Just a quick post to announce that the eleAlert system which I mentioned in a previous post has won an award from the National Science Foundation of Sri Lanka. The system creates an alert when an elephant breaks through an electric fence guarding village buildings and farmland. I helped map the prototype system when I was working in Sri Lanka.
More here
Friday, 19 November 2010
Wednesday, 1 September 2010
When Lakes Burp
In August 1986 a huge cloud of CO2 was emitted from Lake Nyos in Cameroon. The suffocating gas cloud killed 1700 villagers and thousands of livestock. Scientists were initially puzzled and locals blamed a spirit woman named ‘Mammy Water’ who lives in the lakes and rivers. Lake Nyos lies within the Oku Volcanic Field and occupies a maar crater formed from an eruption some 400 years ago. The volcanic activity beneath the lake continues and CO2 seeps through the lake bed and dissolves into the water body where it exists as a dense cold layer trapped below warmer layers of water above. It is the intense pressure from the water above that allows the CO2 to dissolve into the bottom layers without escaping to the surface.
If this layer becomes disturbed then it can rapidly rise to the surface and spread to the surrounding area with disastrous consequences for human and animal life. The disturbance could be a landslide, an earthquake, a volcanic eruption or even increased surface runoff after a very heavy rain storm. In the case of Lake Nyos, scientists believe that it was a rapid accumulation of rainwater in the lake following a storm that caused the disturbance. The rainwater may have been blown to one side of the lake due to the strong August winds. The heavier rainwater sank to the bottom of the lake causing a convective overturn which destabilised the CO2 rich bottom layer. The result was a massive explosion of CO2 form the lake causing the surface to drop by 1 metre.
Images of Lake Nyos before (left) and after (right) the 1986 gas eruption. The rising of carbon dioxide to the surface brought up iron which oxidised at the surface to give the brown colour.
Lake Nyos is still heavily studied and monitored. Pipes have been placed in the lake to siphon off the CO2 slowly over time to avoid another catastrophic build up.
Lake burping also has an impact on biodiversity. In the waters of the crater lake Barombi Mbo, in Cameroon, 11 species of fish are highly threatened and live a precarious existence as deforestation increases the risk of lake ‘burping’, where large levels of carbon dioxide are released from deep within the lake, suffocating the fish. Without management intervention these species, some of which are important food sources, may be lost forever. I’m still not entirely sure how the deforestation increases the risk. It could be due to increased risk of landslides and increased surface runoff during severe storms.
Perhaps of more concern than lake burping is ocean burping. Bacteria produce methane as they decompose organic matter in the ocean sediments, and in cold, high-pressure environments, methane clathrate compounds will form. This is an ice-like solid that consists of methane surrounded by water molecules in a lattice structure. However, if the temperature warms, or the pressure is reduced (for instance if local sea level decreases), the clathrate will break up and release the methane as gas which can bubble up through the ocean and enter the atmosphere. Methane is a much more powerful greenhouse gas than carbon dioxide. Some scientists believe this form of methane emission could have played a key role in the Paleocene-Eocene Thermal Maximum (PETM). This process which is also known as the clathrate gun hypothesis may have been a key cause of past mass extinctions such as the Permian extinction event 251 million years ago. Below is an excerpt from Ryskin (2003)
“The consequences of a methane-driven oceanic eruption for marine and terrestrial life are likely to be catastrophic. Figuratively speaking,the erupting region ‘‘boils over,’’ ejecting a large amount of methane and other gases (e.g., CO2, H2S) into the atmosphere, and flooding large areas of land. Whereas pure methane is lighter than air, methane loaded with water droplets is much heavier, and thus spreads over the land, mixing with air in the process (and losing water as rain). The air-methane mixture is explosive at methane concentrations between 5% and 15%; as such mixtures form in different locations near the ground and are ignited by lightning, explosions and conflagrations destroy most of the terrestrial life, and also produce great amounts of smoke and of carbon dioxide. Firestorms carry smoke and dust into the upper atmosphere, where they may remain for several years, the resulting darkness and global cooling may provide an additional kill mechanism. Conversely, carbon dioxide and the remaining methane create the greenhouse effect, which may lead to global warming.”
