This study was undertaken to assist in flood preparedness and risk management activities for the River Murray. The study predicts the flood extent for a range of flows when measured at the border to South Australia which are expressed in megalitres per day (ML/d). Scenario datasets released include: lOOGL,120GL,130GL,140GL, 160GL, 180GL, 200GL, 250GL, 300GL, 341GL.

River Murray Flood Mapping shows the extent of flooding based on historical records and some associated information (e.g. flood depth contours and levels) captured by two different projects for (1) the River Murray from the mouth to the South Australian border, and (2) the River Murray from the South Australian border to Lake Hume. © Commonwealth of Australia (Murray–Darling Basin Authority) 1999. Some data contributed by the South Australian government.

Boundary showing the extent of land flooded during the 2022/2023 flood event for the River Murray.

The Flood Model User Guideline for Mullet Creek has been developed to accompany the handover of the 2023 Mullet Creek Floodplain Risk Management Study and Plan (FPRMSP) hydrological and hydraulic models to consultants that propose to undertake flood assessments within the catchment. The document defines the modelling approach and details the model parameters that were adopted for the FPRMSP. The primary purpose of the Guideline is to ensure that the unique aspects of the hydrological and hydraulic models are captured in future flood assessments using the Mullet Creek models.

The Murray-Darling Basin Plan (available at http://www.comlaw.gov.au/Details/F2012L02240) was developed under the Commonwealth Water Act 2007 and aims to deliver a coordinated approach to water use by States and Territories in the Murray-Darling Basin (MDB), underpinned by a commitment to restoring the long-term health of rivers and wetlands in the Basin. To achieve this, the Basin Plan sets a long term average Sustainable Diversion Limit (SDL) for surface water and groundwater use across the major valleys in the MDB, and incorporates an Environmental Watering Plan (EWP) that ensures surplus water beyond SDLs is made available for the natural floodplain and wetland systems. The EWP is central to the Basin Plan as it aims to achieve the best possible environmental outcomes in its use of environmental water, in terms of size, timing and nature of river flows. The EWP is supported by the Environmental Water Recovery Strategy, a voluntary water buyback instrument (SEWPAC 2012). The long term average SDL for surface water flow is currently set by the Basin Plan at 10,873 gigalitres per year (GL/y). This includes 3,468 GL/y for the northern Basin, which establishes a water ‘saving’ of 390 GL/y from water allocations previously set under the Living Murray initiative (MDBA 2011). These savings are available as ‘environmental water’ which is regulated by the Commonwealth Environmental Water Office (CEWO) via the EWP. Water allocations in the northern Basin are currently under review via the Northern Basin Review, which is due for finalisation in mid-2016. This review is expected to improve environmental science in relation to floodplain systems in the Condamine-Balonne and Barwon-Darling River systems, and may recommend changes to the Basin Plan accordingly. A key part of the Review is to improve knowledge about environmental assets within river systems of the northern Basin (e.g. floodplain and wetland vegetation, fish, water birds), and how they respond and interact to fluctuations in surface water flow. Improved knowledge about the native vegetation of inland floodplain systems is fundamental to the Northern Basin Review. To improve information about the distribution and extent of floodplain and wetland vegetation types in the northern Basin, Eco Logical Australia (ELA) was commissioned by the Murray Darling Basin Authority (MDBA) to map the distribution of plant community types (PCTs) within a large section of the Darling floodplain west of Louth, and within the Condamine-Balonne system south of the NSW-Queensland border. An improved knowledge about the distribution and extent of floodplain PCTs will inform how environmental water allocations might be refined, and is thus an important component of the Northern Basin Review. For more information please refer to the technical report Eco Logical Australia 2015. Vegetation of the Barwon-Darling and Condamine-Balonne floodplain systems of New South Wales: Mapping and survey of plant community types. Prepared for Murray-Darling Basin Authority. Attributes: PCT_ID = NSW Plant Community Type Code PCT_LABEL = Plant Community Type Label BROAD_VEG = Broad Vegetation Type HYDROL_ECOL = Hydro-Ecological Functional Group VEG_FORMAT = Vegetation Formation VEG_CLASS = Vegetation Class Floodplain = Floodplain vegetation (yes or no) MAP_LABEL = Short vegetation label suitable for display on map products RE = Regional Ecosystem Code RE_LABEL = Regional Ecosystem Label ACCURACY = Attribute accuracy (values 1 to 5) 5 - Verified in the field by either full floristic, rapid or API (observational) site 4 - Not verified in the field but likely to be correct due to extrapolation from similar verified pattern or verified in field but uncertain of boundary 3 - Probably correct although could be one of a few related communities 2 - Possibly correct but might be one of several other communities 1 - Unlikely to be correct VIS_ID 4454

