Evaluation of Scour and Stream Stability by Using CAESAR

摘要

The performance of an expert system (CAESAR for Catalog and Expert Evaluation of Scour Risk and River Stability) for an initial evaluation of scour and stream stability was assessed. Three alternative scour indices are used to compare with the evaluation results of CAESAR. These scour indices include the Observed Streambed Scour index, the INDOT Potential Streambed Scour Index, and the Simon Potential Streambed Scour Index. Ten bridges in Indiana are selected for evaluation in this study. The scour indices and the field inspection information required by CAESAR are retrieved from the USGS data base. In general, the results show that CAESAR is able to reflect current scour risks as well as the Observed Streambed Scour Index, and the results from CAESAR identifies more bridges as scour critical than the INDOT Potential Streambed Scour Index and the Simon Potential Streambed Scour Index. Because the INDOT Potential Streambed Scour Index and the Simon Potential Streambed Scour Index do not take into account the overall stream geometry, bank materials, channel and floodplain widths, and other considerations required by CAESAR, the results of these two indices are not as conservative as that given by CAESAR. It is concluded that the results from CAESAR may be used to estimate the scour risk of bridge piers.