Lake level manipulation

Find further information on the Conservation of Freshwater Ecosystem Values (CFEV) Program and its data at www.dpipwe.tas.gov.au/cfev.

Attribute data

TitleLake level manipulation

CustodianWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment

CreatorGIS Unit, Information and Land Services Division, Department of Primary Industries and Water

DescriptionThe extent of human induced water level variation in Tasmania’s lakes and waterbodies.

Input data

1. Hydro infrastructure and discharge data (location, volume), Hydro Tasmania

Lineage

The lake level manipulation score rates all waterbodies according to the intensity of human management of water surface levels using infrastructure (not catchment-wide effects on water balance). Waterbodies were rated, using expert knowledge (Peter Davies, Freshwater Systems and Mick Howland, Hydro Tasmania) in combination with Hydro data, according to the following categories:

0Extreme human induced variation in waterbody levels (e.g. frequently close to 100% of ‘average’ depth at ‘Full Supply Level (FSL)’).

0.2Severe human induced variation in waterbody levels (e.g. through 75-100% of ‘average’ depth at ‘FSL’).

0.4Substantial human induced variation in waterbody levels (e.g. through 50-75% of ‘average’ depth at ‘FSL’).

0.6Significant human induced variation in waterbody levels (e.g. through 10-50% of ‘average’ depth at ‘FSL’).

0.8Minor human induced variation in waterbody levels (e.g. through <10% of ‘average’ depth at ‘FSL’).

1No human impact on levels, only natural variation in levels (seasonal, wet/dry).

Note, ‘average’ depth means estimated mean depth of entire water body (i.e. not of maximum depth only). ‘FSL’ means Full Supply Level, i.e. level when waterbody (natural or man-made) is ‘full’. Appendix 13 of the CFEV Project Technical Report provides all the lake level manipulation scores for all ‘valid’ named waterbodies. All unnamed ‘valid’ waterbodies received a score of 1 (no locally human induced variation in level). Specific rules are provided below.

Data limitations

The lake level manipulation data inherits all the data limitations of the input data.

Date createdSeptember 2004

Scale and coverage1:25 000; Statewide

Column headingWB_LLEVELM

Type of dataCategorical

Number of classes6

Assigning values to ecosystem spatial units

A lake level manipulation score (e.g. 0, 0.2, 0.4, etc.) was assigned to the waterbodies as WB_LLEVELM according to the following rules:

1. Assign all named waterbody spatial units with a lake level manipulation score according to Appendix 13.
2. Assign remaining unnamed waterbody spatial units with a lake level manipulation score of 1.

CFEV assessment framework hierarchy

1. Waterbodies>Statewide audit>Condition assessment>Naturalness score (WB_NSCORE)>Hydrology (WB_HYDRO)