SABAH FORESTRY DEPARTMENT

SOIL EROSION

The whole USM SFMP areas are classified as Class I Protected Areas and no harvesting to be executed in this project area. However, soil erosion stills the main concern due to past unsustainable logging and land development takes place as it can affect the land quality and its surrounding. It can pose major problems when occurrences are accelerated by human activities. Under undisturbed forest condition, the rate remains low but disturbances by human, both planned and unplanned, would amplify the natural occurrences of soil erosion. The movement of sediments into water courses would lead to sedimentation in the rivers and also the disruption of the ecosystem. The major issues of soil erosion in USM SFMP are as follows:

Building Development
All existing structures within USM SFMP, such as buildings, nursery, sewage, fuel tank, and generator house, were constructed on flat or gentle slope area and located more than 30m from any existing watercourses. Any cleared and opened area were re-vegetated with crops, such as grasses and ornamental plants within the vicinity of the forestry complex, and planting of trees on exposed slope area. In large complexes, proper drainage system with sediment trap pits was installed to reduce surface run-off and sedimentation. All infrastructures within USM SFMP are located 30m away from any existing watercourse. In 2017, no soil erosion was recorded and no cost involved.

Road Development
In USM SFMP, the constructions of new roads are minimal as the existing roads are still usable although some roads need for upgrading or maintenance. The use of existing roads would reduce the creation of exposed areas. However, in any plan to develop new road, the construction will take into consideration the slope steepness to minimize cutting and filling with no pushing of soil towards river banks.

Table 1: Soil erosion impact on road development within USM SFMP in 2017

No. Institution/ Company Location Soil Erosion Impacts Mitigation
Q1 Q2 Q3 Q4
1. Sabah Forestry Dept. Main Line North (Taliwas-Kawag-North Segama Bridge) -34km Yes No No Yes No construction during rainy days
2. C.T. Ent. (Contractor appointed by YS) Main Line West (Silam-Malua) – 95km Yes Yes No No No construction during rainy days

3.

Bukit Piton (Cpt. 121-112) – 20km Yes No No Yes No construction during rainy days
4. Bukit Piton (Cpt. 109-101) – 20km Yes No No Yes No construction during rainy days
5. Collectively done by surrounding oil palm plantations i.e. Tung Hup Estate, Syarimo Estate, Segama Estate and Danum Plantation Sdn Bhd Sungai Pin – Danum Plantation (Palm Oil Access) No No No No  

Most roads within USM SFMP are existing roads that are regularly used to implement forest activities. In 2017, 4 main roads were experiencing soil erosion such as Malua Road, Main Line North (Taliwas-Kawag-North Segama Bridge) and Bukit Piton Roads (Cpt. 121-112 & 109-101) due to continuous heavy Rain especially in the 1st until 4th quarters. As for mitigation measure, road maintenance was done during hot/dry and no construction was carried out during the rainy days. In 3rd quarters, 3 old bridges were replaced with box spiral culvert by SFD’s appointed contractor, Karnia which involved cost about RM248,500.00. In 2017, Yayasan Sabah had contributed about RM3 million to maintain road at Main Line West (Silam- Malua) and Bukit Piton Roads (Cpt. 121-112 & 109-101).