1 / 26

PrePro2004: Comparison with Standard Hydrologic Modeling Procedures

Hydrologic Modeling. The use of physical or mathematical techniques to simulate the hydrologic cycle and its effects on a watershed Most commonly used to simulate stormwater runoff in a watershed. HEC-HMS. US Army Corps of Engineers Hydrologic Modeling SystemUsed to electronically simulate precipitation-runoff processes of dendritic watershed systems Outputs include peak flows and runoff hydrographsOutputs used directly or in conjunction with other programs .

rocio
Download Presentation

PrePro2004: Comparison with Standard Hydrologic Modeling Procedures

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. PrePro2004: Comparison with Standard Hydrologic Modeling Procedures Rebecca Riggs April 29, 2005

    2. Hydrologic Modeling The use of physical or mathematical techniques to simulate the hydrologic cycle and its effects on a watershed Most commonly used to simulate stormwater runoff in a watershed

    3. HEC-HMS US Army Corps of Engineers Hydrologic Modeling System Used to electronically simulate precipitation-runoff processes of dendritic watershed systems Outputs include peak flows and runoff hydrographs Outputs used directly or in conjunction with other programs

    4. 3 Components of HMS Basin Model Watershed Parameters Meteorologic Model Precipitation and Evapo-transpiration Parameters Control Specifications Start and End Date/Time of Simulation

    5. Basin Model Watershed parameters: sub-basins, reachs, junctions, sources, sinks, and reservoirs Commonly data is derived from contour maps (USGS or survey data), land use maps, and soil maps Tedious and time consuming

    6. Sub-basins

    7. Reach Parameters

    8. PrePro2004 A GIS pre-processor which extracts hydrologic information from spatial data for HMS modeling Add-in tool in Arc-GIS interface Much faster than conventional methods for calculating basin model parameters

    9. Study Area College Station, Texas Castlegate Subdivision Spring Creek, before confluence with Lick Creek

    10. Study Area

    11. PrePro2004 Basic Steps Gather data Fill sinks, create FDIR grid, create FACC grid Construct stream network Add inlet, outlet, and/or reservoir Delineate watershed Extract HMS elements Calculate parameters Calculate curve numbers Export data to IDM Export IDM to HMS Setup HMS project

    12. 1. Gather Data DEM, stream vector data, mask grid, soils vector or grid data, land use vector or grid data DEM source: USGS seamless Soils and land use (zoning) from COCS Stream vector data from US EPA Lower Brazos arc data

    13. 2. Fill sinks, create FDIR grid, create FACC grid Fill: Cell elevation raised to lowest surrounding cell elevation FDIR: Flow direction grid FACC: Flow accumulation grid

    14. 3. Construct Stream Network Chose cell threshold = stream drainage area

    15. 4. Add Inlet/Outlet/Reservoir

    16. 5. Delineate Watershed

    17. 6. Extract HMS Elements Under Vectorization tab in Watershed Delineation tool Creates shapefiles to be directly imported to a target geodatabase Elements include watershed, reach, junction, source, and reservoirs Following element extraction can merge basins, but this was not selected in this project

    18. 7. Calculate Parameters Generates longest flow path for each sub-basin, HMSCode, and extracts slope and elevation data from DEM Data stored in ‘watershed’ and ‘reach’ layers

    19. 8. Calculate Curve No. Need soils data, land use data, watershed data (previously created), and CN lookup table

    20. Curve No. Continued Vector data was used, but raster data could be used if available Soils data was given by individual HSG, not a % of each Zoning was used for land use, then equated to the NLCD land use codes manually After calculating CN and impervious cover are stored in the ‘watershed’ layer

    21. 9. Export Data to IDM Prior to this step gage weights can be calculated, a frequency storm is used in this project so gage weighting was skipped Exports data from previous steps to project and basin geodatabases (preferably empty) Following this step time of concentration for each subbasin is calculated (Calculate Parameters)

    22. 10. IDM to HMS Creates input files for HMS from data stored in basin geodatabase Basin file Meteorologic file (if gage data is used) Must propogate fields with chosen methods for loss rate, transform, and routing

    23. 11. Import to HMS Import basin and meteorologic files into HMS Import background map and grid data

    24. Results

    25. Basin Comparison

    26. Comments The sub-basins would have been more similar had I added more user defined outlets Time savings is huge Good for large scale projects, but difficult to accurately define watersheds with tool on small scale (development scale)

    27. Questions?

More Related