Timor-Leste
EXECUTIVE SUMMARY
Recent historical extreme rainfall events in Timor-Leste have caused extensive damage to road sections, highlighting the critical need to address climate change risks at all stages of road infrastructure development, including design, construction, and maintenance. This study aims to identify the causes of damage to roads and bridges; plan effective climate change adaptation measures; introduce innovative technologies suitable for adaptation; and strengthen the capacity of government engineers to properly oversee the design, construction, and maintenance of road and bridge infrastructures.
This study addresses five fundamental questions:
(1) Why are roads frequently damaged only a few years after construction?
(2) How do we assess and predict the impact of climate change on roads?
(3) How can engineers investigate and identify the cause of damage?
(4) What climate change adaptation measures are appropriate for Timor-Leste?
(5) How can these measures be effectively implemented?
The study assessed the impact of climate change on the road sector in Timor-Leste by using various climate change models and data. By estimating the climate change ratio and future design rainfall, it proposed the applicable box culvert size under historical and future climate scenarios, which can be embedded in the national design standard (section 2.2).
The study classified the damages of roads into six cases: (i) landslide, (ii) cut slope failure, (iii) fill slope failure, (iv) settlement, (v) debris flow, and (vi) culvert and ditch. Similarly, it classified the damages to bridges into four cases: (i) inappropriate river cross section, (ii) river course change due to floods, (iii) river course change due to inappropriate installation of revetment walls, and (iv) heavy sedimentation under bridge (section 2.3).
For each road damage case, the study identified causes, measurement methods, and countermeasures. For landslides, a comprehensive approach was recommended, using data from satellite imagery, topographic and geological maps, and aerial drone photography. For cut slope failure, the study recommended countermeasures such as rockfall prevention nets and shotcrete. For fill slope failure and settlement, the study identified external factors such as unstable foundations, high rainwater infiltration, erosion during floods, and erosion at the outlet of the culvert. Recommended countermeasures focused on foundation stabilization, introduction of subsoil drain, and appropriate installation of gabion mat. The study also suggested countermeasures for debris flow protection. For culverts and ditches, it recommended performing flow calculations in response to climate change, designing culvert inlets and outlets to absorb rainfall and rainfall pressure, and incorporating maintenance considerations.
Additionally, the study introduced community-based climate adaptation measures such as bioengineering solutions with community participation (section 2.4)
In the case of bridge damage, the study identified causes and countermeasures from both structural and river engineering perspectives. It proposed installing a relief open bridge, planting trees, conducting rooting works around the piers, and installing groins to protect the riverbank gabion wall. In response to heavy sedimentation under the bridge and changes in the river course, it suggested alternative bypass routes based on flood simulation analysis (section 2.5).
Under the study, field workshops and technical training were conducted for government staff to observe road damages, receive technical briefings, and test innovative technologies such as a light detection and ranging drone, satellite-observed rainfall data, and geographic information system mapping for climate adaptation (section 2.6).
Lastly, the study identified the following key points for future road development (section 3):
Climate adaptation measures are essential throughout all project cycles, including design, construction, and maintenance.
The implementing agency, serving as the Employer, should be empowered to manage climate resilience by adopting technical standards and unified guidelines that are responsive to climate changes.
A comprehensive approach is recommended for technical assessments, encouraging engineers to conduct these from broader perspectives and using various data sources.
A risk-based approach is suggested for selecting climate adaptation measures, based on cost–benefit analysis to ensure alignment with the local context and available technologies.
Community participation and perception are crucial for effective climate adaptation.
Timor-Leste
Timor-Leste
Timor-Leste
Timor-Leste
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