**Abstract Text**
Accumulation of woody debris at bridge piers may lead to concerns regarding flow and debris inundation river floodplains and the failure of bridges. The writers used numerical and laboratory methods to address these concerns. A numerical model was used to elucidate the phenomena of the accumulation of woody debris at bridges and movement onto floodplains. To meet these objectives, the writers developed a 3-D numerical model that reproduced the processes of woody debris accumulation and movement in rivers with flood plains. The model consists of 2-D- and 3- D-components for simulating flow structures. Moreover, the model also used a 3-D Distinct Element Method (DEM) to express the 3-D motion of woody debris in rivers and floodplains. A laboratory-flume was used to obtain data and observations about woody-debris accumulation at bridges and on a floodplain, and to calibrate and validate the numerical model. The flume comprised a straight channel fitted with two piers and a floodplain with three houses. The flume’s main channel was 0.2 m wide and 4 m long; and the floodplain was 0.4 m wide and 2.0 m long. Two hundred pieces of woody debris were modeled (debris length = 0.12 m, and diameter = 0.005 m). The debris entered the upstream end of the flume. The writers then observed the consequent adjustments in water-surface profiles, the accumulation process at the piers, and the behavior of the woody debris outflowing to the floodplain. The combined method enabled reproduction of woody debris accumulation at the piers and outflow to the floodplain.



Floodplain Inundation Caused By Woody-Debris Accumulation At Bridge Piers (Room 312, Wednesday June 28th, 8:30am-10:00am)

Engineers, researchers, and climate scientists share developments and innovative practices in the water engineering industry. The Technical Committee for Hydraulics Measurements and Experimental Methods (TCHMEM) of EWRI has organized the HMEM conference six times since 1994, when the first HMEM conference was held in Buffalo, NY. Since then, successful conferences were held in Estes Park, Colorado (2002), Lake Placid, New York (2007), Snowbird, Utah (2012), and Durham, New Hampshire (2017).