Abstract: The gentle terrain of coastal plain and the insufficient flow of drainage channel are important causes of waterlogging of plain. Arranging multi-stage relay pump stations on the main drainage channel to increase flow velocity in channel and improve drainage efficiency is a novel measure to alleviate waterlogging induced by tide, typhoon, and terrain. In this paper, the application scope, layout, scale, and generalization for hydraulic calculation of relay pump station are discussed. A case study on the flood control and waterlogging drainage in Yuyao City proves that partitioned restraint of flood and relayed intensive drainage are of evident effect in plains of long drainage distance and insufficient hydraulic gradient. Relay pump stations can be promoted in the flood-control work of coastal plains.

Key words: relay pump station, coastal plain, drainage, flow capacity, self-flow rate of river channel, regulating sluice