View
8
Download
4
Category
Preview:
Citation preview
Flood Hydrologyfor
Michigan Watercourses
Michigan Hydrologic Methodologies• FEMA Flood Insurance Study (FIS)• Statistical Analysis of USGS Gage Data (Gage)• Statistical Models for Estimating Flow Characteristics of Michigan
Streams (Regression)• Drainage Area Ratio (DAR)• Michigan’s Modified SCS Method (SCS)• NRCS TR-55 (TR-55)• USACE HEC-HMS (HMS)
Delineate Watershed• Watersheds
delineated in GIS• PDF map or
shapefile provided upon request
Select Method
Flood Insurance Study• Current and historical studies
available from FEMA Map Service Center: msc.fema.gov
• FEMA offers subscription for notification of new/updated studies
• FIS used when available
USGS Gage Analysis• 193 continuously-recording gages
in Michigan• 452 total gages (operating and
discontinued) in Michigan• Data available at
waterdata.usgs.gov• Data searchable by various
parameters
USGS Gage Analysis• 30 peaks for statistical analysis• 20 peaks sufficient in some cases• Longer records preferable• Gage extension• HEC-FFA used for HSDSU analysis• PeakFQ available from USGS
Regression Analysis• Methodology published in Statistical Models for Estimating Flow
Characteristics of Michigan Streams, USGS, 1984• Methodology based on gage analyses• Data published for each studied gage• Ungaged watersheds with DA>20 square miles• Flow adjustment may be applied• NSS available free from USGS
Regression AnalysisInput parameters for Regression method:
• (Contributing) Drainage Area• Slope• Channel Swamp• Slenderness Ratio• Precipitation• Soil Characteristics (geology)
Drainage Area Ratio• Calculate flows based on “known” location• Exponent 0.89• Valid 0.5 to 2.0 times drainage area
SCS Analysis• Methodology published in Computing Flood Discharges for Small
Ungaged Watersheds, MDEQ, rev. 2010• Applies to watersheds up to 20 square miles• Time of concentration >1.0 hour• Underlying methodology is rainfall-runoff unit hydrograph
methodology• Michigan methodology developed using Michigan gages
SCS AnalysisInput parameters for SCS method:
• (Contributing) Drainage Area (DA)• Ponding Adjustment• Time of Concentration (Tc)• Runoff Curve Number (RCN)• Precipitation
SCS AnalysisInput parameters for SCS method:
• (Contributing) Drainage Area (DA)• Ponding Adjustment• Time of Concentration (Tc)• Runoff Curve Number (RCN)• Precipitation
SCS AnalysisInput parameters for SCS method:
• (Contributing) Drainage Area (DA)• Ponding Adjustment• Time of Concentration (Tc)• Runoff Curve Number (RCN)• Precipitation
SCS AnalysisInput parameters for SCS method:
• (Contributing) Drainage Area (DA)• Ponding Adjustment• Time of Concentration (Tc)• Runoff Curve Number (RCN)• Precipitation
SCS AnalysisInput parameters for SCS method:
• (Contributing) Drainage Area (DA)• Ponding Adjustment• Time of Concentration (Tc)• Runoff Curve Number (RCN)• Precipitation
SCS AnalysisInput parameters for SCS method:
• (Contributing) Drainage Area (DA)• Ponding Adjustment• Time of Concentration (Tc)• Runoff Curve Number (RCN)• Precipitation
SCS Analysis
SCS Analysis
SCS Analysis
SCS Analysis
TR-55 Analysis• Free software available from USDA• Used when Tc<1.00 hour• State-specific dimensionless unit hydrograph• DA, Tc, RCN, rainfall same as SCS input• Ponding adjustment applied outside TR-55
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and
input values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry
• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless
unit hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless
unit hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless
unit hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and
input values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
TR-55 AnalysisTR-55 Model Components
• SCS spreadsheet data entry• Open WinTR-55• Add/select dimensionless unit
hydrograph• Enter site information and input
values• Enter rainfall data• Run calculation
HEC-HMS Model• Software available free from USACE• Typical uses:
• Reservoir routing• Combine hydrographs• Hydrograph requests
• Flows from SCS method• Use SCS settings for RCN, precipitation• Use Clark Transform, adjust storage coefficient
Services• Hydrographs
• Matched to estimated peak• Typically constructed/estimated• Extrapolated from gage data where available
• Reservoir Routing• Typically requested for dams• Rating curve must be provided (elevation vs. volume/area vs. flow)
• Hydrology Review• FEMA mapping projects• Letters of Map Revision (LOMR)
Services• Guidance and Training
• Michigan-specific hydrologic methodologies• Appropriate method selection
• Mapping• GIS shapefile or PDF of watershed• GIS backup data if already created• CSS Open GIS Portal
Susan E. Greiner, P.E.Environmental Engineer
Hydrologic Studies and Dam Safety Unit | Water Resources DivisionDepartment of Environmental Quality
517.284.5579 GreinerS@michigan.gov
Recommended