Thailand's massive US$11.8 billion plan for a series of dams and canals to keep the waters of the Chao Phraya River away from Bangkok is drawing concern that it may be inappropriate, too expensive, and a gigantic magnet for corruption. The government set out to put the plan in place after once-in-a-century floods in 2011 caused extensive damage, disrupted supply chains, nearly engulfing the central city. However, Japan's aid agency has presented an alternative plan that costs about half the price, and has questioned some of the assumptions and requirements in the Thai government plan.