영산강 곡류절단부에서의 하도변화에 관한 연구 = River Channel Change by Artificial Meander Cut-off in Yeongsan River

다국어 초록 (Multilingual Abstract)

Yeongsan River has experienced many artificail changes by embanking, straightening, deepening, widening and building dams or estuarine barrage. One of the most remarkable modification is straightening river channel by man-made meander cut-off. It resulted in stream regime changes, so as to produced another new channel forms. The purpose of this paper is to discuss the geomorphological effect of artificial meander cut-off, comparing the forms of natural meander channel. The study area is Weolsan, Sinchang, Chipyeong, Seochang, Yugye, Hagsan, Songweol, and Jugsan meanders in the Yeongsan River. The results of this study are as follows; First, since 1931 meandering sectors in Yeongsan River have experienced straightening by artificial meander cut-off. The channel length of Yeongsan River is shortened by 15.7㎞ compared to that in the 1920`s. In the sectors such as Weolsan, Sinchang, Chipyeong, Seochang, Yugye, I-iagsan, Songweol, and Jugsan, initial channel forms made by artificial meander cut-off have been changed markedly. Second, Man-made cut-off has caused upstream degradation and downstream aggradation. In Sinchang, Chipyeong, Seochang, and Yugye meanders, the bedrock is exposed on meander cut-off section. It is the result of the river bed lowering, due to the increase of stream velocity in meander cut-off section. In Sinchang, Seochang, Yugye, Hagsan, and Jugsan meanders, bars are developed in downstream of meander cut-off section. Bars are made up of sediments transported from the upstream, as a rusult of river bed erosion and bank retreat. Third, upstream degradation and downstream aggradation in meander cut-off section are expression of new equilibrium between production and consumption of energy in artificially straightened channel. Finaly, such artificial channel changes meander cut-off may result in unexpected or undesirable effects in upstream and downstream, for example, accelerlation of river bed erosion, destruction of bridge and bank, downstream flood, ...etc.