Baseflow separation analysis for unregulated rivers (1889 to 2012) in Gippsland

## **Abstract** 

This dataset was supplied to the Bioregional Assessment Programme by a third party and is presented here as originally supplied. Metadata was not provided and has been compiled by the Bioregional Assessment Programme based on known details at the time of acquisition.



Baseflow separation analysis was undertaken for 180 stream gauges on unregulated rivers in Victoria. This included the 178 gauges assessed in previous DEPI and MDBA assessments. The baseflow separation analysis was undertaken on historical river flow records up to 2012 and utilised a filter parameter of 0.98.



To better inform the numerical groundwater model developed for the Gippsland region, a brief assessment of surface-groundwater water interaction across the study area was undertaken, based on available literature (e.g. DSE 2012, SKM 2012a, 2012b; Hofmann, 2011) and analysis of groundwater and surface water information. DSE (2012) collated a state wide dataset of groundwater and surface water interaction from numerous investigations across Victoria.  The dataset described groundwater and surface water interaction in four broad classes: neutral/losing, gaining, variable and unclassified .... SKM (2012a) undertook baseflow separation analysis for 180 stream gauges on unregulated rivers in Victoria. This included 51 gauges in the Gippsland region.  The baseflow separation analysis was undertaken on historical river flow records up to 2012 and utilised a filter parameter of 0.98.  The results of the analysis for the 51 stream gauges in the Gippsland region is summarised ...text taken from The Gippsland groundwater model report, Beverly et al 2015.

## **Purpose** 

The aims of this study were to: (1) generate a Statewide data set of baseflow indices (BFIs) to streams using a consistent method; (2) undertake analysis of this data set to allow more detailed interpretation, including: Seasonal and annual flow duration curves of streamflow, baseflow and surface runoff for each location; Daily variability of BFI for each month; Assessment of trends in baseflow over time (at a subset of locations); and Control charts to help identify deviation in baseflow from reference behaviour in a predictive manner (at a subset of locations).

## **Dataset History** 

Streamflow data analysed for this study was generally obtained from unregulated systems across the State. The data were reviewed to identify periods of missing or poor data quality. This was undertaken by considering respective daily flow data and quality codes for each time step at each location. The daily flow data with a quality code less than 150 was taken as good quality data and used for analyses in this study. The data was considered to be poor quality when the quality code was greater than 150. Periods with poor quality data were infilled to ensure a complete data record at each location. The Lyne and Hollick digital filter was applied to the daily streamflow to generate a time series of estimated baseflow for each location. A single consistent baseflow filter parameter of 0.98 was applied across all sites in this study. This process generated a time series of baseflow for each gauge location. The difference between the total streamflow and the baseflow was calculated as an estimate of the surface runoff (quickflow). The daily baseflow index (BFI, calculated as the baseflow volume relative to the total streamflow) was also calculated for each time step. The outputs from this step include a text file with four time series data sets for each streamflow gauge location.

## **Dataset Citation** 

Victorian Department of Environment, Land, Water and Planning (2015) Baseflow separation analysis for unregulated rivers (1889 to 2012) in Gippsland. Bioregional Assessment Source Dataset. Viewed 05 October 2018, http://data.bioregionalassessments.gov.au/dataset/eb8f516c-a7e2-47d1-99fc-1ba3fc2c0ea2.

Tags: Gippsland Basin bioregion, Victoria, inlandWaters
Organization: Bioregional Assessment Program