HYDROLOGY REPORT HEACOCK & CACTUS CHANNELS MORENO VALLEY, CALIFORNIA NOVEMBER 2005 REVISED APRIL 2006 REVISED AUGUST 2006

Transcription

1 HYDROLOGY REPORT HEACOCK & CACTUS CHANNELS MORENO VALLEY, CALIFORNIA NOVEMBER 2005 REVISED APRIL 2006 REVISED AUGUST 2006 RIVERSIDE COUNTY FLOOD CONTROL AND WATER CONSERVATION DISTRICT

2 TABLE OF CONTENTS GENERAL DESCRIPTION... 1 Introduction... 1 Purpose... 1 Study Area... 1 Existing Watershed... 1 Existing Condition... 4 Cactus Channel... 4 Heacock Channel...4 HYDROLOGIC MODEL... 4 Existing & Future Conditions... 4 Data and Program Resources... 5 Precipitation... 5 Precipitation Loss... 6 Percent Impervious Cover... 6 Routing Method... 6 HEC-1 RESULTS... 8 VALIDATION OF HEC-1 RESULTS... 9 CONCLUSION REFERENCES LIST OF FIGURES Figure 1 VICINITY MAP... 2 Figure 2 SUNNYMEAD WATERSHED... 3 LIST OF TABLES Table 1 Pigeon Pass Rain Gauge... 5 Table 2 Summary of Areally Adjusted Precipitation... 6 Table 3 Percent Impervious Cover... 7 Table 4 Summary of HEC-1 Model Peak Discharges... 8 Table 5 USGS Selected stream Gauges... 9 Table 6 FFA ProgramOutput for Warm Creek Gaged Site & USGS Regression Analysis LIST OF EXHIBITS Exhibit 1 Hydrology Map Exhibit 2 Land Use Map Appendix "A" - HEACOCK & CACTUS CHANNELS, HEC-1 OUTPUT FILES Including Hydrology Maps - i -

3 GENERAL DESCRIPTION Introduction This report presents the results of the existing condition hydrology study for flood control facilities along Heacock Avenue and Cactus Street, in the city of Moreno Valley, Riverside County, State of California as shown in Figure 1 VICINITY MAP. The report is prepared by the Riverside County Flood Control and Water Conservation District (District) which is the lead local sponsor agency providing in-kind services to the United States Army Corps of Engineers (Corps). Purpose The purpose of this study is to determine the peak flows along the Heacock Avenue and Cactus Street Channels for the purpose of having the Corps design these flood control facilities to provide critically needed flood protection to March Air Reserve Base (MARB) and adjacent residential and commercial areas within the city of Moreno Valley. Study Area The study area is located in western Riverside County, west and south of the city of Moreno Valley, southeast of the city of Riverside, and north of the city of Perris, encompassing MARB, approximately 60 miles east of Los Angeles and 90 miles northeast of San Diego. The boundary of the study area is the Sunnymead watershed as shown in Figure 2 SUNNYMEAD WATERSHED, and it includes two earthen channels that are subject to flooding within the MARB, as well as residential and commercial property in the city of Moreno Valley. Cactus Channel flows west to east into Heacock Channel, which flows north to south, then outlets into the Perris Valley Storm Drain Lateral A, which flows west to east. Existing Watershed The Sunnymead watershed of approximately 20 square miles (12,800 acres) is tributary to this location. The headwaters of the watershed begin along the ridgeline of the Box Springs Mountains to the north of the city of Moreno Valley. Elevations in this mountain region reach a height of 3,700 feet at Point Reach, to a low point of 1,670 feet at Pigeon Pass Dam. Pigeon Pass Dam was constructed by the District in 1957 and has 912 acre-feet of storage volume to the spillway. The dam has significant flood retention capabilities with a peak discharge of 120 cfs during a 100-year frequency storm. Downstream of the dam, flows enter a concrete-lined trapezoidal channel that varies from a 2-foot bottom, 5-foot deep channel built in 1966, to a 14-foot bottom, 7-foot deep section built in South of the Pigeon Pass Dam, development has continued on the alluvial fan area

