Actual Evapotranspiration, Urmia Lake Basin 2000-2020, Using MPySEBAL and MODIS

Data of AH.Owlia thesis, The Lake Urmia Basin, Iran.

Actual evapotranspiration is one of the water balance equation and surface energy balance components. The estimation of agriculture water consumption in irrigation projects is based on the determination of this variable. In this study, MPySEBAL based on energy balance budget was developed due to customization of PySEBAL for The Lake Urmia Basin. Results of the models validations with lysimetric data from 2010 to 2011 showed that MPySEBAL (with selecting anchor pixels with land surface temperature and vegetation cover thresholds) is superior to PySEBAL by providing up to 70% less RMSE. After that, the values of evapotranspiration for the period from the beginning of 2000 to the end of 2019 were presented in monthly and annual temporal resolution and 250 meter spatial resolution. Then, using the precipitation data derived from synoptic stations that were located in the basin, precipitation, effective precipitation and agricultural water need maps for the reference period of 2000-2019 were calculated for the basin. Then, by dividing the catchment into three regions, east, west, and south and downscaling precipitation and temperature data on three selected stations in these areas (Urmia, Tabriz, and Miandoab), and using the HadGEM2_ES model, under three RCP2.6, 4.5, and 8.5 scenarios. In the process of downscaling, the 20-year period of 2000-2019 was selected as the reference period (observation data) and the period of 2021-2040 as the period of climate change. The results showed an average increase in air temperature up to 10 and precipitation up to 11 percent per year for the entire basin. By finding the relationship between air temperature, surface temperature, and evapotranspiration rate, the amount of agricultural water consumption in the next years was calculated, which results show an increase in agricultural water consumption (3% to 5%) and agricultural water demand (2% to 5%) in The Lake Urmia Basin. Therefore, it seems that due to the impact of climate change on this basin, the need to manage and exploit the available resources in the basin will be more important in the next years.

伊朗乌尔米耶湖盆地（Lake Urmia Basin）AH.Owlia学位论文数据集。实际蒸散发（Actual evapotranspiration）是水量平衡方程与地表能量平衡的组成要素之一，灌溉工程中的农业用水量估算正是基于该变量的确定。本研究针对乌尔米耶湖盆地对PySEBAL模型进行定制化改进，开发了基于能量平衡预算的MPySEBAL模型。利用2010-2011年的蒸渗仪观测数据对两款模型进行验证，结果表明，通过选取结合地表温度与植被覆盖阈值的锚定像元的MPySEBAL模型，其性能优于PySEBAL模型，均方根误差（Root Mean Square Error，RMSE）最高可降低70%。随后，本研究以250米空间分辨率、月/年时间分辨率，给出了2000年初至2019年末的蒸散发量数据。接着，利用盆地内气象站（synoptic stations）获取的降水数据，本研究计算得到2000-2019年基准期内的盆地降水量、有效降水量与农业需水量空间分布图。随后，本研究将研究流域划分为东、西、南三个区域，选取该区域内的乌尔米耶（Urmia）、大不里士（Tabriz）和米亚内多阿布（Miandoab）三个气象站，对降水与气温数据进行降尺度处理，并结合HadGEM2_ES模式，在RCP2.6、RCP4.5与RCP8.5三种典型浓度路径（Representative Concentration Pathway，RCP）情景下开展分析。本次降尺度分析以2000-2019年这20年作为基准期（观测数据期），以2021-2040年作为气候变化影响分析期。分析结果显示，整个盆地的年平均气温最高可升高10%，年平均降水量最高可升高11%。通过建立气温、地表温度与蒸散发速率之间的关联关系，本研究计算得到未来时段的农业用水量，结果表明乌尔米耶湖盆地的农业用水量将增长3%至5%，农业需水量将增长2%至5%。因此，受气候变化对该盆地的影响，未来对盆地内现有水资源的管理与开发利用将显得愈发重要。