The sand used for renourishment of Buffalo Beach used to be on the beach itself - thousands of years ago.
Environment Waikato coastal scientist Rick Liefting said the sand had become much darker than the current beach sands because it had been buried for thousands of years and saturated with ground water, but it would become a similar colour once dry.
Around 6,500 years ago the sea rose to its current level. Since then Buffalo Beach has been progressively building out to form the shoreline we see today. As the sand for renourishment was once part of Buffalo Beach it’s an ideal source for renourishing today's Buffalo Beach. The age of the sand on Buffalo Beach today may also be up to 6,500 years.”
He said analysis of both the beach sand and the sand from thousands of years ago had shown that they were very compatible.
“Beaches are a highly valued and used resource in the Waikato Region and throughout the country. Beach nourishment is a popular method to remedy the effects of coastal erosion while also allowing the public to enjoy a greater amount of high tide beach. It has been used extensively world wide and on other beaches around New Zealand successfully.”
He said that while this method was only viable for certain situations, placing sand in front of the seawall along Buffalo Beach was appropriate to remedy the loss of sand associated with the beach’s seawall and was part of the seawall’s consent conditions.
“For beach renourishment to succeed, it is very important for the sand to be comparable with the existing beach sand. We analyse sand characteristics such as grain size and density, shell content, colour and the amount of fine sediments within the sand to compare the existing beach sand with sand proposed for renourishment.”
“Normally such beach renourishment projects are hugely expensive as finding suitable sand is expensive. We’re lucky that suitable sand is available on Whitianga's door step from the excavations of the Whitianga Waterways and we should take advantage of this by using as much as possible.”
The supply of sand for beach nourishment is part of the Whitianga Waterways consent conditions imposed by Environment Waikato.
“Once the sand is in place and has been contoured, the beach profile will change so that there will be more beach available at high tide, allowing greater access. As the new sand will be prone to the same processes affecting the rest of Buffalo Beach it may not stay in place and may move offshore or along shore to the south,” he said.
If the sand moved off shore below the low tide mark, it would move back to supply sand to the visible beach over time. The 10,000 cubic metres of sand used for the renourishment is less than one percent of the total Buffalo Beach system and effects, if any, would be extremely minor.
“Any animals that live in this environment are used to sand being deposited and taken away, especially during storm events. As much of the nutrients that the animals live on is sourced from sea water and not the sand itself there should be little adverse effects on the animals that live in the beach environment. “