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E.T. Engman and G.A. Schultz
launched by the Japanese, and RADARSAT launched by the Canadians that will
provide useful data for hydrologists. All carry single polarization, single-frequency
SARs. An additional satellite that was recently launched will have considerable
hydrologic interest is the Tropical Rainfall Measurement Mission (TRMM) (Simpson et aI., 1988).
While, space borne sensors are ideal for long term, large area and global observations, there are a number of cases in which aircraft sensors can be extremely
useful for hydrologic applications. Situations in which airborne sensors may be
optimal are for extremely high resolution sensing, detailed topographic mapping,
and flying of new sensors that are not currently on spacecraft. A good example of
the later is the A VERIS hyperspectral instrument. Additional uses for airborne
instruments are intensive, but short duration field campaigns discussed above or
one time detailed mapping of an area or special situation such as flooding or an
environmental spill.
In the field of ground-based remote sensing the use of weather radar data for
measuring precipitation with a high resolution in space and time is most important.
This information is particularly useful as input to hydrological rainfall-runoff
models for real-time flood forecasting. The implementation of ground-based
weather radar stations is in progress on all continents. Very advanced systems
covering the whole country are already operational in the UK and in Japan. In
western Europe and in North America such integrated weather radar networks are
under construction and partially operational. It can be expected, that in many
countries and even continents, these integrated weather radar networks will be
accessible to flood forecasting centers. Use of these radar data will be available in
real-time to make online flood forecasts for all relevant points in the river network,
for small catchments as well as large river basins.
As far as the satellite borne sensor systems are concerned, not all existing and
approved sensors are ideal for hydrology. The currently available instruments do
provide, however, very useful data for hydrological applications even though none
of the currently available satellite sensors have been designed with hydrological
applications as the primary goal. The result is that we often have to use less than
ideal data for a given application, but in spite of this they have been very useful
under limited circumstances. The listing of currently available satellite systems and
sensors characteristics has been given in the Appendices 20.1 and 20.2 at the end
of this chapter.
20.7 Planned and Proposed Sensors and Platforms
The currently available satellite sensors have not been used optimally in hydrology. However, it is possible that with the future satellite sensors we will really see
an advancement in the hydrologic sciences. This will be accomplished by improved spatial resolution, narrower and more specific spectral bands, but most
importantly more sensors operating in the microwave region of the spectrum. The
microwave region of the spectrum provides the opportunity to make unique measurements of system states under all weather conditions.
E.T. Engman and G.A. Schultz
launched by the Japanese, and RADARSAT launched by the Canadians that will
provide useful data for hydrologists. All carry single polarization, single-frequency
SARs. An additional satellite that was recently launched will have considerable
hydrologic interest is the Tropical Rainfall Measurement Mission (TRMM) (Simpson et aI., 1988).
While, space borne sensors are ideal for long term, large area and global observations, there are a number of cases in which aircraft sensors can be extremely
useful for hydrologic applications. Situations in which airborne sensors may be
optimal are for extremely high resolution sensing, detailed topographic mapping,
and flying of new sensors that are not currently on spacecraft. A good example of
the later is the A VERIS hyperspectral instrument. Additional uses for airborne
instruments are intensive, but short duration field campaigns discussed above or
one time detailed mapping of an area or special situation such as flooding or an
environmental spill.
In the field of ground-based remote sensing the use of weather radar data for
measuring precipitation with a high resolution in space and time is most important.
This information is particularly useful as input to hydrological rainfall-runoff
models for real-time flood forecasting. The implementation of ground-based
weather radar stations is in progress on all continents. Very advanced systems
covering the whole country are already operational in the UK and in Japan. In
western Europe and in North America such integrated weather radar networks are
under construction and partially operational. It can be expected, that in many
countries and even continents, these integrated weather radar networks will be
accessible to flood forecasting centers. Use of these radar data will be available in
real-time to make online flood forecasts for all relevant points in the river network,
for small catchments as well as large river basins.
As far as the satellite borne sensor systems are concerned, not all existing and
approved sensors are ideal for hydrology. The currently available instruments do
provide, however, very useful data for hydrological applications even though none
of the currently available satellite sensors have been designed with hydrological
applications as the primary goal. The result is that we often have to use less than
ideal data for a given application, but in spite of this they have been very useful
under limited circumstances. The listing of currently available satellite systems and
sensors characteristics has been given in the Appendices 20.1 and 20.2 at the end
of this chapter.
20.7 Planned and Proposed Sensors and Platforms
The currently available satellite sensors have not been used optimally in hydrology. However, it is possible that with the future satellite sensors we will really see
an advancement in the hydrologic sciences. This will be accomplished by improved spatial resolution, narrower and more specific spectral bands, but most
importantly more sensors operating in the microwave region of the spectrum. The
microwave region of the spectrum provides the opportunity to make unique measurements of system states under all weather conditions.