If this layer becomes disturbed then it can rapidly rise to the surface and spread to the surrounding area with disastrous consequences for human and animal life. The disturbance could be a landslide, an earthquake, a volcanic eruption or even increased surface runoff after a very heavy rain storm. In the case of Lake Nyos, scientists believe that it was a rapid accumulation of rainwater in the lake following a storm that caused the disturbance. The rainwater may have been blown to one side of the lake due to the strong August winds. The heavier rainwater sank to the bottom of the lake causing a convective overturn which destabilised the CO2 rich bottom layer. The result was a massive explosion of CO2 form the lake causing the surface to drop by 1 metre.
Lake Nyos is still heavily studied and monitored. Pipes have been placed in the lake to siphon off the CO2 slowly over time to avoid another catastrophic build up.
Lake burping also has an impact on biodiversity. In the waters of the crater lake Barombi Mbo, in Cameroon, 11 species of fish are highly threatened and live a precarious existence as deforestation increases the risk of lake ‘burping’, where large levels of carbon dioxide are released from deep within the lake, suffocating the fish. Without management intervention these species, some of which are important food sources, may be lost forever. I’m still not entirely sure how the deforestation increases the risk. It could be due to increased risk of landslides and increased surface runoff during severe storms.
Lake Barimbo Mbo
Perhaps of more concern than lake burping is ocean burping. Bacteria produce methane as they decompose organic matter in the ocean sediments, and in cold, high-pressure environments, methane clathrate compounds will form. This is an ice-like solid that consists of methane surrounded by water molecules in a lattice structure. However, if the temperature warms, or the pressure is reduced (for instance if local sea level decreases), the clathrate will break up and release the methane as gas which can bubble up through the ocean and enter the atmosphere. Methane is a much more powerful greenhouse gas than carbon dioxide. Some scientists believe this form of methane emission could have played a key role in the Paleocene-Eocene Thermal Maximum (PETM). This process which is also known as the clathrate gun hypothesis may have been a key cause of past mass extinctions such as the Permian extinction event 251 million years ago. Below is an excerpt from Ryskin (2003)
“The consequences of a methane-driven oceanic eruption for marine and terrestrial life are likely to be catastrophic. Figuratively speaking,the erupting region ‘‘boils over,’’ ejecting a large amount of methane and other gases (e.g., CO2, H2S) into the atmosphere, and flooding large areas of land. Whereas pure methane is lighter than air, methane loaded with water droplets is much heavier, and thus spreads over the land, mixing with air in the process (and losing water as rain). The air-methane mixture is explosive at methane concentrations between 5% and 15%; as such mixtures form in different locations near the ground and are ignited by lightning, explosions and conflagrations destroy most of the terrestrial life, and also produce great amounts of smoke and of carbon dioxide. Firestorms carry smoke and dust into the upper atmosphere, where they may remain for several years, the resulting darkness and global cooling may provide an additional kill mechanism. Conversely, carbon dioxide and the remaining methane create the greenhouse effect, which may lead to global warming.”
Tuesday, 17 August 2010
IUCN - Species programme: A New Job
I now have that all important paid job in GIS and conservation. The voluntary work I did in Hawaii and Sri Lanka has paid off. I cannot recommend voluntary work high enough to recent graduates. Both in terms of the incredible experience gained and getting your nose in front of the competition. It seems a lot of GIS graduates are really struggling to find work. If you can get a few months experience on your CV then doors begin to open.
My job is working for the IUCN species programme. The IUCN among other things manages The IUCN Red List of Threatened Species which is the most comprehensive and consulted resource for evaluating the status and distribution of plant and animal species. I am based in the Cambridge office and will be working for the Freshwater Biodiversity Assessment Unit and the Climate Change Unit. Freshwater species are a vital part of ecosystems as well as being a dependable source of food for human populations. The main threats to freshwater biodiversity are habitat loss, introduction of alien species, pollution and over-harvesting. Global warming has already been implicated in hundreds of cases of species decline. Approximately 30% of plant and animal species are likely to be at increasingly high risk as global mean temperatures rise by 2-3 °C above preindustrial levels. Thus far it has been hunting and habitat loss that have been the main culprits behind recent species extinction but climate change will begin to show an ever increasing role. The question is which species and which habitats will be most affected?
