In 2011, Thailand faced the worst fl ooding it had seen in 50 years. Floodwaters swamped more than two-thirds of the country, submerging rice fi elds and shutting down hundreds of factories. Severe fl ooding started at the end of July and spread through the provinces of northern, north-eastern and central Thailand along the Mekong and Chao Phraya river basins. In October, fl oodwaters reached the mouth of the Chao Phraya and inundated parts of Bangkok. Flooding persisted in some areas until mid-January 2012, and resulted in a total of 815 deaths and 13.6 million people affected (see Figure 27.1). Sixty-fi ve of Thailand’s 76 provinces were declared fl ood disaster zones and over 20,000 square kilometres of farmland were damaged (see Figures 27.2 and 27.3). The disaster has been described as ‘the worst fl ooding yet in terms of the amount of water and people affected’ (see Table 27.1). The World Bank ranked it the world’s fourth costliest disaster, surpassed only by the 2011 earthquake and tsunami in Japan, the 1995 Kobe earthquake and Hurricane Katrina in 2005 [1].