San Diego Hydrology Model (SDHM 3.0) Reviewer Workshop Doug Beyerlein, P.E., P.H., D.WRE Clear Creek Solutions, Inc. Mill Creek, Washington
Clear Creek Solutions Hydrology Expertise Clear Creek Solutions, Inc., provides complete range of hydrologic and stormwater modeling services. Clear Creek specializes in continuous simulation hydrologic modeling. We have created similar stormwater modeling packages for Orange County, Riverside County, Alameda County, Santa Clara County, San Mateo County, and Sacramento County in California. We teach SDHM and HSPF workshops.
Introduction SDHM 3.0 is available free from the Clear Creek Solutions, Inc., web site. www.clearcreeksolutions.com Go to Free Software Downloads.
Stormwater Stormwater runoff increases whenever it rains due to land use changes.
Stormwater Distribution of San Diego annual rainfall and runoff: Blue: Evapotranspiration Green: Groundwater Yellow: Interflow Red: Surface Runoff A Soil C Soil Impervious
Stormwater Increases in stormwater runoff produces higher peak flows and more stream bank and channel erosion.
Stormwater Stream bank and channel erosion can be prevented by adding stormwater mitigation procedures and facilities (ponds, permeable pavement, bioretention, etc).
Stormwater Stormwater mitigation facilities are sized so that they prevent an increase in the number and size of erosive flows.
Stormwater Hydrologic computer stormwater modeling is used to determine whether or not proposed mitigation measures prevent an increase in the number and size of erosive flows with changes in land use.
Stormwater In San Diego County erosive flows occur when streamflow is between 10% of the 2-year flow and 100% of the 10-year flow.
Stormwater Flow Duration Analysis: Percent of time the flow exceeds a specific value. Continuous simulation hydrology is needed to compute flow duration.
SDHM and Stormwater Continuous simulation hydrology models the entire hydrologic cycle for multiple years. SDHM 3.0 is a continuous simulation hydrology model that calculates the stormwater runoff used for the flow duration analysis.
SDHM s HSPF Computation Engine SDHM 3.0 includes HSPF to do the continuous simulation hydrology computations. HSPF runs in the background with calibrated parameter values and local meteorological data. HSPF is sponsored and funded by US EPA and USGS. HSPF is available free on the Internet.
SDHM s HSPF Computation Engine HSPF: Hydrologic Simulation Program FORTRAN History: 1966 Stanford Watershed Model by Linsley and Crawford 1972 HSP by Hydrocomp (Palo Alto, CA) 1973 ARM (Agricultural Runoff Management) Model for EPA by Hydrocomp 1974 NPS (Non-Point Source) Model for EPA by Hydrocomp 1979 HSPF (combining HSP, ARM, and NPS) for EPA by Hydrocomp
SDHM s HSPF Computation Engine The entire water cycle is modeled on 15-minute time step for multiple years. The model computes changes in soil moisture, evapotranspiration, and runoff every time step. HSPF calculates 3 types of runoff: surface runoff (mostly from impervious surfaces) interflow (shallow subsurface runoff) groundwater/base flow (dry weather flows)
SDHM 3.0 Changes from SDHM2015 Final Version Revised, updated rainfall data (1984-2014). Revised, updated potential evapotranspiration (PET) data. SDHM 3.0 automatically selects rainfall record and multiplication factor based project site location on map. Rainfall and runoff data changed from hourly to 15-minute time step. SDHM 3.0 flow durations percent limit is 110% for 10% of the flow duration levels. New SDHM 3.0 land covers: natural vegetation (NatVeg), dirt, rock. New SDHM 3.0 urban landscape without irrigation (UrbNoIrr). New SDHM 3.0 HSPF parameter values. Flow frequency method changed from Cunnane to Weibull.
SDHM 3.0 Changes from SDHM 2015 Interim Version Revised, updated rainfall data (1984-2014). Revised, updated potential evapotranspiration (PET) data. SDHM 3.0 automatically selects rainfall record and multiplication factor based project site location on map. Rainfall and runoff data changed from hourly to 15-minute time step. SDHM 3.0 flow durations percent limit is 110% for 100% of the flow duration levels. New SDHM 3.0 land covers: natural vegetation (NatVeg), dirt, rock. New SDHM 3.0 urban landscape without irrigation (UrbNoIrr). New SDHM 3.0 HSPF parameter values. Flow frequency method changed from Cunnane to Weibull.
SDHM 3.0 Changes from SDHM 2015 Note: Because of the above listed changes, projects that have been created in SDHM2015 (and earlier SDHM2011) will not work in SDHM 3.0. To convert these older projects to SDHM 3.0 the user needs to manually re-input the project information into a new SDHM 3.0 project file. The project results will change and the hydromod mitigation facility may need to be resized.
SDHM Capabilities SDHM 3.0 uses HSPF continuous simulation hydrology to compute stormwater runoff for both pre-project and postdevelopment conditions. Pre-project Developed
SDHM Capabilities SDHM 3.0 includes a map of San Diego County.
SDHM 3.0 (Final Version) San Diego County s rainfall stations: Bonita Descanso Encinitas Fallbrook Fashion Valley Granite Hills Kearny Mesa Lake Henshaw SDHM 3.0 includes 14 rainfall stations in San Diego County. Lake Wolford Morena Lake Oceanside Poway Ramona Santa Ysabel
SDHM 3.0 (Final Version) The user can zoom in on the map to find the project site. SDHM 3.0 then automatically assigns the appropriate rainfall station and precipitation multiplication factor.
