Preliminary sediment modeling at the confluence of the Mahakam and Karang Mumus River

Abstract

The sedimentation process can move slowly and continuously during sediment transportation is still ongoing from the mainland. The sediment evidence has been done by pairing the current bathymetric measurement of the previous data from the bathymetric map of the DISHIDROS of the Indonesian Navy 2011 in the confluence of the Mahakam and Karang Mumus River. Initially, the tidal measurements were carried out on 15-29 January 2019 while the bathymetry measurements were measured on 21-22 January 2019 during spring tide was over 800 m from upstream to downstream river confluences. Contour modeling measured using Software Surfer while the tidal is using the Admiralty method., to get discharge sediment performed contour coupling from both using AutoCAD software. The results of tidal analysis at the confluence of this river type Mixed Tide, Prevailing Semi Diurnal with MSL119 cm, HHWL 275 cm and LLWL-29 cm. Besides, the results of the sedimentation calculation showed an increase of 251,621.52 m3 in the tempo of 8 years from different Years of measurement. Most of the deposits occur on the opposite side of the Karang Mumus River, and this may be due to the small current velocity of the inner side of the Mahakam River that is curved towards the Karang Mumus River. Further research should also be modeled on current patterns and numerical modeling to ensure the morphological changes of the confluence of the present river.