DRY CREEK WATERSHED
PLAN UPDATE
TASK 4.8 – DRAFT 1 - REPORT
August 31, 2009
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Brief Summary of the Report Scope
(Only Bold items are included in Draft 1)
Chapter 1 – Executive Summary & Introduction
Chapter 2 – Project Background
Chapter 3 – Updated Hydrology & Hydraulics Models
Chapter 4 – Existing and Future Potential Flood Hazards (Partial)
Chapter 5 – Local and Regional Flood Control Projects Completed Since 1992
(Partial)
Chapter 6 – Recommended Improvements and other Mitigation Strategies (Partial)
Chapter 7 – Funding Plan Update
Appendix A – References
Appendix B – Hydrologic Factors and GIS basis
Appendix B-1: SWMM and PDP Update
Appendix B-2: Land Use Hydrologic Factors
Appendix B-3: Planned Land Use
Appendix C – Calibration Events Detail
Appendix D – Peak Flow Summary Comparison Tables
D1 – Peak Flow Summary Comparison 2-YEAR
D2 – Peak Flow Summary Comparison 10-YEAR
D3 – Peak Flow Summary Comparison 25-YEAR
D4 – Peak Flow Summary Comparison 50-YEAR
D5 – Peak Flow Summary Comparison 100-YEAR
D6 – Peak Flow Summary Comparison 200-YEAR
D7 – Peak Flow Summary Comparison 500-YEAR
Appendix E – Existing Detention Investigations and Photo Documentation
Appendix F – Dry Creek Toolbox Software Users Guide
Appendix G1 – Tutorial for Performing Impact Analysis
Appendix G2 – Tutorial for Performing Flood Analysis
OUTLINE
SEC
DRAFT 1 – AUG 2009
1.1
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Executive Summary
This Section intestinally left blank for this draft.
EXECUTIVE SUMMARY
SEC
DRAFT 1 – AUG 2009
1.2
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Introduction
1.2.1 Purpose:
The purposes of this Update to the 1992 Dry Creek Watershed Flood Control Plan are to
update the hydrologic analysis of the watershed and identify possible means to reduce
flood damages. The 1992 Dry Creek Watershed Flood Control Plan recommended
structural and non-structural measures to correct existing deficiencies and mitigate for
impacts of future development. Some of the recommendations have been implemented
while many have not due to environmental and/or economic constraints. This update will
apply more up-to-date methods to evaluate the hydrology of the watershed and
recommendations will be based an overall watershed approach with the objective of
identifying improvements that will be both feasible and effective.
1.2.2 Watershed Description:
The Dry Creek watershed covers and area of 101 square miles in Placer and
Sacramento Counties. The majority of the watershed (%) is contained within the
limits of Placer County. The Cities of Rocklin and Roseville and the Town of
Loomis are wholly or partially contained within the watershed. Other unicorporated
communities in the watershed include Granite Bay, Penryn, Newcastle, Orangevale,
and Rio Linda.
1.2.2.1
Topography
“The lower end of the Dry Creek watershed is on the Sacramento Valley floor and the
headwaters are located in the Sierra Nevada foothills. The mouth of Dry Creek, at its
confluence with the Natomas East Main Drainage Canal, is at an elevation of about
30 feet, above mean sea level (msl). Antelope Creek, Secret Ravine, and Miners
Ravine have headwaters in the vicinity of Newcastle and Penryn at elevations of 900
to 1200 feet, msl, in hilly topography typical of the foothills. Linda Creek, Cirby
Creek, and Strap Ravine have headwaters in Orangevale in Sacramento County, and
in the Granite Bay area at elevations of 300 to 500 feet, msl with less relief than is
found in the other Dry Creek tributaries. The upper portions of the Dry Creek
watershed are characterized by relatively steep slopes and moderate relief. The lower
reaches of the Dry Creek watershed, especially downstream of Roseville, are
characterized by very gentle slopes. The stream channels throughout the watershed
are generally well defined, but are not especially wide or deep.” –1992 Report
1.2.2.2
Soils and Ground Cover
The Dry Creek Watershed Coordinated Resource Management Plan details an
extensive list describing each of the soil types found of the Dry Creek watershed.
The Soil Conservation Service (SCS) has given each soil type a hydrologic
INTRODUCTION
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
classification based on infiltration rates. The hydrologic soil groups are defined as
follows:
“Group A soils have low runoff potential and high infiltration rates even when
thoroughly wetted. They consist chiefly of deep, well to excessively drained sand
or gravel and have a high rate of water transmission greater than 0.30 in/hr).
Group B soils have moderate infiltration rates when thoroughly wetted and
consist chiefly of moderately deep to deep, moderately well to well drained soils
with moderately fine to moderately coarse textures. These soils have a moderate
rate of water transmission (0.15-0.30 in/hr).
Group C soils have low infiltration rates when thoroughly wetted and consist
chiefly of soils with a layer that impedes downward movement of water and soils
with moderately fine to fine texture. These soils have low rate of water
transmission (0.05-0.15 in/hr).
Group D soils have high runoff potential. They have very low infiltration rates
when thoroughly wetted and consist chiefly of clay soils with a high swelling
potential, soils with a permanent high water table, soils with claypan or clay layer
at or near the surface, and shallow soils over nearly impervious material. These
soils have very low rate of water transmission (0-0.05 in/hr).”
(from TR-55)
A map depicting the hydrologic soil group for the soils in the Dry Creek Watershed is
shown in Figure ???
The Dry Creek Watershed Coordinated Resource Management Plan (DCWCRMP)
contains an extensive listing of the soil names and classifications for the soils found
in the Dry Creek Watershed. (pgs 51-60 of that plan)
1.2.3 Land Use Trends and Projections
1.2.4 Data Sources
1.2.4.1
Hydrologic Reports
1988 Dry Creek Hydrology (USACE)
Describes watershed hydrology.
