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Proposal for a remote sensing trophic state index based upon Thematic Mapper/Landsat images
Proposal for a remote sensing trophic state index based upon Thematic Mapper/Landsat images
- Source :
- Revista Ambiente & Água, Vol 8, Iss 3, Pp 65-83 (2013)
- Publication Year :
- 2013
- Publisher :
- Instituto de Pesquisas Ambientais em Bacias Hidrográficas (IPABHi), 2013.
-
Abstract
- This work proposes a trophic state index based on the remote sensing retrieval of chlorophyll-α concentration. For that, in situ Bidirectional Reflectance Factor (BRF) data acquired in the Ibitinga reservoir were resampled to match Landsat/TM spectral simulated bands (TM_sim bands) and used to run linear correlation with concurrent measurements of chlorophyll-α concentration. Monte Carlo simulation was then applied to select the most suitable model relating chlorophyll-α concentration and simulated TM/Landsat reflectance. TM4_sim/TM3_sim ratio provided the best model with a R2 value of 0.78. The model was then inverted to create a look-up-table (LUT) relating TM4_sim/TM3_sim ratio intervals to chlorophyll-α concentration trophic state classes covering the entire range measured in the reservoir. Atmospheric corrected Landsat TM images converted to surface reflectance were then used to generate a TM4/TM3 ratio image. The ratio image frequency distribution encompassed the range of TM4_sim/TM3_sim ratio indicating agreement between in situ and satellite data and supporting the use of satellite data to map chlorophyll- concentration trophic state distribution in the reservoir. Based on that, the LUT was applied to a Landsat/TM ratio image to map the spatial distribution of chlorophyll- trophic state classes in Ibitinga reservoir. Despite the stochastic selection of TM4_sim/TM3_sim ratio as the best input variable for modeling the chlorophyll-α concentration, it has a physical basis: high concentration of phytoplankton increases the reflectance in the near-infrared (TM4) and decreases the reflectance in the red (TM3). The band ratio, therefore, enhances the relationship between chlorophyll- concentration and remotely sensed reflectance.
- Subjects :
- water quality
phytoplankton
monitoring
Environmental sciences
GE1-350
Subjects
Details
- Language :
- English, Spanish; Castilian, Portuguese
- ISSN :
- 1980993X
- Volume :
- 8
- Issue :
- 3
- Database :
- Directory of Open Access Journals
- Journal :
- Revista Ambiente & Água
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.2a45dcc3f45340feb81aa08a0c831944
- Document Type :
- article
- Full Text :
- https://doi.org/10.4136/ambi-agua.1229