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首页> 美国卫生研究院文献>Sensors (Basel Switzerland) >A Coupled Remote Sensing and Simplified Surface Energy Balance Approach to Estimate Actual Evapotranspiration from Irrigated Fields
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A Coupled Remote Sensing and Simplified Surface Energy Balance Approach to Estimate Actual Evapotranspiration from Irrigated Fields

机译：遥感和简化的地表能量平衡耦合方法估算灌溉田的实际蒸散量

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Accurate crop performance monitoring and production estimation are critical for timely assessment of the food balance of several countries in the world. Since 2001, the Famine Early Warning Systems Network (FEWS NET) has been monitoring crop performance and relative production using satellite-derived data and simulation models in Africa, Central America, and Afghanistan where ground-based monitoring is limited because of a scarcity of weather stations. The commonly used crop monitoring models are based on a crop water-balance algorithm with inputs from satellite-derived rainfall estimates. These models are useful to monitor rainfed agriculture, but they are ineffective for irrigated areas. This study focused on Afghanistan, where over 80 percent of agricultural production comes from irrigated lands. We developed and implemented a Simplified Surface Energy Balance (SSEB) model to monitor and assess the performance of irrigated agriculture in Afghanistan using a combination of 1-km thermal data and 250-m Normalized Difference Vegetation Index (NDVI) data, both from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. We estimated seasonal actual evapotranspiration (ETa) over a period of six years (2000-2005) for two major irrigated river basins in Afghanistan, the Kabul and the Helmand, by analyzing up to 19 cloud-free thermal and NDVI images from each year. These seasonal ETa estimates were used as relative indicators of year-to-year production magnitude differences. The temporal water-use pattern of the two irrigated basins was indicative of the cropping patterns specific to each region. Our results were comparable to field reports and to estimates based on watershed-wide crop water-balance model results. For example, both methods found that the 2003 seasonal ETa was the highest of all six years. The method also captured water management scenarios where a unique year-to-year variability was identified in addition to water-use differences between upstream and downstream basins. A major advantage of the energy-balance approach is that it can be used to quantify spatial extent of irrigated fields and their water-use dynamics without reference to source of water as opposed to a water-balance model which requires knowledge of both the magnitude and temporal distribution of rainfall and irrigation applied to fields.
机译：准确的作物生长性能监测和产量估算对于及时评估世界上几个国家的食物平衡至关重要。自2001年以来，饥荒预警系统网络（FEWS NET）一直在使用非洲和中美洲和阿富汗的卫星数据和模拟模型来监测作物生长状况和相对产量，非洲，中美洲和阿富汗由于天气稀缺，地面监测受到限制站。常用的作物监测模型基于作物水平衡算法，并具有来自卫星的降雨估算值。这些模型对于监控雨养农业很有用，但对灌溉区却无效。这项研究的重点是阿富汗，那里80％的农业生产来自灌溉土地。我们开发并实施了简化的表面能平衡（SSEB）模型，以结合使用1公里热数据和250米归一化差异植被指数（NDVI）数据（两者均来自中等水平）来监测和评估阿富汗的灌溉农业绩效分辨率成像光谱仪（MODIS）传感器。我们通过分析每年多达19个无云的热成像和NDVI图像，估计了阿富汗（喀布尔和赫尔曼德省）两个主要灌溉河流域在六年（2000-2005年）内的季节性实际蒸散量（ETa）。这些季节性ETa估计值用作年度产量幅度差异的相对指标。两个灌溉流域的时间用水模式指示了每个区域的特定种植模式。我们的结果与田间报告和基于流域范围的作物水分平衡模型结果的估算结果相当。例如，这两种方法都发现2003年的季节性ETa是六年来最高的。该方法还捕获了水资源管理方案，其中除了上游和下游流域之间的用水差异外，还确定了独特的逐年变化。能量平衡方法的一个主要优点是，它可用于量化灌溉田的空间范围及其用水动态，而无需参考水源，而水平衡模型则需要了解水量和水量田间降雨和灌溉的时间分布。

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