Bright sparks: The colourful pageantry (and burnt effigies) of Valencia's St Joseph's Day

Those dresses – frilly, corseted, handmade confections that are impossible for the girls to wrestle themselves into without help – can cost up to €8,000. Then there are the side orders of elaborate jewellery, sashes and Princess Leia-style hairdos. They are worn during Falles, a centuries-old traditional celebration in the Spanish region of Valencia. The other main attractions of the festivities are enormous wooden structures that cartoonishly mock society's ills, which are burnt in the streets. These constructions – also termed falles – can be 30m high and take a year to build. Yet they go up in smoke in a matter of minutes.

Anna Huix, a photographer from the neighbouring region of Catalonia, was drawn to document the festival partly because she thought it was, to put it bluntly, crazy. "To me, it's insane: how they dress, the money they spend, that they spend a whole year building these structures and then" – she snaps her fingers – "they just burn them. If you think about it rationally, it doesn't make any sense. You need to find another explanation which is not rational at all."

The tradition stretches back far into the region's past. Different groups, or fallera, are made up of families who have been part of the celebration for generations. Over the course of three months, each fallera is introduced to society, going out on to the streets in their elaborate costumes, toting their own, unique wooden structure. Then, on 19 March, St Joseph's Day – the patron saint of carpenters – all the falles are set alight. Think May Day meets Guy Fawkes: as if all the different carnival floats are torched, while a host of pretty May Queens watch.

"Traditionally, people would put old furniture in the streets and would burn it once a year so bad spirits would go away," explains Huix. "Of course, they don't believe this any more, so they make these massive structures and have a theme, criticising something in society. The idea is the same – it's getting rid of bad spirits – it's just that now it's a metaphor." Popular choices for falles include corrupt politicians with their hands in the city's coffers. All that effort – for the structures and the carnival element of dressing up – is released in the final burning, producing a powerful catharsis.

It is a female-centric festival: the women are the peacocks here, decked out in finery, while men's costumes take their cues from the ladies. Though women of all ages get dressed in the colourful, frothy dresses, Huix chose to train her lens on just young girls, as they will be the next generation to continue the tradition. But will they want to?

As far as anecdotal evidence goes, the answer is yes: the little girls, says the photographer, get very excited indeed, and she recalls seeing them crying as their falles burned. She asked one mother why, and the reply came that they were weeping because they knew they are not going to be able to have such fun until the same time the following year.

But not everyone likes Falles. For some the carnival aspect of the festival is seen as backwards; the dresses and comically grotesque structures are naff. It's deemed unsafe (there have been deaths from fire-related injuries), and the amount of noise and smoke the activity produces is a disturbance (each falle is introduced with armfuls of firecrackers, and the whole day is doused in plenty of booze). Plus, it's expensive – perhaps the strongest complaint, in a country in the depths of recession, is that Falles is a waste of money.

"A lot of the arguments against it are, 'Why are we spending this much money?' Because this is a massive industry, it's a lot of money," says Huix. "At the same time, for the people who dress like this and build these falles, it's not frivolous – it's their tradition. For them, it's beyond money. It's part of who they are."

For more from the photographer, visit annahuix.com