单源能量平衡模型反演灌溉牧草场实际蒸散量及其时空特征分析

Single-Source Energy Balance Model Inversion of Actual Evapotranspiration from Irrigated Pasture and Analysis of Its Spatio-Temporal Characteristics

摘要: 水资源短缺是制约干旱地区经济发展的重要因素，所以探究干旱地区生长季人工灌溉牧草实际蒸散量时空变化规律非常必要。本研究使用2013~2021年Landsat-8OIL影像基于pySEBAL模型结合气象站数据反演锡林浩特市沃原奶牛场种植基地人工灌溉牧草实际蒸散量。结果表明：由于人工灌溉牧草水分充足，该区域实际蒸散量较高，介于0~10 mm/d、50~200 mm/m之间。研究区牧草生长季(5~9月)实际蒸散量变化规律整体呈“单峰型”，其中峰值日为2014年7月25日(5.46 mm/d)，峰值月为7月(155.71 mm/m)，种植区界限随牧草蒸散量升高而清晰。此外，实际蒸散量变化规律与降水频率和降水量也有很好的相关性。模型反演所得实际蒸散量与FAO Penman-Monteith算法结果比较(R2 = 0.7504、RMSE = 1.2575 mm/d、MRE = 0.9366 mm/d)，模型整体精度较高，能够较为准确地反映该区牧草实际蒸散情况。反演结果基本符合实际情况，可以为人工灌溉牧草用水管理提供方案，为政府合理政策制定提供依据。

Abstract: Water shortage is an important factor restricting economic development in arid areas, so it is very necessary to explore the spatiotemporal changes in actual evapotranspiration of artificially irrigated forage during the growing season in arid areas. This study uses Landsat-8 OIL images from 2013 to 2021 based on the pySEBAL model and weather station data to invert the actual evapotranspiration of artificially irrigated pasture at the Woyuan Dairy Farm planting base in Xilinhot City. The results show that due to the sufficient water content of artificially irrigated pasture, the actual evapotranspiration in this area is relatively high, ranging from 0 to 10 mm/d and 50 to 200 mm/m. The change pattern of actual evapotranspiration during the pasture growing season (May-September) in the study area showed a “single peak” overall, with the peak day being July 25, 2014 (5.46 mm/d) and the peak month being July (155.71 mm/d). The boundaries of planting areas become clearer as the evapotranspiration of pasture increases. In addition, the change pattern of actual evapotranspiration is also well correlated with precipitation frequency and precipitation amount. Comparing the actual evapotranspiration obtained by the model inversion with the results of the FAO Penman-Monteith algorithm, the overall accuracy of the model is higher and can more accurately reflect the actual evapotranspiration of forage in the area (R2 = 0.7504, RMSE = 1.2575 mm/d, MRE = 0.9366 mm/d). The inversion results are basically consistent with the actual situation, and can provide solutions for artificial irrigation pasture water management and provide a basis for the government to formulate reasonable policies.