CHAPTER 1 • Principles and Benefits of Integrated Coastal Zone Management (ICZM)
15
1.2
Pressure-State-Impact-Response (P-S-I-R) Framework
A particular characteristic of modern economic development (encompassing population and population density increases, urbanisation, intensification of agriculture and
industrial processing) is that it has led, among other changes, to the progressive opening of biogenic nutrient cycles e.g. much increased mobility of nitrogen and phosphorus. The increased mobility of nutrients has meant increased exchanges between land
and surface water and consequent impacts on ecological functioning of aquatic systems. Other process changes involving water and/or sediment movement together with
the transport of heavy metals and other substances have also added to the cumulative
changes experienced in coastal systems.
The\coastal areas interface between the continents and the ocean is comprised of a
continuum of aquatic systems including the network of rivers, the estuaries, the coastal
fringe of the sea, the continental shelf and its slope. These interdependent systems are
characterized by very significant biogeochemical processes - primary productivity
generation, organic matter and nutrient sinks etc. The major flux of nutrients from land
to sea occurs through river transport, via the drainage basins network. The network
contains various "filters" (e.g. wetlands) retaining or eliminating nutrients during their
downstream passage to the sea. The effectiveness and selectivity of these filters depend
on the strong biogeochemical coupling existing between carbon, nitrogen, phosphorus and silica circulation and they are also affected by hydrology and land use/cover
(Billen et al. 1995).
A useful starting point for both natural and social science research would be to seek
(via a more integrated modelling and assessment process) to better describe and understand the functioning of the ecosystems forming the coastal interface, and in particular the filter effect it exerts for nutrients, in response to environmental pressures,
both anthropogenic and non-anthropogenic - climate change, land use/cover change,
urbanisation and effluent treatment from both point and non-point sources. But first
we need some broad analytical framework (rather than a specific model) in which to
set the more detailed analysis.
The P-S-I-R cycle offers such a generalized context - see Fig. 1.2. For any given
coastal area (defined if necessary to encompass the entire drainage network) there
will exist a spatial distribution of socio-economic activities and related land uses -
urban, iridustrial mining, agriculture/forestry/aquaculture and fisheries, commercial
and transportation. This spatial distribution of human activities reflects the final demand for a variety of goods and services within the defined area and from outside the
area.
The production activities result in different types and quantities of residuals,
as well as goods and services measured in Gross National Product (GNP) terms. Environmental processes will transform the time and spatial pattern of the discharged/
emitted residuals into a consequent short-run and long-run time and spatial ambient environmental quality pattern. Thus ,we need to know more about the impacts
of, for example, C, Nand P flux changes on systems (including socio-economic systems).
These state environmental changes impact on human and non-human receptors
resulting in a number of perceived social welfare ,changes (benefits and costs). Such
15
1.2
Pressure-State-Impact-Response (P-S-I-R) Framework
A particular characteristic of modern economic development (encompassing population and population density increases, urbanisation, intensification of agriculture and
industrial processing) is that it has led, among other changes, to the progressive opening of biogenic nutrient cycles e.g. much increased mobility of nitrogen and phosphorus. The increased mobility of nutrients has meant increased exchanges between land
and surface water and consequent impacts on ecological functioning of aquatic systems. Other process changes involving water and/or sediment movement together with
the transport of heavy metals and other substances have also added to the cumulative
changes experienced in coastal systems.
The\coastal areas interface between the continents and the ocean is comprised of a
continuum of aquatic systems including the network of rivers, the estuaries, the coastal
fringe of the sea, the continental shelf and its slope. These interdependent systems are
characterized by very significant biogeochemical processes - primary productivity
generation, organic matter and nutrient sinks etc. The major flux of nutrients from land
to sea occurs through river transport, via the drainage basins network. The network
contains various "filters" (e.g. wetlands) retaining or eliminating nutrients during their
downstream passage to the sea. The effectiveness and selectivity of these filters depend
on the strong biogeochemical coupling existing between carbon, nitrogen, phosphorus and silica circulation and they are also affected by hydrology and land use/cover
(Billen et al. 1995).
A useful starting point for both natural and social science research would be to seek
(via a more integrated modelling and assessment process) to better describe and understand the functioning of the ecosystems forming the coastal interface, and in particular the filter effect it exerts for nutrients, in response to environmental pressures,
both anthropogenic and non-anthropogenic - climate change, land use/cover change,
urbanisation and effluent treatment from both point and non-point sources. But first
we need some broad analytical framework (rather than a specific model) in which to
set the more detailed analysis.
The P-S-I-R cycle offers such a generalized context - see Fig. 1.2. For any given
coastal area (defined if necessary to encompass the entire drainage network) there
will exist a spatial distribution of socio-economic activities and related land uses -
urban, iridustrial mining, agriculture/forestry/aquaculture and fisheries, commercial
and transportation. This spatial distribution of human activities reflects the final demand for a variety of goods and services within the defined area and from outside the
area.
The production activities result in different types and quantities of residuals,
as well as goods and services measured in Gross National Product (GNP) terms. Environmental processes will transform the time and spatial pattern of the discharged/
emitted residuals into a consequent short-run and long-run time and spatial ambient environmental quality pattern. Thus ,we need to know more about the impacts
of, for example, C, Nand P flux changes on systems (including socio-economic systems).
These state environmental changes impact on human and non-human receptors
resulting in a number of perceived social welfare ,changes (benefits and costs). Such