2.1.4 Surface water hydrology and water quality


This product summarises key datasets that are used in surface water modelling of the Hunter subregion. Streamflow data from 14 gauging stations are used to calibrate the Australian Water Resources Assessment (AWRA) landscape model (AWRA-L), and 34 for calibrating the AWRA-R river model.

To represent the geometry of a river, 34 surveyed cross-sections were obtained and associated river lengths were computed from geographic data. At 22 additional locations, where surface water simulations are required but no information on cross-sections were available, a method was developed that related catchment area and mean annual streamflow to an idealised trapezoidal cross-section. At another seven locations, cross-sections from nearby gauging stations were used.

To simulate irrigation demand in the river model, irrigated areas and crop types for river reaches were obtained from land use data.

Surface water modelling results are generated at model nodes. The hydrological changes along the links (reaches) between them must be interpolated from the results at the model nodes. The mapping of links to nodes is presented. It is essential for defining the surface water zone of potential hydrological change from additional coal resource developments. For some links, interpolations are not recommended.

Many datasets have been used to inform the surface water modelling of the Hunter subregion. Some are used directly, while others have been derived from other existing data. Not all the datasets are reported here. Table 7 lists the key datasets for surface water modelling (AWRA-R and AWRA-L), whether they have been derived from existing data for surface water modelling purposes in the Hunter subregion and where they are reported within the Hunter subregion suite of products.

As stated in companion product 2.3 (conceptual modelling) for the Hunter subregion (Dawes et al., 2018), no surface water quality data are used directly in the numerical modelling for surface water, nor were water quality data used indirectly to inform other model inputs. The AWRA-R model represents mine site discharges of mine water as part of the Hunter River Salinity Trading Scheme, but only in terms of volumes and timing of discharges as determined by discharge windows (related to exceedance of defined flow rate thresholds) and permissible discharge volumes used to manage salinity in the Hunter River. Thus no water quality data are considered in this section.

Table 7 Key datasets for surface water modelling for the Hunter subregion


Source or derived

Section or product


Source (Bioregional Assessment Program, Dataset 1)

River cross-sections at gauging stations

Source (CSIRO, Dataset 2)

River cross-sections at simulation nodes

Derived (Bioregional Assessment Programme, Dataset 3)

River reach lengths

Derived from river network data (CSIRO, Dataset 4, Dataset 5)

Irrigation area extents and crop types

Derived (CSIRO Land and Water, Dataset 9) from land use (Department of Agriculture: Australian Bureau of Agricultural and Resource Economics, Dataset 8)

Hunter River Salinity Trading Scheme discharges

Derived from observed daily streamflow data (Bioregional Assessment Programme, Dataset 1) and observed mine discharge data (EPA, Dataset 10)

River extractions

Derived from IQQM modelling data (NSW Department of Primary Industries (Office of Water), Dataset 11) in Surface water numerical modelling

Dam releases, reservoir storage and allocations

Derived from IQQM modelling ( NSW Department of Primary Industries (Office of Water), Dataset 11) and reservoir storage from observed data (CSIRO Land and Water, Dataset 12) in Surface water numerical modelling

Catchment boundaries

Derived from digital elevation models (DEM) (CSIRO Land and Water, Dataset 7) and stream gauging stations (CSIRO Land and Water, Dataset 13) in Surface water numerical modelling

Section provides details of observed data that have been used for surface water modelling. The statistical analysis and interpolation section (Section describes the methods for deriving datasets for input into the AWRA-R river model from existing data. This section also presents the method for interpolating and extrapolating results generated at model nodes to links (river reaches) in the link-node structure.

Last updated:
18 January 2019
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