'One River, Two Systems': Hong Kong's River Management.

Hong Kong (HK), one of the world's most densely populated metropolises, is home to over 200 rivers and streams extending about 2500 km in length. During the 1970s-1990s, most of these rivers were converted into artificial canals, to which the local society pays little attention. Since the 2010s, the HK government has initiated river revitalization to enhance the social-environmental roles of rivers. This study employed a mixed research method, including literature and policy analysis, expert interviews, field visits, and a public survey, to identify key challenges in HK's Integrated River Basin Management (IRBM). The findings highlighted the lack of IRBM's institutional arrangements in HK, characterized by a fragmented 'one river, two systems' approach without both coordination and collaboration. The Water Supplies Department (WSD) impounds upland streams as reservoirs for securing the local water supply, while the Drainage Service Department (DSD) manages heavily channelized, culverted downstream serving as storm drains with diminished ecological functionality. One significant barrier to the implementation of IRBM in HK was the limited public participation, although our survey revealed a high level of public willingness to participate in river management. Presently, river revitalization efforts have achieved limited success, with ecological measures appearing mostly "cosmetic" and the conservation of freshwater biodiversity neglected. This further underscored the pressing need for the embracement of IRBM in HK to safeguard basin-wide freshwater ecosystems. Our survey also indicated low public awareness of river revitalization initiatives and widespread dissatisfaction with their outcomes. In conclusion, we proposed the development of IRBM in HK by instituting river basin coordination, prioritizing river ecosystem restoration in revitalization projects, and involving the public through tailored strategies.