@article{fdi:010087594,
  title = {{A}re the {C}-band backscattering coefficient and interferometric coherence suitable substitutes of {NDVI} for the monitoring of the {FAO}-56 crop coefficient ?},
  author = {{O}uaadi, {N}. and {J}arlan, {L}ionel and {K}habba, {S}. and {L}e {P}age, {M}ichel and {C}hakir, {A}dnane and {E}r-{R}aki, {S}. and {F}rison, {P}. {L}.},
  editor = {},
  language = {{ENG}},
  abstract = {{R}ationalizing the use of agricultural water is a key issue in semi-arid areas that face more and more water shortages while food security is already threatened by the increasing population. {T}he {FAO}-56 approach has been developed to estimate the crop water requirement. {I}t relies on an accurate estimation of the "basal crop coef-ficient" {K}cb-act that has been shown to be closely related to {NDVI}. {N}evertheless, optical data can be inoperant in case of persistent cloud cover. {W}ithin this context, the objective of this study is to assess the potentiality of the all-weather {C}-band {S}entinel-1 radar observations available with 6-day revisit time at the field scale. {T}o this end, the empirical relationships between {K}cb-act, on one hand, and the interferometric coherence at {VV} (p{VV}) and {VH} (p{VH}) polarizations and the polarization ratio, on the other hand, were assessed on two wheat fields during two crop seasons and compared to the classical {K}cb-act-{NDVI} method. {I}t is demonstrated that while good statistical metrics are obviously obtained between {K}cb-act and {NDVI} derived from {S}entinel-2 ({R} = 0.77/0.88 and {RMSE} = 0.14/0.15 for {F}ield 1/{F}ield 2), close results are highlighted with radar data. {T}he best metrics are found with p{VV}: {R} = 0.76 and 0.77 and {RMSE} = 0.18 and 0.28 for {F}ield 1 and {F}ield 2, respectively. {U}sing the calibrated re-lationships on one season of {F}ield 1, reasonable estimates of {ET}c-act was found on {F}ield 1 ({R} = 0.70, {RMSE} = 0.75 mm/day and bias =-0.18 mm/days using {K}cb-act-p{VV}). {B}y contrast, a significant overestimations is high-lighted both with p{VV} (bias = 0.73 mm/day) and {NDVI} (bias = 1.46 mm/day) over {F}ield 2. {I}nterestingly, the {K}cb-act-p{VV} relationship is more consistent in the estimation of {ET}c-act when changing from one plot to another. {T}hese outcomes open new perspectives for the estimation of {ET}c-act from radar data as a potential substitute of {NDVI} in case of persistent cloud cover.},
  keywords = {{B}asal crop coefficient ; {I}nterferometric coherence ; {P}olarization ratio ; {E}vapotranspiration ; {W}heat crop ; {MAROC}},
  booktitle = {},
  journal = {{A}gricultural {W}ater {M}anagement},
  volume = {282},
  numero = {},
  pages = {108276 [16 ]},
  ISSN = {0378-3774},
  year = {2023},
  DOI = {10.1016/j.agwat.2023.108276},
  URL = {https://www.documentation.ird.fr/hor/fdi:010087594},
}