Trail walker Law Kwong-keung never expected the scene he witnessed when he approached picturesque Sai Wan beach with his friends one April morning - a barge carrying two diggers landing on the sand. 'We heard a lot of noise as we headed down to the beach. 'But when we got there, there were at least 20 villagers staring at the landing operation,' he said. Law, also a district councillor, did not take it seriously at the time and thought it might be government work. So he and his team just carried on with their walk. But a few months later, he was shocked to discover the barge and the diggers were sent to the beach for a private development by a businessman. And now, as he moves around the countryside, he keeps his eyes open for any such abuses. Law said: 'I always stay alert to what is happening around me when we are hiking, looking out for any places where vegetation cover is being removed or areas that developers might be looking at.' Law is part of a hikers' network in Hong Kong. The walkers exchange information about suspect activities in the countryside and report them to the authorities when necessary. The network has 20 to 30 core members, who regularly check out and record possible irregularities in protected areas and rural villages prone to development threats. Its unofficial leader, Chan Kwok-keung, said the network was formed after the Sai Wan outrage. He added: 'We want to do what we can to protect these green areas and save them, so that our future generations can still treasure them.' Chan said the network complemented the work of the understaffed departments responsible for policing New Territories land, which has been subjected to rampant illegal development and environmental damage. The Lands Department has about 200 officers who monitor all suspected lease breaches and illegal occupations across the territory. The Planning Department has about 40 people to take care of 22,000 hectares covered by development permission plans in the New Territories And there are 164 rangers responsible for patrolling and providing visitor services at the 24 country parks, which cover more than a third of Hong Kong's total area. It is uncertain how many officers are actually deployed on regular patrol or how they carry out their duties. None of these departments was willing to allow reporters to accompany the officers at work. But it's not the government officers who are uncovering most of the breaches. Figures reveal that increasing numbers of unauthorised developments in the New Territories are being exposed by members of the public. A Planning Department enforcement record summary shows that nearly 60 per cent of all confirmed unauthorised development cases last year originated from public complaints. And up to 90 per cent of illegal dumping cases - the fastest-growing offence - were exposed by the public last year. A similar picture emerges for the Lands Department, with 93 per cent of the 20,485 cases of illegal occupation of government land between 2005 and 2009 coming to light thanks to the public. Some of these are notorious cases, such as last year's dumping of construction waste at Ho Sheung Heung, Sheung Shui, which was reported by villagers after they woke up to find their farmland covered by debris. Another was the removal of vegetation and the occupation of government land in So Lo Pun, a deserted village near the border, which was reported by hikers and green groups. Bill Barron, an environmental economist at the University of Science and Technology, said the government had a serious image problem with respect to monitoring what was going on in the country- side. He said: 'I believe the public feels that the responsible government departments do not even bother to monitor sensitive areas to be sure no illegal activity is going on and to put a hold on them when highly questionable activities are spotted.' But a planning official, who wished to remain anonymous, said under-staffing made it difficult for the department to carry out policing and enforcement. He said its inspectors were loaded with eight or nine site visits a day and given a wide range of duties, including following up complaints, posting notices on sites, conducting land surveys and updating land records. 'They conduct inspections and monitoring works on both private and government land. 'They work in bad weather, encounter hostile landowners and walk on difficult paths. It's never easy,' the official said. Alan Leung Sze-lun, conservation manager of WWF Hong Kong, also said he had doubts if the government had enough manpower to police the land, particularly ecologically significant areas, in the New Territories. He accepted it might be asking too much of enforcement officers to spot by themselves offences being perpetrated in remote areas. But he added: 'The weak policing might induce more people to commit environmental damage.' He urged the government to step up resources for land enforcement in the New Territories and make use of technology when necessary. This could include placing surveillance cameras at known black spots or installing GPS satellite tracking devices on dumper trucks. HELP US REPORT Today sees the launch of the South China Morning Post citizenmap.scmp.com, an online interactive map where you can help report destruction of the environment - from illegal dumping to removal of vegetation to unauthorised development - as well as follow the SCMP's coverage of such issues.