Prediction of Stream Geometry in the Maryland Piedmont Based on Land Use and Urbanization

An investigation into the effects of land use on stream channel geometry was performed in the Maryland Piedmont. The motivation for this study was to increase the understanding of the relationships between watershed characteristics and stream channel geometry. Data collected in the field consisted of the measurement of a series of cross-sections, and various planform features, as well as the sampling of bed material. The drainage area of the 23 sites used in the study ranged between 0.57 km² and 25.74 km², and the basin composition of sites ranged from heavily agricultural and forested to heavily urbanized. A Geographic Information System was used in the site selection process. Various relationships were found to exist between land use and stream channel size, shape, and depth. A series of additive power functions developed in this study describes these relationships. It was found that the increase of urbanization, in the form of residential area, in a watershed is associated with the increase in stream cross-sectional area, as well as deeper and more rectangularly-shaped channels. It is evident from the results of this study that the effects of urbanization play a role in stream channel enlargement in the Maryland Piedmont. As well as quantifying some associations between stream channel geometry and watershed characteristics, this document provides a method to determine relationships between land use and stream channel geometry at a regional level, in hopes that design work performed on stream channels in a region can be sensitive to changes in stream channel geometry.