SDHM 3.0 (Interim Version) The user selects the rainfall station from the available list.
SDHM Capabilities Two Q2 and Q10 calculation methods. (1) Default: Weibull (2) User input: USGS
SDHM Capabilities USGS Q2 and Q10 calculation method: Q2 = 3.60*(A^0.672)*(P^0.753) Q10 = 6.56*(A^0.783)*(P^1.07) Where A = drainage area (sq. miles) P = mean annual precipitation (inches)
SDHM Capabilities Mean Annual Precipitation (inches): Bonita 9.1 Descanso 20.5 Encinitas 9.3 Fallbrook 13.9 Fashion Valley 10.4 Granite Hills 12.8 Kearny Mesa 10.8 Lake Henshaw 22.6 Lake Wolford 16.8 Morena Lake 16.6 Oceanside 11.3 Poway 11.6 Ramona 13.0 Santa Ysabel 21.1
SDHM Capabilities The user represents their project area with elements representing land use info and stormwater mitigation facilities: land use basins stormwater ponds and vaults water quality facilities low impact development (LID) facilities commercial stormwater solutions
SDHM Capabilities The user creates a schematic of the land use basins, flow paths, and mitigation facilities. HSPF uses this schematic diagram to compute and route the stormwater runoff.
SDHM Capabilities SDHM 3.0 statistical tools includes flow duration analysis. This flow duration plot shows that the mitigated (red) erosive flows are less than or equal to the pre-development (blue) erosive flows and meets hydromod requirements.
SDHM Capabilities SDHM 3.0 statistical tools includes plotting options. This plot shows major runoff events between 1984 and 2014.
SDHM LID Options Green/vegetated/eco-roofs Permeable/porous pavement Bioretention/rain gardens
SDHM LID Options SDHM 3.0 includes the following LID options: Green/vegetated/eco-roofs to retain rainfall and increase evapotranspiration and reduce stormwater runoff. Permeable/porous pavement to infiltrate rainfall and reduce stormwater runoff. Bioretention/rain gardens to retain and infiltrate water and reduce runoff.
SDHM LID Options Green roof element: increases evapotranspiration.
SDHM LID Options Porous pavement element: increases infiltration.
SDHM LID Options Evaporation from pavement Rain on pavement Surface Runoff Infiltration through pavement Underdrain Flow Infiltration to gravel subgrade Infiltration to native soil Porous pavement flow paths
Bioretention element: SDHM LID Options increases evapotranspiration and infiltration.
SDHM LID Options Evapotranspiration Rain Surface Runoff Surface ponding Infiltration through top layer Infiltration through second layer Underdrain Flow Infiltration through third layer Bioretention flow paths Infiltration to native soil
SDHM Sample Application Example: Convert undeveloped land to commercial development.
SDHM Sample Application User selects land development location and places red dot on map. Then select rainfall gage (Poway).
SDHM Sample Application User inputs pre- and post-development land use. Pre: D, Dirt, Flat Post: Urban landscape (no irrigation) and Impervious, Flat
SDHM Sample Application USGS Q2 = 0.359 cfs USGS Q10 = 0.717 cfs
SDHM Sample Application User inputs initial specifications or uses Size Facility to optimize biofiltration facility size.
SDHM Sample Application SDHM 3.0 compares predevelopment and post-development routed runoff statistics. Flow duration for hydromod (10% of 2-year to 100% of 10-year):
SDHM Sample Application SDHM 3.0 computes drawdown time:
SDHM Sample Application User outputs report file and project file. Output files can be submitted to the reviewer for approval. The reviewer can load project file and rerun analysis, if needed. Report file summarizes input data and output results.
SDHM File Types Project file:.whm Backup project file:.wh2 Database file:.wdm Report file:.rtf or Report file:.pdf
SDHM Review SDHM 3.0 output summarizes statistics and whether or not the facility meets the jurisdiction s stormwater standards in a project report pdf file:
SDHM Review Project report file includes general project info:
SDHM Review Project report file includes user input info:
SDHM Review Project report file includes stormwater facility dimensions:
SDHM Review Project report file includes Weibull partial duration flow frequency values:
SDHM Review Project report file includes flow duration results:
Review option: SDHM Review
SDHM Review Review option: Checklist and Reviewer Information
SDHM Review Review option: Reviewer Information
Review option: Checklist SDHM Review
SDHM Review Review option: Checklist (reviewer can add notes)
SDHM Review Review option: Checklist (some steps automated)
SDHM Review Major items to check: 1. Project site in correct location on map? 2. Pre- and post-development/mitigated total drainage area the same? 3. Pre- and post-development/mitigated soil the same? 4. Everything is connected to a POC? 5. Flow duration passes for EVERY level? 6. Stormwater facility construction plan dimensions match SDHM 3.0 specified dimensions?
SDHM Help Guidance/help is provided by: SDHM 3.0 User Manual Training workshops CCS tech on-line and phone support
Questions??? Clear Creek Solutions, Inc. Doug Beyerlein, P.E. 425-225-5997 beyerlein@clearcreeksolutions.com Joe Brascher 360-943-0304 brascher@clearcreeksolutions.com