Abstract
The data obtained in Imizu-Seibu Basin resulted in the fact that the stage risings in a drainage canal reduce the runoffs in the lowlands. However, the detailed relations between the stage risings and the reductions on the runoffs were not revealed in the preceding paper. In this paper, tank parameter λ1, 0 referred to in the preceding paper was assmed to be a random variable. The standard deviation and expectation for the distribution of the variable were estimated by making use of the observed data.
In addition, the two tanks named Ts and Tm were considered to analyze the dependence of tank parameter λ1, 0 on storms. Tank Ts with λ1, 0=0.1.53 h-1 was regarded as reservoir for the surface runoffs and tank Tm with λ1, 0=0.096 h-1 was used for the interflow runoffs. The rainfalls were divided into each tank on referring to the critical rate of rainfalls. If the rate of the rainfalls is under the critical rate, then the input rate of tank Tm should be equal to the rate of the rainfalls. If the rate of the rainfalls exceeds the critical rate, then the input rate should be equal to the critical rate. The execssive rate of rainfalls is the input rate of tank Ts. The constants for both of them were obtained through the detailed discussion regarding the observed data.
Finally, the constants mentioned above were applied to the drainage simulations in four typical stormcases. The results of the simulations agreed closely with the observed data.
