1
Introduction
Gert A. Schultz l and Edwin T. Engman 2
IRuhr University Bochum, 44780 Bochum, Germany
2Hydrological Science Branch, Code 974, Laboratory for Hydrospheric ProcessesNASA/Goddard Space Flight Center, Greenbelt, MD 29771, USA
1.1 Introduction
The Nilometer in Cairo may be considered as an ancient device of remote sensing,
since it measures - for millennia - the water level of the river Nile not in the river
itself, but rather in a historic tower building of very fine architecture near the river
Nile. The type of remote sensing discussed in this book is, however, of a rather
different type: It deals with techniques and methodologies the electronic age can
offer to hydrologists and water managers. At present a rather small international
community of hydrological scientists have developed - and are still developing -
methods for application of remote sensing information to the solution of hydrological and water management problems. Although many of these techniques are
already far advanced - several of them are operational - unfortunately many practitioners responsible for hydrological networks a..'ld water resources development
are still reluctant to use these methods. This situation is due to several reasons, e.g.
unavailability of relevant hardware and software, lack of knowledge in the application of remote sensing techniques, reluctance to change conventional and well
established methods etc. It is the aim of this book to overcome these barriers and
show to practitioners the potential of remote sensing and, hopefully convince them
of the advantages of these techniques for their future work. They will soon see,
that several of their problems which could not be treated at all so far will become
tractable and other problems dealt with at present with difficulty may be solved in
a much more elegant way.
1.2 Remote Sensing Defined
The literature provides many definitions of remote sensing and it may suffice here
to cite only one (Ritchie and Rango, 1996), "Remote sensing has been defined as
the science and art of obtaining information about an object, area, or phenomenon
through the analyses of data acquired by a sensor that is not in direct contact with
the target of investigation". It must be recognized at the outset that remote sensing
data are different from traditional hydrologic data. Compared to conventional
hydrological measurements remote sensing has certain significant advantages, but
also some disadvantages. One of the disadvantages of remote sensing is the fact,
G. A. Schultz et al. (eds.), Remote Sensing in Hydrology and Water Management
© Springer-Verlag Berlin Heidelberg 2000
Introduction
Gert A. Schultz l and Edwin T. Engman 2
IRuhr University Bochum, 44780 Bochum, Germany
2Hydrological Science Branch, Code 974, Laboratory for Hydrospheric ProcessesNASA/Goddard Space Flight Center, Greenbelt, MD 29771, USA
1.1 Introduction
The Nilometer in Cairo may be considered as an ancient device of remote sensing,
since it measures - for millennia - the water level of the river Nile not in the river
itself, but rather in a historic tower building of very fine architecture near the river
Nile. The type of remote sensing discussed in this book is, however, of a rather
different type: It deals with techniques and methodologies the electronic age can
offer to hydrologists and water managers. At present a rather small international
community of hydrological scientists have developed - and are still developing -
methods for application of remote sensing information to the solution of hydrological and water management problems. Although many of these techniques are
already far advanced - several of them are operational - unfortunately many practitioners responsible for hydrological networks a..'ld water resources development
are still reluctant to use these methods. This situation is due to several reasons, e.g.
unavailability of relevant hardware and software, lack of knowledge in the application of remote sensing techniques, reluctance to change conventional and well
established methods etc. It is the aim of this book to overcome these barriers and
show to practitioners the potential of remote sensing and, hopefully convince them
of the advantages of these techniques for their future work. They will soon see,
that several of their problems which could not be treated at all so far will become
tractable and other problems dealt with at present with difficulty may be solved in
a much more elegant way.
1.2 Remote Sensing Defined
The literature provides many definitions of remote sensing and it may suffice here
to cite only one (Ritchie and Rango, 1996), "Remote sensing has been defined as
the science and art of obtaining information about an object, area, or phenomenon
through the analyses of data acquired by a sensor that is not in direct contact with
the target of investigation". It must be recognized at the outset that remote sensing
data are different from traditional hydrologic data. Compared to conventional
hydrological measurements remote sensing has certain significant advantages, but
also some disadvantages. One of the disadvantages of remote sensing is the fact,
G. A. Schultz et al. (eds.), Remote Sensing in Hydrology and Water Management
© Springer-Verlag Berlin Heidelberg 2000