THE CAUSE AND MECHANISM OF WATER LEVEL RISE NEAR THE MOUTH OF THE HII RIVER

The water level near the mouth of the Hii River was over the design high water level in the 2006 July flood. The cause and mechanism of water level rise near the river mouth must be clarified from the fact that higher water level had been recorded as well in the past floods. It is shown from data analysis that the rise of water level results from the variation of bed and dune heights near the mouth with increase in flood discharge and water level of the Lake of Shinji. This mechanism was also proved by the one dimensional computation of flood flow and bed variation.