MalaysiaGIS.com

That the local climate in Cameron Highlands, Pahang, is no longer what it used to be has been acknowledged. Both residents and visitors say the place is no longer as cool as before.

Now there is official data to back this view. Figures collected between 1949 and 1997 reveal a marked increase in surface air temperature and a steady drop in rainfall over Cameron Highlands.

A study by TNB Research Sdn Bhd (a wholly-owned subsidiary of Tenaga Nasional Bhd) shows that the average rainfall in Telom, Cameron Highlands, has dropped 2.4mm annually between the 1960s and 1999. The mean temperature has also increased 0.6ºC each year since 1979.

While global climatic patterns may have triggered the changes, the study says the following factors have also played a role: the loss of forest cover, enlarged cultivation plots, increased urbanisation and other human activities.

The TNB initiated the Cameron Highlands-Batang Padang catchment management project in 1997 because it was concerned about siltation in the reservoir of the Cameron Highlands-Batang Padang hydroelectric scheme.

The project involved mapping the catchment of Cameron Highlands to obtain information on the terrain, land use and river networks, explains Nik Nabeelah Nik Ibrahim, a researcher in the geoinformatic section of TNB Research.

"The project results will give a clearer view of what's going on at Cameron Highlands. Such a comprehensive land-use database will help in integrated river basin management, so that there can be more controlled and balanced use of the area," she says.

The project employs the geographic information system (more popularly known by its aconym, GIS), remote sensing and global positioning system (GPS).

Maps dated 1947, 1966, 1974, 1982, 1990 and 1997 from the Agriculture Department and the Mapping and Survey Department were compared to observe changes in Cameron Highlands land use.

The results showed that forest cover in the upper Cameron Highlands catchment (which comprises the Plau, Tenom and Bertam catchments) has dwindled from 95% to 62% - a loss of 10,599ha - between 1947 and 1997. On the other hand, the land area of farms, grew tenfold for the same period: from 1.7% (291ha) of the total area to 17.8% (3,048ha).

By running computer modelling programmes on soil erosion against land-use maps, the study also found worsening soil erosion, according to Mohd Nadzari Ismail, technical manager at the geoinformation technology group of TNB Research.

In tbe Bertam catchment, he says 4,230cu m of soil was washed away in 1947 when land was cleared for farming. Fifty years later, the figure has escalated to 14,000cu m.

Nik Nabeelah says clearing of land - for farms, roads, housing and tourism development - contribute most to soil loss, particularly when it rains.

"Soil erosion is more severe now despite declining rainfall as steep slopes are being cut," she says.

In the absence of flat land - there are only 500ha of land classified as "flat" in Cameron Highlands -farming has moved up hill slopes.

The study found that farms sited on slopes with a gradient of more than 6 had expanded tenfold in 50 years: from 236ha in 1947 to 2,636ha in 1997.

The loss of permeable surfaces, such as forested areas, means more water will run off the land when it rains. This can trigger floods and landslides.

At Sungai Telom, Nik Nabeelah says the discharge volume (amount of river flow) had increased 8% from 1975 to 1997. In addition, the river flow reaches its highest level (the peaking time) 35 minutes faster than it did in 1975. However, she adds that the results are preliminary as more studies are being done in this area.

Indiscriminate land clearing without soil protection measures means that excessive earth will be dumped into rivers.

Sure enough, the project found that sediment load at the Robinson Falls had risen from 1.4 tonnes a day in 1957 to 200 tonnes in 1990. This does not auger well for the TNB hydroelectric scheme as the sediment will eventually accumulate at its Ringlet reservoir.

Nadzari says sedimentation at the reservoir has worsened from 154 million cubic metres in 1984 to 434 million cubic metres in 1999.

"When the plant shuts down for the day at 4pm, you only see flat land at the resorvoir. Two years ago, you could still see a pool of water."

With the reservoir storing less water, the plant is no longer as efficient in generating power.

Operations have had to be halted in the past to avoid damaging mechanical parts due to the massive sediment load.

With a target of 3.5 million visitors by 2020, Nik Nabeelah believes development activities at Cameron Highlands will continue unabated.

"Since Cameron Highlands is the country's main source of highland vegetables, we cannot stop agriculture activities. We should concentrate efforts on controlling the clearing of land," she says.