EVALUATION OF FLOOD RUNOFF CONTROL FUNCTION OF SIMPLE DRAINAGE OUTLET OF PADDY FIELD

Abstract

 The simple drainage outlet in this paper consists of a PVC straight pipe and a 90 degree elbow. We evaluated the flood runoff control function of simple drainage outlet, through numerical simulations of flooding depth and runoff from a paddy field based on drainage characteristics of drainage outlets by hydraulic experiments. The followings are clarified. (1) The elbow pipe of a simple drainage outlet works to suppress runoff from a paddy field. (2) The simple drainage outlet in which the setting angle of the elbow pipe is adjusted to 30 degree angle can be expected to have a flood runoff control function that reduce peak runoff rate by 45 to 50% for the 24hour 30-year return period rainfall and the second highest 24-hour rainfall at Utsunomiya.