天津平原区城市化地区蒸散发特征

Exploring evapotranspiration characteristics in urbanized areas of Tianjin plain

为揭示城市蒸散发特征,采用考虑人为热影响的SEBS-Urban模型计算天津平原区2015—2017年逐月蒸散量。使用两步验证法对结果进行检验,首先利用MODIS MOD16产品对非建成区模拟结果合理性进行验证,其次利用城市耗水(UWD)模型得到的天津大学卫津路校区月蒸散量对建成区模拟结果验证。在SEBS-Urban模拟结果基础上,检验Budyko方程在城市化地区的适用性。结果表明:①SEBS-Urban模型精度可靠,体现了蒸散发项在城市地表能量平衡与二元水循环中的相合性;②人为热或社会侧的耗水会导致蒸散发量增加,建成区增幅达85%~115%,整个研究区增幅为7.2%~8.7%;③Budyko方程在研究区具有较好的拟合效果,可应用于城市地区。本研究成果可为城市化地区蒸散发研究提供必要的参考。

To reveal the characteristics of urban-based evapotranspiration,a SEBS-Urban model was applied to estimate the monthly evapotranspiration(ET)that occurred in the plain area of Tianjin over 2015—2017 considering anthropogenic heat release.A two-step verification method was used.First,a comparative analysis was performed with the MODIS MOD16 products for rural areas.Second,the urban water dissipation(UWD)framework was used to assess the model′s performance in built-up areas.The feasibility of the Budyko formula was explored based on the SEBS-Urban results.Three key results were obtained:①The SEBS-Urban model is reliable,and the results of the built-up area ET analysis are consistent from the perspectives of an urban surface energy balance and a dualistic water cycle.②The ET increment ranges up to 85%~115%for the built-up area but only 7.2%~8.7%for the whole study area after including considerations for anthropogenic heat.③The Budyko formula obtained good results for estimating evapotranspiration in the study area,suggesting that it can also be applied to urban areas.The results of this study can provide a necessary reference for studies on evapotranspiration in urbanized areas.