In recent decades the role of urban growth management has expanded at an accelerating rate as human populations grow and occupy ever-increasing space on the Earth’s surface. The twenty-first century is the first “urban century,” according to the United Nations Development Program. The focus on cities reflects awareness of the growing percentage of the world’s population that lives in urban areas. The need for technologies that will enable monitoring the world’s natural resources and urban assets and managing exposure to natural and man-made risks is growing rapidly. This need is driven by continued urbanization. In the year 2000, about 3 billion people, representing about 40% of the world’s population, lived in urban areas. Urban population will continue to rise substantially over the next several decades according to the United Nations, and most of this growth will be in developing countries.
As one data source, remotely sensed data are inherently suited to provide information on urban land cover characteristics, and their changes over time, at various spatial and temporal scales. The availability of multi-decade remote sensing information provides an important source for monitoring and assessing urban growth and its influences on the environment and ecosystem. Las Vegas as an example is the fastest growing city in the USA. Intense growth has been associated with most of Las Vegas’ 100-year history, with every decade since 1930 experiencing a population increase between 60% and 194%. Since 1990, the population has grown from approximately 750,000 to 2 million residents, which has caused the city’s problematic increases in resource demand. Series of false-color Landsat satellite captures shows its incredible capability of monitoring the urban expansion from 1979 to 2010 as it shown in figure below were vegetation is shown as red – the largest red areas are mostly parks and golf courses – buildings are grey.
Day after day we became convinced that remote sensing opens up enticing new prospects for comparing cities in terms of functional interrelationships and indicators of well-being, and the integration of the study of spatial forms with an understanding of the social, economic, cultural and political dimensions that led to their creation. We should not ignore that the exploitation of remote sensing data in urban areas has been a challenge for quite some time because of the complexity and fragmentation of objects and the combination of manmade and natural features. From that point on, the challenge is to accurately map these features, and then to monitor change over time, and ultimately to model and predict the temporal/spatial dimension of change.
Hopefully we can be certain that the increase in spatial and spectral resolution has led to the ability to characterize, and more importantly quantify, urban land uses and monitor their change. This new ability has had a powerful political impact as well. However, during the post-industrial age, the importance of monitoring conversion of agriculture to urban lands is of national, and even global, concern. As global population increases and cities continue to grow, the most fertile farmlands are being urbanized; this has serious implications for the long-term health of planet.
In conclusion, remote sensing data has proved to be significant for monitoring and detecting urban change, and for providing essential information for future development, the constantly increasing availability and accessibility of modern remote sensing technologies provides the unique capability to support decision-making with spatial, quantitative data and information products to open up new opportunities for urban monitoring.