River plume spreading on a tropical continental shelf semi-insulated by coral reefs

Abstract

The Berau Continental Shelf (BCS) is located in East Kalimantan, Indonesia. The area is part of the Coral Triangle in the central Indo-West Pacific and features an extremely high biodiversity. Like many other coastal ecosystems around the world, the BCS is under pressure from human activities. Land-use changes of the catchment area of the Berau River lead to increased loads of sediment, nutrients and pollutants in river discharge as a result of mining, logging, and agriculture development. These conditions may affect water quality and imply a number of negative impacts on the BCS coastal ecosystems. The main objectives of this thesis are to understand the tidal dynamics and circulation patterns at the BCS, to investigate spatio-temporal river plume spreading at the BCS, to identify the relationship between the salinity levels and coastal ecosystem health and to understand intratidal circulation patterns on the BCS coral reefs system. This study is based on a number of extensive field surveys in combination with numerical modelling. Flow velocities, sea surface elevations, salinity profiles and meteorological data were gathered during three field campaigns in 2006, 2007 and 2008. The field data were collected in the Berau Delta network, estuary and in the close vicinity of coral reefs. The observed data were used to set-up, calibrate and validate hydrodynamic models.