The SWIRC hydrology theme assesses the flow regime of rivers, with flows having a critical role in maintaining ecosystem form, function and the dependant biodiversity.
The flow regime influences or is influenced by all SWIRC themes through relationships with nutrient and sediment transport, connectivity, maintenance of dry-season refuges, and the shape and depth of the river channel.
The SWIRC assesses hydrological changes by comparing the current hydrological pattern (for example, size of high flows or period of no flow) against modelled expectations of flow without the influence of dams or vegetation clearing. This provides a catchment-scale assessment of changes in flow regime.
We also collected flow data at a site and from flow gauges in the system, and manually assess it for interpretation of river condition.
We usually make assessments by comparing the flow data with water quality data to determine the requirements for managing flows. For example, for managing minimum flows required to maintain water quality within acceptable levels for local aquatic biota, or to allow migration of fish at critical times.