The data set contains grain size distributions, organic matter (OM) contents and trace metals distribution metal distribution (Fe, Zn, Cu, Cr and Pb) of seven (7) shallow cores of sediments from the Notwane Dam (southern Botswana). The cores have been collected with a push corer using PVC pipes of 5 cm diameter by a team from BIUST led by Dr. Franchi between November 2017 and February 2018. The data were collected as part of the PULA project, which aimed at understanding the immediate effect of heavy rainfall and floods on water resources in arid Botswana and their transitional hydrologic readjustment towards the dry period, and the role of these events in supporting either or both resources replenishment and contamination. Grain size profiles of the cores have been obtained by analyzing wet sediments with a laser diffraction particle size analyzer. The OM content of the sediments was obtained by measuring the loss on ignition (LOI) of bulk sediments after calcination in a muffle furnace. The sediments have been analyzed for trace metal distribution using a Microwave Plasma-Atomic Emission Spectrometer (MP-AES). The grain size distribution has allowed to pinpoint the presence of flood couplets, characterized by coarse lags followed by fine grained materials. The trace metal distribution profiles have been compared with the flood couplets to assess the entity of metal mobilization during floods and subsequent droughts. Full details about this dataset can be found at https://doi.org/10.5285/022b3fff-55d7-46f5-b11f-2f7366e508b0
