An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data
In this study, we present an operational methodology for mapping irrigated areas at plot scale, which overcomes the limitation of terrain data availability, using Sentinel-1 (S1) C-band SAR (synthetic-aperture radar) and Sentinel-2 (S2) optical time series. The method was performed over a study site...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-07-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/13/13/2584 |
| _version_ | 1797527868756983808 |
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| author | Hassan Bazzi Nicolas Baghdadi Ghaith Amin Ibrahim Fayad Mehrez Zribi Valérie Demarez Hatem Belhouchette |
| author_facet | Hassan Bazzi Nicolas Baghdadi Ghaith Amin Ibrahim Fayad Mehrez Zribi Valérie Demarez Hatem Belhouchette |
| author_sort | Hassan Bazzi |
| collection | DOAJ |
| description | In this study, we present an operational methodology for mapping irrigated areas at plot scale, which overcomes the limitation of terrain data availability, using Sentinel-1 (S1) C-band SAR (synthetic-aperture radar) and Sentinel-2 (S2) optical time series. The method was performed over a study site located near Orléans city of north-central France for four years (2017 until 2020). First, training data of irrigated and non-irrigated plots were selected using predefined selection criteria to obtain sufficient samples of irrigated and non-irrigated plots each year. The training data selection criteria is based on two irrigation metrics; the first one is a SAR-based metric derived from the S1 time series and the second is an optical-based metric derived from the NDVI (normalized difference vegetation index) time series of the S2 data. Using the newly developed irrigation event detection model (IEDM) applied for all S1 time series in VV (Vertical-Vertical) and VH (Vertical-Horizontal) polarizations, an irrigation weight metric was calculated for each plot. Using the NDVI time series, the maximum NDVI value achieved in the crop cycle was considered as a second selection metric. By fixing threshold values for both metrics, a dataset of irrigated and non-irrigated samples was constructed each year. Later, a random forest classifier (RF) was built for each year in order to map the summer agricultural plots into irrigated/non-irrigated. The irrigation classification model uses the S1 and NDVI time series calculated over the selected training plots. Finally, the proposed irrigation classifier was validated using real in situ data collected each year. The results show that, using the proposed classification procedure, the overall accuracy for the irrigation classification reaches 84.3%, 93.0%, 81.8%, and 72.8% for the years 2020, 2019, 2018, and 2017, respectively. The comparison between our proposed classification approach and the RF classifier built directly from in situ data showed that our approach reaches an accuracy nearly similar to that obtained using in situ RF classifiers with a difference in overall accuracy not exceeding 6.2%. The analysis of the obtained classification accuracies of the proposed method with precipitation data revealed that years with higher rainfall amounts during the summer crop-growing season (irrigation period) had lower overall accuracy (72.8% for 2017) whereas years encountering a drier summer had very good accuracy (93.0% for 2019). |
| first_indexed | 2024-03-10T09:49:56Z |
| format | Article |
| id | doaj.art-857891e3203c452fb5fc31c69341877d |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T09:49:56Z |
| publishDate | 2021-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-857891e3203c452fb5fc31c69341877d2023-11-22T02:49:23ZengMDPI AGRemote Sensing2072-42922021-07-011313258410.3390/rs13132584An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 DataHassan Bazzi0Nicolas Baghdadi1Ghaith Amin2Ibrahim Fayad3Mehrez Zribi4Valérie Demarez5Hatem Belhouchette6INRAE, 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, FranceINRAE, 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, FranceCESBIO (CNRS/UPS/IRD/CNES/INRAE), 18 av. Edouard Belin, bpi 2801, CEDEX 9, 31401 Toulouse, FranceCESBIO (CNRS/UPS/IRD/CNES/INRAE), 18 av. Edouard Belin, bpi 2801, CEDEX 9, 31401 Toulouse, FranceCIHEAM-IAMM, UMR-System, 34090 Montpellier, FranceIn this study, we present an operational methodology for mapping irrigated areas at plot scale, which overcomes the limitation of terrain data availability, using Sentinel-1 (S1) C-band SAR (synthetic-aperture radar) and Sentinel-2 (S2) optical time series. The method was performed over a study site located near Orléans city of north-central France for four years (2017 until 2020). First, training data of irrigated and non-irrigated plots were selected using predefined selection criteria to obtain sufficient samples of irrigated and non-irrigated plots each year. The training data selection criteria is based on two irrigation metrics; the first one is a SAR-based metric derived from the S1 time series and the second is an optical-based metric derived from the NDVI (normalized difference vegetation index) time series of the S2 data. Using the newly developed irrigation event detection model (IEDM) applied for all S1 time series in VV (Vertical-Vertical) and VH (Vertical-Horizontal) polarizations, an irrigation weight metric was calculated for each plot. Using the NDVI time series, the maximum NDVI value achieved in the crop cycle was considered as a second selection metric. By fixing threshold values for both metrics, a dataset of irrigated and non-irrigated samples was constructed each year. Later, a random forest classifier (RF) was built for each year in order to map the summer agricultural plots into irrigated/non-irrigated. The irrigation classification model uses the S1 and NDVI time series calculated over the selected training plots. Finally, the proposed irrigation classifier was validated using real in situ data collected each year. The results show that, using the proposed classification procedure, the overall accuracy for the irrigation classification reaches 84.3%, 93.0%, 81.8%, and 72.8% for the years 2020, 2019, 2018, and 2017, respectively. The comparison between our proposed classification approach and the RF classifier built directly from in situ data showed that our approach reaches an accuracy nearly similar to that obtained using in situ RF classifiers with a difference in overall accuracy not exceeding 6.2%. The analysis of the obtained classification accuracies of the proposed method with precipitation data revealed that years with higher rainfall amounts during the summer crop-growing season (irrigation period) had lower overall accuracy (72.8% for 2017) whereas years encountering a drier summer had very good accuracy (93.0% for 2019).https://www.mdpi.com/2072-4292/13/13/2584irrigationsynthetic aperture radarnormalized difference vegetation indexsoil moisturesummer crops |
| spellingShingle | Hassan Bazzi Nicolas Baghdadi Ghaith Amin Ibrahim Fayad Mehrez Zribi Valérie Demarez Hatem Belhouchette An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data Remote Sensing irrigation synthetic aperture radar normalized difference vegetation index soil moisture summer crops |
| title | An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data |
| title_full | An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data |
| title_fullStr | An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data |
| title_full_unstemmed | An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data |
| title_short | An Operational Framework for Mapping Irrigated Areas at Plot Scale Using Sentinel-1 and Sentinel-2 Data |
| title_sort | operational framework for mapping irrigated areas at plot scale using sentinel 1 and sentinel 2 data |
| topic | irrigation synthetic aperture radar normalized difference vegetation index soil moisture summer crops |
| url | https://www.mdpi.com/2072-4292/13/13/2584 |
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