Spatio-Temporal Spectral Analysis of High Mountains Wetlands and Their Relationship to Climate Variability

Calvi, Carolina , Melendi, Edoardo , Carol, Eleonora

2025 CUADERNOS DE INVESTIGACION GEOGRAFICA 2025   51(卷), 1(期), (127-144页)

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The high-altitude wetlands of the Andes in South America are unique ecosystems, characterized by their hyper-humidity and close connection with groundwater discharge or snowmelt. These environments exhibit relatively stagnant waters or low circulation, which favors the proliferation of vegetation that can be monitored through satellite imagery. The objective of this study is to analyze, through the use of remote sensors, the spatiotemporal variation associated with climate cycles in two high-Andean wetlands located in arid environments, where access and working conditions are limited. To achieve this, two case studies were taken: one involving wetlands associated with groundwater discharge, and another supported by river courses with contributions from rainfall and snowmelt. The areal variation was linked to climate cycles, for which the spectral indices Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) were calculated for representative years, selected according to the climate indices Standardized Precipitation-Evapotranspiration Index (SPEI) for dry and wet periods, Oceanic Ni & ntilde;o Index (ONI), and data from available meteorological stations for the period 1980-2022. The results showed a variation in the extent of the wetlands between El Ni & ntilde;o and La Ni & ntilde;a periods. During wet periods (El Ni & ntilde;o), the wetlands reached their largest extents, while in dry periods (La Ni & ntilde;a), a reduction in wetland area of approximately 30% was quantified. This indicates a rapid hydrological response of the environment to climate changes, associated with contributions from shallow groundwater flow. Consequently, it is likely that in the future, the impact of atmospheric cycles, intensified by climate change, will lead to a critical decrease in the surface area of these wetlands. Monitoring the evolution of high-Andean wetlands in arid conditions is essential to characterize their response to climate cycles. Extrapolating these analyses to other wetlands in similar environments will enable future research on a broader regional scale, facilitating a comprehensive approach to their behavior in the face of climate variations. Understanding these fragile ecosystems is key to implementing effective conservation and management measures, especially in the face of growing pressure from global climate change.