No abstract

two-dimensional vertical flow analysis model. The lakebed change analysis that the amount of sedimentation of vertical direction was adopted more than that result is being enforced, and examined comparison and analysis with distribution area and sedimentation point of the fine sediment about Lake Utonai. In this result, confirmed local application in Lake Utonai, and the simulation model that developed in this study clarified a sediment tendency.

Accurate predictions of inflows to dam reservoirs are the most important information for operations and managements. The water levels in the reservoirs are significantly influenced by wind and seiche resulting from gate operations and hence the computed inflow volumes are highly fluctuated with relatively large errors.The characteristics of fluctuations in water levels of reservoirs managed by Regional Hokkaido Development Bureau are practically clarified in this paper. The present study proposes a new smoothing method of fluctuated water levels in dam reservoirs, using Fourier analysis. The proposed method can easily be applied to the practical situations where the inflows are estimated with high accuracy.

The area of this study, Lake Utonai, is in eastern Tomakomai, Hokkaido, Japan. In recent years, the lake has been experiencing the ecological eutrophication resulted from nutrient salts and fine sediments from the rivers, which will damage the ecosystem. The lake water is affected by sea-land wind from costal regions, and by groundwater flow, due to the lake's shallow depth. This study proposed a water quality model and a water flow model for the shallow lake, considering effects of groundwater flow and sea-land wind.

The effect on cross shore sediment transport due to seepage are investigated experimentally. The time series data of phreatic surface and height of runup wave, cross shore changes are collected in swash zone. Calculation of infiltration-exfiltration flux show that, in case of eroded beach, the beach face leads to unstable condition caused by fluidsation of upper layer of sediment. Estimating of tractive force with the uplift force due to seepage, present results indicate that the direction of sediment transport changed from onshore to offshore can be evaluated by the infiltration-exfiltration process.