Effects of Climatic Change on Evapotranspiration in Zhalong Wetland, Northeast China

Key words: 
• climate change /
• evapotranspiration /
• General Circulation Model /
• Zhalong Wetland

Abstract: Evapotranspiration (ET) process of plants is controlled by several factors. Besides the physiological factors of plants, height, density, LAI (leaf area index), etc., the change of meteorological factors, such as radiation, temperature, wind and precipitation, can influence ET process evidently, thus remodeling the spatial and temporal distribution of ET. In order to illuminate the effects of meteorological factors on wetland ET, the ET of Zhalong Wetland was calculated from 1961 to 2000, the statistical relationships (models) between ET and maximum temperature (T_max), minimum temperature (T_min), precipitation (P) and wind speed at 2m height (U₂) were established, and the sensitivity analysis of the variables in the model was performed. The results show that T_max and T_min are two dominating factors that influence ET markedly, and the difference of rising rate between T_max and T_min determines the change trend of ET. With the climatic scenarios of four General Circulation Models (GCMs), the ET from 2001 to 2060 was predicted by the statistical model. Compared to the period of 1961-2000, the water consumption by ET will increase greatly in the future. According to the scenarios, the rise of T_max (about 1.5℃ to 3.3℃) and T_min (about 1.7℃ to 3.5℃) will cause an additional water con- sumption of 14.0%-17.8% for reed swamp. The ecological water demand in Zhalong Wetland will become more severe.