不同土地覆被对区域蒸散的影响

The Effects of Different Land Cover on Regional Evapotranspiration

利用Landsat TM5遥感数据,用简化的遥感-能量平衡模型进行区域实际蒸散量的估算.以美国俄克拉荷马州为研究区域,探讨了不同植被覆盖对区域实际蒸散量的影响,对不同植被类型的月蒸散量和年总蒸散量进行分析.结果表明,无论月蒸散量还是年总蒸散量林地均大于草地,即林地对水分的消耗大于草地;而对于不同林分而言,年总蒸散量常绿林最高,落叶林次之,混交林最低;对不同城市绿地而言,俄克拉荷马的草地和雪松月蒸散量动态变化仍为单峰型曲线,7月份达到最大值,1月份最小;1 ～2月雪松和草地的蒸散量基本一样,3～6月雪松和草地的蒸散量差异非常大,雪松明显高于草地;年总蒸散量雪松明显高于草地.

A Simple-Surface-Energy-Balance gorithm was implemented to estimate ETa at a higher spatial resolution using Landsat 5 sat-ellite images and determine the variation with regards to varying types of land cover. Comparing the monthly ET and annual ET among differentland cover, the results showed that forests had higher average ETa than grass land all over the year. For different forest types, the annual ETwas the highest for the evergreen forest, the medium for the deciduous forest, and the lowest for the mixed forest. Tile monthly ET of mixedforest was lower than the evergreen forest and deciduous forest except for January and December. From March to August, the ET of evergreenforest and deciduous forest were the same. In general, the water consumption of the mixed forest was the lowest. For different green land,grass and cedar had similar ET trends throughout the year, reaching the minimum in January and the maximum in July. Annual ET of Cedarwas generally higher than grass land.