Coastal erosion at Haumoana is made worse by gravel extraction by Winstones at Awatoto, according to a report before the Hawke's Bay Regional Council.
The coastal settlement suffered severe coastal erosion last month and in April 2002, with houses being inundated or destroyed by waves on both occasions.
The report, by Tonkin and Taylor coastal engineer Richard Reinen-Hamill, says the beach between Cape Kidnappers and Napier is losing about 45,000 cubic metres of gravel a year to erosion.
Most of that was going to Winstones, which takes gravel from the foreshore at Awatoto.
Winstones takes about 47,800cu.m. a year from Awatoto and Napier City Council and the regional council take about 12,800cu m from Pacific Beach (for renourishment at Westshore), meaning about 15,600 cu.m. of gravel is being supplied to the coast from the Tukituki River and erosion of Cape Kidnappers.
Scientific modelling shows "the effect of gravel extraction at Awatoto does extend to the south, potentially as far as Haumoana, but certainly to a point between the Ngaruroro outlet and the Hastings (sewage) outfall," the report says.
The findings will be welcome news to those Haumoana residents who last year opposed a resource consent application by Winstones to continue extracting 50,000 cu m of gravel a year from Awatoto.
The Hawke's Bay Regional Council granted consent for just 30,000 cu.m a year - a decision that has been appealed by Winstones. The matter goes before the Environment Court in Napier on May 3.
The report suggests that only between 24,400cu m and 48,000cu m should be taken from Awatoto and Pacific Beach - a view that Winstones will surely contest in court.
The regional council environmental manager Murray Buchanan said the council always suspected that gravel extraction from Awatoto was having an effect at Haumoana.
"The council has always known there was a grain of truth in the concept, but proving it was a difficult kettle of fish," Mr Buchanan said.
The report states that groynes do work on the coast, but may prevent gravel supply to the north.
It also states that renourishment of the beach "may provide a solution".
Mr Buchanan, however, said the cost of renourishment - up $500,000 - made it an unlikely solution.
"Hastings District Council and the regional council will have to work through all options on this coast," he said.
"We believe we have a sound argument and if the court wanted to reduce the length of consent then council would accept that quite happily," Mr Buchanan said.
The report, to be discussed by regional councillors tomorrow, has been peer reviewed by coastal expert professor Paul Komar.