Monitoring of Pollution by Means of Remote Sensing
539
if the samples are taken at clearly identifiable and significant times such as
high and low tide, the data can be more easily extrapolated to different water
masses because the stability of the situations is greater than during the ebb or
flood. Thus one can avoid taking several samples from the same water mass as
it passes from one place to another. Given that sampling cannot be totally
synchronous, it is recommended that sampling should start at the theoretical
high or low tide and continue through the first, or even the second, hour
afterwards, depending on the tidal coefficient, because the tidal currents
continue longer when the coefficient is high
although the information collected at high and low tide is different, both
situations are interesting and sampling should be continued at both under the
monitoring plan, in order to characterize different phenomena:
i) at high tide: the quality of estuarine water and the interchange between
the Odiel and the Punta Umbría channel
ii) at low tide: the interchange process between estuarine and coastal
waters is fundamental to any understanding of the estuary's capacity for
renovation
Concerning the siting of sampling points, the results of the dynamic study reveal two
problems (Fig. 7):
i) there are zones of the estuary not covered by the current sampling
procedure, notably the Punta Umbría and Burro channels
ii) some zones have an excess of sample points giving redundant
information e.g. the junction of the Odiel and Tinto rivers. To produce
information that is basically different, it is proposed to have points
located for high tide sampling and for low tide sampling (Fig. 8) even
though in both cases the proposal would no longer use two of the current
sampling sites
For high tide: five new sampling points are proposed.
in the upper reaches of the Tinto where the most turbid waters are pushed by
the rising tide
in the middle reaches of the Odiel which, in effect, is a slight southward
movement of an otherwise redundant site
539
if the samples are taken at clearly identifiable and significant times such as
high and low tide, the data can be more easily extrapolated to different water
masses because the stability of the situations is greater than during the ebb or
flood. Thus one can avoid taking several samples from the same water mass as
it passes from one place to another. Given that sampling cannot be totally
synchronous, it is recommended that sampling should start at the theoretical
high or low tide and continue through the first, or even the second, hour
afterwards, depending on the tidal coefficient, because the tidal currents
continue longer when the coefficient is high
although the information collected at high and low tide is different, both
situations are interesting and sampling should be continued at both under the
monitoring plan, in order to characterize different phenomena:
i) at high tide: the quality of estuarine water and the interchange between
the Odiel and the Punta Umbría channel
ii) at low tide: the interchange process between estuarine and coastal
waters is fundamental to any understanding of the estuary's capacity for
renovation
Concerning the siting of sampling points, the results of the dynamic study reveal two
problems (Fig. 7):
i) there are zones of the estuary not covered by the current sampling
procedure, notably the Punta Umbría and Burro channels
ii) some zones have an excess of sample points giving redundant
information e.g. the junction of the Odiel and Tinto rivers. To produce
information that is basically different, it is proposed to have points
located for high tide sampling and for low tide sampling (Fig. 8) even
though in both cases the proposal would no longer use two of the current
sampling sites
For high tide: five new sampling points are proposed.
in the upper reaches of the Tinto where the most turbid waters are pushed by
the rising tide
in the middle reaches of the Odiel which, in effect, is a slight southward
movement of an otherwise redundant site