BeckerFraserPhotos April 2011 photograph 467

Images, UC QuakeStudies

The Avon River flooding New Brighton Road at high tide.

BeckerFraserPhotos April 2011 photograph 462

Images, UC QuakeStudies

The Avon River at high tide, along New Brighton Road.

BeckerFraserPhotos April 2011 photograph 553

Images, UC QuakeStudies

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".

BeckerFraserPhotos April 2011 photograph 463

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "At high tide the Avon River is flowing onto the road because the land has sunk below sea level".

BeckerFraserPhotos April 2011 photograph 469

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "This is a very high tide in the Avon River, but shows how the danger of flooding has increased".

BeckerFraserPhotos April 2011 photograph 576

Images, UC QuakeStudies

A submerged walkway next to the Avon River. The water level of the Avon River is higher than normal along Avonside Drive.

BeckerFraserPhotos April 2011 photograph 461

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "New Brighton Road at this point is now below sea level at very high tide!".

BeckerFraserPhotos April 2011 photograph 470

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "This is a very high tide in the Avon River, but shows how the danger of flooding has increased".

BeckerFraserPhotos April 2011 photograph 471

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "This is a very high tide in the Avon River, but shows how the danger of flooding has increased".

BeckerFraserPhotos April 2011 photograph 545

Images, UC QuakeStudies

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".

BeckerFraserPhotos April 2011 photograph 566

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "Slumping near the Avon River on Avonside Drive".

BeckerFraserPhotos April 2011 photograph 542

Images, UC QuakeStudies

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".

BeckerFraserPhotos April 2011 photograph 544

Images, UC QuakeStudies

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".

BeckerFraserPhotos April 2011 photograph 563

Images, UC QuakeStudies

A badly-damaged bridge between Avonside Drive and River Road in Avonside.

20121117_2387_G12-06 New Brighton Road flooded again

Images, eqnz.chch.2010

With the land dropping about 1metre to 1.4metres after the earthquakes, a few roads besides the Avon and Heathcote Rivers are flooded with very high tides. Extra stop banks (on right) erected after the quakes have helped, but the road is now well below high water level. New Brighton Road, just short of New Brighton. The Pages Road bridge may b...

Multi-hazards and the City: Tsunami and River Flooding in Earthquake Impac…

Research papers, University of Canterbury Library

In the aftermath of the 2010-2011 Canterbury Earthquake Sequence (CES), the location of Christchurch-City on the coast of the Canterbury Region (New Zealand) has proven crucial in determining the types of- and chains of hazards that impact the city. Very rapidly, the land subsidence of up to 1 m (vertical), and the modifications of city’s waterways – bank sliding, longitudinal profile change, sedimentation and erosion, engineered stop-banks… - turned rainfall and high-tides into unprecedented floods, which spread across the eastern side of the city. Within this context, this contribution presents two modeling results of potential floods: (1) results of flood models and (2) the effects of further subsidence-linked flooding – indeed if another similar earthquake was to strike the city, what could be the scenarios of further subsidence and then flooding. The present research uses the pre- and post-CES LiDAR datasets, which have been used as the boundary layer for the modeling. On top of simple bathtub model of inundation, the river flood model was conducted using the 2-D hydrodynamic code NAYS-2D developed at the University of Hokkaido (Japan), using a depth-averaged resolution of the hydrodynamic equations. The results have shown that the area the most at risk of flooding are the recent Holocene sedimentary deposits, and especially the swamplands near the sea and in the proximity of waterways. As the CES drove horizontal and vertical displacement of the land-surface, the surface hydrology of the city has been deeply modified, increasing flood risks. However, it seems that scientists and managers haven’t fully learned from the CES, and no research has been looking at the potential future subsidence in further worsening subsidence-related floods. Consequently, the term “coastal quake”, coined by D. Hart is highly topical, and most especially because most of our modern cities and mega-cities are built on estuarine Holocene sediments.