SDHM 3.1 User Workshop Morning Session Instructor: Doug Beyerlein, P.E., P.H., D.WRE Clear Creek Solutions, Inc. www.clearcreeksolutions.com
SDHM 3.1 San Diego Hydrology Model Developed for: San Diego County and cities Replaces SDHM 3.0
SDHM 3.1 Changes from SDHM 3.0 New SDHM 3.1 HSPF parameter values. New vertical orifice outlet control option. New drawdown criteria.
SDHM 3.1 Changes from SDHM 3.0 Note: Because of the above listed changes, projects that have been created in SDHM 3.0 (and earlier SDHM2015) will not work in SDHM 3.1. To convert these older projects to SDHM 3.1 the user needs to manually re-input the project information into a new SDHM 3.1 project file. The project results will change and the hydromod mitigation facility may need to be re-sized.
Presentation Introduction SDHM Background and Theory SDHM and HSPF SDHM Application SDHM Demo Questions & Answers
Introduction SDHM 3.1 software platform is part of WWHM, which was originally developed for the State of Washington Department of Ecology. Now used in California, Oregon, Washington, and Texas.
Introduction SDHM 3.1 is available free from the Clear Creek Solutions, Inc., web site. www.clearcreeksolutions.com Go to Free Software Downloads.
SDHM Background and Theory Flow duration threshold requirements: based on erosive flows. Erosive flow range: varies by location (percent of 2-yr flow to 10-yr flow)
SDHM Background and Theory Flow duration threshold requirements: Default range: 10% of 2-yr flow to 10-yr flow
SDHM Background Flow Duration Analysis: Percent of time the flow exceeds a specific value. Requires continuous simulation hydrology to compute flow duration.
SDHM Background Single event modeling doesn t work because: Single-event flow frequency standards are based on inappropriate assumptions. Single-event modeling cannot compute flow durations (percent of time flows exceed a specific value).
SDHM Background Continuous simulation hydrology models the entire hydrologic cycle for multiple years. Stormwater runoff = surface runoff + interflow.
SDHM Background Distribution of San Diego annual rainfall and runoff: Blue: Evapotranspiration Green: Groundwater Yellow: Interflow Red: Surface Runoff A Soil C Soil Impervious
SDHM Capabilities SDHM 3.1 uses HSPF continuous simulation hydrology to compute stormwater runoff for both predevelopment and post-development conditions. Predeveloped Developed
SDHM Capabilities SDHM 3.1 continuous simulation computations from HSPF (included in software). HSPF runs in the background with local parameter values and local meteorological data. HSPF sponsored and funded by EPA and USGS.
How HSPF works Drainage areas are divided into pervious land segments based on soil, vegetation, and land slope and impervious land segments. Pervious and impervious segments are linked to conveyance pathways (pipes, ditches, ponds, streams, rivers, lakes, etc.) Historic rainfall and evaporation are used as input.
How HSPF works The entire water cycle is modeled on a hourly time step for multiple years. The model computes changes in soil moisture, evapotranspiration, and runoff every time step. Three types of runoff: surface runoff interflow groundwater/base flow
SDHM 3.1 The user selects the rainfall station from the available list (same as SDHM 3.0).
How SDHM works User locates project on county map, inputs pre- and post-development land use, and proposed mitigation measure(s). Predevelopment and mitigated flows are compared at Point of Compliance (POC). Mitigated flows are not allowed to exceed flow duration standards.
SDHM Basic Elements 13 elements: 1. Landuse Basin 2. Trapezoidal Pond 3. Storage Vault 4. Storage Tank 5. Irregular-Shaped Pond 6. Gravel Trench Bed 7. Sand Filter 8. Open Channel 9. Flow Splitter 10. Time Series 11. SSD Table 12. Lateral Flow Soil Basin 13. Lateral Flow Impervious Area
SDHM Pro Elements 3 elements: 1. Biofiltration 2. Porous Pavement 3. Green Roof
How SDHM works User outputs report file and project file. Output files can be submitted to the permitting agency for approval. Permitting agency can load project file and rerun analysis, if needed. Report file summarizes input data and output results.
How SDHM works Guidance/help is provided by SDHM 3.1 User Manual Program Help File Training Workshops Phone and Email Support
SDHM Application Example: Convert undeveloped land to suburban residential housing.
