Tasmanian River Condition Index

A new approach to assess river condition

In 2009 a new approach to assess river condition was developed for Tasmanian catchments. The Tasmanian River Condition Index or TRCI assesses four key components (or sub-indices) of river condition, providing an integrated approach to compare current condition to a pre-European reference. It examines:

Aquatic life - fish, macro-invertebrates and algae
Hydrology - flow patterns such as low flows, floods, flow seasonality, overbank flows
Physical form - physical character of the channel, bank and bed material and flow types
Streamside zone - riparian vegetation

What the TRCI can be used for

TRCI can be used to:

establish a baseline of river condition and measure change in condition over time
inform natural resource management and policy making and assess the effectiveness of natural resource management
determine the degree of departure of flow regimes from natural
provide benchmarks to assess the impacts of various developments on river systems
provide data for relevant information systems such as Conservation of Freshwater Ecosystem Values (CFEV), the Tasmanian Vegetation Monitoring and Mapping Program (TVMMP) and the Natural Values Atlas (NVA).

About the method

The development of TRCI is consistent with the National Framework for Assessment of River and Wetland Health (FARWH) to allow compatible reporting of the condition of Tasmanian river systems at the national level. It also enables consistent application across the state.

TRCI has drawn on existing methods (eg. Victorian Index of Stream Condition and Sustainable Rivers Audit) and latest advances in river assessment to develop a method that is tailored to Tasmania's diverse river systems. Tasmanian benchmarks have been developed to provide a reference for assessing a range of factors including: geomorphology, riparian vegetation, macroinvertebrates, fish and algal condition. The development of the geomorphic benchmarks is based on the classification of physical river types (the physical equivalent of vegetation communities) and tailored to the Tasmanian environment and river systems. TRCI also allows the integration of daily hydrological data.

TRCI methods are applied at the site scale and results can be aggregated to the sub-catchment, regional or state scale as required. TRCI has been designed to enable a range of reporting scales given the requirements of different users in Tasmania. TRCI also allows for a targeted monitoring program to assess the effects of activities such as river works or riparian management practices. The relevant sub-indices can be used or modified to address the type of river works or impacts.