Tadashi Yamada

A nonlinear filter based on fokker-planck equation and its application on rainfall-runoff analysis

Rainfall-runoff process is the central issue of hydrology. The prediction of the runoff has many practical significances. In 1974, M. Hino had firstly applied the Kalman filter in forecasting the rainfall-runoff process, since then many new filters had been suggested and applied in rainfall-runoff process. However, there is no filter can help to recognize the physical meaning of the random external force. On the other hand, recently, K. Yoshimi and T. Yamada have tried to use Fokker-Planck equation to study the uncertainty of stream flow due to the random fluctuation in precipitation. And this can be used in the filter theory to deal with nonlinear systems and also to find the physical meaning of the system noise. The present study is based on K. Yoshimi and T. Yamadas work, aimed at directly using Fokker-Planck equation in the prediction step of filtering, and applied it in the rainfall-runoff process.

A STUDY ON NEW DETEMINATION METHOD OF DAM RESERVOIR DISCHARGE FOR FLOOD CONTROL CAPACITY IMPROVEMENT OF EXISTING DAM RESERVOIR

A new method of flood control by gate operation based on runoff characteristics of a basin is proposed in this paper. This method is based on an anticipatory release approach and the idea that there is no risk in reducing reservoir levels if the amount of anticipatory release is equal to the amount of inflow which will flow into the dam for certain from the rainfall that has already fallen. In this method, rainfall prediction or weather forecasting will not be necessary for flood control. The amount of anticipatory release will be calculated by the real time inflow into the reservoir or accumulated rainfall. And reservoir levels will certainly be restored to there former condition, because the amount of discharge is based on the area under the recession part of the hydrograph.

Fingering in the narrow gap between two parallel plates

Etude experimentale (photographie) de la digitation de linterface air-huile lorsque lair penetre dans lespace etroit entre deux plaques paralleles rempli dhuile