Geological experts have warned against cutting hills in Gulistan-e-Jauhar at a 90-degree angle, as done above on the site of the fatal landslide that killed 13 people this week. They also advise against constructing on the hill but there is a two-storey house perched on top of the hill above. PHOTO: ATHAR KHAN/EXPRESS
Last week's landslide that killed 13 residents of a makeshift colony of huts has exposed a standing time bomb that can explode any moment.
Geological experts are afraid that the haphazard construction on the hills in Gulistan-e-Jauhar — the area where the fatal landslide occurred — are likely to cause more damage unless the authorities take action. The construction of houses just on the edge of those hills with cemented walls is no less than a standing bomb, which can explode any moment, said University of Karachi geology department's assistant professor Adnan Khan.
Once he visited the site, Khan also figured out that the incident was not a landslide but a rock fall, mainly caused by faulty construction.
Read: Man-made or natural calamity?: Nature caused landslide, not china-cutting: KDA
To elaborate just how dangerous it is to cut hills and encroach on the extra land it creates, Khan explained that the hills have been cut at an angle of 90 degrees, which makes them highly vulnerable. "The most stable position of a mountain is at 30 degrees," he said. Even at 45 degrees the slope becomes vulnerable and anything above that is high-risk, he added.
According to him, building houses on top of those hills is weakening their resisting forces. The top thin layer of the hill is limestone and below that is silt clay. "When houses are constructed on those hills, the water penetrates them and reduces the sharing strength," he said, adding that this makes the opposing forces become dominant.
Since the hill has been cut at exactly 90 degrees, the huge rock fell, he explained. "Had the hill been sloping properly, the rock would have slid down slower causing much less damage," he said. Cement walls stand little chance in front of a rock hurtling down these hills at high speed, he added.
Read: Rare landslide kills 13 shanty dwellers
NED University architecture department's Dr Noman Ahmed felt the landslide was fatal due to basic fault in planning. "Those hills should have been marked as non-construction zones," he said.
Safari Park, located near the site of the landslide, has the same topography as those hills, he pointed out. There is hard as well as soft soil with no greenery, he said, adding that such hills cannot bind the soil using vegetation and plantation. Any attempt to remove these hills can affect constructions nearby, he feared.
Ground reality
The sense of urgency regarding these vulnerable hills seems to end with these experts. The government continues to allot land without bothering to consult geologists or conducting geological surveys to make sure people build safe homes.
Read: Seven children among 13 killed in Karachi's landslide
Even the plots in Gulistan-e-Jauhar Block-1 where the fatal landslide claimed 13 lives were allotted by the then Karachi Development Authority without any geological surveys, admitted a former KDA director for the enforcement wing, Jameel Baloch.
Neither the KDA nor the Sindh Building Control Authority (SBCA) have asked for any kind of land or soil survey before allotting land or approving the construction of any structure, claimed Geological Survey of Pakistan assistant director Yasmeen Rizvi.
Rizvi did, however, warn that the entire city can collapse in case of an earthquake as no builder has ever obtained a geological survey certificate before any construction in the city.
SBCA's vigilance director Ali Mehdi Kazmi agreed that they do not conduct any geographical surveys. But its spokesperson, Farhan Qaisar, insisted they have their own engineers who conduct soil testing, which is why they do not need geologists.
For his part, KDA's additional director for land Nadeem Siddiqui said it is not his responsibility to monitor the hills that KDA has allotted for construction. "It's the responsibility of that area's engineer." But the KDA engineer for Gulistan-e-Jauhar, Syed Aurangzeb Ali, said their responsibility ends with measuring the land. "We don't have the capacity to monitor the land on any hill," he said.
Give space
As the blame-game continues, experts shared some basic rules that can help avoid such catastrophes in the future. "It's mandatory to leave space of around 13 to 15 metres away from the edge of hill when building any structure," said the KU professor. "Those houses can fall any time."
Khan is too afraid to even contemplate what will happen if that area receives heavy rainfall. "Any house that is more than two floors high must be demolished immediately as silt clay cannot bear that much pressure," he said, recommending that there should be no more construction on those hills. "More construction means more density and more water infiltration, which will be destructive," he said.
Published in The Express Tribune, October 18th, 2015.
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