THE INFLUENCE OF RIVER DISCHARGE AND TIDE ON RESIDENCE TIME IN BERAU DELTA, EAST KALIMANTAN A. Tarya (a*), M. Ilham (b), S. Nurjaman (a) and F. A. R. Abdullah (a)
a) Oceanography Research Group, Faculty of Earth Sciences and Technology, Bandung Institute of Technology
b) Department of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology
Abstract
Residence time plays important role on biogeochemical processes in the coastal area. Understanding how long water remains in the delta and how quickly it is flushed is critical for estimating delta^s health. The present study aims to identify the influence of river discharge and tide on the residence time in the Berau Delta, East Kalimantan. The Delft3D-FLOW is applied to simulate the hydrodynamic and the particle tracking model. Eight scenarios have implemented based on river discharge and tidal variation. The comparison between model result and data observation for tidal elevation has a good agreement with Root Mean Square Error (RMSE) about 0.16 to 0.29 m and Mean Absolute Percentage Error (MAPE) value is 3.74 to 11.30%. Variation in river discharge has significant factor on the residence time. Simulation with the highest of river discharge (Q = 650 m3/s) result in the lowest residence time (8.36 days), whereas simulation without river discharge (Q = 0 m3/s) has the longest residence time (41.35 days). The difference of residence time between spring and neap tides is 3.20 days. The findings of this study enabled the identification of the most vulnerable areas within the delta as a function of river discharge.
Keywords: Residence Time, River Discharge, Tides, Berau Delta
