EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Detection of irrigation events on maize plots using sentinel-1 soil moisture products

Michel Le Page1, Lionel Jarlan1, Aaron Boone2, Mohammad El Hajj3, Nicolas Baghdadi3, and Mehrez Zribi1
Michel Le Page et al.
  • 1CESBIO (UPS/CNRS/IRD/CNES/INRA), 18, Avenue Edouard Belin, 31401, Toulouse Cedex 9, France
  • 2CNRM (Météo-France/CNRS), Toulouse, France
  • 3INRAE, UMR TETIS, University of Montpellier, 34093 Montpellier Cedex 5, France

An accurate knowledge of irrigation timing and rate is essential to compute the water balance of irrigated plots. However, at the plot scale irrigation is a data essentially known by the irrigator. These data do not go up to higher management scales, thus limiting both the management of water resources on a regional scale and the development of irrigation decision support tools at the farm scale. The study focuses on 6 experimental plots in the south-west of France. The new method consists in assessing surface soil moisture (SSM) change between observations and a water balance model. The approach was tested using both in situ measurements and surface soil moisture (SSM) maps derived from Sentinel-1 radar data. The score is obtained by assessing if the irrigation event is detected within +/- three days. The use of in situ SSM showed that: (1) the best revisit time between two SSM observations is 3 days; short gaps is subject to uncertainties while longer gap miss possible SSM variations; (2) in general, higher rates (>20mm) of irrigation are well identified while it is very difficult to identify irrigation event when it is raining or when irrigation rates are small (<10mm). When using the SSM microwave product, the performances are degraded but are still acceptable given the discontinuity of irrigation events: 34% of absolute error and a bias of 5% for the whole season. Although high vegetation cover degrades the SSM absolute estimates, the dynamic appeared to be in accordance with in-situ measurements.

How to cite: Le Page, M., Jarlan, L., Boone, A., El Hajj, M., Baghdadi, N., and Zribi, M.: Detection of irrigation events on maize plots using sentinel-1 soil moisture products, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8588,, 2020

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