One of the first tasks assigned to be me is to develop some GIS tools for capturing the habitat range of freshwater species (more on this in future posts). While at the IUCN I’m hoping to work on Species Distribution Modelling which will allow us to define species ranges in a more intelligent way than simply capturing a polygon which has been drawn on a map by an expert. SDM which incorporates Habitat Suitability Modelling and Ecological Niche Modelling, involves combining a number of eco-geographical factors such as elevation, precipitation and human disturbance to calculate the probability that a species can exist at a certain location.
Thursday, 20 May 2010
Mr Dodam
Mr Dodam is a Sri Lankan Giant squirrel (Ratufa macroura) that the SLWCS obtained from a temple in Sri Lanka where he lived in a small cage. He was taken to the Wasgamuwa field centre which is where I met him for the first time. He was originally kept in a pet carrier and then moved to a purpose built larger cage before being slowly introduced into the wild around the field centre.
Despite only being with him for a week I became very fond of him. There are few greater joys than seeing a once captive animal given free roam of the wild. You can follow his story here
Friday, 16 April 2010
Human Elephant Conflict
I am currently working for the Sri Lanka Wildlife Conservation Society. The field site is based just outside the Wasgamuwa National Park in the centre of the country. I will be using GIS to help out on a number of projects. The main issue for the organisation is Human Elephant Conflict (HEC). An increasing human population and loss of natural habitat has increased the conflict between the two species. This sadly results in deaths on both sides each year. Farmers will shoot elephants that encroach on their land and sometimes the farmers themselves are killed. Elephants eat crops and can knock down buildings.
We came across a dead elephant and her calf in the park. You can't see the calf in the above photo.We were advised to stay in our vehicle as there were signs that the herd was still in the area. It seems the mother was shot outisde the park and wandered in and subsequently died. Its most likely the elephant was killed for getting too close to a property or crops.
A solution to the problem is to build electric fences around villages and farmland (above). The concept of the fences has evolved from that of keeping the elephants in the protected parks to keeping them away from villages and farms. Keeping the elephants in the park was too restrictive for their movement and bars them unnecessarily from wild habitat outside the park. It is more sensible to place the fences at eco-economic boundaries around villages. Where the fences have been maintained there has been in some places a 100% reduction in human elephant conflict.
A new system is being proposed called ele-alert. This is an alarm system which alerts local administrators when a fence is damaged. A gyroscope device is installed on each fence post. When the fence is knocked down the gyroscope triggers a text message which is sent to the local fence monitoring staff.
Also the elephants do not like citrus fruits so its possible to grow these types of vegetation around areas as a natural barrier. These structures are called bio-fences. Chilli plants are used as bio fences in Africa but interestingly the Asian elephant is not sensitive to chilli. The citrus bio fences do not just act as a barrier to elephants but also the fruits can be sold at local markets.
The happier sight of a elephants in Wasgamuwa Park. The main way I will be helping out using GIS is with land change analysis of remote sensing images and also just general GPS mapping of incidents and fence damage within the area.
We came across a dead elephant and her calf in the park. You can't see the calf in the above photo.We were advised to stay in our vehicle as there were signs that the herd was still in the area. It seems the mother was shot outisde the park and wandered in and subsequently died. Its most likely the elephant was killed for getting too close to a property or crops.
A solution to the problem is to build electric fences around villages and farmland (above). The concept of the fences has evolved from that of keeping the elephants in the protected parks to keeping them away from villages and farms. Keeping the elephants in the park was too restrictive for their movement and bars them unnecessarily from wild habitat outside the park. It is more sensible to place the fences at eco-economic boundaries around villages. Where the fences have been maintained there has been in some places a 100% reduction in human elephant conflict.
A new system is being proposed called ele-alert. This is an alarm system which alerts local administrators when a fence is damaged. A gyroscope device is installed on each fence post. When the fence is knocked down the gyroscope triggers a text message which is sent to the local fence monitoring staff.
