Guidelines for Bridges Over Degrading and Migrating Streams, Part 1: Synthesis of Existing Knowledge (0-2105-2)

This report is a collection of existing knowledge on the following topics: prediction of meander migration rate and stream bed degradation rate, and countermeasures for mitigating meander migration and stream bed degradation. Based on existing knowledge, two main conclusions were reached on the prediction of meander migration and stream bed degradation:|1. There is no reliable formula to predict these erosion movements.|2. The best existing way to predict such erosion movements is by extrapolation of historical data. Based also on existing knowledge, three main conclusions were drawn on the countermeasures for mitigating meander migration and stream bed degradation:|1. There are a large number of countermeasures to choose from.|2. There is no scientific basis for choosing the right countermeasure for a given case.|3. The best current practice is based on local experience and trial and error approach.