Evaluation of the Ambient Water Quality Along the Historical Wah Fu Waterfall, Hong Kong

Abstract:

The freshwater habitats of Hong Kong sustain a high degree of biodiversity and provide invaluable resources. However, the worldwide trend of habitat depreciation as a result of increased human activities has adverse implications on the quality of such habitats. At present, the water quality of an anthropogenically significant area, the Wah Fu Waterfall in Hong Kong, is still unknown due to the lack of active ambient water quality monitoring stations managed by the Agriculture, Fisheries and Conservation Department (AFCD) situated on Hong Kong island. This freshwater cascade runs as a stream from a reservoir before forming a waterfall into Waterfall Bay, a part of the saltwater East Lamma Channel.

The ability for a habitat to sustain marine flora and fauna activity is dependent upon a multiplicity of physical, chemical, and microbiological factors. This study analyses eight physical, chemical, and microbiological parameters at seven different locations, including the reservoir and downstream of the waterfall. These measurements (nitrates, nitrites, dissolved oxygen, ammonia, pH, chlorine, total coliforms, and E. Coli) are used to evaluate the trophic state, potential for life, and microbiological contamination of the site. Samples taken during the rainy season at low tide during a red tide event from these six locations were analysed in situ or preserved to be analysed in a suitable facility shortly after collection. The findings uphold/may refute the hypothesis that the water quality downstream of the waterfall is poorer than that of the quality upstream.

These observations allow one to gain an understanding of the ambient water quality of the Waterfall Bay site, potentially implicating a trend of water quality degradation.