Field evaluation of engineered large woody debris for structure performance and habitat value

摘要

Engineered large woody debris (LWD) structures are frequently used for habitatrestoration and enhancement, bank protection and stabilization, and to alter flowwithin a channel. This paper discusses current LWD guidelines as well as ongoingfield investigations on constructed LWD structures in the Middle Fork John DayRiver near John Day, OR. Low altitude balloon photogrammetry was completed forseventeen structures on the Middle Fork John Day to complete a stability andeffectiveness assessment of the LWD structures. A habitat evaluation of the structureswas also completed. The structures have experienced just over a 2-year peakdischarge since constructed and are still in place. Preliminary findings show that thestructures are generally acting as intended by altering channel morphology throughlocally narrowing the channel, adding pools, forming bars, and providing cover forfish habitat. The next step for the field analysis is to look at the stability of each LWDstructure and perform quantitative comparisons.