Flume experiments on the origin of the cross-lamination from Cisadane River and Jakarta wave ripples sedimentary structure

A sedimentary structure was formed from a sedimentary process that controlled by some external force that mainly formed at the environment with strong air, water, and strong snow current, also by gravitational force to do the transportation process. The water body, like a river and the ocean, are a perfect place to examine the sediment structure because the water medium has a unique characteristic that can transport, erode, and preserved the sediment layer. The result of the latest experiment shows how to scale down the nature scale to the laboratory-scale model with some calculations. This paper discusses how to scale down the sediment habit and structure from the natural scale of Cisadane River and the offshore of the Tanjung Pasir Beach to the laboratory. The experimental facility has been equipped with two flume tanks that have a different dimension, a laser distance meter, a self-made wavemaker, two action cameras, and two water tank. Field observation has done to get the water velocity, air velocity, air temperature, and the coordinate data. Scaling down the process was done by using two references, a Froude Scale Model and Reynolds's Rule. This experiment came with an interpretation that the current shoreline of northwestern Jakarta would be increasing toward the Java Sea. The aim of this study was to get a laboratory-scale model from the field observation data and used to build an experiment set up on both flume tanks. The result of this experiment shows that the wave ripple structure experiment has formed a wave-dominated delta and the current ripple structure experiment has formed and can be observed through the side of the flume tank, which gives the better view of the current ripple structure.