Australian Rabbits

Image result for rabbit australiaThe European rabbit, Oryctolagus cuniculus was first introduced to Australia in 1788 by the First Fleet for food. They remained in a small population for many years, but due to introduction of feral rabbits, a newspaper in Tasmania in 1827 noted that the “common rabbit is becoming… numerous throughout the colony, that they are running about on some large estates by thousands.”

Artificial warrens were used in some areas, such as near Sydney to grow rabbits for their meat, surrounded by a stone wall to prevent- or try to prevent- their escape. Rabbit-theft was common in the 1840’s.

Alexander Buchanan released numerous rabbits into the wild in 1857 for recreational hunting purposes of white settlers into Australia, in South Australia. The number in the wild was fairly constant due to carnivore presence until 1866, but suddenly rocketed upwards due to a decline in predators and the emergence of hardier breeds.

Thomas Austin also released a population of 24 rabbits into the wild in 1859. He had asked his English nephew for 12 rabbits, 5 hares and 22 partridges so that he could continue hunting on Australia. Austin received fewer rabbits so ordered in some domestic rabbits. It is thought that the interbreeding of domestic and wild rabbits contributed to the resilience of the exploding population. Those who released rabbits thought they could do little harm to the environment.

Australia has ideal conditions for rabbits:

  • Mild winters allow year-long breeding
  • Areas cleared for farming which were otherwise forests made large areas of ideal grassland habitat
  • There were a lack of diseases that would target rabbits.

By 1920 some estimates put the number of rabbits in Australia as high as 10 billion, although this is likely to be a high estimate. There are now estimated to be a total of over 200 million Australian rabbits, found throughout the country.

Various methods have been introduced to try to remove or even just reduce the huge rabbit population. Initial attempts of conventional methods such as shooting individuals and destroying warrens have had limited success.

Positive Impacts

The positive impacts of the Australian rabbits are highly limited. By 1869, so many had escaped or been introduced that two million could be caught and killed every year with no significant impact on their population just 10 years after introduction, which provided a constant food source, and allowed enough hunting to prevent other, additional species being introduced. During the collapse of the stock market in 1930, and during the world wars, the rabbits helped provide food and income to Australians, and helped to pay off debts.

Negative Impacts

12-16 rabbits can consume as much as a grown sheep, which demonstrates the huge demands their massive population can put on the environment, when the size of sheep fields are considered. In Hattah-Kulkyne National Park, a population of just 0.6 rabbits per hectare managed to kill all of the Buloke plant saplings.

  • They are considered the most significant factor in the loss of endemic species
  • Compete for resources with native species
  • Have contributed to the decline of the greater bilby, yellow footed rock-wallaby, southern and northern hairy-nosed wombats, the malleefowl and the plains-wanderer.
  • Many Australian plants will only reproduce after extreme weather, meaning that their breeding seasons are very rare and valuable. Rabbits consuming young plants mean that these species may not get to reproduce for decades.
  • Rabbits tend to favour newly growing plants over grown ones, meaning that young plants do not have a chance to reproduce before they are eaten. This makes them a threat to afforestation techniques to help reduce flooding, soil erosion and many other risks.
  • Compete with livestock for pasture
  • Eat crops- leading to the building of the Western Australian rabbit-proof fence to prevent damage to local farms.
  • Australian rabbits cause $113 million per years lost in production and control costs.
  • They often kill young trees by chewing off sections of bark completely around the trees, or even just eating the entire plant.
  • Native plants are not available for horticultural and agricultural work.
  • They eat native plants, laving top soil exposed. This has lead to an increase in erosion as the land is now vulnerable to sheet, gully and wind erosion.
  • It may take 100s of years to restore prior soil conditions. Their soil impact is significant enough to be noted on official government legislation.
  • Local water systems are effected, with increased run off, and increased siltation and bank erosion. This increases local water treatment costs in many areas, as well as natural ecosystems.
  • Dust from wind erosion can reduce air quality.
  • The presence of rabbits encouraged the growth of populations of other invasive species, such as cats and foxes. This increases the effects of predation upon other native animals.

