SciBlogs

Posts Tagged Natural hazards

Hippo surfs flood waters to freedom Daniel Collins Mar 12

No Comments

From flooded elephant research sites to flooded zoos…

Back in January heavy rains flooded a private zoo in Plavinca, Montenegro. 2-ton and 11-year old hippopotamus Nikica flew the coop by swimming over her submerged cage. The natural disasters commission wasn’t happy, and thought they might be able to shoot her. The state veterinary authorities thought otherwise, saying she wasn’t threatening. Apparently when Nikica escapes, she wanders over to the folks in the nearby village but would return of her own accord:

“When the water warms up and does not seem so threatening, she will return of her own free will,”… “She loves mud more than life itself.”

Nonetheless, zoo security were on the case. Food was left out for her. And when flood waters receded, she apparently [was] returned to her enclosure.

YouTube Preview Image

Ugandan rains bury villagers Daniel Collins Mar 10

No Comments

A few days before the Save the Elephant research site was washed away by a flash flood, villages along on the western flank of Mt Elgon were hit by landslides, killing at least 100.

Minister David Wakikona, MP for Manjiya County in Bududa district, said

“Everybody is dead. 320 people are unaccounted for. I don’t know if we shall get any survivors out.”

The trigger was also heavy rain associated with the onset of the March-May rainy season. And while landslides are always to be expected sooner or later on steep terrain, this area had became more susceptible since the 1960s due to land clearance for crops and fuel.

I visited the area in 2008. The local Uganda Red Cross team gave me a tour of the mountain side and I met the elders of one of the villages above Mbale. Both the Red Cross and the villagers were concerned about landslides and rock falls that had claimed several lives. And the village elder seemed at least vaguely clued up about the cause: deforestation. That said, Oxfam released a report in August 2008 about the potential impacts of climate change on Uganda, and suggested climate change would increase the danger of landslides. While that may be true, I think it is rather useless – the important factors around Mt Elgon at least is deforestation and village vulnerability.

Mountain hillslope and village site above Mbale, eastern Uganda.

Mountain hillslope and village site above Mbale, eastern Uganda.

Trees reduce the tendency for soil-mantled slopes to fail in three ways, though not all are relevant at any one site or time. The most obvious is that their deeper and stronger roots bind the soil together vertically and laterally; they may also bind the soil to underlying bedrock if shallow enough. The heavier trees increase the friction of any failure surface within the soil. And the higher transpiration of the trees can dry up the soils more, thus requiring more water-logging for slope failure to occur. Trees are also helpful in limiting the run-out distance of rock falls by serving as a natural debris belt.

With this in mind, the main recommendation I gave to the Red Cross and villagers was to plant fruit trees. They are so below the poverty line that they need both nutritional or economic assistance as well as protection from landslides. Fruit trees hits two birds with one stone. It reduces their vulnerability and increases their resilience to the next natural hazard.

Kenyan rains wash away elephant research Daniel Collins Mar 08

2 Comments

The Save the Elephants research camp in Samburu National Reserve, Kenya, was hit by a flash flood on Thursday. No-one was killed, but according to STE the site was severely damaged and much research lost.

“At approximately 5am this morning, a wall of water akin to a Tsunami surged through Elephant Watch Camp, catching tourists and staff unawares and sweeping away tents and facilities. It has been confirmed that camp owner Oria Douglas-Hamilton and guests managed to escape to safety by climbing to higher ground. Several members of staff were trapped in trees until the water subsided later today.

At approximately 7am the flood hit and decimated Save the Elephants’ research facility down river. Researchers and staff managed to drive to safety within seconds of the flood waters surging through the facility.”

According to the BBC, noteworthy research conducted at the site discovered that a fence of wood, wire and beehives can deter elephants from raiding farmers’ crops. This is important in the on-going struggle for coexistence between food-short elephants and humans.

