A leading environmentalist has called on the government to introduce mandatory assessments of the social impact from large projects, such as hydropower development, which usually involve many people being evicted. He said this would give the public a bigger say and help authorities better handle possible repercussions on communities and individuals. Yu Xiaogang described social impact assessments, widely used in the west but almost unheard of on the mainland, as a way of avoiding undesirable consequences from infrastructure projects. Mr Yu is the winner of last year's Goldman Environmental Prize and founder of the Green Watershed non-governmental organisation based in Kunming . He said social impact assessments could play a similar, and arguably more important, role, like environmental impact assessments, which were made compulsory in 2003. Green assessment has been widely accepted on the mainland as an effective way for otherwise powerless environmental authorities to enlist support from the public and flex their muscle to suspend polluting projects and penalise violators of green laws. While the importance of social impact assessments has been gradually recognised on the mainland in recent years, partly helped by widespread demonstrations and protests over land eviction and dam projects, it remains a largely negligible part of projects' feasibility studies, or 'an accessory' of environmental assessment. 'Not all our lessons should be learned through failure,' Mr Yu said, referring to the negative social impact of numerous infrastructure projects, which could have been prevented with a social impact assessment. Studies show that about 40 million people were displaced by a variety of development projects across the country during the past 50 years, including many that were sponsored by international financial institutions. Mr Yu said the accountability of the central government would be at risk if local authorities were unable to have a reliable assessment of possible social implications in advance and handle repercussions effectively. Describing the assessments as a pre-warning system to social woes, he said they would consider a development plan's social impact from various aspects, such as health, economic, cultural, psychological and ecological implications, and find short- and long-term solutions. 'The key to the success of such assessment is the participation of those affected,' Mr Yu said, adding that local people should be given full access to the assessment process to voice their concerns and help reach solutions. His views are supported by many environmental activists, who say social impact assessments should be carried out in villagers along the Nu River before dam projects are approved. Mr Yu is known for his vigorous advocacy of participatory educational programmes for villagers affected by dams who have been silenced despite their grievances. But he said there were obstacles to the introduction of such an assessment. 'Local governments still pay too much attention to GDP growth and tend to overlook the negative impact of development on communities and the environment,' he said. Powerful interest groups are not keen, as it would almost inevitably prolong approval and building processes for projects and increase costs. 'But I am still optimistic that social impact assessments will be given great importance by the top leadership within three years, because it helps maintain stability and build a harmonious society,' Mr Yu said.