Environmental Engineering Reference
In-Depth Information
guidelines/criteria for natural water quality and incorporate the acting regulations for
effluent discharges in order to achieve the prescribed objectives. In addition, it would
allow in future the implementation of the waste assimilative capacity approach, which
requires a more extensive database, more sophisticated equipment and a higher
professional level of human resources, involved in the process.
The need for introducing the water quality objective approach has been recognized in
the region and many countries have adopted it. The practical implementation of these
instruments is still in its infancy and most probably would be a lengthy process, which
would require a considerable administrative effort and a corresponding restructuring of
the institutional arrangements. Also, it would require the revision of the existing
monitoring programs and their upgrading to a new level, which would provide for the
enforcement of the new legislative documents.
One important point, which should not be omitted with respect to the implementation
of this strategy, is the fact that in numerous cases, in the countries of the region the rivers
under consideration are ephemeral, as it is the case of Botswana. Correspondingly, they
flow only during and immediately after the rain season. In such circumstances, we could
not rely on dilution or any assimilative capacity. Correspondingly, the effluent orientated
approach should be applied and enforced for such localities. This serves to emphasize the
need for the integration and mutual interrelation between the two approaches, as well as
the consideration of the specific site conditions, typical for the locality, country and
region.
3.2
The link between regulatory instruments and monitoring programs
Regulatory instruments, which are not enough explicit in terms of quantitative criteria for
their implementation, but rely on general statements or descriptive formulations could be
regarded as “paper tigers”, which would not help to control and improve the water
quality. In cases where specified values with respect to listed constituents have been
incorporated, providing a dimension of magnitude with respect to maximum permissible
concentrations, it would be necessary also, to specify the method of monitoring,
including sampling procedures and monitoring frequency. This is necessary, considering
the fact that water quality is a random variable as it was explained in section 2. For a
given monitoring station, and a period of observation of one year, two data sets are
available, as illustrated on Figure 12.2. For the data set with 12 observations the 95%
cumulative probability value would exceed the recommended standard and should be
interpreted as non-compliant with the regulatory instruments. The data set with four
observations only would indicate compliance, because the 95% cumulative probability
value is lower than the recommended limit. This example does not mean that the lower
frequency would necessarily mean compliance. It is possible that even when a few
observations are available, the standards could be exceeded. In several case studies
presented in previous chapters, all values of the data sets, with respect to certain
parameter, considerably exceed the recommended values, and do not leave room for
misinterpretation of the results. However, in most cases, the data interpretation and
pollution status evaluation could be very subjective, if regulatory instruments do not
specify the required frequency. Consequently, the regulations enforcement and the
