Central Asia: remote sensing in Uzbekistan
An unexpected phone call with a request to undertake remote sensing work in a remote Central Asia nation took researcher Stella Belliss by surprise.
A Korean company undertaking oil and gas exploration in Uzbekistan needed expertise in mapping land use and land cover and, through contacts, knew of Landcare Research’s capabilities.
Independent from Russia since 1991, the country has 28 million inhabitants, although the exploration area is sparsely populated, being mostly desert. Mining is a major component of Uzbekistan exports, especially gold. The country also contains major reserves of fossil fuels, especially natural gas, and proven reserves lie to the south of this exploration area.
A team consisting of David Pairman, Stephen McNeill (digital elevation modelling and 3-D perspective view preparation), Stella Belliss (geology and project management), Ian Lynn (geomorphology and topography) and Peter Newsome (land cover and land use) was developed and the project began.
‘We used both optical Landsat imagery and PalSAR radar data from a Japanese sensor and got a digital elevation model from a Space Shuttle mission a few years earlier. Stephen processed that and we used it to improve the orthorectification of the images,’ says Ms Belliss.
Orthorectification is the process of making aerial photos and satellite imagery conform to a map projection, including correction for terrain displacement, and a digital elevation model is necessary for this.
‘Without this process, you wouldn’t be able make direct and accurate measurements of distances, angles, positions, and areas, nor would you be able to correctly overlay other geometrically corrected information layers or images,’ Ms Belliss says.
‘However, it’s quite hard to orthorectify images, especially in a part of Uzbekistan that is almost totally desert and where there are few points of reference.
‘Of course it would’ve been great to visit there but that’s one of the downsides of remote sensing, you can do it all from your desk.’
The area researchers were asked to prepare exploration maps for is near the Aral Sea. This is a saline lake 4th largest in the world in 1960 but now a mere 25% of its former volume, due to a combination of overuse (irrigation for ‘white gold’ (cotton) and grain) and environmental change.
The remote sensing team has also worked in other diverse parts of the world in recent years including Ecuador, Papua New Guinea, Tibet, Vietnam, and Tonga.