1992 Dry Creek Watershed Flood Control Plan (JMM)
This study has been the basis of the watershed plan for Dry Creek used by the
Placer County Flood Control and Water Conservation District, Placer County,
INTRODUCTION
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
the City of Roseville, the City of Rocklin and other local communities. This
is the study being updated by this report.
2000 Dry Creek Watershed Flood Detention and Stream Restoration
Feasibility Study (Swanson & EDAW)
This report investigated 19 potential sites for regional flood detention projects
based on project feasibility, relative cost, and environmental issues. Two
sites, Miners Ravine below Sierra College Boulevard and Secret Ravine above
Sierra College Boulevard, were examined conceptually as example projects to
produce preliminary cost estimates for multi-use regional flood detention
projects.
2001 Flood Insurance Study (FEMA)
This study provided an update to the FEMA 100-year floodplain maps, and
basis hydrology. This study was largely based on the hydrology of the 1992
Plan, however, some updates were made for various areas of the watershed,
where new studies with better calibrations had been made.
2001 Town of Loomis Drainage Master Plan (West Yost)
This report outlines the existing storm drain system for the Town of Loomis
and recommends upgrades to the system to decrease localized flooding
problems. The localized flooding issues are due primarily to inadequate storm
drain infrastructure, and not necessarily flood flows from streams in the Dry
Creek Watershed. It also lists several crossings Antelope Creek, Sucker
Ravine, and Secret Ravine that are inundated by flood flows. The crossings
are presented in the Existing Flood Hazard section of this report.
2004 Alternative Regional Detention Sites (URS)
The report analyzes four potential sites for regional detention basins: Strap
Ravine immediately upstream of McLaren Drive next to Maidu Park in
Roseville; Miners Ravine upstream of East Roseville Parkway; Linda Creek
west of Rocky Ridge Drive and south of Meadowlark Way in Roseville; and
Miners Ravine immediately downstream of Sierra College Boulevard. The
report uses the hydrology information developed for the 1992 Dy Creek
Watershed Flood Control Plan and created an unsteady-state HEC-RAS
hydraulic model from various existing hydraulic models. The report
recommended the construction of the Miners Ravine detention basin
immediately downstream of Sierra College Boulevard and reported that
“although the other three sites did reduce peak discharges immediately
downstream of their locations, their hydraulic benefits were localized and only
minor positive impacts downstream near Riverside Ave. and Vernon St.
Bridges (E-1).” The only regional detention basin that was recommend in this
report, Miners Ravine Off-Channel Detention Basin, was completed in 2007.
INTRODUCTION
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
2006 Central Rocklin Drainage Master Plan (West Yost)
The report analyzes mostly the urban drainage through storm drain systems,
but includes sections on the stream. The PCFCWCD HEC-2 models used for
the 1992 report and the 1998 FEMA FIS were converted to HEC-RAS and
used to analyze flooding in the Dry Creek tributary streams in the City of
Rocklin.
2007 Miners Ravine Off-Channel Detention Basin (RBF)
1.2.4.2
Environmental Documents
1994 Dry Creek Watershed Flood Control Program PEIR
Describes the potential environmental impacts of the proposals of the 1992
Flood Control Program as well as presenting mitigation measures to be used
while implementing the recommendations of the 1992 Report.
2002 Miners Ravine Restoration Project (EDAW)
The report describes the plan for improvements of the Miners Ravine Nature
Reserve near the intersection of Oak Glen Lane and Auburn-Folsom Road to
“enhance floodplain function and habitat value”. The plan includes channel
excavation to restore natural floodplain function, removal of debris, bank revegetation, and removal of barriers to fish passage.
2002 Miners Ravine Habitat Assessment (DWR)
The report describes the biological habitat survey of Miners Ravine with
special attention given to Salmon habitat.
2003 Dry Creek Watershed Coordinated Resources Management Plan
(DCC, HLA, Swanson, ECORP)
The broad scope of the report offered a comprehensive review of the Dry
Creek Watershed covering many issues including hydrology, biology and
wildlife, population growth and development projections, and policy
implementation plans.
1.2.5 Historic Flooding
“Floods in the Dry Creek watershed have occurred from October through April. The
floods are generally caused by a combination of prolonged rainfall leading to saturated
soils, and a short period of one to six hours of intense precipitation associated with frontal
convection or severe thunderstorms.” (?from RBF…. Need Source???)
“Dry Creek and its tributaries have an extensive record of historic floods, especially in
the Roseville area. Streamflow records are available for a gage in Roseville beginning in
INTRODUCTION
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
1950. Damaging floods occurred in December 1955, April 1958, October 1962,
December 1964, March 1983, and February 1986. The floods of 1983 and 1986 are the
largest and most damaging on record. Hydrologic studies have shown that the recurrence
interval of the March 1983 flood was approximately 10 years and the recurrence interval
of the February 1986 flood was from 50 to 100 years depending on the specific location
in the Dry Creek watershed.”(1992 report 1-17) Flood events also occurred in 1995 and
2005, with the 1995 flood event causing extensive damage. (Also from RBF what was
the source???)
1.2.5.1 March 1983 (10 yr) – “damaged approximately 25 residences along Linda
and Cirby Creeks in Roseville. Portions of Royer Park were under water was well
as areas in the Sierra Lakes Mobile Home Park. Dry Creek overflowed the
Darling Way and Riverside Avenue bridges, disrupting traffic and flooding six
businesses along Riverside Avenue. (1992 DCWFCP 1-17)
1.2.5.2 February 1986 (50-100 yr) - “The February 1986 flood caused
widespread damage in most of the Dry Creek watershed. Nearly all bridges and
culverts were overtopped, with 30 sustaining embankment damage and the
crossing at Rocky Ridge Drive washing out. Two bridges over Dry Creek were
damaged and suet cave-ins occurred at a number of locations. Flooding caused the
closure of many major streets in the watershed, including Riverside Avenue,
Darling Way, Douglas Boulevard, Vernon Street, Sierra College Boulevard, and
others. Around 100 homes in Roseville along Dry Creek, Linda Creek, and Cirby
Creek were flooded with water levels up to five feet above floor levels. Ten
homes along Antelope Creek and Secret Ravine tributaries in Rocklin and around
sixteen homes in Miners Ravine in Placer County, in the area of Joe Rodgers
Road, were flooded. Roseville City Hall and libraries were temporarily closed
when their basements flooded. Downstream of Roseville, several residences along
Dry Creek in Placer County were flooded. Flooding occurred along most of
Elkhorn Boulevard near Dry Creek in Sacramento County, including many
residences, schools, and businesses. (1992 DCWFCP 1-17 through 1-18) pgs 2-12
The flow rates and stage heights from the February 1986 storm event were used to
calibrate the 1992 model. (More description on pg 3-1).
1.2.5.3 March 25, 1989 (1-2 yr) - The flow rates and stage heights from the
March 1989 storm event were used to calibrate the 1992 model
1.2.5.4 January 1995(100-200yr) - the most severe recorded flooding to date
occurred in the Dry Creek. The storm was actually a series of two high
precipitation storm events spaced about 12 hours apart. The 1st event delivered an
approximate 10-year event rainfall distribution. The second storm event delivered
higher intensities of precipitation. The rainfall distribution for some gages
INTRODUCTION
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
reported near 200-year rainfall depths for the peak 6-hour and peak 24-hours of
the event. As with the 1986 flood, numerous bridges were overtopped
(damage?)....
The Sacramento Bee reported flooded houses at the following locations:



Cherry Lane in Rio Linda (Dry Creek)
Tiffany Circle in Roseville (Between Cirby and Linda Creeks)
Royer Park in Roseville (Dry Creek)
1.2.5.5 December 2005 (10-25 year) – This event often referred to as the “New
Years Eve” event occurred in the early morning hours of December 31st, 2005.
Most gages reported peak 6 hour precipitation between the 10-year and 25-year
precipitation depths reported in the SWMM. Flooding was most noticeable in the
lower watershed where the overtopping of Walerga Road made news as vehicles
& drivers attempting to cross the bridge during overtopping flows required
emergency assistance to have their stalled vehicles pulled to safety. One vehicle
was pushed by the velocities in the overtopping flows, onto the guard rail, and
against a tree, requiring a helicopter rescue.
1.2.6
Existing Conditions:
1.2.6.1 Main Channel and Tributaries:
Dry Creek has four main tributaries consisting of nine streams, namely Miners
Ravine and False Ravine; Sucker and Secret Ravines; Antelope Creek and Clover
Valley; and Linda Creek, Cirby Creek, and Strap Ravine.
“Dry Creek is a second-order perennial stream, approximately 17.6 miles long. In
the lower reaches, it bifurcates around Cherry Island and reconverges prior to
discharge into Steelhead Creek (a.k.a., the Natomas East Main Drain - NEMDC).
This main stem drainage system is composed of 1.3 miles of intermittent
drainage, 20.3 miles of first-order perennial, and 21.6 miles of second-order
perennial streams. The immediate watershed area is 24.4 square miles and the
drainage density is 1.8. From the confluence of Miners Ravine and Secret Ravine,
Dry Creek is somewhat straightened until Watt Avenue, after which it returns to
more natural channel configurations. Nine other unnamed ponds/lakes are present
within this subwatershed.” (DCMP 69)
1.2.6.2 Miners Ravine and False Ravine
Miners Ravine is a perennial tributary that has been studied and assessed for a
number of different purposes; habitat, geomorphology, and flood studies, to name
a few. The main channel is approximately 15.2 miles long. It is entrenched within
INTRODUCTION
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
an alluvial valley floor, and serves to drain approximately 20.1 square miles of
mixed-use land. The upper reaches of Miners Ravine are composed of intermittent
drainages (8.0 miles) and the lower reach are primarily intermittent (12.1 miles)
with some perennial first-order reaches (2.9 miles) and some second-order
reaches (0.6 miles). The calculated drainage density for this subwatershed is 1.1.
“The surrounding uplands are characterized by gently rolling hills separated by
broad flat valleys. The channel position within the alluvial valley floor of the
lower reaches is not fixed and shifts or meanders across the floodplain due to
eroded soils, banks, and redeposited sediments. This is consistent with the slope
gradient, which is approximately 2.4% in the upper 7.2 miles and 0.58% in the
lower 8 miles. Stream gradients less than 2% generally result in meandering
streams that tend to 'wander' back and forth across the flood plain over time.
Entrenchment (incising channel) over time is likely due to historical filling of the
alluvial valleys with re-deposited Placer and quarry mining spoils of sand-sized
granitic material, and possibly channelization and realignment for subsequent
agricultural use and urban development. The valley floor is a flat floodplain that
varies from 100 to 300 feet in width. However, the stream channel itself is only
12 to 30 feet wide and 4 to 12 feet deep. Water flows do not have the energy to
erode bedrock rapidly, so Miners Ravine stays small.
“Apart from the main channel, the watershed drainage is composed of small,
intermittent tributaries that carry only low flows. These intermittent tributaries
can be expected to flood every 5 years on an average. A survey of Miners Ravine
determined that several watershed characteristics have impacted local hydrology.
