| Summary: | Spatially heterogeneous bed is a dominant bedforms in gravel-bed channel of
natural channels. Macroinvertebrates are among the first organism to resettle in
newly rehabilitated channel. This study explores the macroinvertebrates distribution
in relation with physical habitat and hydraulic properties of riffle–pool bedforms,
particularly the variations in hydraulic performance on different bed oscillation
morphologies. Information from the study reach at downstream of Sungai Batu
Sebelah where the river was rehabilitated was used to illustrate the approach of this
study. A hydrodynamic model was developed to reflects base flow discharge of the
study reach. The hydrodynamic model have been sucessfully calibrated with
correlation coefficient R = 0.991 at the upstream, and correlation coefficient R =
0.994 at the downstream. Validation for the model have found the correlation
between the model predicted values are very close with the values from field
measurement and calculational approach, with value of correlation coefficient R =
0.999 to R = 1. Biotic data shows pollution sensitive makroinvertebrata from the
order of Ephemeroptera, Plecoptera and Trichoptera (EPT) such as Baetis sp., Caenis
sp., Heptageniidae, Leptophlebiidae, dan Hydropsyche sp. were found at the study
reach. The biotic data confirmed that the water qualirt at the upstream of the study
reach to be in Class II as showed through Water Quality Indeks in the Interim
National Water Quality Standard , which the water quality was classed as suitable for
sensitive aquatic species. Values of shear stress from the hydrodynamic model were
tested against the preferred shear stress by the macroinvertebrates that were found at
the study reach. Result shows that the existence of benthic macroinvertebrates is
associated with the hydraulics condition in which the organisms makes its home.
|
|---|