Changes in the turbidity of shallow Pampean lakes during the last 30 years using remote sensing data

GAYOL, MAIRA PATRICIA; DOGLIOTTI, ANA INÉS; BABINO, LAURA; SÁNCHEZ, MARÍA LAURA; IZAGUIRRE, IRINA

Bariloche

Congreso; IAL IPA 2022 ?Lagos, Memorias del Territorio?; 2022

International Association of Limnogeology e International Paleolimnological Association

The Pampean Plain host thousands of eutrophic and hypertrophic shallow lakes. In last decades it has been incrementing the proportion of land dedicated to agriculture activities in the region, which impacted the water quality of these lakes. However, there is a lack of long-term monitor programs of Pampean shallow lakes that study the impact of these activities. Remote sensing allows enlarging the time and spatial scale coverage resulting in a very useful tool to analyze possible changes in some water characteristics, like turbidity. We analyzed the changes in turbidity of 6 Pampean shallow lakes (Chascomús, La Limpia, Salada Monasterio, El Burro, La Segunda and El Triunfo) from 1986 to 2021. We used Landsat 5-TM, Landsat 7-ETM+ and Landsat 8-OLI images processed using the ACOLITE software and applied a general turbidity algorithm developed for turbid waters. We validated the satellite-derived values with field turbidity data. The temporal series were analyzed to separate the general trend from the seasonal variability. Chascomús exhibited oscillations, but always around high turbidity values (95.5 - 593.8 FNU). La Limpia shows an increment of turbidity reach a maximum in 2009 (846 FNU) and then diminishing. Salada Monasterio also tended to oscillate, with a minimum of 52.5 FNU and a maximum of 400.2 FNU. In El Burro we detected an increasing trend throughout the analyzed period, with values ranging from 41.8 FNU to 388.5 FNU. Finally, La Segunda and El Triunfo exhibited lower turbidity values respect to the other lakes (mean: 3.2 FNU in La Segunda and 51.5 FNU in El Triunfo). However, due to the presence of macrophytes that interfered in the turbidity algorithm, the temporal series obtained were much more limited. Remote sensing, along with field data, resulted in a very useful tool to study the changes in the water turbidity of these shallow lakes.