In Papua New Guinea (PNG), a country of about 600 small islands, transport is one of the top priorities in the pursuit of connectivity and inclusive economic growth.
The national government in 2013 launched its National Transport Strategy 2014–2030 (NTS), which highlights the country’s goal to develop a well-integrated, multimodal, safe, and financially and environmentally sustainable transport that efficiently serves its economy and people.
ADB, as the country’s largest multilateral development partner, supports the strategy through 12 active projects on land, aviation, and maritime transport. Some of the notable projects, both previous and present, include the Highlands Region Road Improvement Investment Program, the Bridge Replacement project, the Lae Port Development project, and the Civil Aviation Development Program.
The air transport project alone will see to the rehabilitation of 21 airports. Part of this is a new international passenger terminal for the Jackson International Airport in Port Moresby – the capital and largest city of Papua New Guinea – under a transaction advisory services agreement for a public-private partnership that was signed early 2017.
However, in spite of significant investments, major gaps remain throughout the country, crippling access to jobs, education, health services, and other economic opportunities.
It is important, therefore, to consider all the projects together in order to prioritize actions, focus resources where needed, and to define the overall infrastructure development in Papua New Guinea. Assessing spatial information is a critical component of this undertaking. In particular, the most consistent, quality-assured, up-to-date, and high-detail geospatial information is needed to look at the state of the transport infrastructure and where ADB projects are under implementation.
The European Space Agency (ESA) fulfilled this need, as part of their collaboration with ADB to promote and demonstrate the use of satellite-based earth observation technologies in project implementation in Asia and the Pacific. They provided two main services: an up-to-date transport infrastructure inventory of central PNG, and climate-focused products, contributing to the identification of vulnerable areas and quantifying climate risks that the road network is exposed to. These two services mostly covered the Southern Highlands and Hela provinces, although some products are available for the entire country.
According to Luanne Losi Yawingu, PNG Office of Climate Change and Development (OCCD) project manager: “There are ongoing activities which produced maps on hazards and vulnerable areas. [The ESA support project] information will be used to supplement the data and information currently available. Information could also be used for developing management strategies.”
“There are ongoing activities which produced maps on hazards and vulnerable areas. [The ESA support project] information will be used to supplement the data and information currently available. Information could also be used for developing management strategies.”
Luanne Losi Yawingu
Project Manager, PNG Office of Climate Change and Development
Taking stock of transport infrastructure
To provide a timely picture of the transport infrastructure in the two provinces, ESA prepared a land use map focusing on artificial structures and the different transport components such as road networks and associated land, port areas, airports, and bridges, among others. For the road networks, linear features were also extracted into separate vector datasets.
The technology for this service (mainly optical RapidEye imagery) used a five-meter pixel size, and so could not detect small roads. In some cases, very high-resolution imagery (Pléiades) was used to improve the results. Additionally, the process was complemented by another type of imaging technology called RADARSAT-2 (three-meter resolution) for times when optical data was affected with cloud cover. The imagery was also used to update the layer on water bodies, especially the rivers, which are typically dynamic and can change shape frequently.
Ensuring safety and environmentally sustainable transport
A survey of the transport infrastructure in PNG not only helps the government to achieve their aim of well-integrated transport connectivity, but also aids in determining which areas need upgrading or are susceptible to natural hazards. The country – with its harsh topography that ranges from sea level to 4,500 meters – frequently experiences landslides that affect both communities and the roads that link.
Data from ESA underscores ADB’s efforts to develop an approach for assessing climate risks and climate proofing of transportation investment projects. The ESA service provided satellite-based information on environmental parameters such as rainfall, temperature and vegetation indices, as well as terrain instability. Other risks reviewed included floods and droughts, susceptibility to landslides, and infrastructure instability.
All products were generated following the same methodologies that were also adopted by the PNG Resource Information System (PNGRIS) Handbook prepared by the University of Papua New Guinea for the Land Use Section of the Department of Agriculture and Livestock.
