Channel Stability Assessment for Ayer Hitam Forest Reserve, Puchong, Malaysia

The consequence of soil acidity, human behaviors and other improvement are often linked with the changes of aquatic ecosystem water quality. Ayer Hiram is one of the most valued regions of lowland dipterocarp forest remaining in generally developed Selangor, Malaysia. The starting activities and de-gazettements execution have led to the deterioration of Main River in Ayer Hitam forest reserve. A case study using Ayer Hitam forest is aimed for such verification and validation to showcase the applicability of morphological assessment method on channel stability. Field sampling, laboratory analysis, statistical approach and verification process are used to achieve a stability index of channel or river and follow the standard of execution ranges from engineering field, geomorphology and statistical approach. The maximum depth was 0.89 m in cross section (3), however the minimum depth was 0.04 m in cross section (5) and the highest velocity was recorded in cross section (5) which 0.32 m/s and the lowest velocity recorded was 0.02 m/s in cross sections (2, 7and8). Furthermore, the maximum discharge was 0.314 m3/s in cross section (3) while the minimum discharge was 0.037 m3/s measured in cross section (7). This research shows a better approach to assess river stability through hydro-morphological approach. The use of CSI and OSEPI index successfully elucidated the level of channel stability at Sungai Rasau, Selangor. CSI index shows that half of the cross section fall under stable category and another half fall under moderately unstable category. Meanwhile, all cross section falls under highly stable and moderately stable category for OSEPI index. This research can give a better understanding towards knowing channel stability of Sungai Rasa for a long run. The restoration and rehabilitation work could be performed by knowing the gap between stable and unstable channel behavior. The documentation of geomorphic data for Ayer Hiram forest reserve can benefit a lot of agencie