Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events
Comprehensive knowledge about irrigation timing is crucial for water resource management. This paper presents a comparative analysis between C- and L-band Synthetic Aperture Radar (SAR) data for the detection of irrigation events. The analysis was performed using C-band time series data derived from...
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| Format: | Article |
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MDPI AG
2022-05-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/10/2312 |
| _version_ | 1827666811128119296 |
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| author | Hassan Bazzi Nicolas Baghdadi François Charron Mehrez Zribi |
| author_facet | Hassan Bazzi Nicolas Baghdadi François Charron Mehrez Zribi |
| author_sort | Hassan Bazzi |
| collection | DOAJ |
| description | Comprehensive knowledge about irrigation timing is crucial for water resource management. This paper presents a comparative analysis between C- and L-band Synthetic Aperture Radar (SAR) data for the detection of irrigation events. The analysis was performed using C-band time series data derived from the Sentinel-1 (S1) satellite and two L-band images from the PALSAR-2 (ALOS-2) sensor acquired over irrigated grassland plots in the Crau plain of southeast France. The S1 C-band time series was first analyzed as a function of rainfall and irrigation events. The backscattering coefficients in both the L and C bands were then compared to the time difference between the date of the acquired SAR image and the date of the last irrigation event occurring before the SAR acquisition (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula>). Sensitivity analysis was performed for 2 classes of the Normalized Difference Vegetation Index (NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≤</mo><mn>0.7</mn></mrow></semantics></math></inline-formula> and NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>></mo><mn>0.7</mn></mrow></semantics></math></inline-formula>). The main results showed that when the vegetation is moderately developed (NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≤</mo><mn>0.7</mn></mrow></semantics></math></inline-formula>), the C-band temporal variation remains sensitive to the soil moisture dynamics and the irrigation events could be detected. The C-VV signal decreases due to the drying out of the soil when the time difference between the S1 image and irrigation event increases. For well-developed vegetation cover (NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>></mo><mn>0.7</mn></mrow></semantics></math></inline-formula>), the C-band sensitivity to irrigation events becomes dependent on the crop type. For well-developed Gramineae grass with longs stalks and seedheads, the C band shows no correlation with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula> due to the absence of the soil contribution in the backscattered signal, contrary to the legume grass type, where the C band shows a good correspondence between C-VV and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula> for NDVI > 0.7. In contrast, analysis of the L-band backscattering coefficient shows that the L band remains sensitive to the soil moisture regardless of the vegetation cover development and the vegetation characteristics, thus being more suitable for irrigation detection than the C band. The L-HH signal over Gramineae grass or legume grass types shows the same decreasing pattern with the increase in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula>, regardless of the NDVI-values, presenting a decrease in soil moisture with time and thus high sensitivity of the radar signal to soil parameters. Finally, the co-polarizations for both the C and L bands (L-HH and C-VV) tend to be more adequate for irrigation detection than the HV cross-polarization, as they show higher sensitivity to soil moisture values. |
| first_indexed | 2024-03-10T01:57:54Z |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-10T01:57:54Z |
| publishDate | 2022-05-01 |
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| series | Remote Sensing |
