2000-2014年艾比湖流域地表E_a与E_p时空分布特征及成因

Spatio-temporal distribution characteristics and contributing factors of E_a and E_p in Ebinur Lake Basin during 2000-2014

为了探明干旱区流域地表蒸散量时空分布及其变化特征,从而为流域水资源规划、旱涝检测和生态需水量研究提供科学依据,本文基于MOD16蒸散产品和气象站观测数据,运用线性倾向率和相对变化率等方法,分析了艾比湖流域2000—2014年地表实际蒸散(E_a)与潜在蒸散(E_p)的时空分布特征及其变化趋势,进一步揭示二者之间的关系。结果表明:1)近15年内艾比湖流域地表E_a、E_p年际波动不大,多年平均E_a与E_p分别为315.76和1 555.27mm,年平均E_a与E_p的较大差距说明流域整体上缺水、干旱。年内分布处于先增大后减少的单峰型变化趋势,夏季两者差距最大,此时流域最干旱、缺水;2)流域E_a与E_p的空间分布状况正好相反。西北山区、精河—博乐绿洲区、北天山的西段支脉,玛依力山脉等区域水分比较充足。流域东部大范围地区、精河—博乐绿洲周围等区域干旱缺水。3)影响因素分析显示气温是影响流域E_a、E_p时空分布变化的主要因素;4)2000—2014年间E_a总体上处于减少趋势,E_p处于增加趋势,说明流域近15年内干旱加重。

[Background]Water evaporation plays an important role in the hydrological process as it is a major part of the ecological water balance.The evapotranspiration（ET） is the loss of water from the soil both by evaporation and by transpiration from the plants growing thereon.Actual evaporation（E_a）concerns the water evaporation from natural surfaces to the atmosphere.Potential evaporation（E_p） is the amount of water that would be evaporated and transpired if there are sufficient water available.This demand incorporates the energy available for evaporation and the ability of the lower atmosphere to transport evaporated moisture away from the land surface.Therefore,the evaporation can substantiallyinfluence on a regional scale the amount and spatial distribution of water resources.In-depth understanding the spatio-temporal distribution and evolution process of evaporation provides scientific basis for basin water resources planning,evaluating the condition of drought,study on ecological water demand,etc.[Methods] The spatio-temporal distribution characteristics and evolution trend of E_aand E_p were studied by linear trend analysis and relative variation ratio using MOD16 product and observation data of meteorological station during 2000-2014 in Ebinur Lake Basin.[Results] 1） Inter-annual variation of E_aand E_p was not obvious during recent 15 years,the mean annual E_aand E_pwere 315.76 and 1 555.27 mm respectively,and the great discrepancy between mean annual E_aand E_p showed that the whole study area was in the condition of water shortage and drought.2） The spatial distribution of E_awas opposite to that of E_p.The northwestern mountain area,Jinghe-Bole Oasis area,western branch of northern Tianshan Mountain and Mayili Mountain area had sufficient water supply,while the most eastern area of Ebinur Lake Basin,all around of Jinghe-Bole oasis suffered from drought and water shortage.3）Analysis of influencing factors demonstrated that temperature was the most important factor to affecting the spatio-temporal distribution of E_a and E_p in the study area.4） The evolution trend of E_awas decreasing in the fifteen years,and the area with decreasing trend was accounted for 50% of the total.The evolution trend of E_p was increasing in the fifteen years,and the area with increasing trend was accounted for 48.39% of the total.The evolution trend of decreasing E_aand increasing E_pindicated that the condition of drought was aggravated during 2000-2014 in Ebinur Lake Basin.[Conclusions] According to the spatio-temporal variation and evolution trend of E_aand E_pin Ebinur Lake Basin during 2000-2014,the land surface in Ebinur Lake Basin was drought,and the condition was aggravated year by year.