Mud in the streets of Funchal: the Madeira floods of 20 February 2010

It had been raining since before dawn. Between 8.50 and 9.50 on the morning of Saturday 20 February 2010, the weather station at the Funchal observatory caught 51.3 millimetres of rain, a rate expected there perhaps once a century. Up in the mountains above the city, the gauge at Areeiro took 78.5 millimetres in the same hour, and by 11 o'clock 111.5 millimetres had fallen on the observatory in six hours.2 sources2 sources

The three streams that run through the centre of Funchal, the Ribeira de São João, the Ribeira de Santa Luzia and the Ribeira de João Gomes, filled with a brown slurry of water, mud and rock. The João Gomes tore a pump out of a petrol station and carried a large fuel tank through the lower town. The São João burst out of its channel beside the Dolce Vita shopping centre, and the marina at its mouth filled with wreckage.2 sources2 sources

In Rua Pedro José de Ornelas, known as Rua da Pena, water pouring down from the Estrada Luso-Brasileira turned the street into a stream, and several people were swept away and killed, among them a child. Police evacuated buildings in Rua Dr. Fernão de Ornelas in the city centre. On the other side of Funchal, in the high valley of Curral das Freiras, the only road out was damaged and the village was cut off.3 sources3 sources

West of Funchal, the Ribeira Brava valley took the second core of the storm. In the parish of Serra de Água, houses and cars were swept away, and the town of Ribeira Brava at the mouth of the valley was flooded. When Funchal's Diário de Notícias went to press that night, it counted 32 dead, 101 injured and 250 people driven from their homes.4 sources4 sources

Madeira is a volcanic island of 740.7 square kilometres in the subtropical Atlantic, and with Porto Santo it forms an autonomous region of Portugal. Its mountains rise to 1,861 metres at Pico Ruivo and run east to west, so the moist north-easterly winds hit them almost head on. At the 2011 census the region had about 267,000 people, most of them on Madeira's south coast in and around Funchal, one of Europe's earliest tourist destinations.3 sources3 sources

The streams of the south coast are short and steep. The five basins that did the damage in 2010 cover between 8.8 and 15.6 square kilometres each, except the Ribeira Brava at 40.9, with average slopes of 25 to 37 degrees. The risk study estimated that rain falling on their headwaters reaches the sea in little more than an hour. In summer their beds are dry and full of loose boulders waiting for the next flood to move them.3 sources3 sources

The island's history is full of them. The worst on record came on 9 October 1803, when between 800 and 1,000 people died, most of them in Funchal. After it the military engineer Reinaldo Oudinot channelled the city's streams between stone walls, work carried out from 1804 to 1806. Aluviões kept coming in the two centuries that followed, but none was as severe as the one of 2010.3 sources3 sources

The storm fell on ground that was already soaked. From 1 October 2009 to the end of February 2010 the Funchal observatory recorded 1,016.6 millimetres of rain, against an average of 426.4 for those five months. The rain of January and February alone came to about 90 per cent of a normal year.1 source1 source

February was the extreme. Its 458.7 millimetres made it the wettest February in Funchal since records began in 1865. In the mountains the numbers were larger still: the Areeiro gauge, at 1,590 metres, collected more than 4,000 millimetres between October and February, the wettest such season there since 1937.3 sources3 sources

There had been warnings. On 22 December 2009 an aluvião destroyed roads and houses at Madalena do Mar and São Vicente. On 2 February 2010 Funchal took 129.8 millimetres in a day, its wettest February day since daily records there began in 1949, and a stream at Faial on the north coast flooded. Scientists later wrote that the winter's rain had saturated the soil and loaded the slopes with loose material before the storm of the 20th arrived.3 sources3 sources

The cause lay far to the north. That winter the North Atlantic Oscillation, the seesaw of air pressure between Iceland and the Azores, was in a record negative phase. That pushes the track of Atlantic storms south, and it brought low after low across Madeira and southern Iberia.1 source1 source

At midnight on the 20th a deep depression sat near the Azores, with its fronts trailing south into the subtropics. As they moved east, a plume of warm, wet air, probably of tropical origin, was driven onto Madeira by south-westerly winds of up to 30 metres a second at mountain height. The island lay under the point where the fronts met, and great towers of cloud built over it.2 sources2 sources

