1. Data collected from the Papamoa Surf Club site, using Sand Datum Posts placed at the dune toe and at the zero level mark in June 2008. This placement has revealed the following globally-unique information, gathered exclusively where indigenous plant species have been utilised to restore natural dune function:
| ESTABLISHMENT DATES | DUNE DEPTH CHANGES to 2014 | DUNE WIDTH CHANGES to 2014 | DUNE VOLUME CHANGES to 2014 | CHANGES PER ANNUM |
| 1996 Planting: once only - as natural plant colonisation & proliferation ensued | 1996 – assessed as zero | +30metres (m) wide and continuing | Was not quantified originally – suitable instruments were not initially available |
Dune width growth +1.3m/year. This rate of gain continues |
| 2008 Datum Posts added, to quantify changes in sand depth + dune width, i.e. dune volume changes | 2008-2014: sand accretion 1.0m depth (recorded after 2008 datum post placement) | +12m seaward of the original datum post location, and still improving | >22m3/lineal m of beach following the original planting, this gain continues | Dune volume growth +1.8m3/year/lineal metre of beach, and this rate of gain continues |
Data collected from the above has been analysed and this information provided the data-set for a poster published for the ESRI Users Conference, San Diego 2015. Data from the above case study reveals that this dune restoration can completely off-set the impacts of +118cm of sea level rise through to year 2100.
2. Very similar results occur at the northern end of the Tauranga coastline; 12km distant at the popular beach resort town of Mount Maunganui. Here, the dune was restored in 2002, and sand datum posts were similarly installed in 2008, and the volume of accumulated sand recorded through to 2014.
| ESTABLISHMENT DATES | DUNE DEPTH CHANGES to 2014 | DUNE WIDTH CHANGES to 2014 | DUNE VOLUME CHANGES to 2014 | CHANGES PER ANNUM |
| 2002 Planting: once only - as natural plant colonisation & proliferation ensued | 2002 – assessed as zero | +20metres (m) wide and continuing | Was not quantified originally – suitable instruments were not initially available |
Dune width growth +1.6m/year. This rate of gain continues |
| 2008 Datum Posts added, to quantify changes in sand depth + dune width, i.e. dune volume changes | 2008-2014: sand accretion 0.7m depth (recorded after 2008 datum post placement) | +8m seaward of the original datum post location, and still improving | >14m3/lineal m of beach following the original planting, this gain continues | Dune volume growth +1.2m3 /year/lineal metre of beach, and this rate of gain continues |
NOTE: indications of similar improvements to beach processes and sand accretion have been observed at all other successful project sites in NZ. However, due to limited resources available at establishment, precise data was not recorded at these areas – however their photo-records show equally compelling results.