喀斯特山区蒸散发的时空变异特征分析——以贵州省为例

Analysis on spatiotemporal variation characteristics of evapotranspiration in karst mountain areas — a case study area of Guizhou Province

掌握喀斯特山区蒸散发的时空变异特征,为水资源的合理规划和优化配置提供科学依据.利用MODIS16遥感数据,在数据精度验证的基础上,运用GIS统计法、变异系数法和线性趋势法,探讨2000-2014年贵州省蒸散发的空间格局、年际和年内变化规律及不同土地覆被类型下的蒸散发特征.结果表明:(1)2000-2014年,贵州省实际蒸散发(ET)多年平均值为850.36 mm,呈西低东高,南高北低态势;潜在蒸散发(PET)多年平均值为1 473.58 mm,呈东北向西南递增态势.不同土地覆被类型下ET最大的是林地,而林地的PET最小.(2)PET年际变化率为3.88 mm/a,呈弱增加趋势;ET年际变化率为0.39 mm/a,基本保持稳定,表明贵州省水资源呈减少趋势,具有干旱化倾向.ET空间上呈东、西部减少、中部增加趋势,PET呈东、南和西三面减少、北部增加趋势.(3)ET和PET均呈单峰型.ET在7月最大,PET在6月最大,二者均在12月最小.二者在3-6月差距最大,为贵州省春旱和夏旱时期.不同土地覆被类型下ET和PET均呈单峰型,植被生长季节ET差距大,林地增长速度最快,植被成熟期PET差距最大.(4)ET和PET具有较强的季节性.ET季节性空间差异非常显著,在于林地的植被蒸腾作用对全年ET贡献较大.

Mastering the spatial and temporal variation characteristics of evapotranspiration in karst mountain areas can provide scientific basis for rational planning and optimal allocation of water resources.Based on MODIS16 data from remote sensing and its precision verification,we analyze the spatial pattern of evapotranspiration and the spatiotemporal characteristics of interannual and annual evapotranspiration and variation characteristics of evapotranspiration under different land cover types from 2000 to 2014,using statistical analysis of CIS,variation coefficient method,linear trend method,et al.The results show that(1)the averaged ET from 2000 to 2014 is 850.36 mm and the spatial distribution of ET in the east and south is higher than that in the west and north while the averaged PET is 1 473.58 mm and the spatial distribution of PET shows increasing trend from northeast to southwest.The largest ET in different land cover types is forestland,while the forestland has the smallest PET;(2)the interannual variability of PET is 3.88mm/a and shows a weak increasing trend,while ET is 0.39mm/a and shows a basically stable trend.The gap of ET and PET shows an increasing trend,which indicates that water resources in Guizhou Province is decreasing and Guizhou Province has a tendency of aridity.Spatial variation trend of PET is"the decreasing in the East and West and the increasing in the Central"while PET is"the decreasing in the East,South and West and the increasing in the North";(3)both interannual ET and PET are single peak.ET is the largest in July and PET is the largest in June,and both of them are the smal lest in December.The maximum gap between ET and PET is the spring drought and summer drought from March to June.Monthly averages of PET and ET show a single peak type under different land cover types.The difference of monthly ET for different land cover types is obvious in the vegetation growing season when monthly ET in forestland is the fastest growth rate.The difference of monthly ET for different land cover types is obvious in the vegetation maturing season;(4)seasonal averages of ET and PET have obvious differences among the four seasons.Spatial distribution of seasonal ET is very significant which greatly attributes to the transpiration of forestland because it is the greatest contribution to the annual ET.