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 .........................................................................................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 Spatial Parameters............................................................................................ 12
4.2.5 Precipitation ..................................................................................................... 12
4.2.6 Physical Parameters ......................................................................................... 13
4.3 Problems Encountered During the Study................................................................ 13
4.3.1 Special Problems and Solutions....................................................................... 13
4.3.2 Modeling Warning and Error Messages .......................................................... 13
4.4 Calibration............................................................................................................... 13
4.5 Final Results........................................................................................................ 14
4.5.1 Hydrologic Analysis Results........................................................................ 14
4.5.2 Verification of results .................................................................................. 14
Section 5 Hydraulics.........................................................................................14
5.1 Method Description ................................................................................................ 14
5.2 Work Study Maps ................................................................................................... 15
5.3 Parameter Estimation .............................................................................................. 15
5.3.1 Roughness Coefficients ................................................................................... 15
5.3.2 Expansion and Contraction Coefficients ......................................................... 15
5.4 Cross-Section Description ...................................................................................... 15
5.5 Modeling Consideration.......................................................................................... 15
5.5.1 Hydraulic Jump and Drop Analysis................................................................. 15
5.5.2. Bridges and Culverts....................................................................................... 16
2

5.5.3 Levees and Dikes ............................................................................................. 16
5.5.4 Island and Flow Splits...................................................................................... 16
5.5.5 Ineffective Flow Areas..................................................................................... 16
5.6 Floodway Modeling ................................................................................................ 16
5.7 Problems Encountered ............................................................................................ 16
5.7.1 Special Problems and Solutions....................................................................... 16
5.7.2 Model Warnings and Errors............................................................................. 16
5.8 Calibration............................................................................................................... 17
5.9 Final Results............................................................................................................ 17
5.9.1 Hydraulic Analysis Results.............................................................................. 17
5.9.2 Verification of Results ..................................................................................... 17
Section 6 Erosion and Sediment Transport ...................................................17
Section 7 Draft FIS Report Data.......................................................................17
7.1 Summary of Discharges.......................................................................................... 17
7.2 Floodway Data ........................................................................................................ 18
7.3 Annotated Flood Insurance Rate Map .................................................................... 18
7.4 Flood Profiles.......................................................................................................... 18
List of Tables
Table 1 Methods used for a PC-Hydro analysis ............................................................... 13
Table 2 Watershed Characteristics.................................................................................... 13
Table 3 Summary of the Hydrologic Analysis ................................................................. 14
Table 4 Comparison of a peak discharge.......................................................................... 14
List of Figures
Figure 1.1 Watershed Map.................................................................................................. 7
Figure 1.2 Study Limits ...................................................................................................... 8
Figure 1.3 Soil Classification.............................................................................................. 9
Appendix A: References
Appendix B: FEMA MT-2 Forms, 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 Unnamed Wash 1
Exhibit 2 Annotated Flood Insurance Rate Map for the Unnamed Wash 1

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 Unnamed Wash 1 (UN1) located in Pima
County, Arizona. The objective of the TDN and LOMR submission is provide regulatory
discharge rates and floodplain limits along the Unnamed Wash 1 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 Unnamed Wash 1 (UN1) is located within a Federal Emergency
Management Agency (FEMA)-designated “Zone A” flood-hazard area, as depicted on
FIRM Map Panel Number 04019C1605K (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 provide regulatory discharge rates and floodplain limits along the Unnamed Wash 1
using better topographic, hydrologic, and hydraulic data.
The study reach of the Unnamed Wash 1 is located primarily west of Silverbell Rd.
Section 2 and 11, Township 13 South, Range 12 East, Pima County, Arizona (Fig. 1.1).
The Unnamed Wash 1 enters study limit from the west and flows east until it converges
with the Santa Cruz River. The study limit for the Unnamed Wash 1 is from
approximately 1000 ft southwest of Belmont Rd. to the confluence with the Santa Cruz
River in Section 2 of Township 13 South, Range 12 East.

