Mapping and Monitoring Lakes Intra-Annual Variability in Semi-Arid Regions: A Case of Study in Patagonian Plains (Argentina)

In arid and semi-arid regions, the climatic impact on lakes is especially critical, as they are scarce and play an important role as a primary source of the water supply. However, in some extended regions with those climatic conditions, the implementation of an in-situ monitoring program of high temporal resolution of the water resources is not possible due to its logistics and costs. Thus, developing an accurate methodology to monitor the evolution of water bodies is especially critical in these areas. For example, with remote sensing images, lake area fluctuation can be analyzed. The main objective of this study was to identify an efficient remote sensing methodology, with a temporal resolution that allows for analyzing intra-annual lake area variations. For detecting lakes area changes six Moderate Resolution Imaging Spectroradiometer (MODIS, National Aeronautics and Space Administration products) indexes and layers were analyzed and compared. We applied the methods to the Musters (deep) and Colhué Huapí (shallow) lakes, which are located in the extra-Andean Argentine Patagonia plains (semi-arid region). The MODIS products have not been accurate to detect the areal variations of the deep lake, probably because the spatial resolution of these images is not specific enough to identify the slight variation that these lakes usually have on the extension of their area. On the contrary, MODIS products have been accurate to analyze the areal changes of the shallow lake. The Colhué Huapí lake area fluctuated between 105 km[sup.2] to 797 km[sup.2]. The Modified Normalized Difference Water Index (a combination of green and middle infrared electromagnetic spectrum), as well as two bands that include a different range of middle infrared surface reflectance (2105–2155 nm; 1628–1652 nm), were the most accurate to identify the variation of the lake area.