Implications of Deforestation on Climatic and Hydrological Changes at Surat Thani Province, Southern Thailand

Siripong, Absornsuda¹, Siripong, Wish², and Sugimoto, Takashige³

¹Marine Science Department, Faculty of Science, Chulalongkorn University, Bangkok 10330 Thailand ²Chemical Engineering Department, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 Thailand ³Fisheries Environmental Oceanography Department, Ocean Research Institute, University of Tokyo, Tokyo 164, Japan 

Abstract

Tropical forests in Thailand have been destroyed from various factors. The main cause is from the population pressure. The last largest area of tropical forest in Southern Thailand is in Surat Thani. The diminution of forest areas in this region has had some effects on climatic and hydrological changes, namely rainfall, relative humidity, cloudiness, sunshine duration, tropical storm passing Thailand, Tapi River runoff and mean sea level have been reduced. On the other hand, the atmospheric temperature and pressure have risen. The increase of concentration of carbon dioxide in the atmosphere has been attributed to the combustion of fossil fuels, but about a third is thought to come from deforestation. Before 1900 the emissions of this biotic carbon (from deforestation) were greater than those from fossil fuels. The current growth rate of deforestation appears to be greater than that of the use of fossil fuels. The main effect of climate change will be on the unmanaged ecosystems, particularly forests. River runoff is highly sensitive to changes in precipitation patterns. These interrelationships among the climate, hydrological processes and ecosystem are two-way processes. Moreover, changes in climate are also expected to alter the frequency and intensity of the extreme events, such as floods and droughts. In addition, those have been natural disasters, for example, on the catastrophic flood in 1988, typhoon Gay in 1989, and several severe droughts which occurred frequently in the last decade. These phenomena may be related to the rapid deforestation and climate change at Surat Thani.