Land for Sea
4TH YEAR BLA STUDENT, Unitec
Having grown up on beaches, the experience, fulfillment and energy that we get from these sandy shores is unique. The way we all use our coasts, even off the beach and in the water, on a boat, under the water, these amenities that the Pacific Ocean and the Tasman Sea offer us are some of the most valuable public space assets we have. The constant change and uncertainty within the moving sands, estuaries, and oceans is most interesting to some while the endless views and fresh salty air sees frequent visitors converted to residents. Together with the popularity and a high level of demand from these beautiful locations, are we becoming distracted from the reality of the coast as a natural and fragile environment?
Once a relatively flat dune system extending hundreds of meters landwards is now a now a clay capped suburbia (NIWA, 2013). “The interference of man with nature often has detrimental side effects” and a historical observation of Orewa reveals that the coastal morphology of the beach pre-development has been considerably altered when compared against the beach of today (Flemming & Nyandwi, 1994). Historic aerial photography illustrates the change of Orewa, exposes what the original arrangement of dunes looked like and reveals how the south end estuary used to function. The use of these images show how a resilient coastal system has slowly evolved into the ‘unhealthy beach’ of today (Anthoni, 2000).
The Waitemata Reef was the pivotal point for the exit of water from the Orewa estuary. Pre development, the exit took a northerly direction hugging the land before diffusing into the Gulf. This produced a natural circulation of sand, from the sediment that was moving south, caused by long shore drift, to be relocated north by the estuarine currents. According to historic imagery, this was a natural recycling system that produced a closed circuit loop of sediment transport resulting in significantly larger areas of dry sandy beach. The manmade destruction of the reef was a transformation that slowly changed the course of sand movement. “For a finite-size (flow) system to persist in time (to live), its configuration must evolve such that it provides easier access to the imposed currents that flow through it” (Bejan, 1996). This erosive force acquired a new configuration because an easier exit was revealed that “provided more access for the currents that flow through them” (Bejan, 1996). The outcome of this procedure meant that the natural recycling of sand soon grew obsolete. During large storm events, eroded sand now accumulates at the southern end groyne and is pushed out to an off shore location creating the tidal delta. When Orewa Beach is running low on dry sand, expensive dredging is used to move the accumulated south end sand back to severely eroded stretches of beach (Thompson, 2010). However, the problem is now so bad that access to the beach’s amenities at high tide is virtually impossible, highlighting the need for ‘dry sand’ as the major problem for the community of Orewa. How could this issue be explored in a way that focuses on the erosive energy, from Orewa’s coastal dynamic forces, to be used in ways that assist the repair of this now damaged beach? How can the idea of enhancing Orewa’s Beach experience be explored through the means of artificial environmental infrastructure?
Coastal “landscapes are shifting, living material phenomena that demand an attitude of negotiation.” To befit “the temporality, uncertainty, and complexity of a terrain between land and sea,” proposals should be “conceived as seeds” that evolve in harmony with the transforming coastline (Mathur & Cunha, 2009). It is with this idea that I have focused on designing with the existing coastal forces rather than defending against it. By implementing adaption, protection and retreating techniques to Orewa’s specific problems, I have dissolved the idea of hard infrastructure like sea walls and groynes while keeping their function of preserving the beach.
After discovering that the destroyed reef was “likely the largest factor contributing to a lack of high tide beach at Orewa”, I proposed to mimic the original shape and form of the Waitemata Reef to help enhance the resilience and future health of Orewa Beach (Dr. S. Mead, personal communication, October 18 2014). With a final replenishment of Orewa beach sand, to gain the ideal beach profile, this intervention could then be introduced to protect and adapt the way the beach will work in future years.
Splitting the beach into 2 separate systems could also ensure an efficient beach comeback. The idea of a divide is inspired by the natural formations of off shore islands/reefs. The potential to produce a salient formation on the beach side of its location will ensure a consistent area of ‘dry beach’ both before and after storms. Dividing the beach with a recreational island means that the recycling current from the estuary can be concentrated at the south end while the cove like formation of the north end significantly reduces the amount of sand being eroded from the shore.
Other strategic moves could include; the design of an off shore kelp farm which will enhance the degrading marine biodiversity of the Hauraki Gulf. During storm events, the presence of this structure will disturb the frequency of short period storm swells before they reach land and a percentage of kelp will be pushed ashore, with the easterly current, providing organic material for the reclaiming of land inside Orewa’s estuary.
The idea of reclaiming land to prevent inundation, as the Dutch have done in the past, is an efficient way to adapt the landscape with the rise and fall of tides while taking advantage of organic material found in the coastal transition zone.
Elongated beach access points allow for a controlled build up of sand through out the length of the beach. The outcomes are wider ‘dry beach’ spaces and easier beach access.
After understanding the reasons for the failure of previous beach front walk ways, rib like structures could be positioned to fragile areas of the coastal margin which will prevent sand moving into the intertidal zone and entering the sediment train. The idea of weaving this material into the landscape will help to eliminate direct foot traffic on the dunes while providing unique walking paths and new look out points for the public.
A retreat approach to this edge can also be applied that will focus on maintaining the shape and size of certain stretches of land along the coast while allowing the neighboring landscapes erode naturally. The outcome of this intervention will, over time, reveal several mini pocket/cove like spaces along the length of Orewa Beach promoting a controlled change.
The ten storm water pipes that exit directly on to the main beach will be daylighted to take the shape of natural streams. The ponding and meandering lines of the streams will help to shape the build up of sand for larger amounts of ‘dry beach’ while providing exits to flooding water during heavy rainfall.
“Orewa Beach is of key importance to the Orewa community both in terms of its aesthetic and recreational value to the community and in terms of the economic wellbeing of the Orewa business community that depends on the attractiveness of the beach for the visitor traffic that provides a significant part of their business turnover” (Auckland Council, 2010). Speculation around the social outcomes of the future beach reveals a dramatic change to the ‘kiwi beach experience’. By bring to life a series of soft environmental interventions “to safeguard the integrity, form, functioning and resilience of the coastal environment,” the ‘kiwi beach experience’ will be enhanced in ways that allow for stronger connections with every element of the coast (New Zealand Coastal Policy Statement, 2010). Using adaptation, protection and retreat techniques, that have combined yet balanced outcomes in terms of the cultural, commercial and social factors will continue the summer time beach migration we all know and love. Without this, Orewa could soon become a place that people go to, not for walks on the long white sandy beach, but for an exploration through ruins of beachfront properties littered throughout the eroded foreshore…