Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD)
Given the great importance of lakes in Earth’s environment and human life, continuous water quality (WQ) monitoring within the frame of the Water Framework Directive (WFD) is the most crucial aspect for lake management. In this study, Earth Observation (EO) data from Landsat 7 Enhanced Thematic Mapp...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-02-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/3/739 |
| _version_ | 1797484980948959232 |
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| author | Vassiliki Markogianni Dionissios Kalivas George P. Petropoulos Elias Dimitriou |
| author_facet | Vassiliki Markogianni Dionissios Kalivas George P. Petropoulos Elias Dimitriou |
| author_sort | Vassiliki Markogianni |
| collection | DOAJ |
| description | Given the great importance of lakes in Earth’s environment and human life, continuous water quality (WQ) monitoring within the frame of the Water Framework Directive (WFD) is the most crucial aspect for lake management. In this study, Earth Observation (EO) data from Landsat 7 Enhanced Thematic Mapper Plus (ETM<sup>+</sup>) and Landsat 8 Operational Land Imager (OLI) sensors have been combined with co-orbital in situ measurements from 50 lakes located in Greece with the main objective of delivering robust WQ assessment models. Correlation analysis among in situ co-orbital WQ data (Chlorophylla, Secchi depths, Total phosphorus-TP-) contributed to distinguishing their inter-relationships and improving the WQ models’ accuracy. Subsequently, stepwise multiple regression analysis (MLR) of the available TP and Secchi depth datasets was implemented to explore the potential to establish optimal quantitative models regardless of lake characteristics. Then, further MLR analysis concerning whether the lakes are natural or artificial was conducted with the basic aim of generating different remote sensing derived models for different types of lakes, while their combination was further utilized to assess their trophic status. Correlation matrix results showed a high and positive relationship between TP and Chlorophyll-<i>a</i> (0.85), whereas high negative relationships were found between Secchi depth with TP (−0.84) and Chlorophyll-<i>a</i> (−0.83). MLRs among Landsat data and Secchi depths resulted in 3 optimal models concerning the assessment of Secchi depth of all lakes (Secchi<sub>general;</sub> R = 0.78; RMSE = 0.24 m), natural (Secchi<sub>natural;</sub> R = 0.95; RMSE = 0.14 m) and artificial (Secchi<sub>artificial;</sub> R = 0.62; RMSE = 0.1 m), with reliable accuracy. Study findings showed that TP-related MLR analyses failed to deliver a statistically acceptable model for the reservoirs; nevertheless, they delivered a robust TP<sub>general</sub> (R = 0.71; RMSE = 1.41 mg/L) and TP<sub>natural</sub> model (R = 0.93; RMSE = 1.43 mg/L). Subsequently, trophic status classification was conducted herein, calculating Carlson’s Trophic State Index (TSI) initially throughout all lakes and then oriented toward natural-only and artificial-only lakes. Those three types of TSI (general, natural, artificial) were calculated based on previously published satellite-derived Chlorophyll-<i>a</i> (Chl-<i>a</i>) assessment models and the hereby specially designed WQ models (Secchi depth, TP). The higher deviation of satellite-derived TSI values in relation to in situ ones was detected in reservoirs and shallower lakes (mean depth < 5 m), indicating noticeable divergences among natural and artificial lakes. All in all, the study findings provide important support toward the perpetual WQ monitoring and trophic status prediction of Greek lakes and, by extension, their sustainable management, particularly in cases when ground truth data is limited. |
| first_indexed | 2024-03-09T23:12:16Z |
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| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T23:12:16Z |
| publishDate | 2022-02-01 |
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| series | Remote Sensing |