4 PIGEON PASS DAM LEGEND: Figure 1 - VICINITY MAP - 2 -

5 Figure 2 - SUNNYMEAD WATERSHED - 3 -

6 Existing Condition Cactus Channel Cactus Channel is a vegetated earthen channel located south of Cactus Street and north of MARB. The earthen channel collects flows discharging from storm drains along Elsworth, Frederick and Graham Streets, as well as local sheet flows from the north. These storm drains collect and convey runoff from a commercial area within the city of Moreno Valley just north of the channel. Cactus Channel receives sheet flows and flows from six additional small culverts that discharge at various locations. Flooding has been noted along Cactus Channel, more frequently at the intersections of Cactus Avenue and Elsworth Street, and Cactus Avenue and Graham Street. Once the channel reaches its limited capacity, flows easily overtop the banks flooding the roadway to the north and sheet flowing across MARB to the south. This condition consistently occurs during small to moderate storms due to the undersized and vegetated condition of the channel. On October 20, 2004, the Acting Installation Commander closed the runway and sent non-mission essential personnel home due to the flooded conditions. MARB has been the primary departure point for the United States Marines and cargo from Camp Pendleton and Twentynine Palms Marine Corps bases. (See pictures below) Cactus Channel Looking East Cactus Channel Flooding Heacock Channel Heacock Channel, a concrete trapezoidal channel, varies in size from a 14-foot bottom width, 8-foot deep section at its upstream terminus at Heacock Street and Alessandro Boulevard, to a 16-foot bottom width, 9-foot deep section with 1.5:1 (Horizontal:Vertical) sideslopes as it approaches Cactus Street. The south end of the improved Heacock Channel is a double 11-foot wide, 10-foot deep box culvert, which is also the north end of the subject Heacock Avenue channel at Cactus Street. The natural wash downstream of Cactus Street is in various states of disrepair with minimal capacity. Downstream of Cactus, there is significant erosion within the first 0.5 mile of the channel. This 2-mile reach of the Heacock Channel conveys approximately 75 percent of the runoff from the Sunnymead watershed. During the winter storms of 2004 (approximately 10-yr storm events), Heacock Channel overtopped between John F. Kennedy Drive and Iris Avenue. The inadequate capacity of Heacock Channel also caused the local tributary storm drains to back up easterly on Iris Avenue and Gentian Avenue. Road closures were - 4 -

7 implemented at Heacock Street, Cardinal Street, Iris Street, Indian Street and Gentian Avenue at Heacock Street due to flooding hazard. (See pictures below) Heacock Channel Looking South Heacock Channel Looking North below Cactus Ave. HYDROLOGIC MODEL Existing & Future Conditions The existing/base condition is considered the same as the future condition for the Heacock and Cactus Channels, see Exhibit 1 - "Hydrology Map". This assumption is based on the fact that the watershed is almost fully developed and most flood control facilities upstream and downstream of the Heacock Channel have been constructed. All assumptions in the development of the hydrologic model assumed full development. Few areas are still in the process of being developed, such as the area north of the Cactus Channel which contributes a small percent of the runoff to the Cactus Channel and, therefore, is assumed to be fully developed. The City of Moreno Valley provided planning information regarding the potential construction of two basins at the northwest corner of Cactus Avenue and Heacock Street. However, due to the small tributary area, the proposed basins are not considered in the hydrologic model for the Cactus Channel. Data and Program Resources This study was prepared using the Corps' HEC-1 program version 4.1, LAPRE-1 which is a preprocessor program to HEC-1, USGS 7.5 Minute topographic quad maps, the Sunnymead Master Drainage Plan and point precipitation rainfall frequency estimates from the District's Hydrologic Data Collection Section, USGS National hydrology datasets, and area reduction factors from the District's Hydrology Manual. These resources were used to identify the representative tributary watershed areas, watercourses and other data needed for this study. Precipitation The District maintains records of point precipitation data through rain gauge stations within Riverside County. The District analyzes this data based on methods described by the State of California, Department of Water Resources (DWR) in Bulletin Number 195. Evaluation of one rain gauge frequency analysis data representative of the Sunnymead watershed is shown in Table 1 Pigeon Pass Rain Gauge. The District's Hydrology Manual also tabulates a rainfall pattern in Plate E-5.9 for use with the - 5 -

