Symposium on Remote Sensing for Resources Development and Environmental Management/Enschede/August 1986 
© 1987 Balkema, Rotterdam. ISBN 90 6191 674 7 
1005 
Hydrologic and oceanographic applications of remote sensing 
Arthur P.Cracknell 
Carnegie Laboratory of Physics, University of Dundee, Scotland, UK 
ABSTRACT: This is a very wide remit and so an attempt will be made (i) to survey what has already been 
achieved by the use of remotely-sensed data in the fields of hydrology and oceanography, (ii) to assess the 
present position and assess both what can be achieved and what it is unrealistic to expect to achieve in these 
fields with currently-available remotely-sensed data and (iii) to predict the likely advances that can be 
expected to be made with new types of remotely-sensed data that can be expected to become available in the 
near future. 
1 INTRODUCTION 
It is appropriate, since this is a meeting of a 
Commission of ISPRS, to think in terms of synthesis. 
I have in mind particularly a synthesis between two 
fields which have, in the past, often been quite 
separate but which are now already coming closer 
together and which, hopefully, will draw even more 
close together in the future. The fields I have in 
mind are on the one hand the use of air photographs, 
whether for qualitative photo-interpretation or for 
quantitative photogrammetric work, and on the other 
hand the use of data from remote sensing satellites. 
In the past these fields of work have tended to 
remain separated because the nature of the data 
obtained from the two sources was rather different. 
The differences can conveniently be summarised under 
the headings (i) spatial resolution, (ii) spectral 
characteristics and (iii) temporal resolution. With 
the improved spatial resolution of the new generation 
of instruments that have recently been launched into 
space, namely the Thematic Mapper on LANDSAT-4 and 
LANDSAT-5 and the HRV on the SPOT-1 satellite, the 
gap between the spatial resolution of air photo 
graphs and that of satellite-flown scanners is 
becoming very much reduced. 
A great deal of photogrammetric and remote sensing 
work has, in the past, been devoted to study of what 
I might call dry land. By dry land I mean'not just 
the land, as distinct from the sea, but aspects of 
the land in which the presence of water is somewhat 
secondary. Also, because conventional photo- 
grammetry has been based on the use of aerial photo 
graphs it has usually, of necessity, been confined 
to dealing with small areas of the surface of the 
Earth. By contrast, conventional remote sensing has 
been based on the use of low-spatial-resolution 
satellite data which covers much larger areas of the 
surface of the Earth. 
To survey the work that has been done in the past 
and to assess the present position in the fields 
that it is the purpose of this paper to address, one 
can hardly expect to do better than to summarise the 
relevant chapters of the second edition of the 
Manual of Remote Sensing (Colwell 1983). The 
relevant chapters are chapter 28 on "The Marine 
Environment" and chapter 29 on "Water Resources 
Assessment"; I shall, therefore, try (i) to summarise 
the main points from these chapters, (ii) to add any 
more recent material from publications subsequent to 
that edition of the Manual, (iii) to comment on the 
present position and (iv) to make some predictions 
about future developments. 
2 SUMMARY OF PAST WORK ON HYDROLOGY AND OCEANOGRAPHY 
Since, as I have already indicated, the past work in 
these areas has been reviewed meticulously in the 
Manual of Remote Sensing there would be no purpose, 
in the written version of this paper, in giving an 
extensive plagiarism of that work. I shall simply 
give a brief summary, though a more extensive 
discussion will be given in the oral presentation. 
2.1 Hydrology 
Considering hydrology first, the main past 
applications of remote sensing noted in chapter 29 
of the Manual include 
(a) Underground water resources 
(b) Soil moisture and évapotranspiration 
(c) Snow and ice mapping and monitoring 
(d) Estimation of meltwater runoff 
(e) Surface water mapping and monitoring 
(f) Flood monitoring 
(g) Mapping of catchment areas, wetlands, irrigated 
areas, inter-tidal zone, coastal erosion/ 
accretion. 
Behind many of these applications is the question of 
the assessment of water resources. The question of 
pollution, which can be very important in lakes, 
rivers and estuaries is actually discussed in the 
previous chapter. 
2.2 Oceanography 
The main topics which have been studied in the past 
by using remote sensing techniques are noted in 
chapter 28 of the Manual and include : 
(a) Water surface temperature 
(b) Ocean fronts and currents 
(c) Surface topography 
(d) Coastal currents 
(e) Sea state and near-surface winds 
(f) Sea ice monitoring 
(g) Sewage, industrial and oil pollution 
(h) Salinity 
(i) Chlorophyll concentration 
(j) Fisheries 
(k) Submerged aquatic vegetation 
(l) Suspended sediment concentration 
(m) Bathymetry 
(n) Circulation models. 
There is, inevitably, some overlap between the 
material in the two chapters, especially regarding 
the coastal regions where freshwater systems and 
marine systems meet.