By Anastasia Moloney
BOGOTA, March 23 (Thomson Reuters Foundation) - Peru's deadly floods are a wake-up call for cities across Latin America to prepare better for extreme weather as climate change and poor urban planning, alongside rapid population growth, worsen the problem of flooding, experts say.
In Peru, the worst downpours in decades have triggered floods and landslides, killing at least 78 people and making around 70,000 homeless. The government has declared a state of emergency.
The disaster has highlighted the heavy human toll and economic damage floods bring, raising questions over how well prepared the region is to deal with disasters.
"The issue of disaster risk prevention still isn't a priority for many governments in Latin America. There's a long way to go," said Mauro Nalesso, lead water specialist at the Inter-American Development Bank (IDB).
"It seems that we are always waiting for the lessons learnt from the last disaster. I always hope (it) will raise alarm bells among governments in Latin America," he told the Thomson Reuters Foundation in a telephone interview.
Climate change is expected to bring more frequent and intense floods, droughts and storms, making a deeper understanding of the way climate change affects local weather patterns crucial, experts say.
Meanwhile, surging urban populations across cities in Latin America - a result of mass migration from rural to urban areas in recent decades - make them vulnerable to floods.
"Urban flooding is a big issue in Latin America," said Niels Holm-Nielsen, regional coordinator for disaster risk management at the World Bank. "High population growth in cities and inadequate territorial planning contribute to flood risks."
Drainage and sewage systems have often failed to keep up with exploding populations and sprawling urban slums, he said.
Torrential downpours can leave cities from Port-au-Prince to Rio de Janeiro with collapsed drains that lead to rivers of water running through city streets.
Investment is needed to unblock and maintain often outdated city drainage systems, along with ensuring rubbish is collected to prevent drains getting clogged up.
But Holm-Nielsen said how much governments are spending on disaster prevention "is still not well understood" - and is part of the problem.
In Colombia, for example, a March government survey of 14.4 million households across the country showed that nearly a quarter of all homes are not connected to a sewage system.
Some elected officials are reluctant to invest in flood prevention measures because they are largely intangible for city residents, in the way new schools or hospitals are not.
"Infrastructure projects for flood risk mitigation aren't clearly visible," the IDB's Nalesso said. "We're taking about public works that are expensive and carried out over the long term. There are always other priorities."
Basic protection, including early warning systems to evacuate people in time and mapping of flood-plain areas, is still lacking in parts of Latin America, Nalesso added.
Floods are most acutely felt by Latin America's poor.
Tens of millions of people live in the region's urban slums, often built along river banks and on precarious slopes prone to flooding and landslides triggered by heavy rains.
In some countries in Latin America, more than 60 percent of housing is informal, which tends to have lower structural quality, the World Bank's Holm-Nielsen noted.
Preventing the construction of new settlements in precarious locations must be a priority, along with resettling people away from flood-prone areas, experts say.
In Peru about half a million people live on flood plains, according to a recent report by state water agency ANA.
U.S.-based environmental group Forest Trends urges governments to look beyond traditional flood prevention like building dams, dikes and concrete walls along river banks, and consider protecting watersheds surrounding cities.
As forests and wetlands have been cleared in the past century to make way for cities and farmland, land has been degraded and soil eroded. This in turn reduces the ability of soil to retain water, making cities more vulnerable to flooding.
"It's a wake-up call to look beyond traditional measures," said Gena Gammie, associate director of Forest Trends' water initiative, speaking of the recent Peru floods.
"We need to be smarter about reducing our vulnerability to destructive weather events."
Protecting and restoring degraded ecosystems around cities, including forests, grasslands and wetlands, can help contain floods because they collect and store water.
These ecosystems absorb water in the rainy season and slowly release it into streams and rivers during the dry season.
"Watersheds act like sponges," Gammie said. "Green infrastructure - which is any intervention aimed to protect or enhance healthy watersheds - can help build resilience."
(Reporting by Anastasia Moloney @anastasiabogota, editing by Megan Rowling; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)
The Thomson Reuters Foundation is reporting on resilience as part of its work on zilient.org, an online platform building a global network of people interested in resilience, in partnership with the Rockefeller Foundation.