Australian Water Information Dictionary

Water forecasts: 7-day Streamflow Forecasts


Australian Hydrological Geospatial Fabric

The Australian Hydrological Geospatial Fabric (Geofabric) is a specialised Geographic Information System (GIS). It identifies and registers the spatial relationships between important hydrological features such as watercourses, water bodies, canals, aquifers, monitoring points and catchments.

Source: Geofabric website


This definition applies to:

Australian Water Resources Council

Established in 1962, the Australian Water Resources Council (AWRC) was set up by the Commonwealth and Sate Governments as a non-statutory body. The council existed into the 1980s.

Source: National Library of Australia

This definition applies to:

Bayesian joint probability (BJP)

A statistical modelling method to produce predictions of seasonal streamflows. Application of the BJP method to streamflow forecasting was developed by the CSIRO.

See the Seasonal Streamflow Forecast Research papers section for more information.

Alt text

This definition applies to:


A type of resampling where large numbers of smaller samples of the same size are repeatedly drawn, with replacement, from a single original sample. This technique allows estimation of the sampling distribution of almost any statistic using random sampling methods.

Source: Derived from V Fortin, J Bernier, B Bobee 1997, Simulation, Bayes, and bootstrap in statistical hydrology, WATER RESOUCES RESEARCH, VOL. 33, No. 3

For example, in the 7-day ensemble streamflow forecasting system, forecast skill is computed from 200 samples. Each sample is comprised of approximately three years of daily streamflow observations/forecast pairs generated by randomly drawing monthly sub-samples repeatedly from an original dataset of three years of daily streamflow observations/forecast pairs.

This definition applies to:


The land area draining to a point of interest, such as a water storage or monitoring site on a watercourse.


This definition applies to:

catchment area

The extent of land where water from precipitation drains into the water storage.

Related: catchment

This definition applies to:

continuous ranked probability score (CRPS)

A measure of forecast accuracy score calculated in the original measurement space. Both the forecast and the observation are converted to cumulative density functions. In the case of the observation, this is a step function. The squared area between the two functions is the single CRPS value, which is averaged across all forecasts. Alt text

This definition applies to:


Commonwealth Scientific and Industrial Research Organisation

This definition applies to:

drainage division

Representation of the catchments of major surface water drainage systems, generally comprising a number of river basins. In Australia, 12 drainage divisions were first defined in the 1960s by the Australian Water Resources Council. Australian drainage division boundaries were revised by the Bureau in 2010 in line with the creation of the Australian Hydrological Geospatial Fabric (Geofabric) based on the 9 second Digital Elevation Model.

Related: Bureau

This definition applies to:

ensemble forecast

A set of multiple forecasts for the same period and location. The spread of multiple forecasts provides information about forecast uncertainty.

This definition applies to:


The flow of water in streams, rivers and other channels.

Synonym: streamflow

This definition applies to:


The common abbreviation for the Australian Hydrological Geospatial Fabric.


This definition applies to:


A retrospective forecast using observed information to validate or test a mathematical model. Observed inputs for past events are entered into the model to see how well the output matches the observed streamflow volumes.

This definition applies to:

historical reference or historical probability distribution

A probability distribution created by sampling the historical streamflow data record. It is the reference forecast used when skill scores are calculated from hindcast modelling results.

This definition applies to:

interquartile range (IQR)

A measure of statistical dispersion, being equal to the difference between the third and first quartiles. Also called the midspread or middle 50.

This definition applies to:


The middle number of a given sequence of numbers. When the sequence contains an even amount of numbers, the median is the mean of the two middle values.

Source: The first part of definition sourced from Macquarie Dictionary Fifth Edition, 2009, Macquarie Dictionary Publishers.

This definition applies to:

numerical weather prediction (NWP)

A science focused on taking current observations of weather and processing these data with computer models to forecast the future state of weather.

Source: Modified from NOAA, viewed 25 July 2015.

This definition applies to:


One of a series of threshold values that divides a set of ordered data into 100 groups with an equal number of data points in each.

For example, consider a dataset of annual rainfall totals arranged in increasing order. The 20th percentile is a value with 20% of the data below it and 80% above it. The 90th percentile is a value with 90% of the data below it and 10% above it.

Related: quantile

This definition applies to:


All forms in which water falls on the land surface and open water bodies as rain, sleet, snow, hail, or drizzle.


This definition applies to:

probabilistic forecast

A probabilistic streamflow forecast shows the range of possible streamflow volumes and how likely it is that they will occur.

This definition applies to:


Denotes one of a series of threshold values that divides a set of ordered data into groups with an equal number of data points in each. The terms tercile, quartile, quintile, decile and percentile refer to quantiles that divide the distribution of data into 3, 4, 5, 10 and 100 equal parts, respectively.


This definition applies to:

river region

Produced as part of the Australian Hydrological Geospatial Fabric (Geofabric). These regions align with, and are nested within, the revised drainage divisions.

Source: Geofabric Product Guide V2.0


This definition applies to:

skill score

A statistical score used to assess the relative performance (skill) of a model against a reference forecast (e.g. climatology).

Skill Score =(Smod - Sref) / (Sperf - Sref)


Smod = Score for the model forecast

Sref = Score for a reference forecast, e.g. climatology

Sperf = Score for a perfect forecast, usually 0 or 1

This definition applies to:


A pond, lake or basin, whether natural or artificial, for the storage, regulation and control of water.

Synonym: water storage

This definition applies to:

stream length

Longest distance along the stream from the point of consideration to the most distant headwater source.

Source: Modified from USGS, viewed 4 September 2015.

This definition applies to:


The flow of water in streams, rivers and other channels.

Synonym: flow

This definition applies to:


A state of lack of confidence to exactly describe the current or future condition of a system when limited knowledge of that system is available.

This definition applies to:

water storage

A hydrological feature in which water is stored. Surface water storages include natural and artificial ponds, lakes, reservoirs and lagoons, also the bodies of water held behind weirs and dams.

In the National Water Account, surface water storages include only artificial or natural water storages connected to rivers, which primary purposes are medium to long term water storage to service surface water access rights. These storages can be managed by an organisation to provide water to an urban water system.

This definition applies to:


A river, creek or other natural watercourse (whether modified or not) in which water is contained or flows (whether permanently or from time to time); and includes:

(i) a dam or reservoir that collects water flowing in a watercourse;

(ii) a lake or wetland through which water flows;

(iii) a channel into which the water of a watercourse has been diverted;

(iv) part of a watercourse; and

(v) an estuary through which water flows.

Source: Based on content from the Federal Register of Legislation (, at 8 Febraury 2019. For the latest information on Australian Government law please go to Federal Register of Legislation

This definition applies to: