Tafness Drain Beach

Installing a permeable layer under a seaside beach restricts groundwater rise and water currents, helping to prevent coastal erosion. This was a joint development undertaken with Kanto Region Development Bureau Yokohama Harbor and Airport Technical Study Center, Independent Administrative Agency Port and Airport Research Institute, (now National Research and Development Agency Port and Airport Research Institute) and Nippon Steel Metal Products Co., Ltd.

Beach stabilization using permeable layer (image)

Concept Diagram


  • Permeable layer is buried in the ground and is not visible to the naked eye, so coastal erosion is prevented in a close to natural state.
  • A metal-type drain unit is used in the permeable layer so installation is possible at shorelines where the groundwater level is high.
  • Material used has good permeability and is unlikely to be clogged with sand, displaying excellent water catchment and drainage functions.

Permeable layer installation (metal type)

Intensive underwater drainage pipe-laying system

Implementation Method