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in the not too distant future. Setting up a data infrastructure 
sufficient attention should be given to airborne data supply. 
Recent and present developments with respect to processing 
algorithms and data-integration should be incorporated within the 
European and national data-infrastructures. A number of stages of 
processing can be identified in this respect: 
- preprocessing (e.g. geometric and atmospheric correction) 
- processing (e.g. algorithm for deriving water quality 
parameters) 
- post-processing (e.g. integration of remote sensing derived 
water quality products with numerical models and GIS) 
The functional design of a data infrastructure for water quality 
applications is presented in figure 1. Operational use of remote 
sensing not only depends on the availability and flexibility of 
(spaceborne and airborne) platforms, but also on an efficient 
processing chain of the data. As compared to spaceborne data, 
(pre-)processing of airborne data is even more complex, 
especially with respect to geometric and atmospheric correction 
and corrections for the air-water interface. In general airborne 
remote sensing benefits from incorporation of a real-time dGPS 
system in the airborne platform, which will significantly reduce 
the pre-processing time. 
Standard toolkits will not only reduce the time delay between 
acquisition and delivery of information to the end user, but also 
give more objective quality labels to the remotely sensed 
information. It is recommended to implement standard remote 
sensing (pre-)processing tools as public domain software at a 
number of governmental and commercial companies. 
In general, during the summer months, a number of regional and 
local water managers are interested in remote sensing based water 
quality information of their region. A main bottleneck is that these 
water managers are not familiar with practical aspects related to 
the conditions for remote sensing flights. Furthermore, airborne 
remote sensing on a project basis for individual clients is in 
general too expensive. Consequently, operationalization of 
airborne remote sensing for water quality would benefit from 
coordinated data-acquisition, in which a value added company (or 
a consortium) contacts regional and local water managers, 
coordinates flights during the summer months, asks for offers 
from candidate airborne data-providers, distributes the raw data to 
(other) value added companies, etc. 
Internet WWW will play a very important role in the future 
satellite data infrastructure. Almost all satellite data providers are 
currently building meta information systems, including quick 
look browsing facilities. This development will have a 
tremendous impact on the accessibility of satellite data for the 
users. Satellite data sets have large volumes. Currently transfer of 
satellite data through Internet is not an option, although for 
smaller data volumes Internet technology can already be used 
(e.g. processed ERS SAR data for near real time oil spill 
detection). However, as high speed computer links will enable 
near real-time data distribution within a few years from now, the 
user group of "water quality" satellite data should keep an eye on 
these fast developments. 
In an European context (CEO) and at national and institutional 
levels, meta information systems have to be developed, which 
form an information shell around data base systems containing 
remote sensing imagery. These shells must provide entrances and 
links to the actual data base systems where (raw) remote sensing 
13 
data is kept. Furthermore, advertising the potentials of remote 
sensing through the Internet could create new users and products 
and stimulate (inter-)national cooperation between research 
groups and water quality managers. In this respect the EARSeL 
SIG on "marine waters, inland waters and coastal zones" can play 
a role in the context of CEO. 
3. COASTAL MORPHOLOGY 
3.1 Management problems 
For sustainable development and management of sedimentary 
coastal plains, reliable and up-to-date geomorphological infor- 
mation is needed on the bathymetry of the near coastal zone and 
the height of the beach and coastal dunes. In this context for the 
manager of these lowland areas two main tasks can be identified: 
1) management and maintenance of shipping lanes to ensure 
transport and distribution capacity and 2) protection of the in- 
shore area against flooding. 
For safety, efficiency and economic reasons there is a need for 
accurate and reliable depth information in navigation areas. With 
respect to the required type of bathymetric information a 
distinction can be made between two types of in-situ depth 
measurements: 1) monitoring of large scale morphodynamics and 
2) small-scale surveys for management in depth-critical areas. 
Monitoring surveys are carried out to support long-term safety 
strategies. Depth measurements in shipping areas and dump 
locations contribute to short-term management and maintenance 
and they have a strong relationship with economic and legal 
responsibilities of the authorities. 
In most lowland countries the foredunes, beaches and near coastal 
zone are monitored on a regular basis to assure that their primary 
function as defence against the sea is maintained. For instance in 
the Netherlands, as of 1964 the topography of the coast is 
measured in cross sections perpendicular to the coast line. The 
measurements consist of depth measurements of the near coastal 
zone and height measurements of the beach and foredunes. In 
total 1700 of such coastal profiles are measured yearly, through 
acoustic measurements and standard analytical photogrammetric 
means. Based on these observations it is decided where and how 
much sand is to be supplied. For the part five years, in the 
Netherlands "the dynamic maintenance of the coast line" is the 
guiding principle, indicating that some freedom is allowed for the 
dynamic processes to take place. 
Knowledge of the actual depth of the sea bottom and shipping 
lanes and the height of the coastal defense works is fundamental 
to take corrective actions, if necessary. In practice this means that 
either sand nourishment or channel dredging is carried out. On a 
long term basis morphodynamical information is used to make 
predictions of future morphological changes. This type of 
information is used to formulate a long-term strategy towards 
coastal defense matters. 
Besides its function to protect the lowland against flooding, the 
sandy coastal area unites a number of other important functions. 
The dune area serves as an important reservoir proving drinking 
water to cities. Another important aspect concerns tourism and 
recreation. Also claims are exerted on the coastal area with respect 
to housing, industrial and agricultural activities. And, last but not 
least, the coastal zone is of paramount importance in view of the 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996