Inferring volumetric changes at a shallow lake from subpixel satellite-derived shorelines

Abstract

[EN] Lakes with strong variations in their water coverage may act as in dicators of different natural phenomena. Recent techniques for the extraction of Satellite-Derived Shorelines (SDSs) with subpixel accuracy are potentially useful for accurate and continuous monitoring of the limits of water bodies along large periods. This work proposes a method for combining the shoreline position with a digital elevation model to assign elevation values to the points defining the SDSs along the period 1984¿2020 in the shallow Gallocanta Lake (NE Iberian Peninsula). The relationship between the water surface and the elevation allows modeling the phenomena of lake changes as well as an estimation of the volume. The obtained data enables analyzing size and elevation changes of the water surface and the volumetric changes of the lake over more than three decades with a sub-weekly frequency (2¿5 days). The results constitute a valuable data package for robust analysis of lake trends. In the short term, the methodology provides sufficient precision to capture the changes caused by single meteorological events such as rainfall, even of small magnitude. The method constitutes a novel approach for curate hydric monitoring of lakes and water bodies, along large terrtories without requiring continuous in situ data acquisition.