Australian River Assessment System: AusRivAS Physical Assessment Protocol

Melissa Parsons, Martin Thoms and Richard Norris
Cooperative Research Centre for Freshwater Ecology
University of Canberra
Monitoring River Health Initiative Technical Report Number 22
Environment Australia, 2002
ISSN 1447-1280
ISBN 0 642 54888 9

5 Instructions for the Measurement of Each Variable (continued)

Response Variables (continued)

Riparian zone width

The riparian zone is defined as the area from the water's edge (under baseflow conditions) to a distance from the bank where the stream still interacts with and influences the type and density of the bank-side vegetation (Nichols et al., 2000).

At each cross-section, estimate the width of the riparian zone on the left and right banks separately. It is preferable to measure distances with a tape measure at a number of sites, until estimates can be made with accuracy. The left and right bank measures of riparian zone width should be averaged to give an overall riparian width for the sampling site (Figure 5.16).

Figure 5.16 Example calculation of riparian zone width at a sampling site with three cross-sections. Readings of riparian zone width are made at each cross-section and averaged. In the above example, the average width of the riparian zone on the left bank is 33m and the average width of the riparian zone is 27m on the right bank. Overall average riparian width is 30m.

Variable derived from AusRivAS

Longitudinal extent of riparian vegetation

Along the length of each sampling site, visually assess the longitudinal extent, or patchiness, of the riparian zone on the left and right banks separately. Include only the tree and shrub layer components (native or exotic) in the assessment of longitudinal extent, and disregard the ground cover layer. However, for sites where the riparian zone is naturally composed entirely of native grasses, either along the entire site length or in significant patches, include grasses in the assessment of longitudinal extent.

Assess longitudinal extent of riparian vegetation using one of the following categories

Category	Description and examples1 (shown for one bank only)
None
	No trees or shrubs, only exotic grasses or pasture
Isolated / scattered
	Isolated trees or shrubs among exotic grasses or pasture
Regularly spaced, single
	Planted poplars
Occasional clumps
	Clumps of tea tree scrub among exotic grasses or pasture
Semi-continuous
	Native forest with cleared areas of exotic grasses
Continuous
	Undisturbed native forest, river red gum canopy

¹ Examples of vegetation types are not exhaustive

Variable derived from the River Habitat Survey (Raven et al., 1998)

Overall vegetation disturbance rating

This variable considers the condition of the riparian zone and the surrounding valley vegetation simultaneously. The riparian zone is the portion of vegetation that interacts with the stream (see riparian zone composition variable for full definition) and the valley vegetation is the vegetation that is present in the valley in which the channel sits. At each sampling site, assess the condition of the riparian and valley vegetation on the left and right sides together, as one of the following categories:

Category	Riparian vegetation	Valley vegetation
Extreme disturbance	Absent or severely reduced. Vegetation present is extremely disturbed (ie. dominated by exotic species with native species rare or completely absent)	Agriculture and/or cleared land BOTH sides. Plants present are virtually all exotic species (willows, pines, blackberries etc.)
Very high disturbance	Some native vegetation present, but it is severely modified BOTH sides by grazing or the intrusion of exotic species. Native species severely reduced in number and cover.	Agriculture and/or cleared land BOTH sides. Plants present are virtually all exotic species (willows, pines, blackberries etc.)
High disturbance	Riparian vegetation moderately disturbed by stock or through the intrusion of exotic species, although some native species remain	Agriculture and/or cleared land on ONE side, native vegetation on the other side clearly disturbed or with a high percentage of introduced species present.
	Note: Sites with valley vegetation cleared BOTH sides but with riparian vegetation in good condition (eg. fenced off from stock) should be included in this category
Moderate disturbance	Native vegetation on BOTH sides with canopy intact or with native species widespread and common in the riparian zone. The intrusion of exotic species is minor and of moderate impact	Agriculture and/or cleared land on ONE side, native vegetation on the other in reasonably undisturbed state
Low disturbance	Native vegetation present on BOTH sides of the river and in relatively good condition with few exotic species present. Any disturbance present is relatively minor.	Native vegetation present on BOTH sides of the river, with a virtually intact canopy and few exotic species.
Very low disturbance	Native vegetation on both sides of the river in an undisturbed state. Exotic species are absent or rare. Representative of natural vegetation in excellent condition.	Native vegetation present on both sides of the river with an intact canopy. Exotic species are absent or rare. Representative of natural vegetation in excellent condition.

Variable derived from the River Habitat Audit Procedure (Anderson, 1993a).

Local impacts on streams

Indicate whether one or more of the following activities or potential impacts are present at the sampling site or in the local area. Where possible, include a brief description of each selected impact. For example, grazing may be by sheep or cattle, water extraction may be irrigation or rural domestic, litter may be urban rubbish or old car bodies etc.

• sand or gravel mining
• other mining
• road
• bridge / culvert / wharf
• ford / ramp
• discharge pipe
• forestry activities
• sugar mill
• sewage effluent
• irrigation run-off or pipe outlet
• channel straightening
• river improvement works
• water extraction
• dredging
• grazing
• litter
• recreation
• other

Variable derived from the River Habitat Audit Procedure (Anderson, 1993a).

Turbidity (visual assessment)

At each sampling site, visually assess the turbidity of the water as one of the following categories:

Turbidity refers to the relative clarity of water and measures the extent to which light penetration is reduced from suspended materials such as clay, mud, organic matter or plankton. The presence of dissolved materials derived from plant leachates can also reduce water clarity (e.g. blackwater streams) and in such cases, water will be 'tea' coloured. The type of material causing any reduction in water clarity should be noted on the data sheet at each sampling site.

Variable derived from AusRivAS

Water level at the time of sampling

At each sampling site, indicate the water level on the day of sampling as one of the following categories. Water level should be measured relative to the baseflow water mark, which is evidenced by the limit of terrestrial grasses, eroded area or boundary changes in bank sediments.

Variable derived from AusRivAS

Sediment oils

At each sampling site, examine the sediment and visually assess the presence of oily residues as one of the following categories:

• absent
• light
• moderate
• profuse

Variable derived from AusRivAS

Water oils

At each sampling site, note the presence of oils on the water surface as one of the following categories:

• slick
• sheen
• globs
• flecks
• none

Variable derived from AusRivAS

Sediment odours

At each sampling site, take a scoop of sediment and smell for odours that correspond to one or more of the following categories:

• normal odour / no odour¹
• sewage
• petroleum
• chemical
• anaerobic²
• other

¹ Unpolluted sediments may have a naturally 'earthy' odour
² Hydrogen sulphide ('rotten egg gas') is an odour commonly encountered in anaerobic, or deoxygenated, sediments

Variable derived from AusRivAS