Fences and other structures within or immediately adjacent to the watercourse
trap floating debris during high flows, thereby, creating flow obstructions and
flooding problems. Inadequate culvert sizing at bridge crossings also contributes
to obstructed flow. Trash and debris deposited on the floodplain next to Miners
Ravine provide more material for trapping and backing up flows during flood
events where flows over top the banks and carry debris laden water into the
inadequate culverts or blocked fences. New developments often increase the
watershed impervious fraction and storm drains from developments contribute
flows in excess of "natural" flows. Livestock grazing compacts riparian soils,
destroys riparian vegetation, and tramples unstable stream banks. All these factors
have worked to contribute to impacts on Miners Ravine hydraulic and hydrologic
functions.
“Flow through Miners Ravine is flashy, due to the shallow depth to bedrock,
limited soil permeability, and limited water holding capacity. Additionally, the
natural channel is small relative to the floodplain area; therefore, flooding occurs
fairly often...Urbanization has led to reduced floodplain storage and inadequate
channel capacity at road crossings. Summer flow is often less than 1 cfs, whereas
flood flows have been estimated at as high as 8,428 cfs at the confluence with Dry
Creek and Antelope Creek per the 1992 Dry Creek Watershed Flood Control Plan
INTRODUCTION
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
(Placer County Flood Control District, 1992) during the winter wet weather
season (October through April). Summer flows are generally composed of spring
flows and components of urban runoff: ponds, landscape water, and historically,
sewage flows
In addition to streams and creeks, Miners Ravine includes other water features
such as Oak Lake, Cottonwood Lake, Pine Lake, Laurel Lake, Mamouth
Reservoir, another unnamed reservoir, and more than approximately 20 small,
unnamed ponds” (DCMP 67-68)
False Ravine, an approximately 1.5 mile long tributary, empties into Miners
Ravine just west of East Roseville Parkway, upstream of North Sunset Avenue.
1.2.6.3 Secret Ravine & Sucker Ravine
“Secret Ravine is one of the more widely studied tributaries in the Dry Creek
watershed. Secret Ravine is a 7.8-mile long perennial stream that flows in a
narrow valley underlain by recent alluvial deposits. Contributing subwatershed
area is approximately 22.3 square miles. The upper reaches of Secret Ravine are
all intermittent drainageways (12.7 miles) and the lower reaches are intermittent
(8.1 miles) and perennial (6.3 miles). The drainage density of Secret Ravine is
1.2. Above the 220-ft elevation, Secret Ravine is incised in the granitic bedrock
and the riparian corridor is correspondingly narrow. In the lower watershed, the
bedrock is composed of volcanic cap rock. Soils in the watershed uplands are very
shallow or very impermeable; consequently, surface and subsurface runoff are
rapid. The Central Valley alluvial soils are coarse-grained and highly permeable
decomposed granite, resulting from products of Placer mining and sluicing and
runoff from quarry spills. Patches of seasonal wetland are also present in the
Central Valley alluvial floor.
“The main channel is typically 6 to 8 feet deep (sometimes over 12-feet deep),
with a flat bottom, rectangular in shape, and with a median width of 12 feet (range
of 10 to 25 feet). The channel bed is stable; but, meandering is very minimal and
riffle-run-pool habitat is not diverse. Nonetheless, anadromous fish, including fall
run Chinook salmon and steelhead, have been found in Secret Ravine. Dry
weather flows are primarily due to urban inputs, such as lawn irrigation and
excess drainage, sewage effluent, unknown amounts of tailwater delivered by the
Placer County Water Agency's irrigation releases, and other releases such as small
amounts of freshwater seeps. During dry weather, in the upper reaches these
augmentations are more significant in terms of flow proportion compared to lower
reaches. Fields (1999) estimated that dry weather flows were double to triple the
normal amount resulting from these urban inputs. One freshwater seep was noted
just south of Interstate 80 highway crossing, about 500 feet beyond the end of
China Garden Road. Rapid development within the watershed has increased the
INTRODUCTION
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
impervious fraction and, consequently, the peak flows. This change in hydrology
significantly impacts channel hydraulics; therefore, channel capacities are not
sufficient to convey flow for more than the 5-year storm event in the upper
reaches. Larger discharges and faster flows create flood hazards, undermine
structures, and contribute to bank/channel instability and erosion.
“Typical flows in Secret Ravine were measured, or estimated, for two studies.
The Secret Ravine Existing Conditions Report (Dry Creek Conservancy, 2001)
indicated that flows could be as low as 0.5 cubic feet per second (cfs) and 2-3 cfs
during early fall. Li and Fields (1999) estimated that February flows were
approximately 25 cfs in the lower reaches and 5-10 cfs in the upper reaches.”
(DCMP--66)
Sucker Ravine drains an area of approximately ___ , northwest of Interstate-80.
The approximately 5 mile stream joins Secret Ravine after crossing under
Interstate-80 and China Garden Road, near Greenbrae Road.
1.2.6.4 Antelope Creek & Clover Valley Creek
“Antelope Creek is a perennial creek draining the northeast portion of the Dry
Creek watershed. The mainstem is approximately 9.5 miles long and the
watershed area is 21.4 square miles. Little information has been gathered on this
watershed. From U.S. Geological Survey (USGS) topographs, the Antelope Creek
system is composed of approximately 12.4 miles of intermittent tributaries in
addition to a major tributary, Clover Valley Creek (7.1 miles long; watershed area
of 10.2 square miles). The drainage density (ratio of stream length to watershed
area) is 1.6. Higher drainage densities generally denote more rapid responses to
storm events. The Aitken Reservoir is located within the Antelope Creek
subwatershed.” (DCMP pg 65)
Clover Valley Creek drains the northwest portion of the Dry Creek watershed.
Recent development in Clover Valley, including on-channel ponds and
urbanization has altered the timing and quantity of streamflows. The 6.5 mile
stream is bounded by hills in a narrow valley. The drainage density of Clover
Valley Creek is ___, showing a rapid response to storm events. The Clover
Valley Creek joins with Antelope Creek downstream of Argonaut Avenue near
Midas Avenue.