The weather balloon launched from Funchal at midday showed how much water the air held. The precipitable water, the depth of rain the column of air would give if all its vapour fell, had risen from 13.4 millimetres the day before to 37.0, and it stayed that high even after hours of downpour. Madeira had no weather radar in 2010, so forecasters could not watch the storm cells as they crossed the island.1 source1 source

Rain gauges a few kilometres apart told different stories. Over half the island had more than 250 millimetres that day, with two cores of 250 to 370 millimetres: one over the high plateau of Areeiro, at the head of Funchal's streams, and the other over Paúl da Serra and Encumeada, at the head of the Ribeira Brava. Funchal sat inside a crescent of the heaviest rain.1 source1 source

Statistically it was an extreme day, especially low down. Fragoso and colleagues put the return period of Funchal's daily total at about 290 years and that of Areeiro at about 90, while warning that such long return periods rest on only some 70 years of records. The risk study, working from the observatory's shorter hourly records, put Funchal's six- to twelve-hour totals at about a 1,000-year event.2 sources2 sources

By Fragoso's count, about 80 per cent of Funchal's rain fell in six hours, and the 114.8 millimetres of that spell beat the highest six-hour total of 1980 to 2009, 92.6 millimetres on 27 September 1989.1 source1 source

Rain alone would have flooded the streets. What made the day so deadly was the rock. A survey from satellite images and fieldwork found 3,291 landslides in the Funchal basins and about 5,170 in the Ribeira Brava area, most of them high up in the basins. Together they fed soil, stones and trees into stream beds that already held loose material, which the flood also picked up.2 sources2 sources

The streams carried blocks of 10 to 15 tonnes from above 800 metres down to the city centre; the water in these floods can reach 60 to 80 kilometres an hour, according to researchers from the University of Aveiro. A model of the Ribeira de São João by the risk study team showed a steep front of debris moving downstream at an average of 2.6 metres a second, dropping its load wherever a narrowing of the channel slowed it down.2 sources2 sources

When the water drained away, central Funchal was buried. Clearing the streets and the lower stream channels produced about 140,000 cubic metres of fill, which was dumped by the city's wharf, and about 100,000 more were dredged from the port. The finest mud washed out to sea. The risk study and Lira and colleagues estimate that at least 250,000 cubic metres of sediment came to rest in Funchal alone; the regional government later put the material left in the city's channels and streets at up to 390,000.3 sources3 sources

The Ribeira Brava was hit just as hard. It had the biggest peak flow of the five basins studied, and the volume of slope material that slid into its streams was put at between 605,000 and 984,000 cubic metres, against 217,000 to 344,000 for the three Funchal basins.2 sources2 sources

The count rose for days. By Monday 22 February it stood at 42. Telephone lines had been cut, and Francisco Ramos, the regional secretary for social affairs, said that 85 people reported missing had turned up at home; they had simply been unable to reach their families. The government in Lisbon sent three diving teams, 43 doctors, a group of firefighters and a navy frigate.2 sources2 sources

There is still no single final figure. Two scientific studies, published in 2012 and 2013, give 45 dead, 22 of them in Funchal, and 6 missing. Correio da Manhã, reporting the close of the criminal inquiry in April 2011, gave 48 dead and 7 missing. On the tenth anniversary the Lusa news agency gave 47 dead and 4 missing, the figures the Diário de Notícias also uses. The usual figures for the injured and the homeless are about 250 and about 600.5 sources5 sources

Fragoso and colleagues called it the deadliest weather disaster in Portuguese territory in four decades. The flash floods around Lisbon in November 1967 had killed 462 people by the official count, and more than 500 by later scientific estimates. The Public Prosecutor's Office closed its inquiry into the deaths in April 2011. Francisco Ramos called the decision the end of a painful process for the families.4 sources4 sources

The government in Lisbon treated the disaster as a national emergency. On 15 March 2010 it set up a joint commission with the regional government to count the cost, and in April the commission put the damage at €1,080 million, or about 0.68 per cent of Portugal's gross national income. The international disaster database EM-DAT gives US$1.9 billion.3 sources3 sources

The largest share, 45 per cent, was for the streams themselves: about 130 kilometres of watercourses had to be cleared and repaired, 26 main streams and 250 smaller ones. Some 153 bridges were damaged, 66 of them in Funchal. About 3,100 farms suffered losses, and around 800 houses were damaged, 400 of them destroyed, partly destroyed or left structurally unsound.1 source1 source