8 Synthetic Unit Hydrograph Method. The rainfall pattern used in the development of the flood hydrographs is from the Indio storm of September 24, 1939, the largest thunderstorm of record in the Whitewater River basin. The pattern used in the HEC-1 analysis is for the 3-hour storm and is considered to represent a reasonable distribution of rainfall which will cause critical runoff condition during major storm events for this watershed. Point rainfall was then adjusted by areal adjustment factor for 9 square miles and 20 square miles. The areal adjustment factors were derived from Plate E-5.8 of the District's Hydrology Manual which is based on NOAA Atlas 2. These factors were applied to the following frequencies: 2, 5, 10, 25, 50, 100, 200 and 500 year for the 3-hour storm. Table 2 - Summary of Areally Adjusted Precipitation represents a summary of the areally adjusted precipitation for various frequencies. Table 1 - Pigeon Pass Rain Gauge Short Duration-Precipitation Frequency Data Return Period In Years 5M 10M 15M 30M 1H 2H 3H 6H 12H 24H TOTAL n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a PMP n/a Record Maximum Record Year 1981/ / / / / / / / / / N (Years) Mean

9 Table 2 - Summary of Areally Adjusted Precipitation Point Precipitation Frequency for Pigeon Areally Adjusted Pass Rain Gauge Data Return Period (Years) Unadjusted 3-hour Precp.(in/hr) DA=8.948sm (97.5%) DA=19.993sm (94.5%) Rate Loss Rate loss was modeled using the initial and constant loss rate method which is implemented using the LU card in the HEC-1 model. During the final calibration procedures and to validate the HEC-1 results, the initial and constant loss rate values were estimated as 0.1-inch and 0.35 inch per hour respectively for storms with 500-, 200- and 100- year return periods. However, for storms with 50-, 25-, 10-, 5- and 2- year return periods, the initial and constant loss rate values were estimated as 0.1 inch and 0.40 inch per hour, respectively. Percent Impervious Cover Percent impervious cover for each subarea was determined by areally weighting the percent impervious cover assigned to each land use as recommended by Plate E-6.3 of the District's Hydrology Manual. Based on engineering judgment, the percent impervious cover for the various subareas have been changed to a maximum percent impervious cover of 50%. See Table 3 - Percent Impervious Cover for a summary of the values used in the HEC-1 model. The Land Use Map is presented in Exhibit 2 - "Land Use Map". Routing Method Flood routing in the existing flood control facilities was based on the Muskingum-Cunge method. Input parameters for this method was based on information from the as-built drawings for the existing flood control facilities, however, a minimum of 0.12 hour for the Muskingum-Cunge coefficient "K" factor was adopted based on engineering judgment

10 SUBAREA Area 1 Area 2 Area 3A Area 3B Area 3C Area 4B Table 3 - Percent Impervious Cover % IMP % IMP % IMP % IMP % ASSIGNED % Calc'd Used % ASSIGNED % Calc'd Used PRESENT LAND COVERAGE IMPERVIOUS Future Future SUBAREA PRESENT LAND COVERAGE IMPERVIOUS Future Future 52 Natural - Agricultural Natural - Agricultural Light Urban Light Urban Acre Residential Acre Residential /2 Acre Residential /2 Acre Residential /4 Acre Residential /4 Acre Residential Conds 65 0 Area 4D Conds Apartments 80 0 Apartments Mobile Home Park 75 0 Mobile Home Park 75 0 Buisness & Industrial Buisness & Industrial Natural - Agricultural Natural - Agricultural Light Urban Light Urban Acre Residential Acre Residential /2 Acre Residential /2 Acre Residential /4 Acre Residential /4 Acre Residential Conds 65 0 Area 4A Conds 65 0 Apartments 80 0 Apartments 80 0 Mobile Home Park 75 0 Mobile Home Park Buisness & Industrial Buisness & Industrial Natural - Agricultural Natural - Agricultural Light Urban Light Urban Acre Residential Acre Residential /2 Acre Residential /2 Acre Residential /4 Acre Residential /4 Acre Residential 50 2 Conds 65 0 Conds 65 0 Area 4C Apartments 80 0 Apartments 80 0 Mobile Home Park 75 0 Mobile Home Park Buisness & Industrial Buisness & Industrial (ultimate) Natural - Agricultural Natural - Agricultural Light Urban Light Urban Acre Residential Acre Residential /2 Acre Residential /2 Acre Residential /4 Acre Residential /4 Acre Residential Conds 65 0 Conds 65 0 Area 5 Apartments 80 0 Apartments 80 0 Mobile Home Park 75 0 Mobile Home Park 75 0 Buisness & Industrial Buisness & Industrial Natural - Agricultural Natural - Agricultural Light Urban 8 4 Light Urban Acre Residential Acre Residential /2 Acre Residential /2 Acre Residential /4 Acre Residential /4 Acre Residential Conds 65 0 Conds 65 0 Apartments 80 0 Area 6 Apartments 80 0 Mobile Home Park 75 0 Mobile Home Park 75 0 Buisness & Industrial Buisness & Industrial Natural - Agricultural Natural - Agricultural Light Urban 8 0 Light Urban Acre Residential Acre Residential /2 Acre Residential /2 Acre Residential /4 Acre Residential /4 Acre Residential Conds 65 0 Conds 65 0 Apartments 80 0 Area 7 Apartments 80 0 Mobile Home Park 75 0 Mobile Home Park Buisness & Industrial Buisness & Industrial

