Bankfull Discharge for Kansas Natural Alluvial Channel Design

In this study we present an equation that predicts bankfull discharge for Kansas streams based on watershed characteristics. This equation can be used for natural channel design projects such as stream realignments and restorations. To develop this equation, we first determined that the recurrence intervals of bankfull flow on 46 natural streams in Kansas range between <1.0 and 1.7 years. The median and mean recurrence interval are both 1.2 years. We then derived a multivariate regression equation for the 1.2-year discharge from a database of 72 small rural streams in Kansas, using ten different watershed characteristics as possible predictors. The regression analysis led to an equation that predicts the 1.2-year discharge as a function of the drainage area, the mean annual precipitation, and the length of the longest flow path. This equation can be used for natural channel design in Kansas.