1.2.6.5 Cirby Creek, Linda Creek & Strap Ravine
“Cirby Creek is a perennial stream approximately 2.7 miles long with a
watershed area of approximately 3.4 square miles. The drainage density is about
0.8. Linda Creek comprises the upstream subwatershed and Cirby Creek outflows
INTRODUCTION
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
directly into Dry Creek. The Cirby Creek watershed is almost entirely within the
urbanized area of the City of Roseville.” (DCMP pg 69)
“Linda Creek is a perennial stream, approximately 10.8 miles long. The
subwatershed drainage areais 12.2 square miles and there are 7.3 miles of
intermittent drainageways and 11.2 miles of perennial, first-order streams. The
resulting drainage density is 1.5. Overall stream gradient is approximately 0.68.
Other waterbodies within this subwatershed are Swan Lake, an unnamed
reservoir, and approximately 10 unnamed pondsllakes.” (DCMP pg 69)
“Strap Ravine is a perennial waterway that is approximately 3.6 miles long and
drains an area of approximately 4.8 square miles. Strap Ravine is a tributary to
Linda Creek with a drainage density of 0.8. There are 4 unnamed ponds located
on the USGS topograph for this subwatershed.” (DCMP pg 68-69) Strap Ravine
joins Linda Creek near North Cirby Way, just downstream of McLaren Drive.
INTRODUCTION
SEC
DRAFT 1 – AUG 2009
2.0
Project Background
2.1
Topography Mapping
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
<DRAFT 1 DATA NEEDED from CESI write up – This is just the project topography
and DEM data write up>
2.2
Land Use Data
<DRAFT 1 DATA NEEDED from CESI write up>
2.3
Rainfall and Stream Gage Records
<DRAFT 1 DATA NEEDED Paste from CESI write UP>
2.4
Existing Flood Hazards
2.4.1
FEMA FIS 2001
2.4.1.1 Rocklin
Specific problem areas (from Rocklin DMP, Chapter 5): Sucker Ravine at
Dominguez Road: smaller crossings downstream of Dominguez Road cause
backwater problems upstream, including the Dominguez road crossing which may
impact future developments.
Pacific Street near Brace Road: Sheet flooding in the roadway due to backwater in
the western part of Sucker Ravine and inadequately sized culverts forces road
closures.
Brace Road on the eastern tributary of Sucker Ravine is overtopped due to an
inadequately sized 24’ CMP culvert.
Sucker Ravine at Racetrack Road: A house adjacent to Sucker Ravine on
Racetrack Road lies in the floodplain. Future development may increase flood
depths and frequencies at the house.
Sucker Ravine at Sierra Meadows—The water surface elevations are close to
overtopping the road, although it has historically not been overtopped.
Antelope Creek Tributary –Sierra Meadows—Circuit Court - “A small creek
starts west of Sierra Meadows Drive, crosses Circuit Drive, passes under Pacific
Street and continues west where it enters Antelope Creek near Yankee Hill Road.
Culverts under Circuit Drive are undersized for the current runoff from an
industrial area on Sierra Meadows Drive. If a larger culvert is constructed under
PROJECT BACKGROUND
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DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Circuit Court, channel restoration and enlarged culverts between Circuit Drive
and Antelope Creek need to be constructed.”
Sucker Ravine at Rocklin Road (including (I-80, Lakeside Drive, and Sierra
Lakes) - “No flooding has been experienced, but Sucker Ravine flows are close to
the bridge deck during large storm events. These culverts may need to be replaced
as more development occurs upstream.
“Sucker Ravine from upstream of Rocklin Road to downstream of Interstate 80 is
a complex flooding problem that will have to be addressed in a comprehensive
engineering study to arrive at the best solution. Peak runoff during a 100-year
storm event will pond behind Interstate 80 to the top of highway elevation at 254
feet. This backwater will impact the Sierra Lakes Mobile Home Park upstream
1080 feet to the footbridge where the restriction raises the water surface elevation
four feet to elevation 258 causing extensive flooding throughout the park.
Lakeside Drive would be under 2.5 feet of water making the road impassible.
Flooding would extend upstream to Rocklin Road where the road would be
overtopped by one to two feet causing disruption to a major artery. Replacing the
Rocklin Road culverts would send more water quicker into Sierra Lakes, more
water than can pass the bridges and culverts in the park and increases the
backwater caused by the State’s Interstate 80 culvert. A solution may require
additional capacity under I-80 or storage upstream of the highway to lower the
ponded water elevation. A bypass of flood water through or around Sierra Lakes
would be necessary unless the creek with bridges and culverts was completely
reconstructed.” (Rocklin DMP, pg 5-15)
Midas Avenue upstream to Del Mar Avenue (Rocklin DMP pg 4-5)—all the
bridges including, and between, these two bridges are overtopped by 2.25-6.47
feet of water in 100-year event.
