Figure C-1 Model Network Diagram: Existing Land Use

Transcription

1 Figure C-1 Model Network Diagram: Existing Land Use March 2003 P:\GIS\santaclaraWD\projects\Chapter 4\FigureC-1 Model Network Diagram: Existing Land Use Condtions GeoSyntec Consultants

2 Figure C-2 Modeled Network Diagram: Pre-Urban Land Use March 2003 P:\GIS\santaclaraWD\projects\Chapter 4\FigureC-2 Model Network Diagram: Existing Land Use Condtions GeoSyntec Consultants

3 Pre-Urban Q2 Existing Q2 Future Q2 Pre-Urban Q5 Existing Q5 Future Q5 Pre-Urban Q10 Existing Q10 Future Q10 Q (cfs) Time (hours) Figure C-3 Storm Hydrographs at Junction J-3 for a 2-yr, 5-yr and 10-yr Event Using Pre-Urban, Existing and Future Land Use Conditions March 2003 P:\GIS\santaclaraWD\projects\Chapter 4\FigureC-3 Model Network Diagram: Existing Land Use Condtions GeoSyntec Consultants

4 1000 Q (cfs) Pre-Urban Q25 Existing Q25 Future Q25 Pre-Urban Q50 Existing Q50 Future Q50 Pre-Urban Q100 Existing Q100 Future Q Time (hours) Figure C-4 Storm Hydrographs at Junction J-3 for a 25-yr, 50-yr and 100-yr Event Using Pre-Urban, Existing and Future Land Use Conditions March 2003 P:\GIS\santaclaraWD\projects\Chapter 4\FigureC-4 Model Network Diagram: Existing Land Use Condtions GeoSyntec Consultants

5 Pre-Urban Q2 Existing Q2 Future Q2 Pre-Urban Q5 Existing Q5 Future Q5 Pre-Urban Q10 Existing Q10 Future Q10 Q (cfs) Time (hours) Figure C-5 Storm Hydrographs at Junction J-12 for a 2-yr, 5-yr and 10-yr Event Using Pre-Urban, Existing and Future Land Use Conditions March 2003 P:\GIS\santaclaraWD\projects\Chapter 4\FigureC-5 Model Network Diagram: Existing Land Use Condtions GeoSyntec Consultants

6 4500 Q (cfs) Pre-Urban Q25 Existing Q25 Future Q25 Pre-Urban Q50 Existing Q50 Future Q50 Pre-Urban Q100 Existing Q100 Future Q Time (hours) Figure C-6 Storm Hydrographs at Junction J-12 for a 25-yr, 50-yr and 100-yr Event Using Pre-Urban, Existing and Future Land Use Conditions March 2003 P:\GIS\santaclaraWD\projects\Chapter 4\FigureC-6 Model Network Diagram: Existing Land Use Condtions GeoSyntec Consultants

7 Table C-1 Drainage Area Consolidation Subbasin ID Subbasin ID (Exising and Future) (Pre-Developed)

8 Table C-2 Soil Types in the Lower Silver - Thompson Creek Subwatershed Soil Association Soil Hydrologic Grouping Effective Soil Depth Effective Porosity Soil Profile Depth Tension Zone Depth (in) (in) Available Water Holding Capacity, (in) Altamont-Azule D Alvisio D Arbuckle-Pleasanton B Clear Lake-Campbell D Cropley-Rincon D Felton-Mayman C Hennecke D Hillgate-Positas D Hillgate-Soper D Keefers-Hillgate C Los Gatos-Gaviota-Vallecitos C Maymen-Los Gatos-Gaviota D Montara D Orestimba-Willows D San sidro D Sunnyvale-Castro-Clear Lake D Tidal Marsh D olo B olo-esperato B Zamora-Pleasanton C Notes: 1) Soil Associations and Hydrologic Grouping taken from Soils of Santa Clara County (1968) 2) Values for Effective Soil Depth taken from SCCSS by weighting the 'effective depth' (root zone depth) for each Soil Association 3) Values for Effective Porosity taken from Rawls et. al. (1982) for each Soil Hydrologic Grouping 4) Soil Profile Depth is a product of Effective Soil Depth and Effective Porosity 5) Values Tension Zone Depth taken from the SCCSS by weighting the average Available Water Holding Capacity (A.W.C) for each Soil Association

9 Table C-3 Soils Parameters for the Lower Silver - Thompson Creek Subwatershed AVERAGE VALUES FOR SOIL HDROLOGIC GROUP Soil Hydrologic Group Soil Type Porosity Effective Porosity Field Capacity Residual Saturation Wetting Front Suction K sat (in) (in/hr) B Loam Silt Loam C Sandy Clay Loam Clay Loam Silty Clay Loam D Sandy Clay Silty Clay Clay Notes: 1) Soil Hydrologic Group Classification from 'Urban Hydrology for Small Watersheds' (NRCS Tech Release-55) 2) All parameters values taken from from Rawls, et al. (1982) for Soil Hydrologic Groups

