Each year in South East Asia, the months from June through October see monsoon rains, consisting of torrential daily rainfall. This is a predicable annual event in Cambodia, where 75% of the country lies no more than 100m above sea level, and sophisticated irrigation systems and reservoirs were built a thousand years ago. As increasing population, tourism and industrialisation hamper Cambodia’s ability to manage flooding, what can we in the UK still learn from Cambodia about flood management?

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.

Kompong Phluk

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

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