Also the elephants do not like citrus fruits so its possible to grow these types of vegetation around areas as a natural barrier. These structures are called bio-fences. Chilli plants are used as bio fences in Africa but interestingly the Asian elephant is not sensitive to chilli. The citrus bio fences do not just act as a barrier to elephants but also the fruits can be sold at local markets.
The happier sight of a elephants in Wasgamuwa Park. The main way I will be helping out using GIS is with land change analysis of remote sensing images and also just general GPS mapping of incidents and fence damage within the area.
Thursday, 11 February 2010
Forest Eater
My time at HVO is almost up. I have just three weeks left. Whilst here I have developed two GIS models using ArcGIS Model Builder. The first is a probability model to map the probability that an area will be impacted by lava flows, The second is a lava channel model which predicts where lava will flow if there is an eruption by analysing a digital elevation model (DEM). I will post more about these models once they are completed.
Last week we went out to the Kilauea East Rift Zone flow fields. In the days previous to the trip some incredible lava flows had been viewed in the vicinity. The volcano was however now in deflation phase which meant that lava viewing may not be as good. Kilauea undergoes deflation-inflation events or DI events. These events represent phases of inflation and deflation of the volcanic system as magma fills the system and then leaves the system via lava flows or dropping back down into the deep magma chamber. These DI events are captured by GPS units and tiltmeters dotted around the volcano. Despite being in a deflation phase there was luckily still amazing sights to be seen on the flow field. The photo above shows a pāhoehoe lava stream flowing down the pali (cliff) just below the Royal Gardens subdivision.
The lava stream was feeding the a'a flow seen above. This a'a flow was moving slowly down the pali consuming any trees that were its in path. Its easy to understand how the Hawaiian God, Ai-laau which means forest eater got his name.
Friday, 22 January 2010
Kilauea eruption overflight
I went on the weekly Kilauea eruption overflight on 7th January. It was definitely up there with my best experience on Hawaii. The volcano is currently erupting in two locations; at the summit and on the East Rift Zone. We took off from the park visitor centre and headed for the Halema'u ma'u crater at the summit then onto the Pu'u O'o vent on the rift zone (above) and over to the flow fields down by the Ocean.
We landed on the flow fields to put a new memory card in a webcam and took a lava sample from an active lava breakout (above). There is a lava tube system running underground from the East Rift Zone down into the Ocean. Lava can breakout from these tubes when a magma pulse is sent through the rift system. We sampled the lava with a hammer then cooled it rapidly in a bucket of water. The hardened sample is then bagged and sent off to the lab for analysis.
Normally lava flows have been flowing directly into the ocean producing the plume mentioned in previous posts. The ocean entry has temporarily switched off due to a lack of supply to the rift zone (the above photo shows the absence of any plumes). This lack of supply be a blockage which has caused a backing up of magma to the summit area resulting in the increased activity as described below.
Normally lava flows have been flowing directly into the ocean producing the plume mentioned in previous posts. The ocean entry has temporarily switched off due to a lack of supply to the rift zone (the above photo shows the absence of any plumes). This lack of supply be a blockage which has caused a backing up of magma to the summit area resulting in the increased activity as described below.
We also landed right by the Pu'u O'o crater where we cleaned a webcam screen as it gets very murky from the continuous gassing.
Approaching the Halema'u ma'u vent within the Kilauea caldera.
The above picture is looking down into the Halema'u ma'u vent. There has been a lava lake present in the vent for some months but recently activity has increased and the lake has risen to high levels. The picture above shows a rapid lava stream rushing from an upwelling to a draining point on the North side of the vent. A second lava stream is cascading down onto this flow.
images courtesy of USGS
images courtesy of USGS
Monday, 4 January 2010
HVO Fieldwork #2
Unlike the static GPS units mentioned in my previous post, these units are designed for mobility. The survey involves taking readings at set benchmarks along a survey line in the caldera. Any small changes in the position of the benchmarks give indications of deformation which could preceed an eruptive phase.
A gravity survey was also conducted. These expensive and incredibly sensitive devices measure the torque on a metal spring attached to a weight to measure local gravity anomalies. These anomalies could indicate movement of magma beneath the surface.
images courtesy of USGS
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