More detail can be read here on precise impacts onto the ecosystem: http://www.rabbitfreeaustralia.com.au/rabbits/impacts/

Control Measures

By 1887, the New South Wales government had offered a £25,000 reward for “any method of success not previously known in the Colony for the effectual extermination of rabbits” due to losses from rabbit-caused damage. 1456 suggestions were received. A royal commission investigated the situation in 1901.

Shooting

This is a very common method for control of small populations. It also provides earnings on the small scale for individuals. However, it does not work on vast populations effectively.

Warren destruction/attacks

Destroying warrens through ripping, where rabbits are buried by a bulldozer working over their warren is another common technique, as are by ploughing, blasting and fumigating. Sandy soils through much of Australia mean that ripping and ploughing are both fairly effective.

A poison may be introduced into the warren or into the surrounding area, so that the animals are killed off by the toxin.

Ferret hunting is a fairly simple technique, where trained ferrets are  introduced into the warren and are made to chase rabbits out to be shot or caught. The capacity for this is limited, due to the ferret numbers being capped by training requirements and each ferret’s stamina, but in conjunction with other techniques, it can be useful.

Historically, traps were placed near tunnel entrances. However, steel leg-holding traps were banned in much of Australia on the grounds of animal cruelty in the 1980’s.

Myxomatosis

Myxomatosis is often shortened to myxo or myxy, and is a virus caused by the myxoma virus among rabbits, and was introduced to Australia in 1950 to help suppress the growth of the rabbit population. The disease causes skin tumours, blindness, fatigue and fever, and eventually, usually, death within 14 days of contraction. It can be spread by the bites of insects such as fleas, where it does not replicate, but is instead passed along by further later bites while it is in a latent condition.

Cottontail rabbits gained only localised skin tumours whilst the European rabbit will more normally gain large lumps around its head and genitals. This can progress to conjunctivitis and sometimes blindness. They become fatigues, lose their appetite, and start to develop a fever. Secondary bacterial infections are common. Death can occur within just 48 hours.

The virus was first field tested for population control in 1938, and was released in 1950. Initially, the rabbits would die typically within just 4 days, which gave little time for the spread of the virus. A more virulent form soon became prevalent, which spread more effectively because it had a lower potency. It reduced the estimated population from 600 million to 100 million in just two years. However, the remaining rabbits were those least affected by the disease; genetic resistance started to develop very quickly, with partial immunity developing in just two decreased. Resistance has continued increasing since the 1970’s, and now kills about 35% of infected rabbits. A second virus was introduced (rabbit calicivirus) in 1996 to further reduce the population.

Rabbit Calicivirus

In 1991m Czach CAPM 351RHDV, a strain of rabbit calicivirus causing rabbit haemorrhagic disease (RHD), was imported to Australi under quarantine to see if it could be used as a biological agent against the New Zealander and Australian rabbit populations. Testing was performed on Wardang Island in Spencer Gulf, off the coast of Yorke Peninsula, South Australia. In 1995, the virus escaped and killed 10 million rabbits within 8 weeks of its release.

RHD typically only effects adults, with individuals younger than 8 weeks being highly resistant. Victims will tend to die within 36 hours. RHD typically causes rapid blood clot foramtion in major organs. Even those which do not die are typically highly effected, and symptoms can include any of the following:

  • Fever
  • Squealing
  • Coma
  • Uneasiness
  • Anorexia
  • Swollen eyelids
  • Ocular (eye-based) haemorrhages
  • Paralysis
  • Loss of skin
  • Bloody nasal discharges
  • Severe jaundice
  • Lethargy
  • Major weight loss
  • Diarrhoea
  • Constipation
  • Cramping

Within New Zealand the initial attempts to use it in a culling program included a series of cases where farmers would include animals known to be infected into their processing. It was introduced 2 weeks after the breeding season, so all the individuals who survived being born that year survived the virus, showing the need for careful planning of biological techniques.

