Article 17 of the Urban and Rural Planning Law of People's Republic of China (PRC) shall include: the development layout of cities and towns, functional zoning, land use layout, comprehensive transportation system, geographical areas where construction is prohibited, restricted and suitable, and various special plans. The scope of the planning area, the scale of construction land in the planning area, land for infrastructure and public service facilities, water sources and water systems, basic farmland and green space, environmental protection, natural and historical and cultural heritage protection, disaster prevention and mitigation, etc. should be taken as the mandatory contents of the overall urban planning and the overall town planning. The planning period of urban master plan and town master plan is generally twenty years. The overall urban planning should also make predictable arrangements for the longer-term development of the city.