The West Baray

In the 11^th century under the rule of King Suryavarman I, construction began on the Western Baray, a reservoir 8km long by 2km wide which initially served a ceremonial function as a depiction of the Hindu Sea of Creation, has also served as a reservoir for irrigation, and is still to be found today outside the town of Siem Reap. At the weekends, locals flock to the ‘Baray’ to drink beer, eat barbecued fish, and swim.

Siem Reap itself sits towards the top of the Tonle Sap, the largest lake in Southeast Asia. During the monsoon, the Tonle Sap increases 540% in size from 2,500km² to 16,000km² as water from the Mekong River reverses direction and fills the lake. November’s annual water festival Bon Om Teuk is a national event, when Khmers celebrate the bounty of the lake, and hold boat races and parties.

The area surrounding the Tonle Sap is home to over 1 million people, who depend upon it for fishing and irrigation.

Kompong Phluk

The communities living around the lake consist of floating villages like Chong Kneas, where everything from the houses to the schools, churches and pig farms are on floating platforms, to villages like Kompong Phluk that teeter on twenty-foot stilts. Around 80% of the population are agricultural workers, and rice paddies cover vast swathes of the country. Cambodia appears, then, to be a country very much at home around water, and which not only expects, but depends on the flooding brought by the annual monsoon for biodiversity and soil fertility – even the Cambodian currency, the riel, is named after a fish found in the Tonle Sap lake.

The UK Government’s Foresight report estimates that 80,000 properties are at very high risk from surface water flooding, causing on average £270 million of damage each year, as annual precipitation is set to become increasingly variable – increasingly monsoon-like. An analysis of average rainfall data for Cambodia and the United Kingdom shows the difference in variability of rainfall, and hints at how UK rainfall patterns may alter in future:

Data: World Weather Information Service, World Meteorological Association

Flooded fields near Kep

While Cambodia has a population density of 77/km² compared to 248/km² in the UK and a predominantly rural population, we may nevertheless attempt to examine how Cambodia manages flooding, to see if there is anything we in the UK can learn about how to live in a climate with more variable rainfall and higher flood risk:

• Habitation in vulnerable areas is built to deal with flooding. Most traditional Cambodian houses are on stilts, or have bases which are resilient to flood waters. The design of new housing in flood-prone areas in the UK can be informed by the architecture of housing in areas where flooding is common – and a UK flood design competition supported by insurance company Norwich Union encouraged just this in 2008. In Holland, amphibious houses are already being built.
• Most roads and tracks have ditches varying in size from small channels to canals, which absorb rainwater and run-off, channelling it away to fields or storing it. Canals and ditches are a common sight in Cambodia. In the UK, drainage and sewerage systems that often age to Victorian times are struggling with the amount of water flowing into them, from surface run-off to household usage – upgrading these systems, already in progress in many places, may go some way to reducing flood risk.
• Relatively sparsely populated Cambodia, with an abundance of rice paddies and other agricultural land, can hold large quantities of water. Respondents to a recent survey on flood risk agreed that farmland would be the best use of river valley floodplains, above housing. Floodplains, managed properly, act as an effective buffer in times of peak rainfall.
• Finally, Cambodia is a country still rich in vegetation and tree cover, which absorbs rainwater into the ground before it can reach rivers, exacerbating flood risk. In the UK, re-establishing hedgerows is one way that agricultural land is being restored to provide effective means of reducing surface run-off, and the further use of trees and vegetation to lessen flood risk can only improve the situation.

If proof were needed of how Cambodia is able to teach us in the UK lessons on managing flood risk, we only need to look back to Cambodia to see how urbanisation, industrialisation and development are now creating problems.

With Cambodia now firmly on the tourist trail in Southeast Asia after years of conflict, Siem Reap now receives over 2 million tourists every year, who come to see the temples of Angkor. Scores of new hotels have been built in the last five years alone. Every year, the main streets of Siem Reap from Highway 6 to Sivatha Boulevard flood, sewage floating in the streets, because more paved roads and significantly greater water usage have put an immense strain on the infrastructure of the town – so much so that the water table has lowered around Siem Reap and Angkor Wat faces collapse. Floods in the countryside have resulted in fatalities and damaged property, partly as a consequence of damming further up the Mekong River in Laos, and partly due to extensive deforestation. Further fatalities resulted from the flooding caused by Typhoon Ketsana in September 2009.

Angkor Wat

Cambodia, a country that for many hundreds of years has lived with an abundance of water, is increasingly seeing water as an enemy, its problems being worsened by the development that the country craves, and which, without proper planning, is leading Cambodia down the same path as us.

The greatest irony is that, as architectural discoveries suggest, Cambodia has already been down this path. The great Angkorian civilisation had collapsed altogether by the fifteenth century, partly as a result of overpopulation, unsustainable water resource management, and climate change. History could be doomed to repeat itself – for us as well as Cambodia.

Related posts:

1. Are you optimistic about the future? I've just finished an Environment course with the Open University,...
2. The Nasca and us Ancient civilisations usually don't get wiped out by just one...

Conquistadors, wars, slavery and syphilis won’t help, of course, but cutting down all of your trees is asking for trouble. And yet this is still happening all over the world, notably in Indonesia, where giant swathes of virgin rainforest are being felled and replaced with monoculture crops (specifically the oil palm), and in Brazil and Africa.

