This image is familiar to all of us. It is where most Australians live and work. We live in the suburbs and work in the cities. We are urban dwellers. Yet the image we like the rest of the world to have of Australia and of Australians is of unspoiled arid wilderness. The sky is blue and the people are suntanned and self-reliant. It is a pleasant image, a comfortable image, but misleading. Let me show you why.

Most of the readers of this book will be urban Australians. Rural Australians are among the keenest book buyers in the world, but probability indicates that most readers will be urban dwellers.

This statement is based on the premise that there is an equal probability that any Australians will have the chance to read this book. From the 1991 Australian Year Book I know that, as of 1986, some 85% of Australians were urban residents with only 15% living in the rural areas. Therefore on average, the chances are 85 in 100 that you, the reader, live in a city. What is more, the proportion of the Australian population that is urban is steadily increasing. The distribution was 62% urban in 1921 and has steadily increased to 85% as measured in the census of 1986.

What do cities have to do with the theme of this book - the use of satellite images to monitor the change in the landcover of the continent over the last 20 years? Are cities significant agents of landcover change?

This Chapter sets out to examine exactly this question. Before we start, let's focus the question a little to make sure we get it right. Let's expand the question to - are cities agents of landcover change and if so, is this change significant?