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This letter presents an analysis of two synthetic aperture radar (SAR) images time series over a Sahelian area, which is located in the Gourma region, Mali. The first one is acquired at the C-band by the Environment Satellite-Advanced SAR sensor in wide swath (WS) mode and the second one at the L-band by the ALOS-Phased Array-type L-band SAR in fine, dual, and WS modes. A change detection method based on random projection and the hue-saturation-value transform appears to be very well appropriated to detect the temporal changes appearing on both data sets. The results illustrate the higher penetration depth of the L-band over such sandy soils. The C-band time series is found to be very sensitive to surface changes (soil moisture and vegetation growth). By contrast, the L-band time series appear to be very stable over the sandy soils, i.e., the only temporal changes occurring over temporary or permanent ponds.