Author(s): Koichi Suzuki; Akihiro Kadota; Yoshifumi Fujimori
Linked Author(s): Koichi Suzuki, Akihiro Kadota
Keywords: Morphological change; Large sand bar; Vegetation (reed area); Salt; Nitrogen and phosphorus concentrations
Abstract: Morphological change of large sand bars that was caused by several floods and resulted in the change in vegetation (reed) area in the estuary of a small river named Shigenobu in Matsuyama city in Japan was surveyed. Also, considering with the relation between the vegetation growth and the water qualities near vegetation area, the measurement of salt, nitrogen and phosphorus concentrations around the vegetation area were surveyed by scooping up the ground water near the vegetation area. And grain distribution of bed material on the sand bars were measured. It is proved that even a small morphological change in the estuary causes a large change of vegetation area because of the salt water effect at high tides; The vegetation (reed) area on sand bars can be formed when the salt concentration of the ground water at the reed root is less than about 1.24 percent, which is achieved when the area is submerged only at a tide higher than T. P. 1m and where the mean high and low tides are 1.50m and –0.5m, respectively, and the area is covered by silt and fine sand and it was considered that such fine sand protects the vegetation area from salt water. The vegetation area influences nitrogen and phosphorus concentrations. It was considered that the vegetation has its own ability to remove the pollutant.
Year: 2001