Flood Hydrology. for. Michigan Watercourses

Transcription

1 Flood Hydrology for Michigan Watercourses

2 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)

3 Delineate Watershed Watersheds delineated in GIS PDF map or shapefile provided upon request

4 Select Method

5 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

6 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

7 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

8 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

9 Regression Analysis Input parameters for Regression method: (Contributing) Drainage Area Slope Channel Swamp Slenderness Ratio Precipitation Soil Characteristics (geology)

10 Drainage Area Ratio Calculate flows based on known location Exponent 0.89 Valid 0.5 to 2.0 times drainage area

11 SCS Analysis Methodology published in Computing Flood Discharges for Small Ungaged Watersheds, MDEQ, rev 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

12 SCS Analysis Input parameters for SCS method: (Contributing) Drainage Area (DA) Ponding Adjustment Time of Concentration (Tc) Runoff Curve Number (RCN) Precipitation

13 SCS Analysis Input parameters for SCS method: (Contributing) Drainage Area (DA) Ponding Adjustment Time of Concentration (Tc) Runoff Curve Number (RCN) Precipitation

14 SCS Analysis Input parameters for SCS method: (Contributing) Drainage Area (DA) Ponding Adjustment Time of Concentration (Tc) Runoff Curve Number (RCN) Precipitation

15 SCS Analysis Input parameters for SCS method: (Contributing) Drainage Area (DA) Ponding Adjustment Time of Concentration (Tc) Runoff Curve Number (RCN) Precipitation

16 SCS Analysis Input parameters for SCS method: (Contributing) Drainage Area (DA) Ponding Adjustment Time of Concentration (Tc) Runoff Curve Number (RCN) Precipitation

17 SCS Analysis Input parameters for SCS method: (Contributing) Drainage Area (DA) Ponding Adjustment Time of Concentration (Tc) Runoff Curve Number (RCN) Precipitation

18 SCS Analysis

19 SCS Analysis

20 SCS Analysis

21 SCS Analysis

22 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

23 TR-55 Analysis TR-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

24 TR-55 Analysis TR-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

25 TR-55 Analysis TR-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

26 TR-55 Analysis TR-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

27 TR-55 Analysis TR-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

28 TR-55 Analysis TR-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

29 TR-55 Analysis TR-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

30 TR-55 Analysis TR-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

31 TR-55 Analysis TR-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

32 TR-55 Analysis TR-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

33 TR-55 Analysis TR-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

34 TR-55 Analysis TR-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

35 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

36 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)

37 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

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39 Susan E. Greiner, P.E. Environmental Engineer Hydrologic Studies and Dam Safety Unit Water Resources Division Department of Environmental Quality