According to direct observation and analysis of field data collected by the FEH team from dozens of stable channel reaches in Indiana, a general cross-sectional form common in Indiana streams has been recognized.  This cross-sectional form is quantitatively described by the channel’s width/depth ratio. This unitless ratio, simply calculated by dividing the measured bankfull-channel width by the mean bankfull-channel depth, provides a simple description of the cross-sectional shape of natural channels and serves as an additional measure of confidence in the accurate identification of bankfull stage.  In Indiana, these data suggest that:

• Most stable channels with drainage areas less than 3 square miles will have a width/depth ratio greater than 8
• Many channels with drainage areas greater than 3 square miles will have a width/depth ratio greater than 10
• Many channels with drainage areas greater than 100 square miles will have a width/depth ratio greater than 16
• Channels with a width/depth ratio less than 8 may not have bankfull indicators present and may not be stable