Three Dimensional Computational Modeling of Flows through an Engineered Log Jam

Engineered log jam (ELJ) is widely used in the United States for stream and watershed restoration projects. It is economical as the materials are locally available. ELJ itself becomes a natural habitat for aquatic life. The use of ELJ in streams, however, introduces concerns with regard to its safety and impacts on local stream morphology. Design guidelines are still lacking. Laboratory or field study is difficult or costly due to irregular nature. Computational modelling, therefore, becomes an attractive alternative. In this study, a practical, semi-automatic, 3D numerical model is developed to simulate complex flow patterns produced by an ELJ. The ELJ is also placed in a large flume so that velocity is measured and used to verify the numerical model. The ultimate goal is the ability to predict complex river flows and morphological changes induced by in-stream ELJ structures in the field.