气候变化对青藏高原水环境影响初探

利用Penman-Monteith公式和干燥度指数公式，计算并分析了青藏高原65个气象站1972-2011年间记录的气候变化趋势，同时在总结国内外有关气候变化对青藏高原水环境各要素影响研究的基础上，通过简单线性相关统计方法，分析了研究区域气候变化与水环境变化的相关性。结果表明：（1）青藏高原整体升温显著，降水显著增加，最大可能蒸散（ET₀）显著降低，暖湿化趋势显著；高原北部和西部降水显著增加、ET₀显著降低、干燥度指数显著下降，东部和南部ET₀显著降低、干燥度指数显著下降；（2）受升温影响，青藏高原的冰川消融，尤以东部地区变化显著；湖泊因其补给条件不同而分别呈现出扩张、萎缩和基本稳定3种状态，总体上，高原西部的湖泊以扩张为主，东部的湖泊基本稳定，而萎缩的湖泊分布较为分散。水环境的改变对于高原区水循环过程及生态系统都将产生重要影响。

Influence of climate change on water environment in the Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau is one of the most sensitive regions responding to the global climate change. Water environment has changed due to global warming in this area in the last few decades. The changed water environment has a great influence on the local hydrological dynamic processes and the terrestrial ecosystem. In this paper，monthly air temperature and precipitation data derived from 65 meteorological stations，and potential evapotranspiration （ET₀） and annual aridity index （AI） calculated using Penman-Monteith and arid index equation were employed to understand the water environment change in the Qinghai-Tibet Plateau. The changing trends of observed climatic factors （T and P） and calculated factors （ET₀ and AI） were analyzed using linear regression method，which were tested through Mann-Kendall test. Then，the relationship between climate change and water environment change was reanalyzed using Pearson Correlation analysis. Annual mean air temperature and annual precipitation showed the increasing trend with the rates of 0.038 ℃/a and 0.809 mm/a，respectively in the last four decades；ET₀ demonstrated a decreasing trend with a decaying rate of 1.215 mm/a；AI] decreased and the climate is developing toward more humid status in most part of the area. The above mentioned pattern of the factors varied spatially. In the northern and western parts of the Qinghai-Tibet Plateau，T and P significantly increased，and ET₀ and AI significantly decreased. In the eastern and southern parts，T significantly increased，ET₀ and AI significantly decreased. The climate changing trend suggested a warmer and wetter tendency in northern part of the Qinghai-Tibet Plateau. It has been speculated that the significant decrease of ET₀ was probably the result of the lowering wind speed，although air temperature was increasing significantly. Meanwhile，the water environment in the Qinghai-Tibet Plateau also changed in the last few decades. Glaciers melted and shrunk significantly，especially in the eastern part of the Qinghai-Tibet Plateau. Lake areas changed differently because of different recharge conditions. In general，lakes expanded in the western part and kept stable in the eastern part of the Plateau，shrunk lakes distributed dispersedly. Hydrological data such as groundwater level，river runoff and soil moisture are very important for quantitative indicators of water environment change，in the term of water balance. Pearson Correlation analysis between the Qinghai Lake area and climatic factors recorded and computed from nearly four weather stations showed that，the Qinghai Lake area has a significant positive correlation with T，ET₀ and AI] of Xining Station; has a significant negative correlation with T recorded in Gangcha Station，Qiabuqia Station and Guizhou Station，and ET₀ in Qiabuqia Station. It is obvious that the changed water environment has a close relation with the changed climatic factors such as T，P，ET₀ and AI，but the relationship between them is complicated，which requires more researches. At present，meteorological data and water environment data derived from weather stations and records are not precise enough to quantitatively draw a conclusion on the relationship between climate change and water environment change due to complicated topography，the quantity and distribution of weather stations and hydrologic stations. RS and GIS techniques and reanalysis data should be used in the future research.