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)