Week 4a- Water

1.5. Temperature as a contaminant

The actual impact of discharges into surface water features depends on at least some of the following factors:

• Magnitude (maximum & range)
• Duration of exposure
• Frequency of exposure
• Spatial extent of effects

Consider the three examples below which show the different stream environments and how they may be affected by high or low temperature inputs.

1. Bush Stream

• Baseline
• Represents natural condition
• High level of shading
• Habitat complexity

This would be considered to be the most natural ("baseline") stream.

2. Pastoral Stream

• Impacted channel
• Predominantly unshaded
• Reduced habitat complexity/diversity

In concrete channels, elevated temperatures of up to 30 have been measured, made worse by the lack of riparian zone.

• Impacted channel
• Predominantly unshaded
• Modifications to channel morphology
• Modifications to flow patterns