Surge Tank Design for Storage Tunnels

Research output: Contribution to conferencePaperpeer-review


Water conveyance tunnels for hydropower plants in some cases show significant amount of volume. Usually it is only used for the transportation of water from the reservoir to the surge tank and then to the power house. The hydraulic design of pressurised systems are well proven and pressure waves allow quick water mass response. At some sites an additional usage of the storage capabilities of the tunnel might significantly increase the available storage volume. This volume can be used for day storage or increase the flexible operation of a hydro power plant. Such storage-tunnels also can contribute as surge compensation facilities.
The challenge is to provide the ability of sufficient operation either as pressurised or free surface tunnel systems. These boundary conditions define the needs especially of the tank. The present paper provides a suggestion of a storage-tunnel surge tank design. Additionally the surge tank design is to provide sufficient stability area that can rise significantly especially for large discharges at small or medium heads.
This publication underlines the points of the differential surge tank design with chambers and throttle and the hydraulic parameters of the tunnel as well as the preferred use and challenges of a storage-tunnel design. The investigations are examined via 1D-numerical simulations that also allow free surface flow in tunnel systems that was checked by several physical model tests at the hydraulic laboratory at TU Graz.
Original languageEnglish
Publication statusPublished - 2016
Event19 th International Seminar on Hydropowerplants: Flexible Operation of Hydropower Plants in the Energy System - Vienna, Laxenburg, Austria
Duration: 9 Nov 201611 Nov 2016


Conference19 th International Seminar on Hydropowerplants
Internet address


  • Surge Tank
  • Flexible Hydropower

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