Geology and granulometry analysis of Krueng Aceh River floodplain, Aceh Besar

The study aims to understand the geological conditions and examine the size and characteristic of sediment grains in the Krueng Aceh floodplain. The method used was sampling 14 points of soil samples in the floodplains using hand auger with 100 cm deep. Geological outcrop analysis was carried out to determine the geomorphological units of rocks. Mapping and data processing used ArcGIS software and floodplain soil sample employed multilevel sieve. The results show that the outcrop analysis found three geomorphological units, namely, denudational hills, river and floodplain, and river terrace unit and consisted of three rock units: sandstone, conglomerate, and alluvial unit. Based on the percentage of granulometry analysis the fine sand size sediments are dominated. For the analysis based on river channels, the cut bank zone has the size of fine sand to very fine sand and the beach zone granulometry ranges from gravel, very coarse sand and coarse sand.