The virus is generally passed due to other animals picking up the virus and it remaining dormant within their bodies until they pass it out as faeces. Excreted viruses can then infect the rabbits. Fleas and mosquitoes can also spread the virus.

 

Rabbit-proof fence

Image result for rabbit proof fence australiaConstruction started in 1901 by private constructors, but the project to build a fence to prevent rabbit entry was passed over to the government in 1904. The rabbit-proof fence was built across Western Australia in 1907. It was, at the time, the longest unbroken fence in the world, at 1,833 km long.  There are now 3 fences. No 1 crosses Western Australia from north to south, No 2 is further to the west while No 3 runs east to west, so that all three together now make 3, 256 km worth of fencing. The cost was $250 per km length, in total costing $814,000.

It was designed to reduce the passage of foxes and dingoes too, neither of which are native species. Originally wood was used, but termites started to eat through it so it had to be replaces with unattractive woods for termites (pine, mulga, tea tree or wodjil), or with steel.

(Image Sources: http://www.rabbitfreeaustralia.com.au/rabbits/the-rabbit-problem/

http://slwa.wa.gov.au/wepon/land/assets/images/000876d.jpg)

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Zhouqu County Mudslides

On the 8th August 2010, a mudslide occured in Zhouqu county, in southern Gansu province (Gannan Tibetan Autonomous Prefecture) in the PRC. The mudslide was 5km long and 300m wide, and up to 5m thick in places.

Causes

The mudslide was caused by a variety of factors, human and physical.

Forests around Zhouqu had been cut down for mining and agriculture which lead to soil erosion and destabilisation of the slopes, as roots were no longer holding the soil together and trees could no longer absorb water from the soil, leading to faster soil water saturation.  Despite the logging ban in 1998, trees continued to be felled. In the PRC, there had been 53 hydroelectric construction projects in recent years, with 12 just within Gansu province, where Zhouqu county is located. The dams have caused 750,000 tonnes of water and soil erosion and over 3 million cubic tonnes of bulldozed material, throughout the country. This has left the slopes weak and exposed to rainfall, allowing slides to occur more readily.

Oscillations between the patterns of El Nino and La Nina (climatic events where air currents across the Pacific Ocean change, effecting the local weather systems among dozens of countries) caused unusually intense monsoon rains in 2010.  Regions were receiving an extra 24 mm of rain above the normal daily rainfall. In ‘the largest downpour for a century’ 96 mm of rain fell in just one hour in the area.  The earthquake in Sichuan two years previously created cracks in the rock face and destabilised the ground; Zhouqu county is very close to Sichaun province, so instabilities within Sichaun can very easily effect towns within Gansu, directly to the North. The 9-month drought which preceded the heavy rain had added to the weakness and instability of the soil, especially when followed by the heavy rainfall.

Impacts

Social Impacts:

  • 1,471 people died due to the slide.
  • 1,200 people had to be rescued from the debris.
  • 300 people were never found, and are presumed dead.
  • 1,700 people who were evacuated from the immediate area were forced to live in schools. In total 45,000 people in Zhouqu county were evacuated.
  • Medical care in the region was disrupted as 10 doctors from the Zhouqu People’s Hospital were among the missing.

Economic Impacts:

  • 66% of the county went without power, disrupting local businesses and transport.
  • More than $40 billion worth of damage was caused in Gansu.
  • Power lines were down in 2/3 of the county which had to be repaired. Wider infrastructure was destroyed at great cost.
  • Mudslides throughout China in 2010 destroyed 8.76 million hectares of crops to be destroyed.
  •  The livelihoods of millions of people were entirely destroyed or otherwise decimated and China’s capacity to export was massively reduced.

Environmental Impacts:

  • 300 buildings were buried under mud.
  • A 3km temporary lake formed behind a blockage when the mudslide reached the local river at the base of the city of Zhouqu where the slide occured. This dam later burst causing further damage.
  • The river was clogged with debris, damaging habitats and reducing biodiversity.

