Urbanisation in developing countries is marked by large increases in population and has consequences such as sprawl. As a physical phenomenon, urbanisation takes two paths: through expansion of existing urban bodies by engulfing adjoining villages into their territory and through the independent transformation of rural areas into urban areas. Delhi is a classic example of urban sprawl caused by population growth. In the two decades between 1971 and 1991, Delhi's population increased by 4.8 million with the city's sprawl extending by 239 square kilometers