In a worrying recent development, a global forestry treaty, REDD (Reducing Emissions from Deforestation and Forest Degradation), due to be signed at the Copenhagen climate change conference this December is set to allow countries to cut down virgin rainforest, plant monoculture crops such as soy and palm oil, call the results forest, and even claim millions in funding for their preservation. Only if essential safeguards preventing deforestation in favour of monoculture crops is restored will the treaty serve to prevent deforestation, instead of effectively subsidising it.

But why is deforestation such a bad idea? We’ve all been hearing about deforestation for years, but what actually happens, why is it so disastrous, and how does deforested land turn into desert?

No two situations are the same, but here are some of the things that happen when you cut down all of your trees:

Habitat fragmentation

Fragmented habitats - an aerial view of an area deforested by soybean farmers. Image: Greenpeace

Habitat fragmentation is what happens when the preferred physical and biological environment in which an organism or group of organisms live  (their habitat) is broken up. This creates more ‘edge’ or boundary areas with non-preferred habitats, reduces the size of habitats, and alters the micro-climate of each fragmented pocket of habitat. Species immediately become more vulnerable.

Habitat fragmentation in tropical forests is primarily caused by deforestation. Deforestation may be performed for logging, agriculture or rural development, or as a consequence of activities such as oil exploration, mining, road building, and dam construction. Tropical forest habitats may also be fragmented in the longer term by geological or climate change, but the blame for deforestation usually lies at our door.

Species extinction and human cost

Species which would usually avoid living at the edge of their habitat are at greater risk of predation by other species that may avoid venturing within the forest, including humans. The ‘edge effect’ may also increase competition for food and other resources, and a change in microclimate at the habitat edge may cause exposure to higher temperatures and winds, all with less shade and protection. The edge effect is exacerbated the more fragmented the habitat is – like the coast of Norway, there is exponentially more ‘edge’ as time goes by.

Orangutans are reluctant to leave their habitat even if it is destroyed around them. Image: Orangutan Foundation

Habitat fragmentation leads to smaller habitats, increasing competition for resources, creating a scarcity of some resources and having potentially a far greater impact if species within the food web die off and in turn starve dependant species. Finally, smaller populations of species in fragmented habitats are more susceptible to extinction through decreased genetic diversity and disease.

Assessing the vulnerability of a species within a fragmented forest habitat is difficult, as different species of different sizes have different space requirements, and so may be more or less susceptible to habitat fragmentation and reduced size. Some species may also have a symbiotic relationship with partner species within a habitat which, if lost, will be disastrous for them. Finally, some species simply emigrate to alternate habitats – if you have legs and wings, and you’ve run out of food, it’s time to move.

But this doesn’t always happen. Orangutans are unwilling to leave the canopy even if they’re perched at the top of the last tree in the forest. It also goes without saying that humans affected by deforestation and changes to their habitat may simply have nowhere to go. Tribes may not be able to move for economic, political or social reasons. There are many examples of tribes who, having been displaced from their traditional lands, with no source of income and no means of subsistence, fall into a downward spiral of alcoholism, drug use and despair. Right now, the Ayoreo-Totobiegosode tribe, one of the last uncontacted tribes outside the Amazon, are losing their land to beef production.

Soil erosion and desertification

Exposure to higher temperatures and winds at the habitat edge, without the benefit of plant cover and root systems due to the damage to plant species, leads to soil erosion. In the case of most rainforest environments, the nutrients needed for plant and animal life to continue are stored in the canopy, not the ground. Felling and burning the forest leaves soil bereft of nutritional value, unable to support the vegetation that would bind it together and regulate moisture. Crops grow only with the intensive use of fertilizers, polluting watercourses and causing eutrophication (a buildup of algal plant life which chokes all other plant life).

This erosion has the potential to encroach ever further into fragmented forest habitats, increasing fragmentation and eventually leading to desertification, wiping out entire habitats and driving plant and insect species to extinction. An entire habitat may also be at risk from changes in water flows due to erosion, flooding and increased river levels. Changes in wider climate such as precipitation levels may indiscriminately affect the entire habitat, including the interior.

The Nasca and us

The Nasca disappeared around 1500 years ago, and the recent Cambridge University study suggests that a significant factor in their demise was their destruction of the huarango trees that played such an important role in regulating soil moisture and nutrients. The Nasca, in their drive to plant more crops and to build, destroyed their own environment.

World population in the time of the Nasca was around 300 million. It is now over 6.5 billion. The landscape has changed beyond recognition, but the mistakes the Nasca made are being repeated now, on an exponentially wider scale. What’s different now is that we in the Western world are witnessing the destruction of other tribes, species and environments, to maintain ours. Tribes like the Ayoreo-Totobiegosode, and species like the orangutan, are more vulnerable than the Nasca ever were, because they are shouldering the burden of our consumption.

More info and actions:

• Uncontacted tribe’s forest bulldozed for beef – write a letter to the President of Paraguay
• Support the Orangutan Foundation campaign ‘Protect me and my tree’
• Palm oil – rainforest in your shopping (Friends of the Earth)
• Important safeguards to protect rainforests lacking in REDD negotiating text
• Boreal forests store twice as much carbon as tropical – so why aren’t we doing more to protect them?

Related posts:

1. REDD A fascinating article on the Washington Monthly website by (I...

Related posts:

1. Sandbag New website http://sandbag.org.uk/ offers a solution to carbon emissions by...