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.
1. PHIL TWYFORD to the Minister for State Owned Enterprises: What reports, if any, has he received about KiwiRail's plans to get rid of electric locomotives on the North Island Main Trunk Line and replace them with diesel locomotives?
2. JULIE ANNE GENTER to the Minister for State Owned Enterprises: Is he considering replacing the electric locomotives with diesel locomotives on the Main Trunk Line, and would this mean removing electrification on that line.
3. DAVID BENNETT to the Minister of Finance: What reports has he received on the New Zealand economy and business sentiment?
4. Rt Hon WINSTON PETERS to the Minister for Primary Industries: Does he believe the Dairy Industry Restructuring Amendment Act 2012 has achieved "a stable, permanent capital base for the Co-operative, secures our future and will support progress with our strategy to grow volumes and value"; if so, why?
5. MATT DOOCEY to the Minister for Social Development: What announcements has she made to improve statutory child protection in New Zealand?
6. Dr DAVID CLARK to the Minister for Economic Development: What lessons, if any, on regional economic development has he drawn from his recent ministerial visits to Northland?
7. CATHERINE DELAHUNTY to the Minister for State Owned Enterprises: Will he stop any further work on dairy conversions by Landcorp, in light of the drop in the dairy price yesterday and concerns about the impact that those conversions will have on water quality; if not, why not?
8. MARK MITCHELL to the Minister of Trade: What recent steps has the Government taken to promote and support New Zealand exporters?
9. Hon DAVID PARKER to the Minister of Trade: What monetary and other assistance was provided by the New Zealand Government in support of his bid for appointment as Director-General of the World Trade Organisation?
10. BARBARA KURIGER to the Minister for Small Business: How are small businesses benefiting from the Better for Business - Result 9 Programme?
11. POTO WILLIAMS to the Minister for Social Housing: Why are Christchurch's social housing organisations facing increased homelessness four years after the last major earthquake?
12. MAHESH BINDRA to the Minister of Corrections: Does he stand by all his answers given to the House on 1 April 2015?