2.4.1.2 Roseville
Roseville Regulatory Floodway (NEEDS COMPLETION)
2.4.1.3 Loomis (from Loomis Drainage Master Plan, pg 4-25)


Sucker Ravine
o Kings Road backs floodwater
o Saunders Avenue overtops during flood flow
o Sierra College Boulevard backs up floodwater
Secret Ravine
o Horseshoe Bar Road overtopped during 100-year event
o Brace Road overtopped by 3 feet during 100-year event
PROJECT BACKGROUND
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DRAFT 1 – AUG 2009

PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
o Gade Lane overtopped by 100-year event
Antelope Creek
o King Road overtopped by 100-year event; 2 or 3 homes are in the
floodplain just upstream
o Sierra College Boulevard backs up floodwater in 100-year event
o Delmar Avenue overtopped by 100-year event
2.4.1.4 Placer County
“Problem areas for flooding are: upstream of Sierra College Boulevard, near Joe
Rodgers Road, and at the bridges of Leibinger Lane, Carolinda Drive, and Itchy
Acres Road.” (DCMP 67)
2.5
Other Modeling
<DATA FROM CESI NEEDS TO BE TRANSFERRED>
2.6
Reference Documents and Materials
<CUT AND PASTE FROM RBF OUTLINE>
2.7
Hydraulic Routing Model Compilation
<Just a summary here as the full detail is provided later.>
2.8
Local and Regional Flood Control Projects Since 1992
City of Roseville, SP Railroad, and RBF;
Cirby Creek Modifications (1992)
The City of Roseville lowered the Cirby Creek channel bed up to 2’ near
Eich Intermediate school and installed geoweb walls on the edge of the
channel to Sierra Gardens Drive.
Precast Prestressed Concrete Bridge on Dry Creek (1993)
The Southern Pacific Railroad replaced four 18’x13’ elliptical culverts
with a concrete bridge on 4 rows of 15” to 16” piles. The 2 piers adjacent
to Subway Road were lowered to match the existing road grade.
I-80 / Cirby Creek Project (1996)
The City of Roseville regraded portions of the Cirby Creek channel, just
upstream of I-80, and added a floodwall along the north side of the
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
channel. The levees were also regraded and a walkway was installed on
the top of portions of the levee.
Cirby and Linda Creek Confluence to Tiffany Circle (1998)
Two parallel 9’ diameter CIPP bypass pipes on Linda Creek, just upstream
of the confluence with Cirby Creek, was installed by the City of Roseville.
The bypass pipes are 856’ long and bypass collect water from Linda
Creek, bypassing a large bend in the stream, and discharge into Linda
Creek, just upstream of the confluence with Cirby Creek. A bike path and
floodwall were constructed upstream of the bypass to Tiffany Circle.
Rocky Ridge Drive to Old Auburn Road (1998)
The City of Roseville constructed a 115’ long, 25’ wide bypass channel on
Linda Creek, upstream of Rocky Ridge Drive. The bypass channel
parallels Linda Creek and is separated by about 100’. A levee and a
floodwall were also installed along portions of the stream below Old
Auburn Road.
Miners Ravine Detention Basin (2007)
Placer County Flood Control and Water Conservation District constructed
an off-channel detention basin, including inlet and outlet structures, on
Miners Ravine…
Atkinson Street Bridge (?)
Caltrans and the City of Roseville replaced the 2-lane, 5-span Atkinson
Street Bridge with a 5 lane, 4-span bridge. Floodplain Enchroachment
analysis performed for the bridge showed a net decrease in water surface
elevation upstream of the bridge do to the low chord at a higher elevation
and the piers aligned to the direction of flow instead of the previous
configuration with the piers skewed to the direction of flow.
Bypass Channel along Riverside, downstream of Darling Way (?)
Non-Structural Improvements since 1992:
From City of Roseville’s Website
http://www.roseville.ca.us/pw/engineering/floodplain_management/flood_
facts.asp
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
“Flood Control Improvements Completed in Roseville Since 1986
1. 1986 - Quadrupled size of culvert at Rocky Ridge Drive on Linda
Creek to handle 100-year storm. Cost = $250,000.
2. 1986 - Culvert added at Champion Oaks Drive at Linda Creek and
improved channel upstream to increase channel capacity. Cost =
$100,000.
3. 1986 - Improved culvert at Southern (now Union) Pacific tracks on
Dry Creek. Cost = $100,000.
4. 1990 - Enlarged culvert under Diamond Oaks Road thereby protecting
10 homes that flooded in 1986. Cost = $250,000.
5. 1992 - Replaced Loretto Bridge over Cirby Creek and widened
channel between Eich School and Sierra Gardens Drive. This project
brought all nearby homes out of the floodplain. Cost = $700,000
6. 1993 - Diamond Oaks Culvert Replacement. This project brought all
nearby homes out of the floodplain. Cost = $500,000.
7. 1996 - Union Pacific Culvert Removal Project - This project removed
the culverts under the railroad tracks on Dry Creek downstream of
Vernon Street, thereby removing over 150 homes from the floodplain.
Cost = $2 million. (City contributed $220,000).
8. 1996 - Cirby Creek/I-80 Project (the Tina/Elisa area). This project
brought the entire Tina/Elisa neighborhood of 40 homes out of the
floodplain. Cost = $3 million (100% City funded).
9. 2001 – Home Elevation Program. FEMA funded 75% of this $1
million program to elevate flood-prone homes. These are structures
that would not be brought completely out of the floodplain by
construction of our flood control project. Homeowner participation
was voluntary. 27 of 44 homeowners on the list elevated their homes
via this program. Most of those 27 are located in the Folsom/Maciel
neighborhood along Dry Creek.
10. 2001 - Flood control improvements in two areas on Linda Creek: the
Champion Oaks/West Colonial Parkway area, and the
Sunrise/Oakridge area. This project reduced the size of the floodplain
resulting in 233 homes no longer being located in the floodplain, and
reducing the risk of flooding for 44 additional homes. Cost = $16.1
million ($8.7 million FEMA funds, $7.4 million City funds). “
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
3.0
Updated Hydrology and Hydraulics Models
3.1
3.2
3.3
3.4
3.5
3.6
HMS Models
3.7
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Integration of Intermap Topography (New Shed Boundaries)
Shed Splits for added detail points
Land Use Hydrologic Factors for 1992, 2007, and Future General Plan
Rainfall Losses, and Response time factors (Hydrologic Calibration)
HEC-1 Baseline Comparison Model to Previous 1992
HEC-HMS conversion of 1992 Model, and Updated Baseline HEC-
Hydraulic Routing Model for Calibrations
3.7.1 Dynamic Flood Routing in HEC-RAS
The 1992 study modeled the watershed using only hydrologic models that
incorporated storage routing in the HEC-1 hydrology model and steady-state,
gradually varied flow in the HEC-2 hydraulic model where cross sections were
available. The previous models could not adequately or accurately model
potential regional detention projects, such as Miners Ravine Off-Channel
Detention Basin. Consequently, an unsteady-state HEC-RAS model was
developed utilizing a variety of sources for cross sections and varying storage
levels.
