Danger still lurks at Bukit Kukus landslide site

Penang Forum is gravely concerned about recent press reports of authoritative government agencies warning of signs of soil instability and more landslides within the area of the 19 October landslide at the construction site of the Paya Terubong paired road in Bukit Kukus.

In a press interview on 21 October, the head of the Perlis, Kedah and Penang Department of Mineral and Geoscience, Azhari Ahmad, pointed out that his team on-site encountered a natural stream flowing downhill.

Indeed our desktop investigation using geographic information system (GIS) mapping of the river system in the vicinity of the area reveals that there are possibly two streams that flow westward down the slopes of Bukit Kukus, as shown in the map at the top.

The stream that En Azhari’s team encountered is probably Stream 1 in the map. Only personnel authorised within the restricted zone of the construction area can ascertain if Stream 2 does indeed exist.

Azhari explained that “due to its (the stream’s) shallowness, when it rains, the water can become swift and overflow into the nearby area” – hence, the fear that excess run-off from rain can further compromise the stability of the exposed slopes in the vicinity of the landslide that already occurred.

Azhari’s statement underscores the fact that innocent-looking small streams should not be dismissed as inconsequential in hillside development. We should not be underestimate the forces they can unleash after a rainstorm. The lesson from the collapse of the embanked road in Tanjung Bungah less than a year ago (see images below) seems to have been lost on our authorities.

Graphic: Penang Forum

Back to Bukit Kukus, the photo below depicts our observation of the landslide event upon closer examination of photos taken on 19 October 2018.

Graphic: Penang Forum

The bold red dashed line roughly outlines the extent of the landslide. The lower portions of the two pillars exposed by the landslide are covered with soil.

The magenta dashed lines roughly mark the two terraces and two slopes before the landslide occurred.

The remaining terraces and slopes are visible in the area marked with the yellow dashed line. There is still a risk that this area may collapse at or after the next heavy rainfall.

Azhari further said, “For now, we have managed to divert the water flow from the stream to elsewhere.”

Mark the words “for now” – for a temporary diversion done in a morning surely cannot be a long-term, even a middle-term, workaround for such an extensive area of steep slopes rendered completely barren. We can only hope that the temporary diversion of the stream above this site can help somewhat in preventing further slope collapse while the search and rescue operations are ongoing.

Already, in his interview with TV1 late on Sunday evening (21 October), Penang Fire and Rescue Department deputy director Mohamad Shoki Hamzah revealed “ada berlaku sedikit gerakan tanah” (a bit of soil movement has occurred) and “tanah di tebing kami dapati dah renggang dan… runtuh” (we found soil at the banks had moved apart and … collapsed).

Let us really pray that Mother Nature takes kindly to the valiant efforts of all on-site personnel to search for the missing and does not unleash another downpour to further destabilise the landslide area until after the search and rescue efforts are safely completed.

Penang Forum
23 October 2018

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s