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MA BF REFERENCE CURVES
Objective• Develop bankfull regional curves and
equations for estimating bankfull width, mean depth, cross-sectional area, and discharge in Massachusetts
BF REFERENCE STREAMGAGES
• USGS streamflow-gaging stations with 10 or more years of record
• Relatively natural flow, with little to no high-flow regulation dams, diversions, etc.
• Drainage areas of varying sizes
• Less than 25 percent urban land use
• Wadeable for surveying
• Identifiable bankfull indicators
BF REFERENCE STUDY SITES
OTHER STUDY
APPROACH
• Rosgen stream classification method (1994)
• Identify BF indicators - primarily the active floodplain, where the stream overtops its banks
• BF indicator elevations were compared to the streamgage stage of the 1.05 to 2-yr recurrence interval peakflows
• BF indicator, water surface, and thalweg elevations were surveyed at 20 longitudinal locations about one BF width apart to the USGS streamgage datum
• At 2 (riffle section) of the 20 locations detailed cross sections were surveyed
• Wolman (1954) pebble count for each stream reach
FIELD WORK
• 27 USGS streamgage stream channels were surveyed
• Surveyed over 6,000 elevation points
• Surveyed about 36,750 ft (about 7 miles) of stream channel
• Measured the median axis of 4,860 pebbles
• 6 additional BF Reference Study Sites– 1 VT site – VT ANR, 2 MA sites – NRCS, and 3 sites – NY USGS– All used similar methods to this study’s work
BANKFULL ASSESSMENTS
A B
BA
A B
MA BF REFERENCE CURVES
WIDTH
DEPTH
X-SEC
FLOW
DRAFT – SUBJECT TO REVISIONDO NOT COPY OR RELEASE
MA BANKFULLMULTIPLE REGRESSION EQUATIONS
• BF Width = 10.84 (drainage area)0.39 (mean basin slope)0.19
– R2=0.91
• BF Mean Depth = 0.77 (drainage area)0.28 (mean basin slope)0.13
– R2=0.85
• BF XSEC Area = 8.26 (drainage area)0.67 (mean basin slope)0.32
– R2=0.95
• BF Discharge = 8.83 (drainage area)0.75 (mean basin slope)0.77
– R2=0.92
DRAFT – SUBJECT TO REVISIONDO NOT COPY OR RELEASE
MA BF EQUATIONS - STREAMSTATS
• Currently working on integrating the bankfull equations into the USGS StreamStats application http://water.usgs.gov/osw/streamstats/massachusetts.html
• Streamstats is a web-site that allows the user to click any stream location and calculate selected flow and basin characteristics
OTHER AVAILABLE FG DATA
• Bridge Scour database– 2,400 bridge crossing longer than 20 ft– Type, dimensions, x-sec data, bed material, etc.
• NAWQA database– Some geomorphic data
• Hydraulic structures and stream cross-sections surveyed for FEMA flood studies – Taunton River Basin (Spring 2010 flood)– Deerfield River Basin (T.S. Irene 2011 flood) – Hoosic River Basin (T.S. Irene 2011 flood)