Trees And Wind: A Practical Consideration Of The Drag Equation Velocity Exponent For Urban Tree Risk Management

Abstract

Arborists and urban foresters are increasingly concerned with tree risk management. The aerodynamic drag equation is a potentially useful management tool. Some sources question the form of equationspecifically, the velocity exponentthat should be applied to trees. For the tree risk manager, concerned with public safety and legal liability, this is more than an academic curiosity. Uncertainty about the appropriate exponent questions the reliability of the conventional form. This paper reviews the literature, reports on modeling of both equation forms, and concludes that the conventional formvelocity squaredis appropriate for trees. Detailed analysis is presented for the researcher or advanced practitioner. A summary explanation is provided for the typical practitioner.