ABSTRACT
More than half of the world population lives in cities. Many cities in dry land environments, such as Las Vegas and Phoenix in the southwest United States, are increasingly faced with water problems due to their rapidly growing populations. Vegetation indices have been developed to qualitatively and quantitatively assess vegetation covers using spectral measurements. The first earth resources satellite, Landsat 1, launched in 1972, was a remarkable effort to use electromagnetic spectral response to evaluate vegetation cover. The uses of the red and near-infrared spectral bands of the sensors onboard satellites are very well suited for assessing vegetation covers. To measure soil moisture, the satellite sensors can be classified into two categories, namely, optical remote sensing and microwave remote sensing. Optical remote sensing uses optical equipment to detect and record the surface radiation, reflection, and scattering of electromagnetic waves under a corresponding spectrum section and analyze their characteristics and change on the earth’s surface.
