THE IMPACT OF CITANDUY RIVER DISCHARGE TO HYDRODYNAMIC CONDITION IN SEGARA ANAKAN LAGOON, CILACAP

• Main Author: Elan Merdeka, Samudra
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30788
• Institution: Institut Teknologi Bandung

Study about the physical process and hydrodynamic cycle is influenced by tidal wave from Indian Ocean and discharge from various rivers that comes into Segara Anakan, escpecially Citanduy River. Freshwater input from Citanduy River has an effect on how much sediment that comes into and settles in Segara Anakan. The influence of discharge to the hydrodynamic process in Segara Anakan needs to be analyzed in order to understand more about hydrodynamic changes that happen in Segara Anakan. A simulation has been done for Segara Anakan Lagoon, Cilacap, West Java with Delft3D program, developed by Deltares. Tidal current through Indian Ocean and Citanduy River monthly average discharge from 2008-2013 is used to generate hydrodynamic process in the model. Simulasi model is done throughout the year with monthly average input discharge, extreme discharge model in the amount of 300 m/s, and model with no discharge input. Model result shows that the general condition in the lagoon has water mass transport moving from east to west almost all year long. This also held true when the lagoon does not get any discharge input from Citanduy River. However, movement in rainy season (January-February) is inverted as the lagoon net transport move from west to east. Change in net transport movement direction occur when Citanduy River discharge reaches or exceeds ±250 m3/detik. Simulation result also indicates that changes in Citanduy River discharge affect elevation and current in the lagoon. Average elevation difference between model with high discharge input (234,8 m3/s) and no discharge input in Motean reaches 0,219 m, 20% from maximum elevation in the location. Average current magnitude difference between model with high discharge input (234,8 m3/s) and no discharge input in West Pelawangan also reaches 0,186 m/s, which is 19% from maximum current magnitude in the location.