Thailand has an average annual rainfall of over 1,300 mm; however, some parts of the country continue to suffer drought problems due to the uneven distribution of rainfall. Thailand has frequently
suffered from flood and drought as shown in Figure 3. Flooding usually occurs during the monsoon season (September-October) when there is intense precipitation. Drought (mainly water shortages for irrigation purposes) occurs in summer or when rainfall is delayed in the early part of the rainy season (July). Some particular areas experience both flooding and drought conditions in a single year, due to temporal and spatial uncertainties in the monthly rainfall or the poor management of the conveyance infrastructure. The common practice in Thailand is to manage the risks after considering which areas are likely to be vulnerable to either flood or drought. Failure to manage risk by addressing one aspect at a