吉兰泰及周边地区蒸散发的时空变化规律

Spatial and Temporal Variations of Evapotranspiration in Jilantai and its Surrounding Areas

【目的】探索吉兰泰及周边地区蒸散发的时空变化规律。【方法】以吉兰泰为对象,利用MODIS数据通过SEBAL模型估算了研究区2017年植被生长季5—10月的日蒸散发,并分析了蒸散发与环境因子的相关性。【结果】①生长季日平均蒸散量整体趋势呈单峰型分布趋势,日均蒸散量最大值在7月(3.98 mm),最小值在10月(1.11 mm);②在空间分布上,研究区东南部蒸散发最高,东北部蒸散发最低;不同土地利用类型中蒸散发值由大到小分别为林地、耕地、草地、戈壁、沙漠;各土地利用类型蒸散发量的时间动态表现一致,呈生长期>生长初期>生长后期;③归一化植被指数、高程与蒸散发正相关,风速以及地表温度与蒸散发负相关。【结论】SEBAL模型估算的蒸散发与P-M作物系数法的蒸散发进行对比,相对误差在允许范围之内,表明SEBAL模型对本研究区蒸散发的估算是可靠的。研究区靠近山地的蒸散发大于荒漠区的蒸散发。在植被生长季中生长初期的蒸散发受温度和风速影响最大,生长期和生长后期的蒸散发受地表温度和高程影响最大。

【Objective】Study Spatial and Temporal Variations of Evapotranspiration in Jilantai and its Surrounding Areas.【Method】Using MODIS data and SEBAL model,the daily evapotranspiration of vegetation growth season from May to October in 2017 was estimated,and the correlation between evapotranspiration and environmental factors was analyzed.【Result】①In the growing season,the average daily evapotranspiration showed a single peak distribution trend,with the maximum value in July(3.98 mm)and the minimum value in October(1.11 mm);②In the spatial distribution,the evapotranspiration was the highest in the southeast of the study area and the lowest in the northeast of the study area;the evapotranspiration values of different land use types were forest land,cultivated land,grassland and Gogol respectively.The evapotranspiration of different land use types showed the same time dynamic performance,showing growth period>early growth>late growth;③Normalized vegetation index,elevation and evapotranspiration showed positive correlation,wind speed and surface temperature showed negative correlation.【Conclusion】Compared with P-M crop coefficient method,the relative error of SEBAL model is within the allowable range,which shows that SEBAL model is reliable for the estimation of evapotranspiration in this study area.The evapotranspiration in the study area near the mountain area is greater than that in the desert area.In the growing season,the evapotranspiration in the early growth stage is most affected by temperature and wind speed,while that in the later growth stage is most affected by surface temperature and elevation.