I was lucky enough to repeatedly visit the ‘closed border area’ throughout 1998-99. The CBA buffered the new territories from the People’s Liberation Army for nearly a century. Strategically, there were crossing points at Lok Ma Chau in the west (for road haulage), Lo Wu rail crossing for passengers and rail freight, Man Kam To (for road haulage), and finally Sha Tau Kok (in the east) for strange goings on. That’s only four crossing points in 20km, coast to coast, mostly following the Shenzhen River valley. Apart from a small number of villages, for the most part only the British Army and the Hong Kong Police occupied this valley until the 1980s. From that point onwards, a city of a million or more people sprang up on the north bank. The HK side stayed resolutely undeveloped and most of the younger residents moved downtown for better paid jobs, leaving the farmland returning to weeds and scrub.
The fly in the ointment was that Shenzhen city (like HK and Kowloon) was built without a sewage treatment plant. There was a river nearby, however, so engineers piped the sewage untreated in to that. The Shenzhen River discharges into Inner Deep Bay (Hau Hoi Wan), at low tide, a large shallow expanse of mudflat which is internationally recognised as an important wetland for migratory birds on route between northern and southern hemispheres.
The smell from the river was, unbelievably, even worse than the Kai Tak nullah which at least flushed out into HK harbour. Being tidal for the entire length of the river, the septic sewage just slopped backwards and forwards with little escaping only as far as the Ramsar wetland.
Apart from the stink, the left bank of the Shenzhen River was a fascinating recovering ecosystem…about to be delivered the body blow of channelisation. What better way to resolve the open sewer issue, than to remove the natural meanders of the river to make the tidal ebb and flow more efficient? As time passed, channelisation would also liberate developable land on the HK bank.