Management 

  • 7,000 soldiers, firefighters and medical staff were deployed by the government. 20 speed boats and 4 helicopters were also mobilised.
  • Gansu province received 120 million yuan ($17.7 million) by August 13th 2010.
  • The PRC government promised local families $1,182 worth of financial aid for each victim lost.
  • Tents, food and medical supplies were rushed to the stricken area but the remote mountainous location made access difficult.
  • The governmentpromised to help rebuild homes and buildings in the affected area.
  • A National Day of mourning was observed to help with the emotional trauma.

France- Energy Mix

1973 Energy Mix

  • 40% coal
  • 17% oil
  • 19% gas
  • 5% nuclear
  • 6% HEP
  • 13% other renewables

2005 Energy Mix

  • 5% coal
  • 32% oil
  • 15% gas
  • 42% nuclear
  • 2% HEP
  • 4% other renewables

France imports 99% of its oil, largely from Norway and OPEC.

Coal was previously mined in the North East of France but  the difficulty of extracting new coal and the expense of accessing it caused the closure of the remaining coal mines at the beginning of the 21st century. The oil crisis of 1973 drove the creation of 59 nuclear power stations.

The need to comply to greenhouse gas emission regulations has led to a resurgence in interest in nuclear power, largely in replacing, not removing, old plants. Nearly 60,000 people work in the nuclear power plants. Their expertise has allowed the French company EDF to work internationally.

HEP power is concentrated in the alps and along the river Rhone. The Rhone produces 25% of France’s HEP, which is 5% of the country’s generated electricity overall.

There are plans to import electricity from Northern Africa. For instance, Algeria, a former French colony, has operational solar plants already.

France was an early pioneer of tidal power and built a tidal system across the river Rance, but have built no further commercial tidal energy projects.

Most oil used in France is used in transport or heating. HEP is used to back up the nuclear power supply at peak times.

Yorkshire glaciers

The North York Moors has several overflow channels which are thought to have cut through the moors during the last glacial period. The largest is Newtondale; which is 15km long and 80m deep. Peak flow would have been around 10,000 cumecs.

Ice lined the current coastline and trapped in water along the moors. Water couldn’t flow out of the ends of glaciers and built up inland in large lakes between the hills and the other glaciers. As the climate warmed, more water pooled there. The area became a glacier-dammed lake. Water level rose until it spilled over the lowest col, at 200m. The volumes of melt-water cut through the Newtondale overflow channel.

A similar process also occured nearby at Lake Pickering, cutting out the Kirkham Abbey Gorge, and several other sites were effected by the glaciers

Cleaning up the Singapore river

The Singapore river and the Kallang Basin are a major river catchment and port area on the southern part of the island of Singapore. Major industrial and population growth in the area during the 1960’s and 1970’s turned the river basin into what was described as a “black, foul-smelling waterway devoid of any aquatic life”. The reasons for this were:

  • Raw sewage from squatter settlements flowing into the river
  • The river basin being used to dump waste by farmers and other residents
  • Chemical pollution from heavy industry and ships discharging polluted water into the basin

The Singapore government put in place an environmental action plan to clean up the area. This included moving squatter settlements into proper residential areas with sanitation facilities, the development of stricter pollution controls, and the removal of livestock from alongside the river

Once sources of pollution were removed, the whole area started to recover. Riverside walkways and parks have been built and thousands of trees planted. The beach along the Kallang Basin has been imrpoved with recreational facilities developed.

In 2008 the government announced a further plan to “transform the waterfront into a gathering place for recreational and cultural activities” by building a national stadium, leisure developments and further residential areas.

Dereliction in the Lower Lea Valley, London

In the 1970’s and 1980’s globalisation led to deindustrialisation of London. The Thames barrage has only made it harder for shipping to reach companies within the city. Along with this loss of industry came vast amounts of unemployment.

Some restaurants now provide beach volleyball, champagne and similar assets, after the renovations for the 2012 Olympics. The rest of this post concerns the past state of affairs before Newham became the site of the 2012 Olympic Park- and why it became that.