The composite unsteady-state HEC-RAS model of the Dry Creek watershed was
developed using the following sources of cross section and reach information:
Source River Reach Stations
Each of the reaches was imported into HEC-RAS. Bridge definitions, where
applicable, were adjusted to match existing conditions as verified by field
investigation. The cross sections were…
The composite model was constructed to match the approximate 1992 conditions,
without the flood control improvements realized since that time.
3.8
Synthetic Model Performance Calibrations
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
3.8.1 DECEMBER 1995 Event
3.8.2 JANUARY 1997 Event
3.8.3 DECEMBER 2005 Event
3.8.4 Added Hydraulic and Hydrologic Performance Calibration of
JANUARY 1995 for Vernon Gage Only. To Compare with USGS Rating Curve.
3.9
Baseline Conditions Modeling for 1989/1992 in HEC-HMS
3.10
Current Conditions (2007) Modeling
3.10.1 for “without local detention” alternative in HEC-HMS
SP Railroad Bridge: For the pre-1992 model, 4 elliptical culverts were added to
the crossing, each with a span of 12.5 feet and a rise of 17.5 feet. The bridge deck
was extended to the bottom of the channel with the top of the deck at 135.5 feet.
The length of the culverts is 98 feet. For the existing conditions model, the
culverts were removed and the low chord of the bridge deck was raised to 127.9
feet. A 6’ wide pier in the center of the channel was placed, because the other 3
piles are located outside the channel.
<PASTE FROM CESI WRITE UP>
3.10.2 for “with local detention” alternative in HEC-HMS
Various local detention basins have been constructed to mitigate the increase of
runoff flows do to development. A summary of the local detention basins
constructed in the Dry Creek Watershed is listed in Table ___.
Table located at: <NEED TO GET FROM RBF>
H:\PDATA\60100402\Project Info\Data-in\From Civil
Solutions\PCFCWCD\2008_03_13-DarrowBackground\DetentionInventory.1.xls
Miners Ravine Off-channel Detention Basin: For the existing conditions model
to reflect the construction of the detention facility, the rating curves were replaced
with post-construction rating curves. An additional storage area was Included
upstream, east of Sierra College Boulevard, including adding a weir and flap gates
to connect the upstream storage area to the new detention basin. The culvert size
was increased to match the replaced culverts under Sierra College Boulevard.
The spillway of the detention facility was added as a storage area connection to
the downstream storage area. The lateral weirs connecting the channel to the
detention basin were also adjusted to reflect the post-construction elevations.
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Linda Creek Bypass Channel: To model the channel built after 1992, the
present conditions model was altered to include an additional 1208 foot reach, just
downstream of River Station 8810 on Below Strap reach on Linda Creek.
Because the new reach was added, the resulting new downstream reach of Linda
Creek was renamed “Below Bypass”. The trapezoidal cross sections were taken
from the construction plans for the project. A section was added at each end, with
inverts at 146 feet upstream and 144 downstream per the construction plans. A
lateral weir at an elevation of 146 feet was used to connect Linda Creek at River
Station 9500, next to the left bank station, to the upstream segment of the reach.
An initial flow was added in the channel to stabilize the data for unsteady-state
flow modeling.
Linda Creek Bypass Piping: For the present conditions model, a lateral weir
was added at River Station 3019.3 on the Below Strap reach on Linda Creek. The
points on the channel bottom were lowered to flow into the lateral weir per the
construction drawings for the project. Two parallel, 9’ diameter circular culverts,
860 feet in length, were connected from the lateral weir to River Station 1235.899
downstream on Linda Creek, in the same reach.
<PASTE ADDED CESI Write UP>
3.11
Storm Centering Analysis for Key Locations of Interest (HEC-1)
<PASTE FROM CESI WRITE UP>
3.12
General Plan Buildout Modeling (HEC-HMS)
<PASTE FROM CESI WRITE UP>
3.13 HEC-HMS Alternative Model Comparison of Results for Key
Locations for 100-year event.