10 Table C-4 Land Use Parameters for the Lower Silver - Thompson Creek Subwatershed Land Use Type Land Use Class Interception (% ann. precip) Runoff Curve Numbers (CN) for Soil Types A B C D (in.) Urban Land Cover Lawns Other Irrigated landscape (shrubs, groundcovers) Structures Paved surfaces (concrete, asphalt) Agricultural Land Cover Orchards (apricot, avocado, ornamental eucalyptus, tree farms Vegetables (tomato, pepper, lettuce, flowers, fava beans) Row crops (corn) Vineyards Irrigated pasture Alfalfa Other Land Cover Grasslands (natural grasses, dry farm hay) Trees Bare ground (fallow field) Water features Shrubs/herbaceous Notes: 1) Values for Interception (% ann. precip) from Leopold and Dunne (1978). 2) Values for Interception (in.) are a product of Interception (% ann. precip) and depth of 2-year precip. event (1.0 in.) 3) Values for Surface Depression taken from HEC-HMS users manual 4) Values for Mannings 'n' and CN taken from Santa Clara County Hydrology Manual (SCCHM) Interception (in.) Maximum Surface Depression Storage Mannings 'n'

11 Table C-5 Drainage Area Curve Numbers and Initial Abstraction Losses Runoff Curve Number (CN) Initial Abstraction Subbasin ID Type Existing Future Pre-Developed Existing Future Pre-Developed P P P P P P P P P P P P P P P P P P P P P P Note: I = value for impervious area, P = value for pervious area

12 Table C-6 Drainage Area Parameterization for SMA Modeling in HEC-HMS in the Lower Silver - Thompson Creek Subwatershed Table C-6 Area (mi 2 ) Canopy Interception (in) Surface Depression (in) Soil Infiltration (in/hr) Soil Profile Capacity (in) Tension Zone Capacity (in) Percolation (in/hr) Subbasin ID Type Existing Future Pre-Developed Existing Future Pre-Developed Existing Future Pre-Developed Existing Future Pre-Developed Existing Future Pre-Developed Existing Future Pre-Developed Existing Future Pre-Developed 0 1 I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P I P Note: 1) I = value for impervious area, P = value for pervious area

13 Table C-7 Time of Concentration and Storage Coefficient, Pre-urban Condition for All Subbasins Subbasin Length (ft) Min. Elev. (ft) Max. Elev. (ft) Slope (ft/ft) n Tc (hr) R / (Tc + R) R Notes: Overland flow Manning's roughness coefficient 0.07 represents "sparse vegetation" (SCVWD, 1998). The ratio of R / (Tc + R) lies between.5 and.9 for pervious and rural areas (SCVWD, 1998); a ratio of 0.75 was chosen for rural hillside open space, and 0.9 for agricultural land use.

14 Table C-8 Time of Concentration and Storage Coefficient, Existing Conditions for Urban Areas Only sub urban basin area i.d. (sq mi) urban area (sq ft) impervious % impervious area Ai Urban 9 Urban Impervious urban Pervious Street Street Time of pervious Time of width Length Concentration area (to Concentrati Wst Lst Overland Impervious Gutter TCimp s.d.) Overland Pervious on TCperv Street area Ast (sq ft) (sq ft) (ft) (ft) Li (ft) n L Emin Emax S (ft/ft) TCi (hr) Urban: R Lcb (ft) n S (ft/ft) TCcb (hr) (hr) (sq ft) Lp (ft) n S TCp (hr) (hr) Imp Perv Imp Perv E E E E E E E E Urban: R / (TC + R) 1 Source: Nolte & Assoc 2000, Table 1 gives street area as 20% of total area for range of urban land uses 2 Source: SCVWD Hydrology Procedures, Typical average street width = 50 ft. 3 Source: SCVWD Hydrology Procedures, Lst=Ast/Wst 4 Source: SCVWD Hydrology Procedures, Li=Ai-Ast/2Lst 5 Source: SCVWD Hydrology Procedures, Kerby-Hathaway Tc equation 6 Source: Nolte & Assoc 2000, average gutter length between catch basins = 300 ft. 7 Source: SCVWD Hydrology Procedures, TCimp= TCi + TCcb 8 Source: SCVWD Hydrology Procedures, TCperv= TCimp + TCp 9 Source: SCVWD Hydrology Procedures, 1998 (p.26, range); Nolte & Assoc 2000 uses 0.4 and Note: All Tc and R values less than 0.1 are rounded up to 0.1 for input into HEC-HMS.