The Lower Lea Valley was used for the Olympic water park during the games. The canals had been unused for 30 years, so they were clogged by silt and weeds.

Newham contained 42% of London’s brownfield- previously used- land. Brownfield sites had been vacant for 20 to 30 years. It was unattractive to developers due to:

  • Being fragmented into small plots
  • Some sites containing pollutants that would need to be cleaned out
  • Being criss-crossed with overhead powerlines, sewers, waterways, roads and rail lines.

These factors all lead to the regeneration for the 2012 Olympic park being so expensive to build.

 

Bangladesh flood action plan

The Flood Action Plan (FAP) relies on huge levees along the rivers’ length. At an estimated US$10 x10^9 they could take 100 years to build. Up to 8000 km of levees are planned for the 1600 km of river in Bangladesh. They are not able to withstand the most severe flooding, such as in 1987, 1998 or 2007. The embankments contain sluices to reduce water flow and to control damage caused by flooding.

They are set back from the river, which protects them from constant erosion and is also cheaper to install.

The FAP still has many issues:

  • Increased time of flooding, since embankments prevent back flow into the river
  • River channelization by levees may increase the risk of flooding downstream and in the area between the levees
  • Channelisation will also increase deposition between levees rather than on the floodplain, which has been seen to be an issue in Lousiana during Hurricane Katrina
  • Not enough sluices have been built to control the level of floodwater in rivers. There may be increased damage to land if embankments are breached
  • Sudden breaches of embankments may also deposit deep layers of infertile sand reducing soil fertility and affecting agriculture
  • Compartmentalisation of the drainage basin may reduce the flushing effect of floodwaters to remove pollutants
  • By preventing back flow to the river, areas of stagnant water will be created which may increase the risk of diseases related to water supply
  • embankments may cause wetlands to dry out, losing biodiversity
  • Decreased flooding will reduce the number of fish, which is a major source of protein

The rivers are largely controlled by factors outside the country. Floods in Bangladesh are also not just related to rivers, and the rivers are needed for agriculture and other industries.

The FAP has overall led to social, environmental and economic issues within the Bangladeshi population.

Costa Del Sol- part I

Tourism is a major economic asset in Mediterranean countries, with a strong emphasis on the coast, putting pressure on coastal areas. Despite environmental protection, 200 km of coastline is being developed each year and by 2025, it’s predicted that half of the coastline will be built upon, with some conurbations lasting for hundreds of km.

Pressures on the Costa Del Sol

  • Growing population of coastal areas
  • Development of airports, holiday resorts and general urban sprawl leading to damage to disappearance of fragile wetland ecosystems
  • Poor management of coastal areas leading to change in sediment flows
  • Removal of marine sediment for construction sites has damaged the sea bed
  • Oil and gas infrastructure development has seen a rise in the numbers of oil tankers- about 30% of all oil transits go through the Mediterranean
  • Use of chemicals in agriculture has increased river and sea pollution.
  • Rising rates of eutrophication
  • Industrial developments have increased chemical discharge
  • Uncontrolled waste management
  • Untreated water waste being discharged to the sea
  • 650 tons of sewage, 129,000 tons of mineral oil, 60,000 tons of mercury, 3,800 tons of lead and 36,000 tons of phosphates are dumped in the Mediterranean annually

Shipping- it is estimated 220,000 merchant ships transporting 100 tons of material cross the Mediterranean annually.

Fish stocks- 65% of stock within the region are outside safe biological limits, and many important stocks are threatened

Industry- fish farming in the Mediterranean accounts for 30% of global fish consumption. The industry claims this reduces pressure on wild stocks, but farmed species are often carnivorous so need 5x their weight in wild fish to support them

Management

In 1975, the Mediterranean Action Plan (MAP) was set up as part of the United Nations’ Environmental Programme (UNEP). MAP’s goal was to protect marine environments along the Mediteranean. In 1995, this was widened to include the whole coastal region.

