QGIS 5) calculate stream area

Two maps show stream area of Korea.

1) http://water.nier.go.kr/front/riverNetwork/riverNetwork.jsp -

2) https://egis.me.go.kr/bbs/boardView.do?id=3158&section=1&pageNo=1&keyword=

The aim of first map is to show the water reach and direction. Second map is a landcover map.

If you want to see the landuse ratio, than select second site but if you want to see the stream reach and flow choose first site.

The map from first site.

The map from second site

After get the water stream map, calculate the length of strea with QGIS with filed calculator. Then find the width of stream here;

http://hrfco.go.kr/web/sumun/floodgate.do?year=2010

download "유량측정 성과표"file

You can find the water width value from file.

area = length * width