Campbell, B. A., Marsden, I. D., & Hart, D. E. (2013). Characterisation of earthquake induced environmental degradation in Bexley Wetland, South Island, New Zealand and options for future management.

Bexley Wetland is one of the few remaining Ōtautahi Christchurch wetlands preserved against urban development pressures. Prior to the 2010-11 Canterbury earthquakes, it was a true asset to Christchurch residents due to its ecological and recreational value. However, Bexley wetland experienced severe liquefaction and degradation during the 2010-11 Canterbury earthquakes.

To gain understanding of the effects of multiple earthquakes on the vegetation and physical characteristics of Bexley Wetland, this 2013 study used plant and elevation surveying. Overall, it found that post-earthquake ground subsidence reduced the elevation of Bexley Wetland to 0.33 metres above sea level, causing most areas to become inundated at high tide, including freshwater areas. It also found there was a large loss of vegetation across the wetland, especially where elevations were below ~0.58m above sea level. This left the wetland more characteristic of intertidal mudflats with algal growth. Species like Carex secta experienced 100% mortality, while herbaceous salt marsh plant species appeared most tolerant of the new tide and elevations.

Before the consideration of management options, the researchers recommended that a period of natural recovery be allowed for at least a year alongside regular sedimentation and erosion monitoring. In areas where plant loss continued, they recommended that intervention may be needed in the form of low groyne structures and transplanting species, and that any options should be guided by a new development plan.

Bexley Earthquake Degradation - 2013

Bexley Wetland Earthquake Degradation - Campbell et al., 2013