Abstract
The tendency in river management is to become more integrated in fluvial fan. Especially, the interaction of the surface and subsurface flow should be considered. The pool-riffle-pool sequences in a river with alternate sandbars govern the surface water profile and also subsurface flow in the river. Surface water flow usually changes near the alternate sandbar with high permeability due to the interaction of surface and subsurface flow. The study on the relationship of the upstream total discharge, the required minimum discharge for certain purpose (such as fishery, navigation), and the amount of leakage from surface to subsurface becomes very significant in the river management. As the initial framework, this problem is discussed in a river reach scale in this study. The required environmental discharge is assumed to be the minimum surface flow, and the relationship between leaking flux and the required upstream total discharge is discussed based on the result of flume experiment.
