INTEGRATING TOOLS FOR SURFACE WATER QUALITY MANAGEMENT - Integrating GIS, Remote Sensing, and Mathematical Modelling for Surface Water Quality Management - page 65

Measurements have been made in situ (Quibell 1992; Han et al. 1994;Rundquist et al. 1996) and from
aircraft (Dekker et al. 1992; Gitelson et al. 1994; Harding et al. 1995), Landsat and SPOT (Carpenter
and Carpenter 1983; Lathrop and lillesand 1989; Strumpf and Tyler 1988; Dekker and Peters 1993)
and CZCS (Hovis 1981; Gordon et al. 1983), Figure (3-4) . These studies have used a variety of
algorithms and wavelengths to successfully map CHL-aorophyll concentrations of oceans, estuaries
and fresh waters. Harding et al.
While measuring CHL-aorophyll by remote sensing is possible, studies have also shown that the broad
wave length spectral data available on current satellites do not permit discrimination between CHL-
aorophyll and suspended sediments (Dekker and Peters 1993; Ritchie et al. 1994) due to the
dominance of the spectral signal from suspended sediment. These discoveries suggest new approaches
for application of airborn and spaceborne sensors to exploit these phenomena to estimate CHL-
aorophyll in surface waters under all conditions. New hyperspectral sensors have been launched and
data have become available. Data from several satellite sensors (i.e. Sea WiFS, modular Optical
Scanner (MOS), Ocean color and Temperature Scanner (OCTS) are now becoming available and hold
great promise for measuring biological productivity in aquatic systems.
Chl-aorophyll-a
3
Figure (3-4): The relationship between reflectance and wavelength for different CHL-aorophyll-a concentrations
(Ritchei et al., 1976).
Satellites such as (SEA-WIFS, MOS, OCTS, QuickBird, Resource21, Orbview, etc.) and sensors
(hyperspectral, high spatial resolution) should provide both the improved spectral and spatial
resolution needed to monitor water quality parameters in surface waters in fresh water in lakes and
streams, estuaries, and oceans and to differentiate between different water quality parameters.
Research needs to focus on the understanding of the relationship between water quality parameters and
their effects on the optical and thermal properties of surface waters so that physically based models
can be developed (Jerome et al. 1996). Such information should facilitate progress from the empirical
approaches now being used to the development of algorithms that will allow the use of the full
resolution electromagnetic spectrum to monitor water quality parameters.
In one of the remote sensing applications in water quality, Dekker et al. (2001) applied airborne
remote sensing for inland water quality detection and monitoring on Friesland waters, the Netherlands.
The study resulted in developing maps of CHL-aorophyll and suspended matter concentrations using
analytical algorithms. The study showed that the real problem for getting an emerging technology such
as high spectral and radiometric resolution remote sensing accepted and implemented, lies in making it
clear to the end-users that the application of the technique is beneficial in their work. Therefore it is
necessary to provide the end user with adequate water quality information from remote sensing at the
right time in the right format. For this purpose, the study developed a generic methodology in the
Netherlands, applicable anywhere in the world, with the following guidelines: