Abstract
The long term existence of a low-head dam in the river channel significantly affects river geomorphology and river ecosystem. Because more and more low-head dam structures have deteriorated in recent years, the attention for low-head dam removal is increasing as one of alternatives for river restoration. Thus, this study intends to investigate the impacts of low-head dam removal on river geomorphology and riparian vegetation with developing a quantitative method to predict the changes of river morphology as well as invasion, growth, expansion and destruction of riparian vegetation after a low-head dam removal. To verify the numerical simulation model, the low-head dam removal case in Gongreung River was employed with investigation of low-head dam removal responses on river geomorphology and riparian vegetation. Following the low-head dam removal, the results of monitoring and numerical simulation indicated that new sand bars has formed as well as increasing the extent of existing sand bars in the upstream of the low-head dam. The sand bars have been colonized in a year after the low-head dam removal by grass type plants. After a decade to several decades, the riparian vegetation in sand bars often developed to tree type plants in several low-head dam removal cases. As other cases, Gongreung River also showed the growth of tree type plants in 5 years after the removal.
Highlights
In recent years, the number of deteriorated low-head dam structures is drastically increasing due to their lifeHow to cite this paper: Kim, S.N., Toda, Y. and Tsujimoto, T. (2014) Effects of a Low-Head Dam Removal on River Morphology and Riparian Vegetation: A Case Study of Gongreung River
In upstream of the low-head dam, the numerical simulation results shows that large scale of sand bars have been created with exposing deposited sediment after the low-head dam removal
The newly formed sand bars in upstream side of the low head dam were colonized by grass type plants
Summary
The number of deteriorated low-head dam structures is drastically increasing due to their life. Layered or cohesive deposits have been shown to produce stepped knick point or head cut following dam removal [2] resulting in channel incision, widening by bank failure, and building floodplains [3] [4]. These morphological changes create suitable surface for riparian vegetation [5]. To develop a quantitative method, this study intends to 1) investigate a low-head dam removal impacts with the monitoring results of Gongreung 2 dam removal; and 2) develop a numerical simulation model for river morphology and riparian vegetation changes following a low-head dam removal with verification by the case of Gongreung River
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