3.14 Discussion of Selection of Key Locations of Interest
3.15 HEC-HMS Peak Flow Summary Tables for Various Recurrence
Intervals
3.16 Miners Ravine Detention Facility (Benefit assessment is in section 3.20)
3.17 Hydraulic Routing Model use in the Update Plan
3.18 Comparison of Hydraulic Routing Model Results
3.18.1 to FEMA FIS published peak 100-year flow rates
3.18.2 to other published and accepted peak flow estimates
3.19 System Flows and Capacities at Key locations (results of Hydraulic
Routing Models)
3.20 Impact/benefit of Miners Ravine Facility demonstrated in updated
modeling
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
4.0
Existing and Future Potential Flood Hazards
4.1
Discussion of known Flood Hazards
4.2
Discussion of Urbanization Impacts
4.2.1 Computed effects of past urbanization on the watershed
4.2.2 Computed potential effects of future urbanization on the
watershed
4.3
Discussion of urbanization impacts to Flood Hazard locations
4.4
Identification of potential added flood hazards with added urbanization
4.5
Flood Damage Frequency relationships
4.6
Identification of urbanization impacts to specific Flood Hazard Locations
4.7
Comparison of Flood Hazards to FEMA FIS
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
5.0
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Local and Regional Flood Control Projects after 1992
5.1
Detention Basins
5.2
Flood Improvement Projects
5.3
Planned, Listed and Concept Projects
5.3.1 Bridge Removals/Reconstruction to Pass Flood Events
5.3.2 Cottonwood Dam Removal - reoperation
5.3.3 Rocklin Stream Restoration Plan Area
5.3.4 Miners Ravine / Secret Ravine Confluence Area
5.3.5 Low Impact Development & Hydromodification
5.3.6 Dick Cook Wastewater Treatment Plant Abandonment
5.3.7 Auburn Folsom Road Retrofit
5.3.8
5.4
Evaluation of Effectiveness of Planned Projects
5.5
Flood Damage Reduction Measures
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
6.0
Recommended Improvements and Other Mitigation Strategies
6.1
Potential Attenuation Enhancement Projects
6.1.1 Miners Ravine/Secret Ravine Confluence area
6.1.2 Etc…
6.2
Update estimate of added attenuation storage since 1992
6.3
Guidance for future planning and design of detention facilities
6.3.1 Quantification and Identification of Geographic criteria for
detention requirements
6.3.2 Mitigation Objectives
6.3.3 Etc…
6.4
Conveyance Improvement Options
6.5
Summary of Bridge and Culvert Attenuation benefits
6.6
Buy-out projects Cost/Benefit Analysis
6.7
Use of ALERT system in Dry Creek Watershed
6.7.1
Discussion of Current use
“The City of Roseville and Sacramento County own and maintains an ALERT system
for the Dry Creek watershed. The ALERT system is a radio telemetered system
jointly coordinated by the National Weather Service and the California Department of
Water Resources. Remote stations located within the watershed are linked to
communicate with base stations. These remote locations contain water level sensors
and/or precipitation gages.” (DCWCRMP pg 74). (Table of gages listed on page 75,
map also included).
<INCLUDE FIGURE HERE OF ALERT SYSYTEM STREAM AND
RAIN GAGES WITHIN THE DRY CREEK WATERSHED>
6.7.2
plan
Potential Future added features with updated modeling from this
6.8 Quantification of potential reductions to flood hazard increases through
the use of Low Impact Development in future developments, and an
Identification of which watersheds are best suited for LID.
6.9 Project Alternative Cost Estimates and Benefit Analysis
6.10 Project Recommendations
6.11 Policy Recommendations
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
7.0
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Dry Creek Trust Fund Plan
7.1
Review of existing funding plan, and current fund balances and liabilities
7.2
Evaluation of income potential from future development
7.3
Impact Fee updates
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendices
Appendix A – References
Appendix B – Hydrologic Factors and GIS basis
Appendix B-1: SWMM and PDP Update
Appendix B-2: Land Use Hydrologic Factors
Appendix B-3: Planned Land Use
Appendix C – Calibration Events Detail
Appendix D – Peak Flow Summary Comparison Tables
D1 – Peak Flow Summary Comparison 2-YEAR
D2 – Peak Flow Summary Comparison 10-YEAR
D3 – Peak Flow Summary Comparison 25-YEAR
D4 – Peak Flow Summary Comparison 50-YEAR
D5 – Peak Flow Summary Comparison 100-YEAR
D6 – Peak Flow Summary Comparison 200-YEAR
D7 – Peak Flow Summary Comparison 500-YEAR
Appendix E – Existing Detention Investigations and Photo Documentation
Appendix F – Dry Creek Toolbox Software Users Guide
Appendix G1 – Tutorial for Performing Impact Analysis
Appendix G2 – Tutorial for Performing Flood Analysis
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix A – References
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix B – Hydrologic Factors and GIS
basis
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix B-1: SWMM and PDP Update
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix B-2: Land Use Hydrologic
Factors
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix B-3: Planned Land Use
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix C – Calibration Events Detail
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix D – Peak Flow Summary
Comparison Tables
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D1 – Peak Flow Summary Comparison 2YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D2 – Peak Flow Summary Comparison
10-YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D3 – Peak Flow Summary Comparison
25-YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D4 – Peak Flow Summary Comparison
50-YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D5 – Peak Flow Summary Comparison
100-YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D6 – Peak Flow Summary Comparison
200-YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
D7 – Peak Flow Summary Comparison
500-YEAR
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix E – Existing Detention
Investigations and Photo Documentation
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix F – Dry Creek Toolbox Software
Users Guide
(NOT IN THIS DRAFT)
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix G1 – Tutorial for Performing Impact
Analysis
(NOT IN THIS DRAFT)
PROJECT BACKGROUND
SEC
DRAFT 1 – AUG 2009
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
Appendix G2 – Tutorial for Performing Flood
Analysis
(NOT IN THIS DRAFT)
PROJECT BACKGROUND
SEC
PLACER COUNTY
FLOOD CONTROL AND WATER CONSERVATION DISTRICT
Update to the 1992 Dry Creek Watershed Flood Control Plan
DRAFT 1 – AUG 2009
January 2005 Event Calibration at Vernon
Flow
Vernon Rating Curve - RAS - JAN 1995 EVENT
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
RAS Rating
GAGE Rating
110
115
120
125
130
135
Stage
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
RAS CALIB
1/11/95 20:00
1/11/95 14:00
1/11/95 8:00
1/11/95 2:00
1/10/95 20:00
1/10/95 14:00
1/10/95 8:00
1/10/95 2:00
1/9/95 20:00
1/9/95 14:00
1/9/95 8:00
1/9/95 2:00
1/8/95 20:00
1/8/95 14:00
GAGE RECORD
1/8/95 8:00
Flow (cfs)
Compare 1603 Jan 1995
Date/Time
PROJECT BACKGROUND
SEC