SDHM Application Stormwater Vault Sizing Example Predevelopment land use: Project: 10 ac D soil, Natural vegetation (NatVeg), Moderate land slope (5-15%) 1 ac C soil, Rock, Flat land slope (0-5%) Developed mitigated land use: Project: 6.5 ac D soil, Urban landscape with no irrigation (UrbNoIrr), Moderate slope 1.0 ac D soil, Urban landscape with irrigation (Urban), Moderate slope 1.0 ac Impervious, Flat slope 2.5 ac Impervious, Moderate slope
SDHM Application Stormwater Vault Sizing Example 12 steps from start to finish: 1. Select project location. 2. Set up Predevelopment land use scenario. 3. Set up Mitigated (developed) land use scenario. 4. Calculate lower and upper HMP thresholds based on Predevelopment runoff. 5. Calculate lower and upper HMP thresholds based on USGS regional equations (optional).
SDHM Application Stormwater Vault Sizing Example 12 steps from start to finish: 6. Compare sets of threshold values (optional). 7. Change thresholds (optional). 8. Size Mitigated scenario HMP facility. 9. Review analysis. 10. Produce report. 11.Save project. 12.Exit SDHM.
SDHM Application: Step 1 User selects land development location and places red dot on map. Then selects rainfall station record.
SDHM Application: Step 2 User sets up Predevelopment land use scenario. Selects Landuse Basin element.
User inputs Predevelopment land use. SDHM Application: Step 2 Pre: C, Rock, Flat: 1 ac D, NatVeg, Mod: 10 ac
SDHM Application: Step 2 User connects Landuse Basin element to Point of Compliance (POC 1).
SDHM Application: Step 2 POC 1 shows up in the lower right corner of the Landuse Basin element.
SDHM Application: Step 2 User computes Predevelopment scenario runoff by clicking on the Run Scenario button.
SDHM Application: Step 3 User sets up Mitigated land use scenario using the same procedures as used in Step 2.
SDHM Application: Step 3 User inputs Mitigated (developed) land use. Mit: D, Urban, Mod 1.0 ac D, UrbNoIrr, Mod 6.5 ac Impervious, Flat 1.0 ac Impervious, Mod 2.5 ac
SDHM Application: Step 3 User connects Landuse Basin element to Point of Compliance (POC 1).
SDHM Application: Step 3 ONLY FOR THE PURPOSE OF CALCULATING THE Q2 AND Q10 FLOW FREQUENCY VALUES FOR COMPARISON WITH THE USGS REGIONAL VALUES we will select the exit from this Landuse Basin element as the Point of Compliance for the Mitigated scenario. We will change the location of the Mitigated POC when we size our HMP facility in Step 8.
SDHM Application: Step 3 User computes Mitigated scenario runoff by clicking on the Run Scenario button.
SDHM Application: Step 4 User calculates the lower and upper HMP thresholds based on the Predevelopment runoff.
SDHM Application: Step 4 The Predeveloped Q2 value is 1.7417 cfs; the Q10 value is 3.9846 cfs.
SDHM Application: Step 5 User calculates the lower and upper HMP thresholds based on USGS regional equations (this step is done outside of SDHM and is optional). 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 Application: Step 5 P = mean annual precipitation (inches) Mean annual precipitation values for the standard 18 San Diego County rain gages are shown in the table below. Rain Gage Mean Annual Rainfall (in) Bonita 8.9 Borrego 3.2 CCDA Lindbergh 9.9 Encinitas 10.3 Escondido 13.9 Fallbrook 15.3 Fashion Valley 10.4 Flinn Springs 13.2 Kearny Mesa 11.1 Lake Cuyamaca 30.9 Lake Henshaw 22.4 Lake Wohlford 17.0 Lower Otay 10.5 Oceanside 11.8 Poway 12.2 Ramona 14.4 San Onofre 11.6 San Vicente 12.7 Santee 13.1
SDHM Application: Step 5 For 11 acre site in Fashion Valley: A = 11 ac = 0.0171875 square miles P = 10.4 inches USGS Q2 = 1.368 cfs USGS Q10 = 3.337 cfs
SDHM Application: Step 6 User compares the two sets of threshold values (optional). The Predeveloped Q2 and Q10 values from Step 4 are: Pre Q2 = 1.7417 cfs Pre Q10 = 3.9846 cfs The USGS Q2 and Q10 values from Step 5 are: USGS Q2 = 1.368 cfs USGS Q10 = 3.337 cfs
SDHM Application: Step 6 User selects the set with the largest Q2 value. The Predeveloped Q2 and Q10 values from Step 4 are: Pre Q2 = 1.7417 cfs (use this set) Pre Q10 = 3.9846 cfs (use this set) The USGS Q2 and Q10 values from Step 5 are: USGS Q2 = 1.368 cfs USGS Q10 = 3.337 cfs
SDHM Application: Step 6 Lower and upper HMP thresholds: Lower: 10% Q2 = 0.17417 cfs Upper: Q10 = 3.9846 cfs Note: No need to change SDHM default lower and upper HMP thresholds in Step 7.
