesday, November 10, 2009 2:44 PM To: Manny M. Rosas Cc: Terry Hendricks; Lucero, Andrew; Caldwell, Jason; Akl, Pascal Subject: RE: PAG 2008 Orthos/Lidar Mr. Rosas – I apologize for the delay in responding to you regarding the Sanborn LiDAR report. Pascal Akl of Michael Baker, Jr. reviewed the updated July 2009 report on behalf of FEMA and advised me that all of the concerns raised in his May 18, 2009 memorandum titled “Pima County, CA [sic] Sanborn LiDAR Report Items” were addressed in the updated report except the comment that the original report lacked a sufficient number of checkpoints in urban areas and dense vegetation areas. No additional checkpoints were surveyed in such arease to permit analysis of data accuracy in these land cover categories. However, in the data voids analysis section of the updated report (p. 16), Sanborn states the following: "Specific areas, dense vegetation or undergrowth near small streams, for example, prevents the LiDAR pulses to fully penetrate to the true ground surface. Thus, for mapping products such as floodplain or contour mapping, LiDAR data must often be manually supplemented with breaklines and mass-points to accurately model the terrain surface." As long as the data is used with caution and supplemented with additional ground survey data where necessary in accordance with this statement, I am satisfied that the terrain data meets FEMA standards for use in detailed flood studies. Please contact me if you have any questions regarding our review and comments. Ed Curtis, P.E., CFM Risk Analysis Branch FEMA Region IX (510) 627-7207 - office (510) 295-5249 - mobile 2/25/2010