Abstract: One of the main challenges in the world is adaptation to the impacts of climate change, and it is important to understand which impacts will take place in each region. Thailand endures substantial damage from floods every year and needs accurate measurement to mitigate flood disaster predicted under the looming scenario of climate change. The predicted impacts of climate change on flood discharge need to consider land use changes in the future, especially in developing countries because of their vulnerabilities to economic growth. The objective of this study was the quantitative predictions of the impacts of climate change and land use changes on flood discharge, using two simulation models at one watershed in the Song Khwae District, Nan Province, Northern Thailand. This study has three steps: (1) predictions of future land uses (14 scenarios having different proportion of forest cover), (2) calculation of 3.3 and 10-year return period rainfall for the period of 2006-2016 and 2040-2050, and (3) comparisons of average daily discharge from 3.3 and 10-year return period rainfall in 14 land use patterns. The results showed that although climate change will decrease the average daily discharge from the 3.3 and 10-year return period rainfall, discharge from future rainfall that has a 10-year return period, where land use patterns limit forest areas to less than 45%, will be greater than present levels. These quantitative predictions can lead to cost-benefits performance analysis and contribute to positive adaptation to climate change.
Keywords: Climate change, Adaptation, Land use, Flood, CLUEs, SWAT