SDHM Application: Step 7 Change thresholds (optional): View, Options, Duration Criteria. (1) Default: SDHM (2) User input: USGS
SDHM Application: Step 8 User selects and sizes the Mitigated scenario HMP facility based on the lower and upper threshold values selected in Step 6. For this example project we will size a stormwater storage vault.
SDHM Application: Step 8 User disconnects the Mitigated scenario Landuse Basin from POC 1.
SDHM Application: Step 8 User adds a Storage Vault element for the HMP facility.
SDHM Application: Step 8 User connects the Landuse Basin element to the Storage Vault element.
SDHM Application: Step 8 User connects the Landuse Basin element to the Storage Vault element.
SDHM Application: Step 8 User connects the outflow (Outlet 1) from the Storage Vault element to POC 1.
SDHM Application: Step 8 POC 1 shows up in the lower right corner of the Storage Vault element.
SDHM Application: Step 8 User inputs initial vault specifications or uses Auto Vault to size vault storage volume and outlet control configuration.
SDHM Application: Step 8 User inputs Auto Vault sizing info: (1) Amount of sizing (little to everything possible). (2) Vault Depth (including freeboard). (3) Outlet structure (1 orifice + notch or 3 orifices no notch).
SDHM Application: Step 8 User options: Create Vault: Creates a vault from scratch, ignoring userinput dimensions and outlet control values. Optimize Vault: Starts with user-input dimensions and outlet control values and tries to improve on them.
SDHM Application: Step 8 Sizing is done by iterating to find the smallest vault dimensions (length and width) that produce outflow that meets the HMP flow duration criteria.
SDHM Application: Step 8 Iterations continue until no smaller vault dimensions (length and width) meet the HMP flow duration criteria..
SDHM Application: Step 9 User reviews the flow duration analysis. Flow duration (10% of 2-year to 100% of 10-year)
SDHM Application: Step 9 SDHM 3.1 computes the vault drawdown/drain time for the maximum (riser height) stage:
SDHM Application: Step 9 SDHM 3.1 computes the vault drawdown/drain time for the maximum (riser height) stage: 1 day, 6 hours, 43 minutes.
SDHM Application: Step 10 User produces Project Report:
SDHM Application: Step 10 Project Report summarizes statistics and whether or not the facility meets the jurisdiction s standards.
User saves project file. SDHM Application: Step 11
User exits SDHM. SDHM Application: Step 12
After Sizing Facility User outputs report file and project file. Output files can be submitted to the permitting agency for approval. Permitting agency can load project file and rerun analysis, if needed. Report file summarizes input data and output results.
SDHM 3.1 File Types Project file:.whm Backup project file:.wh2 Database file:.wdm Report file:.rtf or Report file:.pdf
SDHM: LID Options SDHM 3.1 includes the following LID options: Dispersion of impervious surface runoff on adjacent pervious surface (example: roof runoff to lawn). Biofiltration to filter and infiltrate stormwater. Infiltration to retain and infiltrate stormwater. Porous pavement to retain and infiltrate stormwater.
SDHM 3.1 Questions? Contact: Doug Beyerlein 425.225.5997 beyerlein@clearcreeksolutions.com Joe Brascher 360.943.0304 brascher@clearcreeksolutions.com