| spelling | doaj.art-edbcd48e6be54027b7c7217aa054efc82023-11-23T17:42:42ZengMDPI AGRemote Sensing2072-42922022-02-0114373910.3390/rs14030739Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD)Vassiliki Markogianni0Dionissios Kalivas1George P. Petropoulos2Elias Dimitriou3Institute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research, 46.7 km of Athens-Sounio Avenue, 19013 Attica, GreeceDepartment of Natural Resources Management and Agricultural Engineering, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, GreeceDepartment of Geography, Harokopio University of Athens, El. Venizelou 70, Kallithea, 17671 Athens, GreeceInstitute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research, 46.7 km of Athens-Sounio Avenue, 19013 Attica, GreeceGiven the great importance of lakes in Earth’s environment and human life, continuous water quality (WQ) monitoring within the frame of the Water Framework Directive (WFD) is the most crucial aspect for lake management. In this study, Earth Observation (EO) data from Landsat 7 Enhanced Thematic Mapper Plus (ETM<sup>+</sup>) and Landsat 8 Operational Land Imager (OLI) sensors have been combined with co-orbital in situ measurements from 50 lakes located in Greece with the main objective of delivering robust WQ assessment models. Correlation analysis among in situ co-orbital WQ data (Chlorophylla, Secchi depths, Total phosphorus-TP-) contributed to distinguishing their inter-relationships and improving the WQ models’ accuracy. Subsequently, stepwise multiple regression analysis (MLR) of the available TP and Secchi depth datasets was implemented to explore the potential to establish optimal quantitative models regardless of lake characteristics. Then, further MLR analysis concerning whether the lakes are natural or artificial was conducted with the basic aim of generating different remote sensing derived models for different types of lakes, while their combination was further utilized to assess their trophic status. Correlation matrix results showed a high and positive relationship between TP and Chlorophyll-<i>a</i> (0.85), whereas high negative relationships were found between Secchi depth with TP (−0.84) and Chlorophyll-<i>a</i> (−0.83). MLRs among Landsat data and Secchi depths resulted in 3 optimal models concerning the assessment of Secchi depth of all lakes (Secchi<sub>general;</sub> R = 0.78; RMSE = 0.24 m), natural (Secchi<sub>natural;</sub> R = 0.95; RMSE = 0.14 m) and artificial (Secchi<sub>artificial;</sub> R = 0.62; RMSE = 0.1 m), with reliable accuracy. Study findings showed that TP-related MLR analyses failed to deliver a statistically acceptable model for the reservoirs; nevertheless, they delivered a robust TP<sub>general</sub> (R = 0.71; RMSE = 1.41 mg/L) and TP<sub>natural</sub> model (R = 0.93; RMSE = 1.43 mg/L). Subsequently, trophic status classification was conducted herein, calculating Carlson’s Trophic State Index (TSI) initially throughout all lakes and then oriented toward natural-only and artificial-only lakes. Those three types of TSI (general, natural, artificial) were calculated based on previously published satellite-derived Chlorophyll-<i>a</i> (Chl-<i>a</i>) assessment models and the hereby specially designed WQ models (Secchi depth, TP). The higher deviation of satellite-derived TSI values in relation to in situ ones was detected in reservoirs and shallower lakes (mean depth < 5 m), indicating noticeable divergences among natural and artificial lakes. All in all, the study findings provide important support toward the perpetual WQ monitoring and trophic status prediction of Greek lakes and, by extension, their sustainable management, particularly in cases when ground truth data is limited.https://www.mdpi.com/2072-4292/14/3/739geoinformationLandsatlake WQtrophic statusMLR analysisWFD |
| spellingShingle | Vassiliki Markogianni Dionissios Kalivas George P. Petropoulos Elias Dimitriou Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD) Remote Sensing geoinformation Landsat lake WQ trophic status MLR analysis WFD |
| title | Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD) |
| title_full | Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD) |
| title_fullStr | Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD) |
| title_full_unstemmed | Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD) |
| title_short | Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD) |
| title_sort | modelling of greek lakes water quality using earth observation in the framework of the water framework directive wfd |
| topic | geoinformation Landsat lake WQ trophic status MLR analysis WFD |
| url | https://www.mdpi.com/2072-4292/14/3/739 |
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