Two girls paddle a kayak down the Avon river through Hagley park.
The Canterbury region of New Zealand experienced a sequence of strong earthquakes during 2010-2011. Responses included government acquisition of many thousands of residential properties in the city of Christchurch in areas with severe earthquake effects. A large and contiguous tract of this ‘red zoned’ land lies in close proximity to the Ōtākaro / Avon River and is known as the Avon-Ōtākaro Red Zone (AORZ). The focus of this study was to provide an overview of the floodplain characteristics of the AORZ and review of international experience in ecological restoration of similar river margin and floodplain ecosystems to extract restoration principles and associated learnings. Compared to pre-earthquake ground levels, the dominant trend in the AORZ is subsidence, together with lateral movement especially in the vicinity of waterway. An important consequence of land subsidence in the lower Ōtākaro / Avon River is greater exposure to flooding and the effects of sea level rise. Scenario modelling for sea level rise indicates that much of the AORZ is exposed to inundation within a 100 year planning horizon based on a 1 m sea level rise. As with decisions on built infrastructure, investments in nature-based ‘green infrastructure’ also require a sound business case including attention to risks posed by climate change. Future-proofing of the expected benefits of ecological restoration must therefore be secured by design. Understanding and managing the hydrology and floodplain dynamics are vital to the future of the AORZ. However, these characteristics are shared by other floodplain and river restoration projects worldwide. Identifying successful approaches provides a useful a source of useful information for floodplain planning in the AORZ. This report presents results from a comparative case study of three international examples to identify relevant principles for large-scale floodplain management at coastal lowland sites.
Following the Canterbury earthquake sequence of 2010-11, a large and contiguous tract of vacated ‘red zoned’ land lies alongside the lower Ōtākaro / Avon River and is known as the Avon-Ōtākaro Red Zone (AORZ). This is the second report in the Ecological Regeneration Options (ERO) project that addresses future land uses in the AORZ. The purpose of this report is to present results from an assessment of restoration opportunities conducted in April 2017. The objectives of the assessment were to identify potential benefits of ecological restoration activities across both land and water systems in the AORZ and characterise the key options for their implementation. The focus of this report is not to provide specific advice on the methods for achieving specific restoration endpoints per se. This will vary at different sites and scales with a large number of combinations possible. Rather, the emphasis is on providing an overview of the many restoration and regeneration options in their totality across the AORZ. An additional objective is to support their adequate assessment in the identification of optimum land uses and adaptive management practices for the AORZ. Participatory processes may play a useful role in assessment and stakeholder engagement by providing opportunities for social learning and the co-creation of new knowledge. We used a facilitated local knowledge based approach that generated a large quantity of reliable and site specific data in a short period of time. By inviting participation from a wide knowledge-holder network inclusivity is improved in comparison to small-group expert panel approaches. Similar approaches could be applied to other information gathering and assessment needs in the regeneration planning process. Findings from this study represent the most comprehensive set of concepts available to date to address the potential benefits of ecological regeneration in the AORZ. This is a core topic for planning to avoid missed opportunities and opportunity costs. The results identify a wide range of activities that may be applied to generate benefits for Christchurch and beyond, all involving aspects of a potential new ecology in the AORZ. These may be combined at a range of scales to create scenarios, quantify benefits, and explore the potential for synergies between different land use options. A particular challenge is acquiring the information needed within relatively short time frames. Early attention to gathering baseline data, addressing technical knowledge gaps, and developing conceptual frameworks to account for the many spatio-temporal aspects are all key activities that will assist in delivering the best outcomes. Methodologies by which these many facets can be pulled together in quantitative and comparative assessments are the focus of the final report in the ERO series.
An aerial photograph of New Brighton. The photograph has been captioned by BeckerFraserPhotos, "Anzac Drive Bridge over the River Avon. The houses in the bottom half of this photograph are residential red zoned".
Photograph captioned by BeckerFraserPhotos, "The Avon River is at this point on Avonside Drive 10 km from the estuary. At high tide the river now overflows its banks showing that the ground has sunk by about 40 cm".
Photograph captioned by BeckerFraserPhotos, "The Avon River is at this point on Avonside Drive 10 km from the estuary. At high tide the river now overflows its banks showing that the ground has sunk by about 40 cm".
A photograph of earthquake damage to the Canterbury Provincial Chambers Buildings, taken from Oxford Terrace, across the Avon River. One of the chimneys has fallen onto the roof, knocking off tiles and pieces of masonry.
Photograph captioned by BeckerFraserPhotos, "Avonside Drive looking down North Avon Road".
Photograph captioned by BeckerFraserPhotos, "Avon River near the Anzac Drive bridge".
A photograph captioned by BeckerFraserPhotos, "The River Avon along Avonside Drive".
A photograph captioned by Paul Corliss, "Red stickered. 402 Oxford Terrace, Avon Loop".
A photograph captioned by Paul Corliss, "Red stickered. 402 Oxford Terrace, Avon Loop".
An aerial photograph captioned by BeckerFraserPhotos, "Anzac Drive and Avon River".
A photograph captioned by Paul Corliss, "Red stickered. 402 Oxford Terrace, Avon Loop".
A photograph captioned by Paul Corliss, "Red stickered. 402 Oxford Terrace, Avon Loop".
Aftermath of September 4th Earthquake in Christchurch, NZ. Footbridge over Avon river
Photograph captioned by BeckerFraserPhotos, "The Avon River is at this point on Avonside Drive 10 km from the estuary. At high tide the river now overflows its banks showing that the ground has sunk by about 40 cm".
Water and liquefaction flows into the Avon River in Richmond. The water level is very high, and the water is cloudy with silt. The photographer comments, "Water from Dudley Creek took a shortcut across the road into the Avon. It doesn't have much of a drop from the road to the river".
A view over the Avon River to a building being constructed on Oxford Terrace.
The water level of the Avon River is higher than normal along Avonside Drive.
Photograph captioned by BeckerFraserPhotos, "The Colombo Street bridge over the Avon River".
Aftermath of September 4th Earthquake in Canterbury, NZ. Footbridge over Avon river, Christchurch
Photograph captioned by BeckerFraserPhotos, "Avonside Drive. Building up the Avon River stop banks".
Photograph captioned by BeckerFraserPhotos, "Avonside Drive. Building up the Avon River stop banks".
A photograph of the gravel flood banks built on the banks of the Avon River.
A photograph of the gravel flood banks built on the banks of the Avon River.
A photograph of workers from Treetech digging up tree stumps next to the Avon River.
A photograph captioned by Paul Corliss, "Community Law Centre, Madras Street, from Avon River side".
A photograph captioned by Paul Corliss, "Community Law Centre, Madras Street, from Avon River side".
A photograph captioned by Paul Corliss, "Community Law Centre, Madras Street, from Avon River side".