1.3 Hydrologic and Hydraulic Methods
Hydrologic analysis was preformed to estimate regulatory discharge rate at Silverbell Rd
using PC-Hydro Version 5.4.2 (PC-Hydro). The parameters for PC-Hydro, such as
rainfall intensity and subbasin characteristics (e.g. soil, vegetation, slope, flow distance,
roughness), were selected using PC-Hydro User Guide (Arroyo Engineering, 2007). 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 Unnamed Wash 1
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 1229 cubic feet per second (cfs) with a drainage
area of 0.81 square mile at CP A.

6

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Pima County Regional Flood Control District

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This product is subject to the Department of Transportation
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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 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.

0
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Aerial: 2008 Pima Association of Governments
Topo: 2008 Pima Association of Governments

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Figure 1.1
Watershed Map
Unnamed Wash 1

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6

09/2010
\\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Unnamed_1_wash_Watershed_Fig1_1.mxd

1,000 Feet

0
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FR

Figure 1.2
Study Limit Map
Unnamed Wash 1

O
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TA
G
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RT
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M

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Discharge Point

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A

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D
E

0
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Watershed

Existing FEMA Floodplain
ZONE A
Study limit

ZONE AE
ZONE X - SHADED
Aerial: 2008 Pima Association of Governments

UN1

Pima County Index Map
SUNSET

CAMINO DE OESTE

S
E ROCK
PICT UR

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

1,000

500

0

EL CAMINO DEL CERRO

09/2010
\\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Unnamed_1_wash_Watershed_Fig1_2.mxd

1,000 Feet

CO

RT
AR

O

0
I1

Figure 1.3
Soil Classification Map
Unnamed Wash 1
0
I1
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FR
O
A
NT
G

0
I1

E

INA
0
I1
G

L

TA

EL

N

B

O

R

FR

E
LV
SI

Unnamed Wash 1 Watershed

E

C

WADE

Soil Classification
A
SA

Soil Group: B (82%) C (18%), PINALENO-STAGECOACHPALOS VERDES COMPLEX, 10 TO 35 PERCENT SLOPES

G
R
A
N
D
E

Soil Group: C (100%), TUBAC GRAVELLY LOAM,
1 TO 8 PERCENT SLOPES
Soil Group: C (47%) D (53%), PANTANOGRANOLITE COMPLEX, 5 TO 25 PERCENT SLOPES

Aerial: 2008 Pima Association of Governments
ROCKS

UN1

Pima County Index Map
SUNSET

CAMINO DE OESTE

E
PICT UR

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

1,000

500

0

EL CAMINO DEL CERRO

09/2010
\\gislib\rfcd\projects\imd\xavi\mxd\AKITSU\Unnamed_1_wash_Watershed_Fig1_3.mxd

1,000 Feet

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:
Bill Zimmerman, Division Manager and 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 Unnamed Wash 1 is located within a Federal Emergency
Management Agency (FEMA)-designated “Zone A”, as depicted on FIRM Map Panel
Number 04019C1605K (February 8, 1999). The study reach of the Unnamed Wash 1 is
located primarily west of Silverbell Rd., Pima County, Arizona (Fig. 1.1). The study
reach of the Unnamed Wash 1 is primarily composed of sand and gravel channel. 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 PCHydro. The parameters for PC-Hydro, such as rainfall intensity and subbasin
characteristics (e.g. soil, vegetation, slope, flow distance, roughness), were selected using
PC-Hydro User Guide (Arroyo Engineering, 2007). 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
None.

