Environmental Engineering Reference
In-Depth Information
measures but should be advised and given guidelines with a strict time frame for their
implementation. The final choice of pollution abatement measures should be left to the
responsible authority, which will implement it. A clear and understandable report is
always cost effective, as it enables the implementation of decisions to protect, improve
and restore water quality and to optimize the monitoring process.
Computer processing and presentation become an essential part of the data storage,
handling and presentation process. Only for simple water quality projects, manual data
processing, handling and reporting could be used. Care should be taken during the data
processing operations to preserve and secure the integrity of the original data set.
Finally, the water quality monitoring report must show a clear structure and be
understandable for all readers, including non-specialists. The minimum number of items
in the report content should include:
• A short summary;
• An introduction to the objectives of the program;
• A description of the catchment and corresponding monitoring network;
• The methodologies applied, both in the field and in the laboratory, including quality
assurance and control protocols;
• A clear presentation of results followed by analysis, including statistical processing and
the interpretation of these results in the form of water quality assessment and
evaluation;
• Conclusions and recommendations for the decision-making process.
2.9
Specific aspects of diffuse pollution monitoring
Considering the fact that in the vast majority of the cases, the monitoring of diffuse
pollution means the monitoring of natural water bodies, it is unreasonable to expect or to
plan, that every water body could be monitored continuously and at numerous locations.
For this reason, a careful network design, based on a catchment principle, is imperative in
order to obtain meaningful information at an acceptable cost. As a minimum requirement,
locations at catchment boundaries, flow rate gauge stations, and major suspected
pollution sources must be included. The frequency of sampling and parameters tested
could vary for the different stations within a catchment, or among basins, based on
specific conditions.
Another important consideration during the monitoring process of diffuse pollution is
the need to identify the background pollution level, as diffuse pollution itself could be
identified only if the background quality is known. Therefore, the network design must
include points of pristine conditions, within a similar geographic region, which could
serve as a control reference for background quality evaluation.
It has been emphasized that diffuse pollution is due to polluted runoff, and as such
varies extremely in terms of quantity and quality, depending on the status of the washed
up surface. Therefore, it is an event-orientated phenomenon, related to the type of land
use practice in the area. In order to minimize monitoring efforts and costs, the monitoring
practice of diffuse pollution is orientated towards the determination of “event mean
concentrations” (EMC), which are statistical values of constituents, measured and
statistically characterized for most common land uses within a given geographical
boundary. EMCs are statistically related to specific rainfall events. Once EMCs are