When I look at pictures of the site – close-up and satellite – vulnerability to flash-flooding is not a real surprise. Flash floods results from the perfect storm of intense rainfall and an inability for the soil to absorb the water. Mean annual rainfall in the area is on the order of 700 mm, but a large proportion falls during the March-May rainy season. With higher temperatures and associated convective air movement, when it does rain it can rain a lot. And images of the river in flood depict a very muddy river. Indeed, Ewaso Ng’iro – the river running through the camps – means the river of brown or muddy waters. Combined with a guesstimate of the regional geomorphology, this suggests the soils are predominantly fine-to-medium grained – soil grain sizes that are readily swamped by convective rainstorms.

When they re-build (if you’re a fan, go donate!), I hope they consider a better site. While it is nice to build near the river amidst the riparian trees, and probably more economical on the short term in terms of energy savings due to the shade, they put themselves at the mercy of a capricious and occasionally dangerous environment. It would be wise to install flow sensors at strategic locations up-river to give a warning of any impending flood, and have a prioritised plan to bring people, belongings and data to safety in the event of a flood warning.

Haiti earthquake Daniel Collins Jan 14

1 Comment

The magnitude 7.0 earthquake that Haiti on Tuesday is estimated to have killed more than 100,000 people. With the collapse of hospitals and impoverished emergency services, fatalities will continue to mount.

In disasters like this, unless you have particular expertise in disaster response, donating to the Red Cross is the best thing you can do. Either NZ Red Cross or, probably better, the American Red Cross.

Disasters like this can be broken down into several phases.

Phase 1 – The initial earthquake and aftershock levels buildings, immediately killing and injuring a huge number of people. Infrastructure such as power or water supplies are damaged or destroyed, as are service providers such as hospitals and security.

Phase 2. Search and rescue begins immediately, at least by the locals. Fatalities continue as the injured are unable to get necessary treatment. Haiti is the poorest nation in the Americas; its vulnerability is high and resilience extremely low. While the country remains in shock, international attention starts to bring disaster relief, which is best aimed at treating the injured and supplying food and water. Since this is Haiti, international aid will also come in the form of security. Low-level crime begins, though it will be tempered by culture and available resources to loot.

Phase 3. Search and rescue is now supported by international teams. Most of those injured during phase 1 have either died or are stable. Public health will begin to be a problem due to the many corpses. Corpse removal and mass burial begins. International aid subsides a little, with the balance shifting to restoring life-support services (power and water). Low-level crime continues, but given the willingness for the international community to send security personnel to Haiti, it will not get out of hand. The initial shock will transition into a variety of other emotions, ranging from fatalism and depression to courage. The flow of international concern will play a significant role here.

Phase 4. Post-disaster reconstruction. Haiti has no capacity for this, so it will again be supported by international aid. Corpse removal continues. Public health is still a concern. Attention will spread from life-supporting services to longer-term services: rebuilding hospitals, roads, schools. While international donations will have fallen off, they are still extremely valuable. Used wisely, they can be administered in ways that reduce the impacts of “the next one” – earthquake resistant hospital buildings at the top of the list. Aid will now be directed at rebuilding what little economic and agricultural activities Haiti can sustain.

For continuing coverage, as well as historical articles that can provide a social context for the disaster, see the New York Times’ Haiti archive.

For footage and images of Haiti between phase 1 and phase 2, see BBC and NYT.

For on-going collation of facts, visit Wikipedia.

For a basic description of Haiti’s geological setting, visit Highly Allochthonous.

My thoughts go out to those affected.

Update 14/1/10: I was remiss not to mention shelter. Phase 1: In this size of earthquake, many people would have lost their homes, and as the aftershocks roll on, survivors would have gathered important resources and found places to sleep – perhaps makeshift, perhaps in less-than-ideal locations. Phase 2: International aid brings in tents, tarps and blankets. If fitting, a tent city may emerge in an open space, though I imagine people in Haiti will just continue to retrofit what they have. Phase 4: Rebuilding begins, even before all debris is removed. While most buildings will look as they were before the earthquake, I expect the magnitude of the impacts this time will encourage rebuilding with more resistant structures for the more important functions (e.g., hospitals, government).