I was reflecting on the saying that “ignorance is bliss” as our plane was landing in Tuvalu, a small island nation in the South Pacific. We had been advised that portions of the recent runway resealing was failing in a number of locations, but it was the video below—showing the runway ‘floating’ under the weight of someone walking on it—that was particularly disconcerting. Runways are supposed to be solid!
Tuvalu has regularly been called the ‘canary in the coal mine’ when it comes to climate change. The country is comprised of three reef islands and six coral atolls. With the maximum elevation of 3-4 m, and sea level rise of some 5 mm/year, it is already at a risk of a range of climate change challenges. Now we have a new one: runway failure from beneath caused by what appears to be a combination of very high (‘king’) tides and increased rainfall.
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The rains in northern Peru have been 10 times stronger than usual this year, leading to floods, landslides and a declaration of a state of emergency in 10 regions in the country. Together with the human and economic toll, these downpours have inflicted tremendous damage to transport infrastructure with added and serious consequences on people’s lives.
These heavy rains are blamed on El Niño, a natural phenomenon characterized by an unusual warming of the sea surface temperature in the central and eastern equatorial Pacific Ocean. This phenomenon occurs every two to seven years, and lasts about 18 months at a time. El Niño significantly disrupts precipitation and wind patterns, giving rise to extreme weather events around the planet.
In Peru, this translates into rising temperatures along the north coast and intense rainfall, typically shortly before Christmas. That’s also when “huaicos” appear. “Huaico,” a word that comes from the Quechua language (wayq’u), refers to the enormous masses of mud and rocks carried by torrential rains from the Andes into rivers, causing them to overflow. These mudslides result from a combination of several natural factors including heavy rains, steep slopes, scarce vegetation, to name a few. But human factors also come into play and exacerbate their impact. That includes, in particular, the construction of human settlements in flood-prone basins or the absence of a comprehensive approach to disaster risk management.
This year’s floods are said to be comparable to those caused by El Niño in 1997-1998, one of the largest natural disasters in recent history, which claimed the lives of 374 people and caused US$1.2 billion worth of damages (data provided by the Peruvian National Institute of Civil Defense).
Development professionals often complain about the absence of good-quality data in disaster-prone areas, which limits their ability to inform projects through quantitative models and detailed analysis.
Technological progress, however, is quickly creating new ways for governments and development agencies to overcome data scarcity. In Belize, the World Bank has partnered with the government to develop an innovative approach and inform climate-resilient road investments through the combination of creativity, on-the-ground experience, and strategic data collection.
Underdeveloped infrastructure, particularly in the transport sector, is a key constraint to disaster risk mitigation and economic growth in Belize. The road network is particularly vulnerable due to the lack of redundancy and exposure to natural hazards (mostly flooding). In the absence of alternative routes, any weather-related road closure can cut access and severely disrupt economic and social movement.
In 2012, the government made climate resilience one of their key policy priorities, and enlisted the World Bank’s help in developing a program to reduce climate vulnerability, with a specific focus on the road network. The institution answered the call and assembled a team of experts that brought a wide range of expertise, along with experience from other climate resilience interventions throughout the Caribbean. The program was supported by Africa, Caribbean and Pacific (ACP) European Union funds, managed by the Global Facility for Disaster Reduction and Recovery (GFDRR).
Our strategy to address data scarcity in Belize involves three successive, closely related steps.
In 2015, severe floods washed away a series of bridges in Mozambique’s Nampula province, leaving several small villages completely isolated. Breslau, a local engineer and one of our counterparts, knew that rebuilding those bridges would take months. Breslau took his motorbike and drove the length of the river to look for other roads, trails, or paths to help the villagers avoid months of isolation. He eventually found an old earth path that was quickly cleaned up and restored… After a few days, the villagers had an alternative to the destroyed bridge, reconnecting them to the rest of the network and the country.
What happened in the Nampula province perfectly illustrates how a single weather event can quickly paralyze transport connections, bringing communities and economies to a screeching halt. There are many more examples of this phenomenon, which affects both developing and developed countries. On March 30th, a section of the I-85 interstate collapsed in Atlanta, causing schools to close and forcing many people to work from home. In Peru, food prices increase in Lima when the carretera central is disrupted by landslides because agricultural products can’t be brought to market.
How can we help countries improve the resilience of their transport networks in a context of scarce resources and rising climate uncertainty?
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Bridges are critical links in the transport network. In their position across waterways, they are exposed to the full effects of flooding and landslides, and are often the first pieces of infrastructure to be damaged in the event of a disaster. They also typically take weeks or months to repair. Besides causing expensive damage to the infrastructure itself, disruptions in connectivity also have a much broader impact on economic productivity and people’s ability to access essential services. As many places are expected to witness more intense and frequent rainfall as a result of climate change, the risk to bridges will only worsen: more rainfall will lead to bigger river flows and more damage to bridges, especially those designed to handle smaller storms.
At each end of a bridges is a structure which supports the weight of the deck. These are known as abutments, and they are often the first part of the bridge to fail. Blockage of the main channel by debris can cause water to look for the path of least resistance around the sides of the bridges, thus placing the abutments at risk.
Traditional bridge construction requires the installation of piles for the foundations of abutments—a lengthy and expensive process that involves specialist materials, skills and equipment.
But there is another promising solution: Geosynthetic Reinforced Soil (GRS) abutments. These allow for rapid and resilient construction of bridge abutments using locally available materials, without specialized equipment. With GRS, bridges can be constructed in as little as five days (Von Handorf, 2013) and at a cost 30-50% lower than traditional approaches (Tonkin and Taylor, 2016) .
GRS abutments are based on ‘geogrids,’ a high density mesh made out of polyethylene (plastic). Layers of soil and geogrid are combined to create a solid foundation for the bridge deck. Construction can be completed with basic earthmoving and compaction equipment, and a range of local fill materials can be used with guidance from geotechnical specialists.