近40年西藏“一江两河”流域气候变化特征
Climate Variation Feature and Its Effect on Environment Change in Central Tibet from 1961 to 2000
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摘要: 利用近40年的降水、气温、小型蒸发量、大风日数和沙尘暴日数等气象资料, 采用现代气候统计诊断和环境综合评价方法, 分析了西藏“一江两河”农业综合开发区域的气候特征。结果表明:该流域呈现气温升高、降水量增加的暖湿化气候特征。区域内年平均气温每10年升高了0.24 ℃, 降水量前20年平均每年减少2.9 mm, 而后20年呈显著的增加趋势, 平均每年增加9.6 mm; 蒸发量、大风日数和沙尘暴日数呈明显的减少趋势; 区域环境综合评价指数提高了5.24%。近期暖湿化的气候变化趋势对干旱半干旱的河谷地带而言, 有利于生态环境的改善, 但因洪涝、冰雹等自然灾害的频繁和人为因素使水土流失和土地沙漠化正在加剧。Abstract: Climate change is a global issue. It's very difficult to distinguish the climatic impacts from the variation of atmospheric constituents by human activities among human activities influences on climate. In order to demonstrate the environmental effect over Tibetan agricultural integrated development area (central Tibet) from 1990 to 2000, using meteorological factors such as precipitation, temperature, evaporation, accumulated days of gale and sandstorm in the recent 40 years and environmental integrated assessment index, it investigates the variation of regional climate feature and the environmental effects over Tibetan agricultural integrated development area.The analysis shows that the annual temperatures and precipitation exhibit increasing tendency over central Tibet, the annual mean temperature increases 0.24 ℃/10a; the precipitation decreases 2.9 mm in the earlier 20 years, but it shows distinct increasing tendency from 1981 to 2000 and the average increase is 9.6 mm/a; evaporation quantity, strong wind days and sandstorm days exhibit decreasing trend. In the target region, the evaporation quantity decreases averagely 24.4 mm/10a before 1983, and then decreases 22.1 mm/a; the accumulated days of gale present a decreased tendency, with the average of 3 d/a from 1990s. In the same way, the accumulated days of sandstorm has decreased 1—2 d/a, in which Zedang station has no record of sandstorm after 1995. Comparing with the earlier 30 years, the sandstorm days decrease by 22—31 d in 1990s.Considering arid and semi-arid river valley area, the variation trend of warm and humid climate is beneficial to environment improvement, the regional integrated environmental assessment index increases 5.24% during 1990—2000. But natural environment lose and desertification are getting worse because of the frequent natural disasters like flood, hail and human activities. Especially human activities accelerate the development of land desertification. The main problem is that human activities such as farmland expansion and deforestation caused by the population growth and the lack of fuel material, over breeding of livestock, which lead to the expanding of bare land and the acceleration of soil erosion in the remote area far from the river valley. Facing the vulnerable environment, with the strict controlling of the population growth, it is a powerful approach of agricultural integrated development and an important act to achieve the goal of sustainable development of region's society and economy that the government ought to actively adjust the structure, develop highly effective and advanced industry, attempt to strengthen the ability of the exploitation of renewable energy such as wind and solar energy.
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Key words:
- central Tibet;
- climate variation;
- the environmental effect
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表 1 “一江两河”流域各站年、季平均气温变化趋势
表 2 “一江两河”流域平均气温20世纪90年代与前30年的比较
表 3 20世纪60—90年代“一江两河”流域年降水量的年代际变化
表 4 “一江两河”流域开发前后各参评因子综合评价指数对比
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