蒸散发(Evapotranspiration,简称ET)是研究地表水循环过程变化和开展田间水分管理的核心变量之一。遥感是获取大范围动态蒸散发的一个主要手段,但现有蒸散发产品分辨率主要以中低分辨率(1—25 km)为主,难以满足田间水分管理的应用需求...蒸散发(Evapotranspiration,简称ET)是研究地表水循环过程变化和开展田间水分管理的核心变量之一。遥感是获取大范围动态蒸散发的一个主要手段,但现有蒸散发产品分辨率主要以中低分辨率(1—25 km)为主,难以满足田间水分管理的应用需求。国产高分一号宽幅相机具有高时空分辨率特点,空间分辨率为16 m,能够为高时空分辨率蒸散发产品生产提供数据支撑。本文利用国产高分一号卫星遥感数据反演的地表参数(包括叶面积指数、植被覆盖度和反照率等)作为驱动,评估了采用ETMonitor蒸散发遥感模型获取高分辨率蒸散发的能力和精度。研究中收集黑河流域、闪电河流域、河北怀来、西藏纳木错等16个站点的涡动相关仪地面观测数据开展蒸散发估算的验证,下垫面类型主要涵盖农作物、草地、森林和裸地等。验证结果表明:高分一号卫星遥感估算日蒸散发均方根误差为0.85 mm d^(-1),相关系数为0.79,偏差为0.16 mm d^(-1),估算精度较高。与中低空间分辨率(例如1 km)蒸散发数据相比,基于高分一号卫星遥感估算的16 m分辨率蒸散发在地表异质性较强的区域更具优势,能较好地反映田块尺度的蒸散发空间分布差异。整体来说,基于国产高分卫星遥感结合ETMonitor模型能够获取精度较高的高时空分辨率蒸散发产品,有望满足日益精细化的农业水资源利用及管理的应用需求。展开更多
Improving irrigation water management is a key concern for the agricultural sector,and it requires extensive and comprehensive tools that provide a complete knowledge of crop water use and requirements.This study pres...Improving irrigation water management is a key concern for the agricultural sector,and it requires extensive and comprehensive tools that provide a complete knowledge of crop water use and requirements.This study presents a novel methodology to explicitly estimate daily gross and net crop water requirements,actual crop water use,and irrigation efficiency of center pivot irrigation systems,by mainly utilizing the Sentinel-2 MultiSpectral Instrument(MSI)imagery at the farm scale.ETMonitor model is adapted to estimate actual water use(as the sum of canopy transpiration and evaporation of water intercepted by canopy and evaporation from soil)at daily/10-m resolution,benefiting from the high-resolution Sentinel-2 data and thus to assess the irrigation efficiency at the farm scale.The gross irrigation water requirement is estimated from the net crop water requirement and the water loss,including the water droplet evaporation directly into the air during application before droplets fall on the canopy and canopy interception loss.The method was applied to a pilot farmland with two major crops(wheat and potato)in the Inner Mongolia Autonomous Region of China,where modern equipment and appropriate irrigation methods are deployed for efficient water use.The estimated actual crop water use showed good agreement with the ground observations,e.g.the determination coefficients range from 0.67 to 0.81 and root mean square errors range from 0.56 mm/day to 1.24 mm/day for wheat and potato when comparing the estimated evapotranspiration with the measurement by the eddy covariance system.It also showed that the losses of total irrigated volume were 25.4%for wheat and 23.7%for potato,respectively,and found that the water allocation was insufficient to meet the water requirement in this irrigated area.This suggests that the amount of water applied was insufficient to meet the crop water requirement and the inherent water losses in the center pivot irrigation system,which imply the necessity to improve the irrigation practice to use the water more efficiently.展开更多
文摘蒸散发(Evapotranspiration,简称ET)是研究地表水循环过程变化和开展田间水分管理的核心变量之一。遥感是获取大范围动态蒸散发的一个主要手段,但现有蒸散发产品分辨率主要以中低分辨率(1—25 km)为主,难以满足田间水分管理的应用需求。国产高分一号宽幅相机具有高时空分辨率特点,空间分辨率为16 m,能够为高时空分辨率蒸散发产品生产提供数据支撑。本文利用国产高分一号卫星遥感数据反演的地表参数(包括叶面积指数、植被覆盖度和反照率等)作为驱动,评估了采用ETMonitor蒸散发遥感模型获取高分辨率蒸散发的能力和精度。研究中收集黑河流域、闪电河流域、河北怀来、西藏纳木错等16个站点的涡动相关仪地面观测数据开展蒸散发估算的验证,下垫面类型主要涵盖农作物、草地、森林和裸地等。验证结果表明:高分一号卫星遥感估算日蒸散发均方根误差为0.85 mm d^(-1),相关系数为0.79,偏差为0.16 mm d^(-1),估算精度较高。与中低空间分辨率(例如1 km)蒸散发数据相比,基于高分一号卫星遥感估算的16 m分辨率蒸散发在地表异质性较强的区域更具优势,能较好地反映田块尺度的蒸散发空间分布差异。整体来说,基于国产高分卫星遥感结合ETMonitor模型能够获取精度较高的高时空分辨率蒸散发产品,有望满足日益精细化的农业水资源利用及管理的应用需求。
基金supported by the National Natural Science Foundation of China(NSFC)[Grant no.42090014,42171039,42271394]the Open Research Program of the International Research Center of Big Data for Sustainable Development Goals[Grant no.CBAS2023ORP05]+2 种基金ESA-NSRCC Dragon 5 Program[Grant no.59061]MOST High Level Foreign Expert program[Grant No.G2022055010L]the Chinese Academy of Sciences President’s International Fellowship Initiative[Grant No.2020VTA0001].
文摘Improving irrigation water management is a key concern for the agricultural sector,and it requires extensive and comprehensive tools that provide a complete knowledge of crop water use and requirements.This study presents a novel methodology to explicitly estimate daily gross and net crop water requirements,actual crop water use,and irrigation efficiency of center pivot irrigation systems,by mainly utilizing the Sentinel-2 MultiSpectral Instrument(MSI)imagery at the farm scale.ETMonitor model is adapted to estimate actual water use(as the sum of canopy transpiration and evaporation of water intercepted by canopy and evaporation from soil)at daily/10-m resolution,benefiting from the high-resolution Sentinel-2 data and thus to assess the irrigation efficiency at the farm scale.The gross irrigation water requirement is estimated from the net crop water requirement and the water loss,including the water droplet evaporation directly into the air during application before droplets fall on the canopy and canopy interception loss.The method was applied to a pilot farmland with two major crops(wheat and potato)in the Inner Mongolia Autonomous Region of China,where modern equipment and appropriate irrigation methods are deployed for efficient water use.The estimated actual crop water use showed good agreement with the ground observations,e.g.the determination coefficients range from 0.67 to 0.81 and root mean square errors range from 0.56 mm/day to 1.24 mm/day for wheat and potato when comparing the estimated evapotranspiration with the measurement by the eddy covariance system.It also showed that the losses of total irrigated volume were 25.4%for wheat and 23.7%for potato,respectively,and found that the water allocation was insufficient to meet the water requirement in this irrigated area.This suggests that the amount of water applied was insufficient to meet the crop water requirement and the inherent water losses in the center pivot irrigation system,which imply the necessity to improve the irrigation practice to use the water more efficiently.
