Relationship between ground deformation time series and coverage dynamics: laguna Tebenquinche case study, Salar de Atacama, Chile

For being able to accomplish the Sustainable Development Goals is needed to understand the dynamic of the ecosystems where the human activities are developed. For these reasons to understand the baseline and monitoring the environmental variables is fundamental. Earth Observation plays a key role in the management of the anthropic activities.

In the recent years, Lithium become one of the key raw resources to accomplish the Sustainable Development Goals, because is the main component for avoid the use of fossil fuel. Atacama Desert is one of the main places where Lithium is extracted, but also is a fragile ecosystem, due to the presence of endangered fauna (Flamingos) and highly specialized communities of organisms (extremophile microorganisms for example).

It´s been considered the Laguna Tebenquinche for analysing the impact of the land use and land cover change, and its impact on ground deformation (Persistent Scatterer Interferometry) from Sentinel 1. The last one was computed using the CTTC´s processing chain. Vegetation dynamics, water presence and soil moisture has been obtained using NDVI, NDWI and NDMI indexes from Sentinel 2 data (level L2, S2_SR_HARMONIZED) from Google Earth Engine. Both analyses considered the period between 2022 to 2024.

The first analyses were performing the identification of the presence or absence of persistent scatterers and their relationship to the land cover. Then it was conducted an analysis of related to the ground deformation´s mean velocity and the effects of the surface dynamics from Sentinel 2. These results were compared with precipitation rates, temperature of the air, air moisture and underground water levels in the salt flat.

The results show a difference between the northern area of the lagoon, which have a mean ground deformation velocity between -5 to -2 mm/yr, versus the southern part, which has a mean ground deformation velocity between -5 to 2 mm/yr. For the coverage, the northern part of the lagoon has been flooded temporarily and with increase of soil moisture.

For the precipitation, from the end of November 2022 the rain in the salt flat (LZA12-3 station) increase, but it’s now only needed to consider the rain in the salt flat, also the rain in the upper part of the catchment. The Cerro Cosor Station shows a high value of precipitation since January 2024 to April 2024. The water surface and vegetation surface show a relationship with the precipitation pattern, but there is no direct relationship with the soil moisture time series.

Seasonal analysis of surface coverage could help to improve the understanding of the dynamic of the temporal cinematic of the Persistent Scatterers. The integration of Earth Observation helps us to understand and model relationships between climatic events (like ENSO), the hydrological dynamic of the lagoon, connections between the lagoons and the aquifers, evaluation of possible overexploitation of groundwater and saline intrusion, impacts of the climate change on the ecosystem and conditions for the local flora and fauna.