11 HEC-1 RESULTS The Corps' HEC-1 computer program was used to determine peak discharges for the 2-, 5-, 10-, 25-, 50-, 100-, 200- and 500-year storm events. HEC-1 output files for Heacock and Cactus Channels at various concentration points for each storm event are presented in Appendix A. Summary of the peak discharge results are shown in Table 4 - Summary of HEC-1 Model Peak Discharges. Table 4 - Summary of HEC-1 Model Peak Discharges Conc. Discharges (ft 3 /s) Point # Location DA (mi) YR 200-YR 100-YR 50-YR 25-YR 10-YR 5-YR 2-YR 1 Upstream of Pigeon Pass Reservoir Downstream of Pigeon Pass Reservoir Upstream of Festival Development Basin Downstream of Festival Development Basin Downstream of confluence for Sunnymead Ch. Stage 1 & Pigeon Pass Ch Heacock Alessandro Blvd B Downstream of confluence for Heacock Ch. & Sunnymead MDP Line F A Cactus Ch. Tributary to Area 4A AC Cactus Ch. just upstream of Heacock Ch. confluence tributary to Areas 4A & 4C Downstream of confluence for Heacock Ch. & Cactus Ch Downstream of confluence for Heacock Ch. & MARB lateral south of Meyer Dr./JFK Dr Downstream of confluence for Heacock Ch. & MARB lateral north of Iris Avenue Upstream of confluence for Heacock Ch. & MARB lateral south of Iris Avenue

12 VALIDATION OF HEC-1 RESULTS The District evaluated the reasonableness of flood discharge estimates obtained from the HEC-1 model by comparing the discharge values to the discharge values obtained from various data sets developed by the following procedures: Research of available published stream gauge data, near the project site, from U.S.Geological Survey (USGS). Three stream gauges were selected based on drainage area and proximity to the project site. The three stream gauges are listed in Table 5 - USGS Selected Stream Gauges Table 5 - USGS Selected Stream Gauges Gauge # Gauge Name Gauge Records (Years) USGS Bautista Creek North Hemet, CA. 22 USGS Cajon Creek North Keenbrook, CA. 58 USGS Warm Creek Floodway San Bernardino, CA. 20 USGS data sets were used as input into a Flood Frequency Analysis (FFA) program developed by the Corps. In the FFA program, a Log-Pearson Type III distribution was used to analyze the data to compute the frequency curve in accordance with "Guidelines for Determining Flood Flow Frequency", Bulletin 17B by Water Resources Council, September After researching the National Oceanic & Atmospheric Administration (NOAA) data, annual precipitation records were checked for all three gauges. The Cajon Creek stream gauge showed a high annual precipitation and, therefore, was not considered for the calibration since it is not representative of the Sunnymead watershed. The first data set was developed for each gauge based on the yield values obtained from the FFA program output file for 500-, 200-, 100-, 50-, 25-, 10-, 2-year storm events. These values were then transposed to the Heacock site by using the yield discharge values and multiplying it by the unregulated drainage area of 9 square miles for Pigeon Pass Reservoir. These values are summarized in Table 6 - FFA Program Output for Warm Creek Gaged Site & USGS Regression Analysis The second data set was developed based on the USGS regression equations obtained from "Nationwide Summary of U.S. Geological Survey Reqional Regression Equations for Estimating Magnitude and Frequency of Floods for Ungaged Sites, 1993" by USGS, Water-Resources Investigations Report This reference listed regression equations for regions within each State. For southern California, the South Lahontan-Colorado Desert Region set of equations were selected since it simulates a desert type environment. These equations were used for the transposition of the values for the gaged site obtained from the FFA output file to the ungaged Heacock site by multiplying the discharge values by the ratio obtained from dividing the USGS regression Q's at Heacock over the regression Q's at the gaged site. These values are also summarized in Table 6. Based on a comparison of all data sets, the regression analysis for the Warm Creek stream gauge results show a discharge at Pigeon Pass estimated at 3,713 cfs. The HEC-1 model results show an estimated discharge of 4,176 cfs at Pigeon Pass Dam. Based on that, the District concludes that the results of the HEC-1 model, attached as Appendix A, provides a reasonable estimate of discharges

