Abstract: Session E  1:55 pm (Back to Session F)
Living Erosion Pins – Streambank and Hillslope Erosion Rate Assessments using Exposed Tree Roots  

Bryan Dick, PE, PH
Freese and Nichols, Inc.
Greensboro, NC

Author: Bryan Dick, PE, PH

Streambank and hillslope erosion can threaten infrastructure, water quality and ecological diversity, and cause flooding from a loss of channel capacity in downstream receiving waters.  A fundamental issue for owners and the planning community is the overwhelming number of potential erosion sites that are in need of repair.  Additionally, threats to utility lines, bridges, buildings and other infrastructure are often un-noticed until the issue has become more severe. Decision-makers need a realistic assessment of the level of risk posed by an erosion site in a timely manner and can rarely afford to wait for multi-year erosion studies using traditional monitoring and survey methods.  Traditional direct measurement methods of erosion assessment and monitoring (eg: survey and erosion pins) are both expensive and relatively time consuming and are often financially impractical or do not provide a decision criterion in a timely manner.

Changes in the annual growth rings of exposed tree roots after exposure to the elements allow us to utilize exposed tree roots that are available on project sites for erosion rate assessment.   This method, known as dendrogeomorphology, has been predominantly used in Europe for land slide and hillslope erosion assessment.  I will present the simple and practical approach to using exposed roots of trees to measure erosion and how various field methods may be used for risk assessment, site prioritization and long term-sediment modeling of watersheds.