15 Table C-9 Time of Concentration and Storage Coefficient, Existing Conditions for Rural and External Pervious Urban Areas Only Subbasin Length (ft) Min. Elev. (ft) Max. Elev. (ft) Slope (ft/ft) n Tc (hr) R / (Tc + R) R Rural Subbasins plus Urban Tc-Impervious External Pervious Subbasins Notes: Overland flow Manning's roughness coefficient 0.07 represents "sparse vegetation" (SCVWD, 1998). The ratio of R / (Tc + R) lies between.5 and.9 for pervious and rural areas (SCVWD, 1998); a ratio of 0.75 was chosen for rural hillside open space.

16 Table C-10 Time of Concentration and Storage Coefficient, Future Conditions for Urban Areas Only sub basin i.d Street width Wst Urban Impervious Time of Concentration TCimp Urban Pervious Time of Overland Impervious Gutter urban pervious area (to s.d.) Overland Pervious Concentration TCperv Urban: R / (TC + R) urban area (sq impervious impervious area Street Length mi) urban area (sq ft) % Ai Street area Ast Lst Urban: R (sq ft) (sq ft) (ft) (ft) Li (ft) n L Emin Emax S (ft/ft) TCi (hr) Lcb (ft) n S (ft/ft) TCcb (hr) (hr) (sq ft) Lp (ft) n S TCp (hr) (hr) Imp Perv Imp Perv Source: Nolte & Assoc 2000, Table 1 gives street area as 20% of total area for range of urban land uses 2 Source: SCVWD Hydrology Procedures, Typical average street width = 50 ft. 3 Source: SCVWD Hydrology Procedures, Lst=Ast/Wst 4 Source: SCVWD Hydrology Procedures, Li=Ai-Ast/2Lst 5 Source: SCVWD Hydrology Procedures, Kerby-Hathaway Tc equation 6 Source: Nolte & Assoc 2000, average gutter length between catch basins = 300 ft. 7 Source: SCVWD Hydrology Procedures, TCimp= TCi + TCcb 8 Source: SCVWD Hydrology Procedures, TCperv= TCimp + TCp 9 Source: SCVWD Hydrology Procedures, 1998 (p.26, range); Nolte & Assoc 2000 uses 0.4 and Note: All Tc and R values less than 0.1 are rounded up to 0.1 for input into HEC-HMS.

17 Table C-11 Time of Concentration and Storage Coefficient, Future Conditions for Rural and External Pervious Urban Areas Only Subbasin Length (ft) Min. Elev. (ft) Max. Elev. (ft) Slope (ft/ft) n Tc (hr) R / (Tc + R) R Rural Subbasins plus Urban Tc-Impervious External Pervious Subbasins Notes: Overland flow Manning's roughness coefficient 0.07 represents "sparse vegetation" (SCVWD, 1998). The ratio of R / (Tc + R) lies between.5 and.9 for pervious and rural areas (SCVWD, 1998); a ratio of 0.75 was chosen for rural hillside open space.

18 Table C-12 Clark Unit Hydrograph Parameter Estimation: Storage Routing ("STO") STO i.d. area, ac (1) Levees? /N (2) N N N N N N N N N N vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) vol(ac-ft) Q(cfs) Unitized Storage-Discharge Relationships (3) (1) "Total area" reflects sum of Pervious, Impervious and Undeveloped areas contributing to storm drains for each STO module condition (2) Areas upstream of erba Buena were assigned "w/o levee" status, downstream of erba Buena assigned "w/levee" status 1 A > 400 ac w/o levees following general guidance in SCVWD, 1998 vol (ac-ft/sq mi) Q (cfs/sq mi) (3) Tables derived from plot in SCVWD, 1998 Fig 7 2 A > 400 ac w/ levees vol (ac-ft/sq mi) Q (cfs/sq mi) A < 400 ac w/o levees vol (ac-ft/sq mi) Q (cfs/sq mi) A < 400 ac w/ levees vol (ac-ft/sq mi) Q (cfs/sq mi) E = Pervious "External" I = Impervious P = Pervious