A special funding law followed, Organic Law 2/2010 of 16 June, known as the Lei de Meios. It gave Madeira €740 million over four years to the end of 2013: €200 million from the state budget, €265 million from the EU Cohesion Fund, a €250 million loan from the European Investment Bank and €25 million from the central investment programme. The remaining €340 million was to come from the regional and municipal budgets, EU regional programmes and private money.2 sources2 sources

Portugal also applied to the EU Solidarity Fund on 20 April 2010, and on 5 April 2011 it was awarded €31.255 million. The money came slowly at first: by the end of 2010 the region had received €191.3 million under the Lei de Meios and paid out €56.3 million.2 sources2 sources

Ten years on, the regional government said it had spent €631 million: €556.3 million on reconstruction and protection works, €43.1 million on businesses and farms and €31.6 million on housing. About 1,200 households whose homes were hit had received help, and the regional housing company had rehoused 198 families and steered 220 more towards repairing their own homes. Six households were still waiting for a permanent solution.1 source1 source

Five weeks after the floods, three researchers from the University of Aveiro, the geological engineer João Baptista Pereira Silva, the mining engineer Fernando Ernesto Almeida and the geologist Celso Gomes, set out their case in Funchal's Diário de Notícias. Of the 22 aluviões of the twentieth century, they noted, 13 had come since 1970. They suggested three possible reasons: a changing climate, more ground sealed under concrete and asphalt, and the occupation and narrowing of the stream beds.1 source1 source

Their list of what stood on the banks and flood plains of Funchal's streams was long: businesses, sports grounds, health centres, fire stations, electricity substations, bus depots, waste plants, family homes and blocks of social housing.1 source1 source

Until the 1940s, they wrote, the lower Ribeira de São João ran in the open to the beach at São Lázaro. It was then closed in and narrowed step by step: by the Infante roundabout, the marina wall, new apartment and office blocks and, most recently, the foundations of the Funchal Centrum, the building of the Dolce Vita shopping centre. On 20 February the stream overflowed on the stretch between that building and the marina.1 source1 source

They also blamed the deep basements dug under the old town for car parks and stores, in some cases 30 metres deep. These flooded on the 20th, and at the Anadia shopping centre 50 million litres of water had to be pumped out of the car park. In 2006 the same team had published a study of these underground works, and they wrote that about 90 per cent of the risk situations it had identified came about in the floods.1 source1 source

The regional government asked the Instituto Superior Técnico in Lisbon, the University of Madeira and the regional engineering laboratory for a risk study, known by its Portuguese initials as EARAM. Carried out from May to December 2010, it proposed works to hold back solid material in the headwaters, to catch boulders in barriers above the towns, to clear obstructions from the channels through them and to control what could be built near the streams. Homes on slopes where the risk was intolerable, it said, should be removed.2 sources2 sources

What was built afterwards leaned heavily on engineering. A 2015 review for the regional climate strategy listed several dozen protection works finished, under way or planned since February 2010; 40 of them were works on stream channels, against 11 to stabilise slopes and 3 to hold back sediment. Four boulder barriers went up on each of Funchal's three main streams, twelve in all, which the regional government says can hold back about 64 per cent of the material that reached the city in 2010. A weather radar now stands on Porto Santo.3 sources3 sources

Planning moved more slowly. The first flood risk management plan, drawn up in 2016, listed 27 critical zones in ten municipalities of Madeira and in Porto Santo. Oliveira wrote in 2020 that its rules still had to be made to work in the licensing of new buildings. Reforestation of the mountains is part of the strategy too, though he notes that large trees can do damage and block channels when a flood carries them off.1 source1 source

The argument has not ended. In October 2020 the geological engineer João Baptista warned that the Ribeira de Santa Luzia and the Ribeira Grande de Santo António were still too narrow, and that what happened at Serra de Água in 2010 could happen in the capital. The regional infrastructure department replied that it respected the researchers but stood by a strategy followed since 2010.1 source1 source

In Madeira the disaster is often called simply the 20 de Fevereiro. The barriers above Funchal, the rebuilt channels and the weather radar on Porto Santo all came out of it, and so did a long effort to spread a civil protection culture across the population.3 sources3 sources

The scientists who studied the storm stress that the conditions behind it are part of the island itself: short, steep valleys, loose rock and rain that can come in bursts of 100 millimetres an hour. Engineering can catch boulders and widen channels, but where homes stand in the flood path, the risk remains. The risk study said as much in 2010, and Oliveira said it again ten years later.2 sources2 sources