South East Queensland


eWater CRC is working on water management issues in partnership projects with organisations in south-eastern Queensland.

The project teams are focusing on the rapidly growing urbanised area in catchments draining into Moreton Bay near Brisbane. They are ‘roadtesting’ eWater software in relation to the water quality and ecosystem health of the bay itself and the streams that run into it.

About the Focus Catchment

In south-eastern Queensland (SEQ) around Brisbane, the population, currently about 2.8 million, is expected to reach over 4 million by 2031. Most growth is expected to occur in the Logan-Albert catchments to the south, and in the catchments of the Bremer and Lockyer rivers, tributaries of the Brisbane River. These catchments, and several others, drain into Moreton Bay, parts of which are ‘internationally significant’ under the Ramsar
Convention.

Poor water-quality and aquatic ecosystem health in areas of Moreton Bay have been identified as being largely caused by diffuse contamination with sediment and nutrients from the non-urban areas west of Brisbane. Research has found that these ‘non-urban’ sources are largely the river and creek channels themselves and gully erosion. In-channel works that slow the movement of runoff during and after heavy rain can reduce channel erosion, but resources are limited, confining the restoration to soil types and areas where it can have best effect.

eWater is trialling software in these areas aiming to help our partners with this river-erosion challenge.

Using modelling trials and field based studies we are helping the SEQ Healthy Waterways Partnership (SEQHWP, at least 10 members of which are also eWater partner organisations) to consider restoration works to reduce channel erosion, and to monitor the effects on ecosystems in the streams leading to the bay.

Application

eWater CRC’s next-generation water management software tools are being demonstrated and further developed via this application:

(i) predicting sediment yields under rehabilitation options;

(ii) developing predictive models for ecosystem health, based on stream condition;

(iii) enabling optimal spacing of restoration works.

In meeting the specific needs of this region, this application will also expand the models’ functionality for use in other situations.

Runoff and erosion challenges

Studies show that the bay is receiving about 300,000 t/year of fine sediment, and that 80% of this sediment comes from 20% of its catchment area, mostly from streambank and gully erosion. The challenge is to place erosion control works where they will be most effective.

How eWater is helping

eWater teams are adapting our catchment modelling framework to help optimise rehabilitation so that it reduces the supply of sediment to the waterways.

For the various stream-rehabilitation options, eWater is
using modelling and local data to predict the effects of a
range of possible spatial confi gurations across the  whole region – a very complex challenge.

And our ecological modelling software is helping predict
how ecosystems in the catchments’ streams will  respond to the rehabilitation options. The team is also developing a monitoring and evaluation plan for the essential tracking of the results of restorative work.