Protecting roads from landslides
Among the climate risks, vulnerability to landslides was important for PNG to address. Landslides, due to heavy rains, have been common in the past decade, affecting national highways and the livelihoods that depend on the transfer of goods and people. In 2013, the Okuk Highway was deteriorating due to landslides impacting outdated and poorly maintained infrastructure, while in 2012 Hela Province had one of PNG’s worst landslides, affecting about two kilometers of the highway connecting the mountainous region to the port city of Lae.
An updated landslide inventory is essential for the assessment of the impact of slope failures on the main transport infrastructure. ESA’s terrain instability datasets consisted of a landslide inventory and a map of terrain displacement measurements over the two provinces. Landslides were identified primarily through the use of RapidEye imagery. The 5-m pixel size allowed the detection of medium- to large-sized landslides.
Also similar to the transport infrastructure inventory, a number of smaller slides were identified by using higher-resolution imagery (Pléiades and imagery available in Google Earth). In particular, on-screen visualization and interpretation of Pléiades imagery represented the main approach to identify and delineate slope instability phenomena along some of the main roads of the study area. Significant details of several landslides were obtained due to the increased resolution.
Terrain displacement map over the city of Port Moresby. The points are Persistent Scatterers extracted by SPINUA software by processing a stack of Sentinel-1 SAR data (ascending mode).
Large landslide observed on RapidEye image (2012 September 30). RepidEye data©BlackBridge. Pléiades data©CNES.
The same location on a Pansharpened Pleiades image (2014 February 4), where more detailed geomorphic features (e.g. head scarp, drainage) are clearly visible.
The images also indicate an apparent decrease of the landslide area that can be linked to the vegetation re-growth. RepidEye data©BlackBridge. Pléiades data©CNES.
“This optical data, from RADARSAT-2 for instance, not only shows the road condition but also the slopes flanking it as the satellite can look at contour lines, where landslides have occurred before and whether there is ongoing land movement. Above ground all could be well, but beneath the road land could be moving, so it is important to understand the potential risks,” explained Paolo Manunta, ADB infrastructure specialist and ESA secondee.
Feedback and the way forward
ESA’s two main services were packaged as open-source desktop-based geographic information systems (GIS), so as to facilitate immediate transfer of knowledge to end-users. An online GIS version, however, remains a low priority due to internet connectivity issues. Still, the effort of putting the data online was evaluated positively by the project partners, especially in light of the intensive international cooperation in the area. Aside from ADB, other donor institutions include the Japan International Cooperation Agency and the World Bank.
The earth observation service portfolio was presented at OCCD’s Adaptation Technical Working Meeting at Port Moresby in November 2015. Representatives from several government offices, local NGOs, and other stakeholders attended the meeting. The solutions raised much interest in the OCCD group as well as in the PNG Department of Mineral Policy and Geohazards Management. Particular interest was shown for the landslide and terrain motion products since adaptation to climate change should be inclusive of measures to mitigate the risk of geohazards.
After the project, ESA continued to support the assessment of the country’s transport infrastructure using the new Sentinel-1 satellite. The Copernicus program provides complete, free, and open access to Sentinel-1 data, said Manunta. “There are more images available than before and what we did is to show conceptually more of the terrain stability or instability of Port Moresby and Mendi. Taking the raw data we conducted a complex analysis using appropriate, sophisticated tools to come up with a Persistent Scatterers map, which is essentially numerous color-coded identified points that signify whether an artificial structure is stable or not based on the land it is on,” he added.
Apart from transport infrastructure, applying earth observation or gathering geospatial information in other areas was welcomed by the government, such as in the possibility of extending the study areas to coastal and cash crop areas.
*This project story is based on the original article in the publication, Earth Observation for a Transforming Asia and Pacific. For this project, ESA worked with Italian earth observation service providers, G.A.P. and Planetek Italia.