Abstract
In the past decades, multispectral and multitemporal remote sensing has been popularly used for estimating actual evapotranspiration (ETc) across the globe. It has been proven to be a cost-effective tool for understanding agricultural practices in a region. Today, because of the availability of different onboard sensors on an increasing number of different satellites, land surface activity can be captured at fine spatial and time scales. In the present study, three multi-date satellite imageries were used for the evaluation of remote sensing-based estimation of actual evapotranspiration in paddy in the command area of the tropical Kangsabati river basin. A surface energy balance model, the Simplified-Surface Energy Balance Index (S-SEBI), was applied for all three dates of the Rabi season (2014–2015) for the estimation of actual evapotranspiration. The crop coefficient was calculated using the exhaustive survey data collected from the command area and adjusted to local conditions. The ETc estimated using the S-SEBI-based model was compared with the Food and Agriculture Organization Penman–Monteith (FAO-56 PM) method multiplied by the adjusted local crop coefficient and lysimeter data in the command area. The coefficient of determination (r2) was applied to examine the accuracy of the S-SEBI model with respect to lysimeter data and the FAO-56 PM-based ETc. The results showed that the S-SEBI model performed well with the lysimeter (r2 = 0.90) in comparison with FAO-56 PM, with an r2 of 0.65. In addition to this, the S-SEBI-based ET estimates correlated well with the FAO-56 PM, with r and RMSE values of 0.06 and 1.13 mm/day (initial stage), 0.85 and 0.48 mm/day (development stage), and 0.77 and 0.52 (maturity stage) for paddy, respectively. The S-SEBI-based ETc estimate varied with different stages of crop growth and successfully captured the spatial heterogeneity within the command area. In general, this study showed that the S-SEBI method has the potential to calculate spatial evapotranspiration and provide useful information for efficient water management. The results revealed the applicability and accuracy of remote sensing-based ET for managing water resources in a command area with scarce data.
Highlights
Monitoring the spatial and temporal variation of actual evapotranspiration of agricultural crops helps in making future decisions at the macro-level, in rainfed agriculture
Variability in cropping is very closely related to irregular rainfall. This type of study is very critical for water-limited environments because in these regions, evapotranspiration is a dominant factor in water balance [1,2]
The present research provides a comparative assessment of S-SEB-based ETc with lysimeter data and FAO-56 PM for a fine resolution satellite image, such as Landsat 8, which can be used to monitor irrigation water use over command scales
Summary
Monitoring the spatial and temporal variation of actual evapotranspiration of agricultural crops helps in making future decisions (e.g., about water management and crop management) at the macro-level, in rainfed agriculture. Variability in cropping is very closely related to irregular rainfall. This type of study is very critical for water-limited environments because in these regions, evapotranspiration is a dominant factor in water balance [1,2]. Sustainability 2021, 13, 13786 cultivated in the command area is very crucial to water managers for releasing water in the command area. Spatial information on water consumption in irrigated areas is very important for ameliorating water productivity [3,4,5,6]. Evapotranspiration (ET) is a critical parameter for improving water productivity. Precise monitoring of ET in a catchment is required to improve the water productivity in the command area. ET is spatial–temporal in nature for a heterogeneous area, which makes it impossible to compute ET for large areas with ground observation data [8,9]
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