3.2 Mapping
The topographic data was obtained using HEC-GeoRas and ArcGIS. Digital Elevation
Model (DEM) derived from 2008 Light Detection and Ranging (LiDAR) data was used
to create 5-foot interval contour map. The documentation showing that this Lidar data set
is FEMA-compliant is included in Appendix C.
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 watershed outlet of the Unnamed Wash 1 (CP A;
Fig. 1.3) were calculated using PC-Hydro Version 5.4.2 (PC-Hydro). The PC-Hydro uses
a semi-empirical method, which is similar to the Rational Formula. The method is unique

11

to Pima County. Pima County has been using the Pima County Hydrology Procedures
(PC-Hydro method) for over 30 years for a floodplain management. The method has been
deemed as a FEMA-accepted hydrologic method for prediction of 100-yr peak discharge
in Pima County. The method was used for the Friendly Village LOMR (case# 08-090473P) and it was approved by FEMA. The PC-Hydro method generally produces higher
discharge values compared to HEC-HMS or USGS Regression equations. Peak discharge
values produced by the PC-Hydro would be conservative, compared to using HEC-HMS
or USGS Regression equations. The PC-Hydro model requires the parameters regarding
rainfall, topography, soil, and vegetation to determine peak discharge. Those parameters
were determined following the PC-Hydro User Guide (Arroyo Engineering, 2007). The
PC-Hydro 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 2-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. 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.

4.2.4 Spatial Parameters
No spatial parameters were used in this TDN.

4.2.5 Precipitation
One-hour rainfall was used to estimate 100-year peak discharge at the Silverbell Rd. The
rainfall intensity at the time of concentration for the Unnamed Wash 1 watershed is 3.78
inches. No area reduction factor was applied.

12

4.2.6 Physical Parameters
Methods are summarized in Table 1. The PC-Hydro model calculates runoff coefficients
using adjusted Curve Number (CN), which has been developed based on the results of the
USDA-ARS research. This procedure assumes that high intensity, short duration storms
result in raindrop impacts causing the surface of soils to seal up, resulting in reducing
infiltration (Caliche Effect). The CN in the PC-Hydro model increases with increasing
rainfall depth and intensity. The detail of the method was described in PC-Hydro User
Guide (Arroyo Engineering, 2007).
Table 1 Methods used for a PC-Hydro analysis

Rainfall Depth
Rainfall Loss
Time of Concentration

Selected Method
NOAA 14, upper 90% Confidence Interval
Adjusted SCS Curve number
Pima County Hydrology Procedure

Table 2 Watershed Characteristics
Sub-Basin
UN1

Area
(acre)
519

CN
85.3

Impervious Area
(%)
10.0

Vegetation Cover
(%)
20

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
None

4.4 Calibration
No calibration was conducted in this study.

13

4.5 Final Results
4.5.1 Hydrologic Analysis Results
The 100-year peak discharges at CP A (at Silverbell Rd.) were determined using the PCHydro. The results are summarized Tables 3.

Table 3 Summary of the Hydrologic Analysis
Sub-Basin
UN1

Area
(sq mile)
0.81

CN

Impervious Area
(%)
10.0

85.3

Vegetation Cover
(%)
20

4.5.2 Verification of results
The estimated peak discharge at CP A was also compared with the peak discharge
obtained from USGS Regression Equation 13 (Thomas et al., 1997) (Table 4). The
comparison showed that the PC-Hydro-derived peak discharge is 12.5% higher than the
one derived from the Regression Equation.
Table 4 Comparison of a peak discharge
Concentration
Point
CP A

Location
at Silverbell Rd.

Area
(acre)
0.81

Q100 PCHydro(cfs)
1229

Q100
RRE (cfs)
1092

RRE: USGS Regression Equation 13

Section 5 Hydraulics
5.1 Method Description
The hydraulic modeling for the Unnamed Wash 1 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 Und, and the plan
name is Plan 01.
As previously mentioned, DEM derived from 2008 LiDAR data was used to create a 5foot contour map. The locations of the stream centerline, cross-sections, and bank of the
Unnamed Wash 1 were determined using the contour map and 2008 PAG aerial photos.
The physical attributes of the wash were digitized in ArcGIS using the HEC-GeoRAS
extension and then exported to HEC-RAS to create geospatially referenced geometric
data (cross section, reach profile). Other parameters for the steady-state analysis, such as
Manning’s n-values, expansion and contraction coefficients, boundary condition, and

14

ineffective flow areas were manually added in the HEC-RAS model. The hydraulic data
obtained from HEC-RAS were then imported into HEC-GeoRAS to delineate a
floodplain boundary of the Unnamed Wash 1.
Hydraulic analysis was performed in the area currently mapped as FEMA Zone A. Steady
flow analysis was performed to determine 100-year water surface elevations in the study
area by using HEC-RAS. As described above, geometric data for HEC-RAS including
stream centerline, flow paths and cross-sections were obtained using HEC-GeoRAS.
Normal-depth with a slope of 0.02 was assumed for the upstream boundary condition for
the western reach.

