Engineer Identifies 5 Causes Of Massive Floods

(The Sun Daily) – A hydrologist and irrigation engineer has attributed the massive flooding in the east coast to five man-made and natural causes.

They are – unusually heavy rainfall in the water catchment areas upstream; the low water-holding capacity of the lower Sungai Kelantan; excessive logging and land-clearing; sediment build-up of rivers; and the large amount of mud and debris carried by the flood water, adding to its volume.

Chong Sun-Fatt, the principal adviser at G&P Water and Maritime, which is involved in designing numerous flood mitigation projects, told Sin Chew Daily in an interview published today that the main natural cause is the unusually large amount of rain dumped over large catchment areas upstream of Sungai Kelantan over an extended period, whereas the key man-made factor is the extensive land-clearing at these catchment areas, resulting in serious erosion and swift draining of water.

“Kelantan and Pahang were the hardest-hit states. This was because the rainfall was concentrated at the catchment areas in the upper reaches of Sungai Kelantan, such as Gua Musang and Gunang Gagau, and the upper reaches of Sungai Pahang, such as the Taman Negara National Park. Prior to this, the rain brought by northeast monsoon was concentrated in the lower areas of these two river basins,” he said.

The report said the highest rainfall was recorded in Gunang Gagau – 624mm during the first wave of torrential rain from Dec 15 to 19 and 1,395mm during the second wave from Dec 20 to 24.

The rainfall, the highest in 40 years during the first wave, and the highest in 1,000 years during the second wave, far exceeded the capacity that the current mitigation measures are designed to cope with.

He said Sungai Kelantan basin, which is shaped like a triangle, also made the lower regions of the basin such as Tanah Merah and Kota Baru flood prone.

Chong also pointed out that compared with logging activities, excessive land-clearing for crops is the main cause of the environmental problem.

“This is because a whole swath of land is cleared in the case of crop cultivation, leaving no trees at all, whereas trees are felled selectively at logging areas.”