Evapotranspiration partitioning at field scales using TSEB and multi-satellite data fusion in the middle reaches of Heihe river basin, northwest China

Authors: LI, Y. - Nanjing University Of Information Science And Technology (NUIST); HUANG, CH. - Chinese Academy Of Sciences; Kustas, William - Bill; NIETO, H. - University Of Alcala; SUN, L. - Chinese Academy Of Agricultural Sciences; HOU, J. - Chinese Academy Of Sciences

Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2020
Publication Date: 10/3/2020
Citation: Li, Y., Huang, C., Kustas, W.P., Nieto, H., Sun, L., Hou, J. 2020. Evapotranspiration partitioning at field scales using TSEB and multi-satellite data fusion in the middle reaches of Heihe river basin, northwest China . Remote Sensing. 12(9):3223. https://doi.org/10.3390/rs12193223.
DOI: https://doi.org/10.3390/rs12193223

Interpretive Summary: Accurate spatiotemporal patters of evapotranspiration (ET) are needed to manage water resources rationally and maintain ecosystem health in semiarid and arid regions. The partitioning of ET between soil evaporation (E) and plant water use of transpiration (T) at field scale is required to assess and monitor the spatial and temporal distribution of regional water use efficiency and plant stress. In this study, multiyear daily ET, E and T at a spatial resolution of 100 m were computed based on an ET partitioning method developed by combining remote sensing-based ET model and multi-satellite data fusion methodology. The results demonstrate that accurate daily ET is produced by using the remote sensing-based data fusion methodology for both for cropland and desert areas and the E and T partitioning for the cropland agreed with observations. This modeling system provided, for the first time, a means to assess multi-year agricultural water use efficiency and showed a larger fraction of soil evaporation versus plant transpiration occurring in the irrigated cropland. This increase in fraction of E versus T indicates that improved irrigation and water management strategies are urgently needed for conserving water resources in this agricultural region.

Technical Abstract: Daily evapotranspiration (ET) and its components of evaporation (E) and transpiration (T) at field scale are often required for improving agricultural water management and maintaining ecosystem health, especially in semiarid and arid regions. In this study, multi-year daily ET, E and T at a spatial resolution of 100 m in the middle reaches of Heihe River Basin were computed based on an ET partitioning method developed by combing remote sensing-based ET model and multi-satellite data fusion methodology. Evaluations using flux tower measurements over irrigated cropland and natural desert sites indicate that this method can provide reliable estimates of surface flux partitioning and daily ET. Modeled daily ET yields the root mean square error (RMSE) values of 0.85 mm for cropland site and 0.84 mm for desert site, respectively. The E and T partitioning capabilities of this proposed method was further assessed by using E/ET and T/ET derived from isotopic technology at the irrigated cropland site. Results show that apart from early in the growing season when the actual E was affected by plastic film mulching, the modeled E/ET and T/ET agree well with observations in terms of both magnitude and dynamics. The multi-year seasonal patterns of modeled ET, E and T at field scale from this ET partitioning method shows reasonable seasonal variation and spatial variability, which can be used for monitoring plant water consumption in both agricultural and natural ecosystems.