surface water, groundwater, land use/cover, soil, and environmental hazards. For
most water resources investigations, GIS provides an extremely useful technology
for interaction between remote sensing data and a multitude of geographic data such
as topography, rainfall, evaporation, vegetation, and geomorphology. This chapter is
intended to provide the background information necessary to successfully use GIS
technology in conjunction with remotely sensed data to plan and manage water
resources projects. The chapter also provides case studies that demonstrate the
proper application of GIS and remote sensing principles.
A GIS references real-world spatial data elements to a coordinate system. Spatial
data elements are also known as graphic or feature data elements. The feature data
elements can be separated into different layers or map themes. A layer is a thematic
set of spatial data described and stored in a database or map library. Layers organize
a database or map library by subject matter such as soils, rivers, and wells. A GIS can
also store attribute data, which is a descriptive information of the map features. GIS
can combine satellite data and other types of geographic data to generate maps and
reports, enabling users to collect, manage, and interpret location-based information
in a planned and systematic way. A satellite is the vehicle or platform which carries a
sensor. Some important satellite platforms are Satellite Pour l’Observation de la
Terre (SPOT), Landsat, Ikonos, and Indian Remote Sensing satellite (IRS-1A and
IRS-1C). The HRV (High Resolution Visible) sensor carried on SPOT satellite
operates into two modes: the XS or multispectral mode and P or Panchromatic
mode. The three sensors carried on Landsat satellites are MSS (MultiSpectral
Scanner), TM (Thematic Mapper), and ETM (Enhanced Thematic Mapper). The
readers are referred to the Glossary Section of this book chapter or the USEPA web
site for the glossary details.
2 Fundamentals of Remote Sensing
Remote sensing may be broadly defined as the collection of information about an
object without being in physical contact with the object. Since 1972, satellites have
provided repetitive, synoptic, global coverage of high-resolution imageries of the
earth surface that can be used to interpret numerous phenomena. Satellites measure
and record the spectral reflectance (the portion of the incident energy that is
reflected) of the earth’s surface in several different wavelength ranges, from microwave to visible light. The electromagnetic spectrum illustrated in Fig. 5.1 is the basis
of all environmental remote sensing. Ultraviolet, visible, and short infrared radiations (<3 μm wavelength) are mainly reflected solar energy while mid-infrared,
thermal infrared, and microwave radiations (>3 μm wavelength) are mostly emitted
from the earth’s surface. For more in-depth information on basic remote sensing, the
reader is referred to remote sensing books by Lillesand and Keifer [2] and Barret and
Curtis [3].
5 Geographic Information Systems and Remote Sensing Applications in Environmental. . . 199
most water resources investigations, GIS provides an extremely useful technology
for interaction between remote sensing data and a multitude of geographic data such
as topography, rainfall, evaporation, vegetation, and geomorphology. This chapter is
intended to provide the background information necessary to successfully use GIS
technology in conjunction with remotely sensed data to plan and manage water
resources projects. The chapter also provides case studies that demonstrate the
proper application of GIS and remote sensing principles.
A GIS references real-world spatial data elements to a coordinate system. Spatial
data elements are also known as graphic or feature data elements. The feature data
elements can be separated into different layers or map themes. A layer is a thematic
set of spatial data described and stored in a database or map library. Layers organize
a database or map library by subject matter such as soils, rivers, and wells. A GIS can
also store attribute data, which is a descriptive information of the map features. GIS
can combine satellite data and other types of geographic data to generate maps and
reports, enabling users to collect, manage, and interpret location-based information
in a planned and systematic way. A satellite is the vehicle or platform which carries a
sensor. Some important satellite platforms are Satellite Pour l’Observation de la
Terre (SPOT), Landsat, Ikonos, and Indian Remote Sensing satellite (IRS-1A and
IRS-1C). The HRV (High Resolution Visible) sensor carried on SPOT satellite
operates into two modes: the XS or multispectral mode and P or Panchromatic
mode. The three sensors carried on Landsat satellites are MSS (MultiSpectral
Scanner), TM (Thematic Mapper), and ETM (Enhanced Thematic Mapper). The
readers are referred to the Glossary Section of this book chapter or the USEPA web
site for the glossary details.
2 Fundamentals of Remote Sensing
Remote sensing may be broadly defined as the collection of information about an
object without being in physical contact with the object. Since 1972, satellites have
provided repetitive, synoptic, global coverage of high-resolution imageries of the
earth surface that can be used to interpret numerous phenomena. Satellites measure
and record the spectral reflectance (the portion of the incident energy that is
reflected) of the earth’s surface in several different wavelength ranges, from microwave to visible light. The electromagnetic spectrum illustrated in Fig. 5.1 is the basis
of all environmental remote sensing. Ultraviolet, visible, and short infrared radiations (<3 μm wavelength) are mainly reflected solar energy while mid-infrared,
thermal infrared, and microwave radiations (>3 μm wavelength) are mostly emitted
from the earth’s surface. For more in-depth information on basic remote sensing, the
reader is referred to remote sensing books by Lillesand and Keifer [2] and Barret and
Curtis [3].
5 Geographic Information Systems and Remote Sensing Applications in Environmental. . . 199