Mark Gordon, Chris Spoons
According to the World Bank, flooding is the most frequent of natural disasters globally. In 2010 alone, 178 million people were affected by floods. The total monetary losses in years with an exceptional amount of flooding, such as 1998 and 2010, exceeded $40 billion. These statistics show flooding is a serious challenge which present an urgent need for better planning to manage future risks.
One of the costliest disasters occurred in 2011 during the monsoon season in Thailand. Flooding began in Thailand’s northern and central plains along the Chao Phraya and Mekong river basins. Floodwaters descended over several months and reached parts of the capital city of Bangkok in October, leaving it a virtual island among the floodwaters.
The country saw severe flooding in 1983 and 1995, but the 2011 floods caused greater damage. As of December, 2011, more than 500 lives were lost and 12 million people affected. Sixty-five of Thailand’s 77 provinces were declared disaster zones, more than 7,700 square miles of farmland submerged, and more than 1,000 factories were closed. The World Bank estimated the economic loss was more than 1.4 trillion Baht ($45.7 billion).
While there is often some flooding during the rainy season, there were several factors contributing to the severity of the 2011 floods. The three large dams that help regulate water flow in the central plains were unable to cope with the large amount of rainfall. Authorities had to release water into already very full rivers. In addition, the high tides in October and November meant the water level of the Chao Phraya was already high, making it more difficult to accommodate the runoff of floodwaters from the north.
The situation was further complicated by the government’s decision to keep the center of Bangkok dry by shoring up floodwalls. The rationale was to try to save the economic engine of the country, and flooding the inner parts of the city arguably would not have a great enough impact on draining surrounding suburbs to justify the cost. However, this resulted in some communities being flooded in order to spare the capital, leading to resentment among those who ended up on the wrong side of the sandbags. There were protests in some affected communities and reports of residents intentionally breaching the floodwalls. In some cases, this happened while the authorities and police looked on, not wanting to intervene in an explosive political and public safety situation.
Causes of Flooding
Attempts have been made to mitigate flood damage in the Chao Phraya River Basin through the construction of dams, reservoirs, dikes and pump stations, but flooding is still an issue due to both natural causes and human intervention.
The main natural causes are excessive water flow of the river, heavy rainfall, and tides. Excessive water flow of the river can cause widespread flooding. According to the Royal Irrigation Department, approximately 400 million cubic meters of water from the Chao Phraya River can usually empty into the sea by a combination of natural water flow and a network of sluth gates. During the 2011 flooding, an estimated 16 billion cubic meters needed to drain.
Heavy local rainfall is usually the main cause of inland floods, as it often exceeds the drainage capacity of the local areas or streams. Tidal fluctuation at the river mouth of the river can affect the drainage of floodwaters into the Gulf of Thailand, and likely played a role in October and November of 2011. This prolongs the period of flooding, especially in the coastal regions.
The most common human-made causes of flooding in the region are deforestation and expansion of farmlands and urban areas. Rapid urbanization and land development in downstream areas along the Chao Phraya River have led to an increased potential for flood damage. A substantial amount of industrial growth has also taken place on the flood plain north of Bangkok. Rice paddies were paved over to make way for factories, housing, and other services, impeding the natural path of water runoff during the monsoon season.
Lessons from the 2011 Thai Flood
Bangkok is a member of the United Nations International Strategy for Disaster Reduction “Making Cities Resilient” campaign. Among the ten essential actions promoted by the campaign is the maintenance of critical infrastructure to reduce the risk of disaster.
In order to reduce the risk of future flooding, the Thai government has created a water management program, but the plan will take time to implement. The master plan includes an allocation of 50 billion Baht ($1.6 billion) to build dams in four basins in the northern region of the country. Another 120 billion Baht ($3.9 billion) have been designated for the construction of floodways and flood diversion channels, with work scheduled to begin this year to enhance canals.
Sixty billion Baht ($1.9 billion) have been allocated to convert two million rai (800,000 acres) of farmland along the Chao Phraya into water retention areas. This would require moving current residents elsewhere.
A World Bank publication, “Cities and Flooding: A Guide to Integrated Urban Flood Risk Management for the 21st Century,” is available free of charge and provides guidance on how to manage the risk of floods in the urban environment. Among the cautions in the document is the reminder that heavily engineered structural measures (such as the construction of dams) can be effective when used properly, but they reduce flood risk in one location and transfer risk to other areas upstream and downstream. Non-structural measures are usually designed to minimize rather than prevent risk.
Effective flood risk management requires the cooperation of multiple stakeholders. Effective engagement with those at risk is key to successful implementation. Engagement increases a sense of involvement, increases compliance, and reduces conflict.
The public should keep in mind that any measures, when complete, are designed to mitigate the impact of floods, but cannot prevent flooding from occurring.
Mark Gordon is associate dean of the School of Public Policy and Administration at Walden University.
ASPA member Chris Spoons is a Ph.D. candidate in public policy and administration at Walden University. Both may be reached at: firstname.lastname@example.org.