5.2 Work Study Maps
The work study map for the Unnamed Wash 1 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 for the overbank with desert
brush along the Unnamed Wash 1. The value of 0.04-0.045 was assigned to a channel.

5.3.2 Expansion and Contraction Coefficients
The channel of the Unnamed Wash 1 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 entire study reach.

5.4 Cross-Section Description
A 5-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

15

No hydraulic, drop analyses or adjustment of the floodplain was conducted in this study.

5.5.2. Bridges and Culverts
None.

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 situation that overbank areas are disconnected
and would not convey flow to the next downstream cross-section.

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

5.7 Problems Encountered
5.7.1 Special Problems and Solutions
There are no special problems in the study limit.

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.

16

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 model is included in Appendix E.

5.9.2 Verification of Results
The floodplain limit produced in this Unnamed Wash 1 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.

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 discharges at CP A was used for the hydraulic analysis in this study. The estimated
regulatory discharge rates are 1229 cubic feet per second (cfs) with a drainage area of
0.81 square mile.

17

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 included in the HEC-RAS model in Appendix E.

18

0
221

2190

10
22

2

0
2170

70

2

Exhibit 1
100-year Floodplain
with cross sections
Unnamed Wash 1

0
17

2160

21

2160

217

2170

Study Limit

0
20

2170

70

0

2170 2170

61

12
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222

0

22

123 8

00

219 3. 23

22

2195.089

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05

Pima County Index Map

7
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534

6. 3

1. 5

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Aerial: 2008 Pima Association of Governments
Topo: 2008 Pima Association of Governments
Vertical Datum: NAVD 1988

70

21

2379

80

226

220 6. 5

230 8

70

70

7

1. 5

70

220

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2170

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217

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2199.569

1672

Discharge Point
River
Cross Sections
Countour 2ft
Countour 10ft
Existing Zone AE
Proposed 100yr Floodplain

21

U
V
V
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RB

2198.211

1591

L
EL

U
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CP A

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88

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00
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Index Map Scale 1:1,500,000

22

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6

Study Limit

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.

22
88
. 94

0

200

100

0

200 Feet

10

230

0

23

230

2270

20

7

23

2293.422

2295.459

2330

This product is subject to the Department of Transportation
Technical Services Division's Disclaimer and Use Restrictions.
Pima County Regional Flood Control District

22
80
23

2350

60

20

40

23

23

22

40

04/2010
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

gislib\rfcd\projects\imd\xavi\mdx\AKITSU\Unnamed_wash_1_100yrFINALexh1.mxd

6

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ZONE X- SHADED

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LOMR Case 98-09-353P Effective Date 8/31/1999

21
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LOMR Case Studies

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FIRM - Flood Insurance Rate Map

6

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DD

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)

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ZONE X - SHADED

LOMR Case 00-09-346P
Effective Date 4/26/2010

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5
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LOMR Case 07-09-1759P Effective Date 12/13/2007

8

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28

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24

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6

3
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Exhibit 2
Annotated Flood
Insurance Rate Map
04019C1605 K
Unnnamed Wash 1

EB

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FR
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NT

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E

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2170

2166
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7
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Pima County Index Map

DR

01

02

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04

Proposed
100 year
Floodplain

93
21 94
21

ZONE X

SAGUARO NATIONAL PARK WEST
09

10

11

12

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.
1,000

500

0

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

gislib\rfcd\projects\imd\xavi\mdx\AKITSU\Unnamed_1\unnamed_1_watershed_Anno_FIRM28x40.mxd

1,000 Feet

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.