Experts recommend tracking land-use trends from the sky

Anissa S. Febrina ,The Jakarta Post, Jakarta

The regular evaluation of satellite images of the city could be useful in further efforts to monitor land use trends and their impact on the environment, an urbanist suggests.

Speaking at a public lecture Wednesday at Tarumanagara University, Andrea Peresthu of Technische Universitet Delft in the Netherlands explained that satellite imaging technology could help provide the government with a picture of the distribution of the city's ecosystem and land conversion patterns.

"The city administration could evaluate the GIS (geographical information system) images every six months, for example, to track which areas have been overutilized for commercial or residential purposes," Andrea said.

Overutilization and rapid land conversion, especially the conversion of water catchment areas for commercial and residential facilities, was one of the major contributors to the massive flooding in Greater Jakarta last week.

However, there is no valid data on the actual scale of land conversion and how much it contributed to the flooding, urban planning expert Suryono Herlambang said.

The Spatial Planning Agency, which is responsible for monitoring land use in the city, has complained its limited human resources make keeping a close eye on land conversion an impossibility.

Here is where GIS comes into play.

The Geographical Information System (GIS) brings together all types of information based on geographic location for the purposes of query, analysis and the generation of maps and reports.

It is a computer-based method of recording, analyzing, combining and displaying geographic information such as roads, streams, land formations or habitat types, sensitive areas, soil types, or any other feature that can be mapped on the ground.

Its product, a satellite photograph of a certain area, has been widely used in developed countries to assist in city planning and land-use management.

One of the most popular publicly accessible GIS images is provided by Google Earth.

The technology is already available at the National Aeronautics and Space Institute (Lapan), but is still underutilized by city administrations.

"We can provide images up to 1:25,000 in scale," Lapan remote sensing research and development division head Ratih Dewanti said.

A 1:25,000 image is three times more detailed than the regular city map and can show actual building density.

Lapan provides the 1:25,000 image for commercial use, while for public use it only provides a 1:500,000 image.

Despite the availability of the technology, the Spatial Planning Agency has not made use of it in urban planning and land management efforts, Ratih said.

According to Andrea, tracking changes through GIS images could be followed up with further analysis and evaluation, including tracking land conversion rates and population growth patterns, as well as sociodemographic patterns and land prices.