Understanding Sentinel-1 backscatter response to sugarcane yield variability and waterlogging
Nadja den Besten (TU Delft - Civil Engineering & Geosciences, Planet Labs Inc.)
Susan Steele Dunne (TU Delft - Civil Engineering & Geosciences)
Ashfak Mahmud (University of Helsinki)
Daniel Jackson (Planet Labs Inc.)
Benjamin Aouizerats (Planet Labs Inc.)
Richard de Jeu (Planet Labs Inc.)
Rogier Burger (Planet Labs Inc.)
Rasmus Houborg (Planet Labs Inc.)
Mark McGlinchey (SQR Software)
Pieter van der Zaag (TU Delft - Civil Engineering & Geosciences, IHE Delft Institute for Water Education)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Sentinel-1 observes the whole globe every 12 days (6 days when both satellites were operational) and provides a wealth of data relevant to agriculture. Sugarcane cultivators could potentially benefit from these data by using them to assist operational and management practices. However, first, thorough understanding is needed of Sentinel-1 backscatter and its behavior over sugarcane canopies. In this study, we aimed to improve understanding of how Sentinel-1 backscatter responds to sugarcane yield variability and waterlogging. In order to do so we focused on an irrigated sugarcane plantation in Xinavane, Mozambique. In the analysis presented, we assessed different polarizations, their ratio, and benchmarked them against optical indices and passive microwave observations in different seasons. With the help of a large sugarcane yield dataset, we analyzed how backscatter relates to sucrose yield variability in different seasons. We found VV backscatter related to the stalk development, the most important reservoir for sucrose accumulation. In addition, in a season with reported waterlogging, optical and radar observations showed a delay in sugarcane crop development. Further analysis showed the presence of water underneath the canopy caused an increase in all polarizations and the cross ratio (CR). The results imply that Sentinel-1 backscatter contains information on both waterlogging under the canopy as well as sucrose development in the stalk. By isolating and quantifying the impact of waterlogging on backscatter, it will be possible to further quantify sucrose development with backscatter observations and identify waterlogging simultaneously.
help_outline