THE EFFECT OF CITANDUY RIVER DISCHARGE AND MONTHLY AVERAGED CURRENT ON SPATIAL AND TEMPORAL VARIATION OF TOTAL SUSPENDED SOLID (TSS) AT SEGARA ANAKAN LAGOON, CILACAP

• Main Author: Nafiz Almira, Fauzia
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/44099
• Institution: Institut Teknologi Bandung

Distribution of Total Suspended Solid (TSS) at Segara Anakan Lagoon is affected by Citanduy River discharge and monthly averaged current. TSS concentration analysis is conducted spatially dan temporally. The lagoon region is divided into 3 zones, which are Western Zone, Middle Zone, and Eastern Zone. This research is done on rainy season (February 2008 and 2009) and dry season (September 2008 and 2009). Observation of TSS concentration variation is based on the results of analysis for every zones and times. Data of TSS concentration and sediment percentages (sand, silt, and clay) are obtained from the research done by Moll (2012). The TSS concentration datas are made into spatial plot using ArcGis, while sediment percentage datas are averaged on every zones to observe their contribution on TSS concentration at each zone and to support the analysis of TSS concentration’s variation. In addition, the monthly averaged current is obtained from the modification of hydrodynamic model by Merdeka (2017). The modification is done by changing the simulation time and river discharge to match this research. The data of Citanduy River discharge that’s being used is gathered from Balai Besar Wilayah Sungai (BBWS) Citanduy, while the other river discharge’s data is obtained from calculation of ratio to Citanduy River discharge. The result of monthly averaged current shows that the biggest current is located at the Western Zone on February 2009 (Citanduy River debit reached 326,5 m3/s) with a magnitude that reached >0,16 m/s. The current magnitude decreases from west to east because it’s getting further from Citanduy River. Water from the Western Zone mostly moves out of the lagoon through Western Outlet, while the rest move to the Middle and Eastern Zone. On rainy season, the biggest TSS concentration is in the Western Zone especially in Citanduy River with a value of 1558,24 mg/l. Current generated by Citanduy River discharge weakens the current from Eastern Zone, causing an increase of silt percentage from Western Zone to Middle zone, while sand percentage decrease from Eastern Zone to Middle Zone. On dry season, the biggest TSS concentration is at Middle Zone and the dominant type of sediment generally is sand (especially at Eastern Zone). This is caused by a small discharge of Citanduy River that makes the monthly averaged current decreased, so that more TSS are settled at the Middle Zone and the input of silt decreased too.