19 Table C-13 HEC-HMS Reach Routing, Pre-urban Conditions HMS ID Creek Connection Shape Length, ft Slope, ft/ft Width or Diameter, ft H:V Manning's n Source Information (width, diameter, H:V, & n) 1 Thompson 27TR - J-1 Prism A 2 Thompson J-1 - J-2 Prism B 3 Hawk 33HR - J-2 Prism A 4 Thompson J-2 - J-3 Prism B 5 Misery 34MR - J-3 Prism A 6 Thompson J-3 - J-5 Prism B 7 38CR - J-4 Prism A, B 8 Cribari 29CR - J-4 Prism A, B 9 Cribari J-4 - J-5 Prism A, B 10 Thompson J-5 - J-6 Prism B 11 Thompson J-6 - J-7 Prism B 12 erba Buena 21R - J-7 Prism B 13 Thompson J-7 - J-9 Prism A, B 14 Evergreen J-8 - J-9 Prism A, B 16 Thompson J9 - J-10 Prism B 17 26WR - J-10 Prism A, B 18 Fowler 3WR - J-10 Prism A, B 19 Thompson J-10 - J-11 Prism B 20 Quimby 4QR - J-11 Prism A, B 21 Thompson J-11 - J-12 Prism B 22 Norwood 10NR - J-12 Prism A, B 23 Thompson J-12 - J-13 Prism B, D 24 Thompson J-13 - J-14 Prism B, D 25 Flint 11FR - J-14 Prism A, B 26 Lower Silver J-14 - J-15 Prism D 27 South Babb 22BR - J-15 Prism A, B 28 Lower Silver J-15 - J-16 Prism D 29 North Babb STO-19 - J-16 Prism A, B 30 Lower Silver J-16 - J-17 Prism D 31 Lower Silver J-17 - J-18 Prism D 32 Miguelita 12GR - J-18 Prism A, B, D 33 Lower Silver J-18 - J-19 Prism D Lengths approximated by querying WLA creek and storm drain GIS layers. Slopes approximated using length estimates and USGS DEM elevations. Past reach lengths validated or changed based on 1964 arial photographs (Pafford & Associates, suveyors). Existing storm drains throughout watershed NOT present in 1964; historic channel charactersitcs estimated for these reaches. Source information used to approximate width, diameter, H:V, and Manning's n: A - Nolte (2000) B - PWA and Balance Hydrologics survey (2002) D - Lower Silver HEC-RAS model Note: there is no R-15

20 Table C-14 HEC-HMS Reach Routing, Existing and Future Conditions HMS ID Creek Connection Shape Length, ft Slope, ft/ft Width or Diameter, ft H:V Manning's n Source Information (width, diameter, H:V, & n) 1 Thompson 27TR - J-1 Prism A 2 Thompson J-1 - J-2 Prism B 3 Hawk 33HR - J-2 Prism A 4 Thompson J-2 - J-3 Prism B 5 Misery 34MR - J-3 Prism A 6 Thompson J-3 - J-5 Prism B 7 38CR - J-4 Circle C 8 Cribari 29CR - J-4 Circle C 9 Cribari J-4 - J-5 Circle C 10 Thompson J-5 - J-6 Prism B 11 Thompson J-6 - J-7 Prism B 12 erba Buena 21R - J-7 Prism B 13 Thompson J-7 - J-9 Prism A, B 14 Evergreen J-8 - J-9 Prism A, B 16 Thompson J9 - J-10 Prism B 17 26WR - J-10 Circle C 18 Fowler 3WR - J-10 Circle C 19 Thompson J-10 - J-11 Prism B 20 Quimby 4QR - J-11 Circle C 21 Thompson J-11 - J-12 Prism B 22 Norwood 10NR - J-12 Circle C 23 Thompson J-12 - J-13 Prism B, D 24 Thompson J-13 - J-14 Prism B, D 25 Flint 11FR - J-14 Circle C 26 Lower Silver J-14 - J-15 Prism D 27 South Babb 22BR - J-15 Prism A, B 28 Lower Silver J-15 - J-16 Prism D 29 North Babb STO-19 - J-16 Prism A, B 30 Lower Silver J-16 - J-17 Prism D 31 Lower Silver J-17 - J-18 Prism D 32 Miguelita 12GR - J-18 Circle C 33 Lower Silver J-18 - J-19 Prism D Lengths approximated by querying WLA creek and storm drain GIS layers. Slopes approximated using length estimates and USGS DEM elevations. Source information used to approximate width, diameter, H:V, and Manning's n: A - Nolte (2000) B - PWA and Balance Hydrologics survey (2002) C - Storm drain analysis D - Lower Silver HEC-RAS model Note: there is no R-15

21 Table B-15 DESIGN STORM RESULTS Q-peak, cfs V-total, ac-ft Return Period (years) Pre-Urban SCS (24-hr balanced) Junction J J J J J J J Subbasin SB SB SB Reach Total uerba Buena SB Exsiting SCS (24-hr balanced) Junction J J J J J J J Subbasin SB SB SB SB-41-Impervious SB-41-Pervious Reach STO Total uerba Buena SB-39-Impervious SB-39-Pervious Total SB Future SCS (24-hr balanced) Junction J J J J J J J Subbasin SB SB SB SB-41-Impervious SB-41-Pervious Reach STO Total uerba Buena SB-39-Impervious SB-39-Pervious Total SB Historical Flood Quantile (SCVWD, 1998) Junction J J J J