Water quality management is complex and it is best to simplify the process whenever possible. Managers often use conceptual models to better understand and communicate complex water quality issues. The conceptual approach to managing water quality comprises three main components: the identification of (i) causal pressures on a waterway; (ii) the stresses that can result from causal pressures; and (iii) environmental values (EVs) and uses that could be impacted upon. Theoretically, indicators can be developed for all three of these components.
Causal pressures or threatening processes are the driving forces behind changes in waterways. Causal pressures often result from human activities and uses, although natural climate change and natural disasters can also constitute causal pressures or ecosystem forcing functions. The Natural Resource Management community in Australia recognises five common areas of human-related causal pressures for management:
- Industrial point sources;
- Urban stormwater;
- Rural land use and management change;
- Flow alterations; and
- Riparian habitat removal (e.g. mangroves)
However, causal pressures can encompass a range of different levels, e.g. from population density, to number of nutrient point-sources, through to pollutant concentrations. The inherent breadth of the causal pressures concept has been a source of confusion for many. It was for this reason that the “in-stream-pressures” or “stressors” terminology was developed.
Information on 15 stressors that impact Australian coastal waterways.
Consequent in-stream pressures/stressors
From an ecological perspective, a stress is a change that causes a response in a system or population of interest. In the context of environmental management, in-stream pressures or stressors are the stresses that directly impact upon a system. Stressors generally result from causal pressures.
Impacts on values/uses
- Aquatic ecosystems
- Primary industries
- Recreation and aesthetics
- Drinking water
The aquatic ecosystem category has four key components:
- water (and sediment) quality;
- physical form (geomorphology) and