Environmental Engineering Reference
In-Depth Information
preparation and implementation of diffuse pollution abatement programs, with
considerations of the social, economic and built environments.
6.1
The diffuse pollution management program
In order to achieve the cycled approach to the watershed management, the preparation
and execution of diffuse pollution abatement programs is essential, as it provides the
means for the formulation of objectives, and corresponding activities to achieve them, as
well as, benchmarks for the control of their implementation and the final assessment of
the achievements obtained. The preparation of a diffuse pollution abatement plan was
discussed in Chapter 2, and it was emphasized that such programs should form an
integral part of a holistic catchment management plan. Therefore, it follows logically,
that the programs could be developed for different localities and at different scales,
ranging from small urban or rural streams, to larger river basins, lakes (reservoirs) or
large catchment basins. The subsequent steps of a program could be defined briefly,
based on recommendations by Novotny (2003).
• Define objectives - requires the formulation of goals to be achieved based on detected
imbalancesbetween the desired status of the corresponding water body, with respect to
a designated water use, and the actual perception of its quality. These are narrative
statements, based on the desires of all stakeholders and the responsibilities of the
institution, which will implement the program.
• Develop design criteria - this step provides for the conversion of the formulated
objectives to numerical criteria, guidelines and standards, as prescribed by the existing
regulatory instruments and engineering practices, such as prescribed water demand
figures, population number and trends, design storms and corresponding return
periods, etc. This would enable the quantification of the formulated goals.
• Use or develop numerical pollution criteria - the water quality objective approach
would require different quality criteria for the different basins or sub-basins, which are
site specific. They could be formulated in the context of an “ecoregion” - a
geographical region with similar ecological, geological, geomorphological and land
use characteristics. Most countries in the region have developed or are in the process
of developing such criteria. One important aspect of this stage is the level of
“attainability” of the criteria, which should be reflected in the subsequent stages of the
program implementation and should provide for their practical implementation.
• Conduct water body assessment - this stage is most demanding, as it serves to quantify
the imbalance between the desired and actual water quality. The need for continuous,
regular and reliable water quality monitoring, of both point and diffuse sources, which
has been emphasized throughout this topic, including the determination of background
pollution values, as well as the need to implement GIS for data handling, serves to
backup this stage of the program and to provide reliable information for determination
and implementation of the following stages.
• Formulation of an implementation plan, including activities to be undertaken, funding
sources, time-frames, and other requirements is described in Chapter 2.
More complex programs, which are related to large catchment basins, lakes or dams of
national importance or other high-priority water bodies, provided that the necessary
