ABSTRACT
A large number of weirs have been being removed or abandoned due to the deterioration of structures or the loss of its functions in recent years. To date, more than 1,000 dams and weirs have been removed in Korea, and 99% of removed structures were weirs which were less than 2 meters in height. However, it is insufficiently documented that how physical characteristics response to weir removal. In order to identify the geomorphological changes by weir removal, this research has established the numerical simulation model. Using the model, the responses of fluvial geomorphology on weir installation and removal were examined. As a result of the geomorphological analysis by weir installation, deposition rates in the upstream of the weir have correlation with hydraulic conditions such as discharge and sediment diameter, while local scour rates in the downstream of the weir were not related with hydraulic conditions. Consequently, it is found that the weir construction and removal have influenced on overall river bed aggradation and local sand bar formation by the effects from long term weir existence.
