In December 2009, a late-afternoon storm unleashed torrential rain over Ayacucho, Peru, hitting poor hillside neighbourhoods hard. The deluge overwhelmed drainage systems, turning streams into lethal flows of mud, stones, and debris that flooded houses and streets, trapping drivers at a busy junction. Ten people died, 18 were injured, and 530 houses were destroyed or damaged, according to a government inquest. "It was a disaster," recalls Edgar Castro, a leader in Ayacucho's largest informal neighbourhood, Mollepata.
Nearly 17 years on, thousands more have built houses in areas at high risk of extreme weather on the outskirts of Ayacucho. Castro, who lives with the threat of history repeating itself, represents 34 community groups working with local government to bring these areas—starting with Mollepata—into the fold of urban planning.
Growing Vulnerability in Informal Settlements
Throughout Latin America, one in five people live in unplanned settlements built haphazardly, often in high-risk zones for flooding, landslides, or drought. These areas are inherently more vulnerable to natural disasters worsened by the climate crisis. "As extreme weather events become more frequent, the urban poor are simultaneously exposed to temperature extremes and least equipped to manage them," says Cynthia Goytia, professor of urban economics at Torcuato Di Tella University in Buenos Aires.
Mollepata is a telling example. Self-built adobe or brick houses with corrugated metal roofs balance precariously on steep slopes bordering the road from Ayacucho's centre. What starts as a paved road soon turns into a dusty, pothole-ridden path. Until the early 2000s, few people lived here. But as property prices soared, new arrivals occupied former grazing land on the city's rural outskirts. This grew into Mollepata, where people crowd into informal dwellings at about seven times the density of Ayacucho itself.
Between 2007 and 2017, Mollepata's population increased 20-fold, from 316 to 6,624, according to Ayacucho authorities, who estimate it will reach 17,000 by 2027. Yet residents say official data bears little relation to reality. "Mollepata has more than 30,000 inhabitants if you count kids, adults, and old people," says Castro, adding that they live "in a no-man's land."
Extreme Weather and Water Scarcity
Two-thirds of Mollepata's population and all its schools are in areas deemed high-risk for natural disasters. The neighbourhood is just one of several whose rapid growth aggravates the risk of extreme weather disasters for both the settlements and Ayacucho as a whole. Ayacucho lies in the heart of the Peruvian Andes, where annual rainfall has halved since 1984. The local glacial peak has lost 95% of its snowcap. For city dwellers, this means shorter, less predictable rainy seasons. Rainfall now comes in short, increasingly intense storms that cause floods and landslides. The rest of the time, people face severe water shortages and soaring temperatures, made worse by concrete structures that trap heat. Poorly constructed dwellings in informal settlements are worse still, with inadequate ventilation and inefficient cooling systems. This way of building turns whole neighbourhoods into "little ovens," says Juan Carlos Prado, an environmental specialist working for the municipality.
Lack of Services and Relocation Challenges
The informal neighbourhoods at highest risk also tend to be the most underserved. They lack reliable water systems and accessible emergency or medical services—so when a catastrophe hits, they are the least prepared to respond. Many rely on just one unpaved access road; a single bridge connects Mollepata to the rest of Ayacucho. "If that collapses, they're isolated in an instant," Prado says. With this in mind, the municipality runs education campaigns, but Castro says many people "still don't take these consequences into account."
According to experts, the only solution for those in risky terrain is to move. "We can't negotiate with nature. We can't get in the way of the rivers," Prado says, though he doesn't know a single case in which people voluntarily abandoned their plots. "Families make calculated trade-offs between affordability, proximity to livelihoods, and existing social networks, often accepting elevated environmental risk as the price of urban access," says Goytia. The city has no money for relocation programmes. "They say to us, 'Where can I go?' 'Where do you want me to live?' 'Solve it for me,'" Prado says. "But what solutions can we give? The only thing we can say is, 'Try to find another place because you are too exposed.'"
Efforts Toward Integration and Upgrading
In 2025, Ayacucho's municipal government published a plan to improve public services, structure private and public land, and establish measures to manage disaster risks. Since then, it has begun meeting association leaders to bridge the gap between plans drawn up in municipal offices and reality on the ground. The climate crisis is making the environment more arid and the dirt road dustier, damaging people's health and quality of life. By grading and compacting the main road, officials hope to minimise dust and improve access to Ayacucho, where most emergency services are concentrated. Drainage ditches will be built to mitigate flash flood risks. Yet retrofitting comes with challenges. Because of existing irregular water infrastructure under the road, the drainage ditches must be shallow. While the government will provide machinery, local people must remove debris and guide the machines, as only they know where underground tubes run.
Mollepata's community leaders seem more than ready to meet these demands, promising to rent a dump truck and coordinate volunteer groups. They also discuss the need to increase green areas, vital to mitigating the urban heat-island effect. The town official in charge of reforestation promises to provide tree seedlings in the rainy season. There is even land set aside for a park.
Financial and Social Hurdles
"Over the past four decades, Latin American governments have largely moved away from demolition and forced eviction toward formalisation, regularisation, and comprehensive neighbourhood upgrading programmes," Goytia says. But the efforts in Mollepata demonstrate how challenging this policy shift can be given local governments' resource constraints. Integrating Mollepata into the city will cost more than 530 million soles (about £116 million), almost five times Ayacucho's municipal annual budget. A shorter list of high-priority projects would still cost 460 million soles. For local people, issues such as insecurity, lack of transport, and rubbish disposal are often more urgent than water shortages, floods, and avalanches. While authorities and established residents work to integrate Mollepata, new settlements are emerging as rural Peruvians seek footholds there. With most relatively safe areas already built up, recent years have seen a sharp increase in building on steep slopes, ravines, and riverbanks. "The situation is becoming critical," Prado says.
Still, in Mollepata, local people and municipal workers strike a hopeful tone. Castro sees the approval of his settlement plan as a great achievement and lauds officials for travelling to the settlement to meet the people. "By getting their boots dirty," Castro says, "they see how we live here and the situation we are in."