13 Table 6 - FFA Program Output for Warm Creek Gaged Site & USGS Regression Analysis FFA results Warm Creek San Bernardino, CA NOAA average Annual Precipitation = 15.0 inches Drainage Area = 47.8 square miles Heacock-Pigeon Pass (Q@gage adjusted by drainage area ratio) Heacock Site Elevation = 1485 above MSL NAVD 88 NOAA average Annual Precipitation = 13.8 inches Drainage Area = square miles USGS Regression Equation South Lahontan Colorado Desert Region Un-gaged Site at Heacock- Pigeon Pass Gaged Warm Creek Heacock- Pigeon Pass (Q@gage adjusted by USGS Regression ratio Freq. Event From FFA output File Discharge Computed HEC-1 results (cfs) (cfs) (cfs) (cfs) (cfs) CONCLUSION The District performed a HEC-1 hydrologic model for Heacock and Cactus Channels at various concentration points. Results of the HEC-1 model output files for 2-, 5-, 10-, 25-, 50-, 100-, 200- and 500-year storm events are included in Appendix A and summarized in Table 4 - Summary of HEC-1 Model Peak Discharges. Based on the HEC-1 model and the calibration procedures followed in this report, the District concludes that the results of the HEC-1 model attached provide a reasonable estimate of the peak discharges for Heacock and Cactus Channels project

14 REFERENCES 1. Riverside County Flood Control and Water Conservation District - Hydrology Manual 2. Riverside County Flood Control and Water Conservation District - Sunnymead Master Drainage Plan 3. State of California, the Resources Agency, Department of Water Resources Rainfall Analysis for Drainage Design, Volume I "Short-Duration Precipitation Frequency Data" Bulletin # U.S. Army Corps of Engineers, Los Angeles District, LAPRE-1 (Preprocessor to HEC-1), Users Manual 5. U.S. Army Corps of Engineers, the Hydrologic Engineering Center HEC-1 Flood Hydrograph Package Users Manual 6. U.S. Army Corps of Engineers, the Hydrologic Engineering Center HEC-FFA Flood Frequency Analysis, Users Manual 7. USGS - Nationwide Summary of U.S. Geological Survey Reqional Regression Equations for Estimating Magnitude and Frequency of Floods for Ungaged Sites, 1993" by USGS, Water- Resources Investigations Report

15 RIVERSIDE COUNTY FLOOD CONTROL AND WATER CONSERVATION DISTRICT RIVERSIDE, CALIFORNIA Legend A AREA ROADS 2 CONCENTRATION POINTS 3C HYDROLOGY AREAS RCFC FACILITIES AREA FLOWLINES EXHIBIT 1 HYDROLOGY MAP SCALE 1"=3000' Miles Kilometers (MAP REVISED 06APR06)

16 RIVERSIDE COUNTY FLOOD CONTROL AND WATER CONSERVATION DISTRICT RIVERSIDE, CALIFORNIA Legend A A AREA ROADS HYDROLOGY AREAS AREA FLOWLINES FINAL LAND USE ANALYSIS COMMERCIAL/INDUSTRIAL LIGHT URBAN NATURAL URBAN EXHIBIT 2 LAND USE MAP SCALE 1"=3000' Miles Kilometers (MAP REVISED 06APR06)

17 APPENDIX "A" HEACOCK & CACTUS CHANNELS HEC-1 OUTPUT FILES - 13-

18 Full HEC-1 output is not included in hard copy (please see digital copy on enclosed CD)