Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia
The incredible drying of the Aral Sea has resulted in a large area of exposed seafloor with saline soils, which has led to catastrophic consequences. This study investigated ground-truth soil salinity data and used Landsat data to map the soil salinity distribution of the exposed seabed of the Aral...
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MDPI AG
2022-04-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/14/9/1438 |
| _version_ | 1797502462278500352 |
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| author | Zihao Duan Xiaolei Wang Lin Sun |
| author_facet | Zihao Duan Xiaolei Wang Lin Sun |
| author_sort | Zihao Duan |
| collection | DOAJ |
| description | The incredible drying of the Aral Sea has resulted in a large area of exposed seafloor with saline soils, which has led to catastrophic consequences. This study investigated ground-truth soil salinity data and used Landsat data to map the soil salinity distribution of the exposed seabed of the Aral Sea from 1960 onwards. The soil salinity distribution, with the depth from 0 cm to 100 cm, was analyzed. The correlation analysis was applied to find the best performance index in describing soil salinity changes. The results showed that ground-truth data of topsoil salinity (depth of 0−5 cm) exhibited a significantly strong correlation with soil salinity index 4 (SI4) among seven indices, where the Pearson correlation coefficient (r) was up to 0.92. Based on the relationship between soil salinity sampling data and SI4, a linear regression model was employed to determine the capability of evaluating the soil salinity distribution of the Aral Sea with the coefficient of determination (R<sup>2</sup>), root mean squared error (RMSE), and ratio of performance to deviation (RPD) values of 0.84 and 0.86 dS m<sup>−1</sup> and 2.36, respectively. The SI4 performed well and was used to predict the soil salinity distribution on the exposed seabed. The distribution showed that soil salinity increased from the former to current shoreline. In the North Aral Sea, compared to 1986, the water area remained stable, accounting for 50.3% in 2020, and the soil salinization level was relatively low. However, the moderately and slightly saline areas dominated 73.8% and 7.5% of the South Aral Sea in 2020, with an increase of 53% and 6% transformed from the water area. The area of salinized soils dramatically increased. The strongly and extremely saline areas were mainly located in the northeastern part of the eastern basin and western part of Vozrozhdeniya Island, respectively, and were the main source of salt-dust storms. These results support the dynamic monitoring and distribution patterns of soil salinization in the Aral Sea. |
| first_indexed | 2024-03-10T03:33:25Z |
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| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-10T03:33:25Z |
| publishDate | 2022-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-9db90fd714254c37b7f2d4d20a3a24462023-11-23T09:35:46ZengMDPI AGWater2073-44412022-04-01149143810.3390/w14091438Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central AsiaZihao Duan0Xiaolei Wang1Lin Sun2Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaThe incredible drying of the Aral Sea has resulted in a large area of exposed seafloor with saline soils, which has led to catastrophic consequences. This study investigated ground-truth soil salinity data and used Landsat data to map the soil salinity distribution of the exposed seabed of the Aral Sea from 1960 onwards. The soil salinity distribution, with the depth from 0 cm to 100 cm, was analyzed. The correlation analysis was applied to find the best performance index in describing soil salinity changes. The results showed that ground-truth data of topsoil salinity (depth of 0−5 cm) exhibited a significantly strong correlation with soil salinity index 4 (SI4) among seven indices, where the Pearson correlation coefficient (r) was up to 0.92. Based on the relationship between soil salinity sampling data and SI4, a linear regression model was employed to determine the capability of evaluating the soil salinity distribution of the Aral Sea with the coefficient of determination (R<sup>2</sup>), root mean squared error (RMSE), and ratio of performance to deviation (RPD) values of 0.84 and 0.86 dS m<sup>−1</sup> and 2.36, respectively. The SI4 performed well and was used to predict the soil salinity distribution on the exposed seabed. The distribution showed that soil salinity increased from the former to current shoreline. In the North Aral Sea, compared to 1986, the water area remained stable, accounting for 50.3% in 2020, and the soil salinization level was relatively low. However, the moderately and slightly saline areas dominated 73.8% and 7.5% of the South Aral Sea in 2020, with an increase of 53% and 6% transformed from the water area. The area of salinized soils dramatically increased. The strongly and extremely saline areas were mainly located in the northeastern part of the eastern basin and western part of Vozrozhdeniya Island, respectively, and were the main source of salt-dust storms. These results support the dynamic monitoring and distribution patterns of soil salinization in the Aral Sea.https://www.mdpi.com/2073-4441/14/9/1438salinizationsalinity indicesremote sensingexposed seafloorlake |
| spellingShingle | Zihao Duan Xiaolei Wang Lin Sun Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia Water salinization salinity indices remote sensing exposed seafloor lake |
| title | Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia |
| title_full | Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia |
| title_fullStr | Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia |
| title_full_unstemmed | Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia |
| title_short | Monitoring and Mapping of Soil Salinity on the Exposed Seabed of the Aral Sea, Central Asia |
| title_sort | monitoring and mapping of soil salinity on the exposed seabed of the aral sea central asia |
| topic | salinization salinity indices remote sensing exposed seafloor lake |
| url | https://www.mdpi.com/2073-4441/14/9/1438 |
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