Analysis of water surface oscillation in a dam reservoir using the data of water level from the multiple water gauges

It is important to know the exact amount of water flowing into a dam reservoir for operating a dam. Usually, this inflow is estimated from a data of the water level. Accuracy of measurement of water level necessarily reflects the accuracy of estimation of inflow into the reservoir. But, data of water level include many kind of noise, for example, seiche, wind wave, swell, and so on. In this paper, we analyzed the data of water level obtained from multiple water gauges installed in Jozankei Dam Reservoir. We found characteristic of water surface oscillation such as several kind of seiche, swell, and wavy displacement by wind. We could confirm that the wavy displace-ment of water surface caused by wind gives much error to estimate the inflow into the reservoir.