A strategy was drawn up by 300 scientific experts in a report presented in 2006 which gave the following recommendations:

  • 10% of all marine and coastal habitats should be protected, adding to 80 currently protected wetland areas
  • Green areas between urban areas are to be encouraged to reduce linear development
  • Reduction of linear road building
  • Inland tourism should be encouraged to reduce pressure on the coast
  • Future tourist development should show awareness for the environment in planning and show economic responsibility for the environment when completed
  • Stricter rules to combat pollution from boats
  • Improved energy management in order to reduce the need for coastal power stations
  • All waste water should be fully treated before being discharged into the sea.

San Gabriel River Flood Controls

The San Gabriel river is situated in California, and runs through Los Angeles. It has the most extensive water control system in the world, in a basin 3,000 km^2.

The Ovens lake is 400km from LA, Sacremento river is 600km away and Parker Dam is 400km away. Between them 300 million m^3 of water is transported to LA daily.

Problems regarding the river- why is flood control needed?

LA is the fastest growing urban area in the USofA. In 1890, LA had a population of 11,000, which was largely made of native American tribes, but by 1990 it had a population of 11 million. In 2015 the population was 3.884 million people.

The headwaters where the San Gabriel starts are in mountains up to 3,000 m high. The valleys are unstable and steep-sided. They are fairly straight with gullying along hillsides; overall they are v-shaped with a steep gradient.

Where the valleys meet with the lowlands below, there are large alluvial fans of depositional material, and there was, previously, large amounts of river braiding.

  • Large population growth
  • Quickly saturated soil in mountains during rain
  • Little vegetation present in the mountains- semi arid environment 
  • Concrete surfaces in town

Past flood

In 1938 there was a flood of the San Gabriel due to a lack of river controls. This was during the economic depression that affected much of the world, so there simply wasn’t funding to help prevent flooding. There was also less money available to build so that structures could withstand flooding.

Control measures

The Los Angeles Flood Control Authority was set up in 1915, after flooding in 1914. The first flood control works started in 1917. There are five main components (listed in order from the headwaters):

  1. Check dams on upper tributaries. These stop debris from the uppermost points in the stream.
  2. Debris dams at exits from the mountains. These collect dirt and sediment carried from higher up. This reduces damage caused by flooding and reduces the chances of there being blocked channels.
  3. Control dams. These control the flow of water downstream. Water is trapped behind and released at a steady rate as water levels lower. The first control dams along the river are 25 km from the source and control water flowing from 500 km^2
  4. Spreading grounds.  Water is absorbed into the soil here- a sort of holding pen is built where water is trapped. These occupy vast areas with only a shallow layer of water, so water readily either evaporates or percolates into the soil. One examples of these is Rio Hondo.
  5. Concrete-lined channels.  These control the direction of travel of the water. A deep channel with a large hydraulic radius is provided, so water travels efficiently down it. As it is very deep, even if water gets past the other measures, such as if there is a storm and a lot of water falls away from the mountains, then there is still a very low chance of flooding. There are over 640 km of concrete lined channel.

Only 2% of the rainwater within the San Gabriel basin ever reaches the sea. The rest percolates into permeable rocks, evaporates, or is used by people.

The dams have to be emptied after rain to remove the debris. The debris is either dumped elsewhere or used as aggregate for engineering.

The Whittier Narrows are an example of a site where a single dam has blocked two tributaries.

One of the large dams is the Santa Fe dam, which is 7 km long and contains an area of water of 445 hectares.

Issues with the management

  • Less sediment reaching the coast.
  • Beaches are not being built up
  • Removes natural attraction of the beaches
  • Removes natural shoreline protection from the beaches, putting beach-side properties at risk.

 

(Image Sources: https://en.wikipedia.org/wiki/San_Gabriel_River_(California) https://dpw.lacounty.gov/wmd/watershed/sg/ http://pubs.usgs.gov/wri/wrir034279/wrir034279.pdf https://www.kcet.org/shows/departures/the-other-river-that-defined-la-the-san-gabriel-river-in-the-20th-century )