The purpose of this study is to provide information of climate, hydrology, and ecosystems for writing our National Communication Report. This study focuses on climate and hydrology in the first year. Climate analysis includes setup climate change scenarios and climate simulation for Taiwan region. The tasks of impact assessment include streamflow, irrigation water demand, water supply systems, groundwater recharge, and flood mitigation. The major findings are (1) Climate Analyzing recorded weather data of 1942 through 2001, the trend of temperature increase for the whole Taiwan area can be confirmed, but the trends of precipitation are not consist in different locations or different seasons. On the other hand, although predictions by different GCMs or region climate model are different, the trend of increase temperature and more extreme precipitation can be seen in most cases. (2) Streamflow Simulation results from most scenarios indicate that streamflows in humid period increase due to climate change, but decrease in dry period. It may cause the risk of more serious flood and drought. Besides, the enlarged difference of streamflows between two seasons will bring more difficulty in water resources management. (3) Irrigation Water Demand Due to higher temperature, both quantity and distribution of irrigation water may be changed. In the first growing season, the water requirement for irrigation is increased in early growth stage, but significantly reduced in later months due to shorten growth periods. In the second growing season, increase of irrigation water in early growth stage is not significant due to increase of rainfall. Centralized irrigation water demand will cause difficulty in water resources management. (4) Water Supply Simulation results indicate the increase of difference between streamflows of humid and dry seasons may bring difficulty to water resources allocation and operation. Centralized irrigation water demands and new industrial water uses may increase more pressure on water supply system. Thus, managing water resources systems, saving water uses, developing alternative storage and water resources are important issues. (5) Groundwater Recharge Groundwater is closely related to evapotranspiration, surface runoff, and rainfall. Simulation results indicate that groundwater recharge of Taiwan Island will very likely gradually decrease. The difference of groundwater recharge in humid and dry seasons will become more. (6) Flood Mitigation Because streamflow increases, there is more potential risk of overflow from embankment. Besides, the design standard of pumping station and drainage systems may need to be evaluated accordingly. The integrated operational rules of flood mitigation also require regularly being re-evaluated and adjusted. This study not only evaluates the impacts of climate change, but also provides adaptations. These adaptations are suggested based on major findings in this study and experiences of studies of other countries.

Global Warming, Greenhouse Effects, Greenhouse Gases, Water Resources, Simulation