On the Pmpagation Speed of a Flood Wave in the Takaragawa Experimental Basin

Abstract

The relation between the peak discharge and the propagation speed of floods were investigated in Takaragawa Honryu basin (1905.66 ha) by the records of the three water-stage recorders arranged from the upper stream to the lower stream and also in Shozawa basin (117.90ha) by the records of the two water-stage recorders similarly arranged in the upper stream and the lower stream.
As the result, constant values a & b were obtained for each observation section of the water-stage gauging stations along the following equation:
t=L/a×60 Q_a^-b
where t (min) is propagation time of flood, L(m)is the distance between the two gauging stations, Q_a (m³/s) is the average of the peak discharge in the two gauging stations.
At the same time, it is confirmed that the propagation time of floods reduces as the peak discharge increases.
Simultaneously, if we put the mutual relation between the average of the peak discharge Q_a and the average propagation speed ω_a as following equation,
ωa=L/t=aQ_a^b
where a takes the value 0.65-0.89 and b takes the value 0.35-0.40 through Takaragawa
Honryu basin and Shozawa basin and make very similar relations.
Synthetically, the relation between Q_a and ω_a through Takaragawa basins is judged as follows.
ω_a=0.73Q_a^0.37