Ocean Dynamics

, Volume 61, Issue 12, pp 2211–2228

Tidal impact on the division of river discharge over distributary channels in the Mahakam Delta

Authors

    • Hydrology and Quantitative Water Management Group, Department of Environmental SciencesWageningen University
  • A. J. F. Hoitink
    • Institute for Marine and Atmospheric Research Utrecht (IMAU), Department of Physical GeographyUtrecht University
  • Benjamin de Brye
    • Institute of Mechanics, Materials and Civil Engineering (IMMC)Université Catholique de Louvain
    • Earth and Life Institute (ELI), G. Lemaître Centre for Earth and Climate Research (TECLIM)Université Catholique de Louvain
  • Bart Vermeulen
    • Hydrology and Quantitative Water Management Group, Department of Environmental SciencesWageningen University
  • Eric Deleersnijder
    • Earth and Life Institute (ELI), G. Lemaître Centre for Earth and Climate Research (TECLIM)Université Catholique de Louvain
Article

DOI: 10.1007/s10236-011-0473-9

Cite this article as:
Sassi, M.G., Hoitink, A.J.F., de Brye, B. et al. Ocean Dynamics (2011) 61: 2211. doi:10.1007/s10236-011-0473-9
Part of the following topical collections:
  1. Topical Collection on Physics of Estuaries and Coastal Seas 2010

Abstract

Bifurcations in tidally influenced deltas distribute river discharge over downstream channels, asserting a strong control over terrestrial runoff to the coastal ocean. Whereas the mechanics of river bifurcations is well-understood, junctions in tidal channels have received comparatively little attention in the literature. This paper aims to quantify the tidal impact on subtidal discharge distribution at the bifurcations in the Mahakam Delta, East Kalimantan, Indonesia. The Mahakam Delta is a regular fan-shaped delta, composed of a quasi-symmetric network of rectilinear distributaries and sinuous tidal channels. A depth-averaged version of the unstructured-mesh, finite-element model second-generation Louvain-la-Neuve Ice-ocean Model has been used to simulate the hydrodynamics driven by river discharge and tides in the delta channel network. The model was forced with tides at open sea boundaries and with measured and modeled river discharge at upstream locations. Calibration was performed with water level time series and flow measurements, both spanning a simulation period. Validation was performed by comparing the model results with discharge measurements at the two principal bifurcations in the delta. Results indicate that within 10 to 15 km from the delta apex, the tides alter the river discharge division by about 10% in all bifurcations. The tidal impact increases seaward, with a maximum value of the order of 30%. In general, the effect of tides is to hamper the discharge division that would occur in the case without tides.

Keywords

Subtidal dynamicsFinite elementsRiver-tide interactionHydrodynamic modelDeltasMahakamRiver dischargeDifferential water level setup

Copyright information

© Springer-Verlag 2011