کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6413578 | 1629950 | 2013 | 11 صفحه PDF | دانلود رایگان |
- We successfully estimated ET and separated it into evaporation and transpiration.
- The modeled absolute error was 0.08Â mm/d, and with a relative error of 10.67%.
- Forest has the highest ET, followed by grassland, farmland, and desert.
- ET rendered a decrease from the upper reaches to Gobi desert of the lower reaches.
- About 38-72% soil water returned to the atmosphere in the form of evaporation.
Evapotranspiration (ET) is an energy balance component and a key component of water budget; thus, accurate estimates of ET are critical for understanding hydrological processes and water resources management. Despite growing concerns, challenges remain in estimating ET by remote sensing technology for regional applications, due to the difficulty in determination of aerodynamic, canopy and soil resistance. Instead of using resistance, ET and their partition of evaporation (Es) and transpiration (Ec) can be evaluated based on an extended three temperature model (3T model) and Moderate Resolution Imaging Spectroradiometer (MODIS) products for the period of 2001-2009. A case study was conducted in the Heihe River Basin in northwestern China. Validation results indicated that the mean absolute error was 0.08Â mm/d, with a maximum and minimum absolute error of 1.28Â mm/d and 0.02Â mm/d, respectively, which presented a simple extended 3T model in estimating ET with adequate accuracy and could satisfy regional research requirement at large scales. Results showed that: (1) seasonally, ET was highest (varied from 0.80Â mm/d to 1.27Â mm/d with a mean value of 1.05Â mm/d) in summer and lowest in winter (varied from 0.35Â mm/d to 0.44Â mm/d with a mean value of 0.37Â mm/d); (2) spatially, it rendered a decrease from the Qilian Mountain of the upper reaches (515Â mm/a) to the Gobi desert of the lower reaches (82Â mm/a), which was closely related to land covers and climate conditions; (3) the comparison of different ecosystems indicated that forest has the highest ET (588Â mm), followed by grassland (308Â mm), farmland (225Â mm), and desert land (160Â mm); (4) ET was separated into Es and Ec, and about 38-72% soil water returned to the atmosphere in the form of Es. This information will prove to be useful for water-use efficiency of the Ecological Water Conveyances Project (EWCP) conducted in the basin.
Journal: Journal of Hydrology - Volume 498, 19 August 2013, Pages 210-220