Retrofitting of existing housing stock has great potential to manage earthquake risk effectively
By Bernardo Cocco, Deputy Resident Representative, UNDP Nepal
The earthquake of 2015 claimed 9,000 lives and brought down more than 800,000 houses in 32 districts across Nepal. More than 70,000 houses were damaged alone in the Gorkha district alone, where UNDP has been working since on supporting an ambitious and innovative reconstruction program. Damage was not limited to the housing stock, of course. Hundreds of public buildings, community facilities, hospitals, roads and other infrastructure were also damaged, often beyond repair. The country’s GDP took a hit — a 3% reduction. Lives, and livelihoods, were lost across the country.
It is a matter of pride for us at UNDP in Nepal to have had the opportunity to partner with visionary government officials, international donors, and fellow UN actors on a vast reconstruction program. The Nepal Housing Reconstruction Project (NHRP), which has just been come to a successful completion in Gorkha and Nuwakot districts, was a cooperation with the Government of Nepal, with the financial support from the Government of India. The program assisted in rebuilding close to 50,000 private houses. UNDP and UNOPS were privileged to be the implementing partners of choice of such an ambitious program.
In Gorkha, UNDP provided socio-technical facilitation support for housing reconstruction to close to 27,000 house owners which were identified jointly by the Government of Nepal and the Government of India, from two urban municipalities and six rural municipalities. Tailored support was provided to the vulnerable households with a keen eye on those men and women who would be most at risk of being left behind in the reconstruction process.
The ‘build back better’ adage was never more apt. As housing was the sector that bore the brunt of the earthquake, safer housing became a priority intervention. Interestingly, as well as building new earthquake-resistant housing units, very soon we realized that safeguarding traditional houses, including those made of readily available material such as mud and stones, remained a concern — and a potential avenue to explore innovative approaches.
By some count, there are almost 3.5 million rural houses in Nepal. They are often beautiful, efficient structures, with cultural and historical significance, just like an adobe house in the South West of the United States would be. But they are structurally fragile and prone to collapsing or to sustaining heavy structural damage making them unfit for habitation in the wake of a tremor of the magnitude of the 2015 Gorkha earthquake.
Retrofitting the existing stock of traditionally build houses is therefore critical for western Nepal where the probability of next earthquake is high and building quality is poor by most reasonable assessment. Retrofitting — if properly done and if based on a detailed understanding of how a traditionally built structure would behave when subjected to the immense dynamic stresses of an earthquake — can save lives, preserve culturally and economically relevant structures, and ultimately save money.
What we also found in Gorkha is that many houseowners are reluctant to trade their old, damaged house, for a new construction that, while earthquake safe, was perhaps smaller and lacking the cultural or design appeal they cherished. To many, retrofitting is a more appealing option when looking to making their existing home safe.
But effective retrofitting techniques must be based on engineering research, and on a close, evidence-driven analysis of the structural strength of any housing typology in relation to potential seismic activity of varying magnitude. Through our reconstruction program, UNDP has accumulated significant knowledge about how a building will fare during an earthquake. Short of the testing opportunity that would be afforded by an actual earthquake, numerical modeling and experimental investigation in a controlled environment are the two methods to understand with some reasonable degree of certainty how a structure behaves during a tremor.
And this is where the ‘shock table’ comes in.
As part of the program, we at UNDP Nepal are proud to have worked with leading engineers to develop a 20-ton Shock Table sited at the Tribhuwan University Institute of Engineering, Pulchowk Campus. The table will generate scientific and engineering evidence to prove the effectiveness of retrofitting techniques specific to materials traditionally used in Nepal. This testing facility is critical for testing of vernacular construction and earthquake resilient buildings constructed using locally available materials that could be used especially for the construction of private and public buildings in Nepal.
It is our hope that such evidence and scientific basis will contribute to ‘clear the air’ around the application of retrofitting as a viable, cost-effective, and sensible option for earthquake risk resilience in Nepal.
The investment on a shock table facility is a strategic one. It goes beyond creating a research facility to test seismic performance of buildings. It contributes to build collective confidence on the technology.
The shock table itself is no panacea, of course. Investments must come in the form of policy advocacy and demonstrable models — such as through building codes. We at UNDP would like to build on the policy support work we did to bring a national policy on retrofitting in 2016 and develop design manuals for retrofitting of rural houses with four options based on our experience in Gorkha. Our future priorities and commitments in Nepal lie with the much needed work to build resilience against earthquake risks through implementation of national building code as well as retrofitting of existing houses.