Tourism peaks and troughs a challenge for disaster planning
On tourism's busiest day in 2016 the number of overseas visitors in New Zealand was almost equivalent to the population of Christchurch.
Statistics New Zealand (SNZ) said the peak of 354,000 visitors here on short term trips of less than 12 months was on December 29, a significant rise when compared with the 191,000 peak in 2000.
The lowest number of visitors on a single day was 112,000 and occurred on August 31.
SNZ said the peak reflected the upsurge in people visiting friends and family, or taking summer holidays.
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Many were Kiwis living overseas, and of the 99,000 New Zealand citizen visitors arriving in December, three-quarters were living in Australia.
Seasonal fluctuations also showed up in locals' travel habits.
The number of New Zealand residents temporarily overseas in 2016 ranged from 72,000 on March 1 to 235,000 on December 29. Peaks tended to coincide with school holidays.
SNZ said knowing how many tourists were in New Zealand on any given day was important for Civil Defence or flu pandemic planning, but it also had implications for transport, accommodation, and tourist activities.
Lincoln University tourism professor David Simmons agreed but he said that as well as monitoring tourist numbers, we needed more information about their travel patterns.
Such data was vital when it came to managing disasters or disease outbreaks, as was illustrated by the Kaikoura earthquake which trapped 1200 tourists and 300 rental vehicles, he said.
"Imagine if [the earthquake] had happened 12 hours earlier in the middle of the day when people were not nearly as tightly located around Kaikoura township.
"They would have been distributed along the road and we wouldn't have known where they were given the amount of rubble".
Simmons said we had to stop thinking of tourists as "walking wallets" and consider the risks they might be exposed to.
If the South Island's alpine fault ruptured, Civil Defence would need an accurate picture of who was in the area.
"There may be 30,000 people normally resident on the West Coast but would there be 12,000 or 15,000 visitors there at peak time? That's the problem.
"If you think of tourists as disease vectors, whether its animal, or plant or human bio security [risks], then the big call is for a much better model for understanding tourism flows".
Knowing how long tourists stayed in each place and their travel routes was also important for apportioning spending on visitor infrastructure, Simmons said.