A Coupled Remote Sensing and Simplified Surface Energy Balance Approach to Estimate Actual Evapotranspiration from Irrigated Fields

摘要: Accurate crop performance monitoring and production estimation are critical fortimely assessment of the food balance several countries in world. Since 2001, theFamine Early Warning Systems Network (FEWS NET) has been cropperformance relative using satellite-derived data simulation models inAfrica, Central America, Afghanistan where ground-based is limitedbecause a scarcity weather stations. The commonly used arebased on water-balance algorithm with inputs from rainfallestimates. These useful to monitor rainfed agriculture, but they ineffectivefor irrigated areas. This study focused Afghanistan, over 80 percent ofagricultural comes lands. We developed implemented aSimplified Surface Energy Balance (SSEB) model assess performanceof agriculture combination 1-km thermal 250-m Normalized Difference Vegetation Index (NDVI) data, both Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. estimated seasonal actual evapotranspiration (ETa) period six years (2000-2005) for two major river basins Kabul Helmand, by analyzing up 19 cloud-free NDVI images each year. ETa estimates were as indicators year-to-year magnitude differences. temporal water- use pattern was indicative cropping patterns specific region. Our results comparable field reports based watershed-wide results. For example, methods found that 2003 highest all years. method also captured water management scenarios unique variability identified addition water-use differences between upstream downstream basins. A advantage energy-balance approach it can be quantify spatial extent fields their dynamics without reference source opposed which requires knowledge distribution rainfall irrigation applied fields.