Catchment hydrology modelling for stormwater harvesting study in SEQ: from instrumentation to simulation

Catchment hydrology modelling for stormwater harvesting study in SEQ: from instrumentation to simulation

Hydrology modelling is essential for stream flow simulation and to define hydrologic characteristics of streams. A reliable flow simulation depends on availability of reliable stream flow data and a reliable rainfall runoff model. In this project, considerable effort has been invested in instrumentation of 12 catchments located in South East Queensland (SEQ) in order to obtain continuous rainfall and creek flow data. These catchments represent a diverse range of land use characteristics. Using one year (April 2009 to March 2010) of continuous rainfall and flow data, six catchments have been calibrated and validated at hourly time scale using the Storm Water Management Model (SWMM). The calibrated model was then used to simulate 30 years of creek flow data using historic rainfall data from 1975 to 2005. Simulations were carried out to predict creek hydrologic responses to catchment urbanisation. This was performed by increasing catchment imperviousness. We found that catchment imperviousness increases runoff percentage from 12% at unimpacted condition to 38% at 50% impervious condition. Number of flow events increased from seven events/year to 37 events/year at 50% imperviousness. The one-month to six-month ARI peak flow events were observed to increase significantly with imperviousness. This continuing study will help to identify ecologically sustainable stormwater harvesting practices in SEQ.

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