| spelling | doaj.art-7a2c46a0160142e59415041899c3f0df2023-11-23T12:54:04ZengMDPI AGRemote Sensing2072-42922022-05-011410231210.3390/rs14102312Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation EventsHassan Bazzi0Nicolas Baghdadi1François Charron2Mehrez Zribi3INRAE, UMR TETIS, University of Montpellier, AgroParisTech, 500 Rue François Breton, CEDEX 5, 34093 Montpellier, FranceINRAE, UMR TETIS, University of Montpellier, AgroParisTech, 500 Rue François Breton, CEDEX 5, 34093 Montpellier, FranceUniversity of Montpellier, G-EAU Unit, AgroParisTech, CIRAD, INRAE, Institut Agro, IRD, Domaine du Merle, 13300 Salon de Provence, FranceCESBIO, Université de Toulouse, CNES/CNRS/INRAE/IRD/UPS, 18 Av. Edouard Belin, bpi 2801, CEDEX 9, 31401 Toulouse, FranceComprehensive knowledge about irrigation timing is crucial for water resource management. This paper presents a comparative analysis between C- and L-band Synthetic Aperture Radar (SAR) data for the detection of irrigation events. The analysis was performed using C-band time series data derived from the Sentinel-1 (S1) satellite and two L-band images from the PALSAR-2 (ALOS-2) sensor acquired over irrigated grassland plots in the Crau plain of southeast France. The S1 C-band time series was first analyzed as a function of rainfall and irrigation events. The backscattering coefficients in both the L and C bands were then compared to the time difference between the date of the acquired SAR image and the date of the last irrigation event occurring before the SAR acquisition (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula>). Sensitivity analysis was performed for 2 classes of the Normalized Difference Vegetation Index (NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≤</mo><mn>0.7</mn></mrow></semantics></math></inline-formula> and NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>></mo><mn>0.7</mn></mrow></semantics></math></inline-formula>). The main results showed that when the vegetation is moderately developed (NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≤</mo><mn>0.7</mn></mrow></semantics></math></inline-formula>), the C-band temporal variation remains sensitive to the soil moisture dynamics and the irrigation events could be detected. The C-VV signal decreases due to the drying out of the soil when the time difference between the S1 image and irrigation event increases. For well-developed vegetation cover (NDVI <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>></mo><mn>0.7</mn></mrow></semantics></math></inline-formula>), the C-band sensitivity to irrigation events becomes dependent on the crop type. For well-developed Gramineae grass with longs stalks and seedheads, the C band shows no correlation with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula> due to the absence of the soil contribution in the backscattered signal, contrary to the legume grass type, where the C band shows a good correspondence between C-VV and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula> for NDVI > 0.7. In contrast, analysis of the L-band backscattering coefficient shows that the L band remains sensitive to the soil moisture regardless of the vegetation cover development and the vegetation characteristics, thus being more suitable for irrigation detection than the C band. The L-HH signal over Gramineae grass or legume grass types shows the same decreasing pattern with the increase in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi mathvariant="normal">t</mi></mrow></semantics></math></inline-formula>, regardless of the NDVI-values, presenting a decrease in soil moisture with time and thus high sensitivity of the radar signal to soil parameters. Finally, the co-polarizations for both the C and L bands (L-HH and C-VV) tend to be more adequate for irrigation detection than the HV cross-polarization, as they show higher sensitivity to soil moisture values.https://www.mdpi.com/2072-4292/14/10/2312irrigation eventsSynthetic Aperture RadarSentinel-1ALOS-2 |
| spellingShingle | Hassan Bazzi Nicolas Baghdadi François Charron Mehrez Zribi Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events Remote Sensing irrigation events Synthetic Aperture Radar Sentinel-1 ALOS-2 |
| title | Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events |
| title_full | Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events |
| title_fullStr | Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events |
| title_full_unstemmed | Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events |
| title_short | Comparative Analysis of the Sensitivity of SAR Data in C and L Bands for the Detection of Irrigation Events |
| title_sort | comparative analysis of the sensitivity of sar data in c and l bands for the detection of irrigation events |
| topic | irrigation events Synthetic Aperture Radar Sentinel-1 ALOS-2 |
| url | https://www.mdpi.com/2072-4292/14/10/2312 |
| work_keys_str_mv | AT hassanbazzi comparativeanalysisofthesensitivityofsardataincandlbandsforthedetectionofirrigationevents AT nicolasbaghdadi comparativeanalysisofthesensitivityofsardataincandlbandsforthedetectionofirrigationevents AT francoischarron comparativeanalysisofthesensitivityofsardataincandlbandsforthedetectionofirrigationevents AT mehrezzribi comparativeanalysisofthesensitivityofsardataincandlbandsforthedetectionofirrigationevents |