International Journal of Science, Engineering and TechnologyAuthors: T K Prasad, Sreerama Naik S R, Asim P T
Abstract: The present study analyses the mangrove distribution and vegetation index changes within the basin of the Valapattanam River located in Kerala from 2017 to 2026. The data were gathered through land cover classification using satellite imagery and green chlorophyll concentration measurements. Mangrove changes were assessed using multi-temporal classification that included mangrove, non-mangrove, and water classes. Overall accuracy and the Kappa Coefficient were used to validate the results. The trends of forest cover changes were evaluated using an annual change analysis, while the vegetation concentrations were determined using the green chlorophyll index (GCI). The results indicated that the mangrove area increased thrice in ten years, from 195.5 km² in 2017 to 548.9 km² in 2026. With an overall accuracy of 96.4% and the kappa coefficient of 0.946, the study finds that 353.4 km² of non-mangrove land gained coverage over ten years, whereas the water did not demonstrate significant changes. It also found that the majority of the area under mangrove coverage fell from 2017 to 2018 before gradually climbing up until 2026. Specifically, there was an increase from 548.9 km² (41.4%) in 2020 to 574.3 km² (43.6%) in 2021 and further to 626.8 km² (47.5%) in 2022, with the next three years recording an interval increase of between 20.6 and 52.0 km² of coverage. On the contrary, the vegetation index recorded a contrary trend, peaking at 5.24 µg/mL in 2017, then dropping to a minimum of 4.05 µg/mL in 2021 before climbing unevenly to a secondary peak in 2025 (4.81 µg/mL) and subsequently decreasing slightly to 4.77 µg/mL in 2026.
