The only thing worse than taking 5 hours to drive 106 km along winding and often damaged mountainous roads, is the realization that having reached your destination you have to turn around and repeat the trip to get home. That was in the forefront of my mind as I sat in the very quiet town of Ainaro, south of the capital in Dili. The second thing I thought about was that we had to do a lot of work to help Timor Leste make their roads more resilient to the effects of climate: or more particular, water.
Timor‐Leste is a small and mountainous island country surrounded by Indonesia, with a population of about 1 million. It has a dramatic topography dominated by the Ramelau Mountains stretching across the middle of the island from the east to the west. About 44% of the Timor‐Leste's total land area lies between 100 and 500 meters in elevation, and 35% above 1,000 meters. My trip took me across this mountainous spine towards the south of the country.
An assessment of the likely impact of climate change on Timor Leste done in 2009 by the consultant Cardno Acil forecasted that rainfall would increase in the future. This may bring fewer extreme rainfall events but their intensity would be more important.
Water and roads do not mix, particularly in mountainous areas such as in Timor Leste. This was obvious during my field trip where there was ample evidence of erosion, slope failures, and pavement damage from water. The photos give an idea of the types of issues encountered. With the likelihood of more rain, with higher intensity, it is necessary to take steps to build some resilience into Timor Leste’s roads.
Traditionally, the responses to hazards such as flooding and landslides were to desig and provide additional or reinforced engineering structures such as more/better drainage, culverts, higher bridges and re-aligned road sections. However, it is now recognized that re-vegetation and bioengineering measures for water courses and road slopes are key to implementing a lasting solution.
Bio-engineering improves slope stability, controls storm water and sediments, and helps absorb pollutants through natural processes. There are a variety of measures that can be taken including tree and shrub planting on unstable slopes, and the use of vegetated erosion control blankets which are natural fibres able to retain soil and sediments while providing a medium for planting shrubs. The goal is to increase water retention capacity and slow infiltration through natural or bioengineered systems.
There is still a place for civil engineering measures—such as providing sufficient capacity longitudinal and transverse drainage, as well as improved retaining walls, gabions (i.e. stone filled nettings)—but without bio-engineering they are only partial solutions.
The Timor Leste government is already taking steps to address the issues, and there were quite a few locations where civil engineering works were going on. There were many good examples of well constructed gabions, as well as other examples where they had not been so effective.
There were workers constructing excellent quality retaining walls from local stone, of which there is abundance. It was impressive to see a crew quarrying stone from the side of a mountain, attacking large rocks with sledge hammers and then moving the stone around as if it weighed very little.
A major benefit from constructing stone retaining walls, gabions and stone drainage is that it creates work for local communities. This can provide much needed stimulus and support to the local economy. The team building the gabion below were all recruited from the local village. They estimated that it would take them a month to gather the necessary stone and construct the gabion, and said they were very grateful to have the opportunity to work. The ILO has been working on labor based methods for road construction in Timor Leste, and it is clear that there are a number of areas of success.
We plan on exploring how we can assist the government of Timor Leste with building resilience into their road network to better cope with rainfall and the potential future climate changes. Relatively modest investments will yield major benefits not only in keeping roads open, but in saving on potentially large future maintenance or rehabilitation investments.