Makhtesh Hatzera Erosion Cirque (MHEC) is a deep (300-400 m) oval-shaped depression (5 × 7 km) with a NE-SW long-axis developed in the center of the Hatzera anticline. The surrounded vertical cliffs are composed of relative friable Lower Cretaceous quartz sandstone covered by resistant Upper Cretaceous carbonate rocks. Transitional colluvial-alluvial units (pediments), connect and integrate the lower parts of the slopes with coarse sandy-gravelly, Pleistocene –Holocene alluvial terraces covering most of the area of the cirque.
Quantitative GIS-based analysis of the morpho-stratigraphic map of the MHEC, together with systematic TL dating of the eight alluvial terraces (Plakht 2003) and a few OSL ages (Fruchter et al.2011) were used to calculate the volumes and rates of sediments transported outside the cirque through its opening, specifically during the last >500 ka and since its initiation in the Pliocene (5 Ma). The sediment transport rates for the alluvial terraces range between 344 and 1328 m3 yr-1, and 2028 m3 yr-1 for the earlier 4.5 Ma. These rates are within the same order of magnitude to the present-day rates – 2190-3260 m3 yr-1, as documented at a small reservoir within the erosion cirque. Floods such as the 2004 flood (470 m3 s-1) can transport boulders up to 2.1 m and weighing up to 15 ton at least once in 120 years, which is about the maximum boulder size that was found on the terraces within the cirque. The boulder size is reduced up the alluvial terraces sequence – i.e. with time, due to desert weathering and they almost completely disappear within about 100 ka. Sediment evacuation from the erosion cirque and the size of the opening are highly controlled by the flood regime. Periods of slow sediment aggradation coincide with the build-up the alluvial terraces during more humid periods, whereas rapid incision phases characterize arid conditions.