The impact of climate change needs to be addressed when establishing the context and must continue to
1.1.1 Risk assessment
Risk assessment features an analysis of the types of risk in an area, the time of year when the risk is likely to occur, its potential severity, and the likelihood of it occurring. This article focuses only on the physiographical assessment of risk, whereas the bigger picture includes the additional evaluation of social, economic, and environmental factors.
O Traditional methods
Traditional methods of risk assessment such as rainfall analysis, flood and risk map creation, and water balance (the balance of water supply and demand) have often been conducted on an annual basis and are statistically-based. There is a danger with examining the risks on an annual basis, since flooding and drought problems take place over a shorter time period. The annual water balance may conceal either problem since the total annual water supply may exceed annual demand, but, in any particular month, demand may overshoot the supply and vice versa. This is very likely because the monsoon season begins in May; however, from July to August, sporadic low precipitation is often experienced, followed by intense rainfall in September and October over most parts of Thailand.
Statistically-based studies of flooding and drought risks frequently exclude the consideration of spatial and temporal climate variability; an average is usually reported. For example, the nationwide average precipitation for 2008 was 1,543 mm, 5% higher than the value in 2007. If we look at the country as a
be considered throughout the risk management framework. The major source of risk in water resources, especially water supply, is rainfall. We cannot control where, when, and how much it will rain, and these factors are what causes flooding and drought risks. These risks pose a threat to economic development, from rain-fed agriculture to water utilization in the industrial sector. As for flooding threats, the highest loss was 13,385 million Baht in 20021 , with a total of 72 provinces affected.