Options for opening/closing Te Waihora

Many options have been proposed to open/close Te Waihora.  Summaries of over 27 options are presented here categorized into:

  • Mechanical
  • Structural general
  • Structural - channels
  • Structural - culverts/siphon/weirs
  • Combined options
  • Other options

Opening options are desired because if left in its natural state, the water level would rise to ~4m before naturally breaching the Kaitorete Barrier.  The corresponding water surface area would be very large, causing widespread flooding in the Canterbury plains. 

Some of challenges to opening/closing the Lake are:
  • Tides, Swells, and Wave action
  • Hydraulic Gradients between Lake and Sea
  • High winds affecting lake water levels
  • Unstable, poorly graded gravels and eroding coastline
Te Waihora is an extremely complex system with many stakeholders and interested parties.