A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept
Submersed aquatic plant (SAP) communities are important determinants of estuarine and lacustrine food web structure, nutrient cycling, and water quality. Variation in water quality, SAP community composition and cover present challenges when mapping SAP robustly across estuarine ecosystems. We propo...
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Taylor & Francis Group
2024-12-01
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| Series: | GIScience & Remote Sensing |
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| Online Access: | https://www.tandfonline.com/doi/10.1080/15481603.2024.2399386 |
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| author | Shruti Khanna Erin L. Hestir Joaquim Bellvert Jennifer D. Boyer Kristen D. Shapiro Susan L. Ustin |
| author_facet | Shruti Khanna Erin L. Hestir Joaquim Bellvert Jennifer D. Boyer Kristen D. Shapiro Susan L. Ustin |
| author_sort | Shruti Khanna |
| collection | DOAJ |
| description | Submersed aquatic plant (SAP) communities are important determinants of estuarine and lacustrine food web structure, nutrient cycling, and water quality. Variation in water quality, SAP community composition and cover present challenges when mapping SAP robustly across estuarine ecosystems. We propose three new spectral indices based on the soil-line concept that overcome the confounding influence of varying water quality and SAP cover in shallow inland waters. Spectral variability of water due to water quality differences can be modeled using a “water line” while SAP spectral differences due to cover and/or composition, can be modeled using a “SAP line.” Spectral distance of the pixel from the SAP line in a hypothetical two-band spectral space represents the inverse probability that the pixel contains SAP. This distance from the SAP line represents the Perpendicular SAP Index using an SAP line (PSIS). Correspondingly, the distance of a pixel from the water line represents the Perpendicular SAP Index using a Water line (PSIW). We also tested a compound index, PSIΔ, the difference between PSIS and PSIW, following the reasoning that an SAP pixel is closer to the SAP line compared to a water line and a water pixel is closer to the water line compared to the SAP line. The results of this study indicate that yellow and red-edge band-pairs performed best for calculating PSIS and red and red-edge band-pairs performed best for calculating PSIW. The same band-pairs as PSIW worked best for PSIΔ. The accuracy for PSIΔ was either as good as or better than the accuracy for PSIS or PSIW. The red-edge band required to calculate three PSI indices should be narrow (10–20 nm bandwidth) and centered around 700 nm. Bands ideal for calculating PSI are available on the Sentinel-2 and WorldView-3 satellite sensors. When compared to seven other narrow and broadband spectral indices from the same spectral region, PSIW and PSIΔ performed best for separating water and SAP classes. Thus, this family of indices shows promise for detection of SAP mats in shallow inland waters over a wide range of water quality parameters as observed in our estuarine study system and could prove to be a major step forward in detection of SAP using multispectral data. |
| format | Article |
| id | doaj-art-7bfd11ef66fa4593876511075f5075a8 |
| institution | OA Journals |
| issn | 1548-1603 1943-7226 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Taylor & Francis Group |
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| series | GIScience & Remote Sensing |
| spelling | doaj-art-7bfd11ef66fa4593876511075f5075a82025-08-20T01:59:30ZengTaylor & Francis GroupGIScience & Remote Sensing1548-16031943-72262024-12-0161110.1080/15481603.2024.2399386A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line conceptShruti Khanna0Erin L. Hestir1Joaquim Bellvert2Jennifer D. Boyer3Kristen D. Shapiro4Susan L. Ustin5Center for Spatial Technologies and Remote Sensing, University of California, Davis, CA, USADepartment of Civil & Environmental Engineering, University of California, Merced, CA, USACenter for Spatial Technologies and Remote Sensing, University of California, Davis, CA, USACenter for Spatial Technologies and Remote Sensing, University of California, Davis, CA, USACenter for Spatial Technologies and Remote Sensing, University of California, Davis, CA, USACenter for Spatial Technologies and Remote Sensing, University of California, Davis, CA, USASubmersed aquatic plant (SAP) communities are important determinants of estuarine and lacustrine food web structure, nutrient cycling, and water quality. Variation in water quality, SAP community composition and cover present challenges when mapping SAP robustly across estuarine ecosystems. We propose three new spectral indices based on the soil-line concept that overcome the confounding influence of varying water quality and SAP cover in shallow inland waters. Spectral variability of water due to water quality differences can be modeled using a “water line” while SAP spectral differences due to cover and/or composition, can be modeled using a “SAP line.” Spectral distance of the pixel from the SAP line in a hypothetical two-band spectral space represents the inverse probability that the pixel contains SAP. This distance from the SAP line represents the Perpendicular SAP Index using an SAP line (PSIS). Correspondingly, the distance of a pixel from the water line represents the Perpendicular SAP Index using a Water line (PSIW). We also tested a compound index, PSIΔ, the difference between PSIS and PSIW, following the reasoning that an SAP pixel is closer to the SAP line compared to a water line and a water pixel is closer to the water line compared to the SAP line. The results of this study indicate that yellow and red-edge band-pairs performed best for calculating PSIS and red and red-edge band-pairs performed best for calculating PSIW. The same band-pairs as PSIW worked best for PSIΔ. The accuracy for PSIΔ was either as good as or better than the accuracy for PSIS or PSIW. The red-edge band required to calculate three PSI indices should be narrow (10–20 nm bandwidth) and centered around 700 nm. Bands ideal for calculating PSI are available on the Sentinel-2 and WorldView-3 satellite sensors. When compared to seven other narrow and broadband spectral indices from the same spectral region, PSIW and PSIΔ performed best for separating water and SAP classes. Thus, this family of indices shows promise for detection of SAP mats in shallow inland waters over a wide range of water quality parameters as observed in our estuarine study system and could prove to be a major step forward in detection of SAP using multispectral data.https://www.tandfonline.com/doi/10.1080/15481603.2024.2399386Hyperspectral remote sensinginland estuarymappingenvironmental monitoringaquatic vegetation |
| spellingShingle | Shruti Khanna Erin L. Hestir Joaquim Bellvert Jennifer D. Boyer Kristen D. Shapiro Susan L. Ustin A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept GIScience & Remote Sensing Hyperspectral remote sensing inland estuary mapping environmental monitoring aquatic vegetation |
| title | A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept |
| title_full | A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept |
| title_fullStr | A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept |
| title_full_unstemmed | A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept |
| title_short | A new index for detection of submerged aquatic plants under variable quality water: an extension of the soil-line concept |
| title_sort | new index for detection of submerged aquatic plants under variable quality water an extension of the soil line concept |
| topic | Hyperspectral remote sensing inland estuary mapping environmental monitoring aquatic vegetation |
| url | https://www.tandfonline.com/doi/10.1080/15481603.2024.2399386 |
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