This data set extends the MDBA published Murray-Darling Basin managed floodplain (https://data.gov.au/data/dataset/murray-darling-basin-managed-floodplain) to include all areas watered with Commonwealth environmental water 2014-2021. Areas that are added are mapped by polygons from the ANAE classification of the Murray-Darling Basin data set that were identified as receiving inundation by Commonwealth environmental water by the Commonwealth Environmental Water Holder’s (CEWH) Long Term Intervention Monitoring (LTIM) project (2014-2019) and the first two years of the Monitoring, Evaluation and Research (Flow-MER) program. The MDBA published Murray-Darling Basin managed floodplain (https://data.gov.au/data/dataset/murray-darling-basin-managed-floodplain) is a spatial data set that estimates the extent of the Murray-Darling Basin that can be influenced by environmental water under the Basin Plan. It includes: * actively managed areas that can receive environmental water via large headwater storages or via The Living Murray ‘environmental works’ sites on the River Murray floodplain * passively managed areas that receive environmental water via flow rules in water resource plans or via natural events * areas that may be inundated with high flows if key constraints are overcome The CEWH’s Flow-MER program examines the contribution of Commonwealth environmental water to the environmental objectives of the Basin Plan 2012 (Basin Plan) and is assisting the CEWO to demonstrate environmental outcomes and adaptively manage the water holdings. For more information on methods and reporting using these data see https://www.dcceew.gov.au/water/cewo/monitoring/mer-program ###Acknowledgement The Commonwealth Environmental Water Holder and Flow-MER program participants acknowledge the First Nations peoples as the Traditional Owners and Custodians of the lands, waterways and skies of the Murray-Darling Basin. We respect their continuing connection to culture and Country, and we thank them for their knowledge and science and the values reflected in these data. ###Citation CEWH Flow-MER (2022) Flow-MER MDB managed floodplain. Flow-MER Program. Commonwealth Environmental Water Holder, Australian Government Department of Climate Change, Energy, the Environment and Water. Sourced from https://data.gov.au/data/dataset/flow-mer-managed-floodplain on [date-accessed]

The Murray-Darling Basin Plan (available at http://www.comlaw.gov.au/Details/F2012L02240) was developed under the Commonwealth Water Act 2007and aims to deliver a coordinated approach to water use by States and Territories in the Murray-Darling Basin (MDB), underpinned by a commitment to restoring the long-term health of rivers and wetlands in the Basin. To achieve this, the Basin Plan sets a long term average Sustainable Diversion Limit (SDL) for surface water and groundwater use across the major valleys in the MDB, and incorporates an Environmental Watering Plan (EWP) that ensures surplus water beyond SDLs is made available for the natural floodplain and wetland systems. The EWP is central to the Basin Plan as it aims to achieve the best possible environmental outcomes in its use of environmental water, in terms of size, timing and nature of river flows. The EWP is supported by the Environmental Water Recovery Strategy, a voluntary water buyback instrument (SEWPAC 2012). The long term average SDL for surface water flow is currently set by the Basin Plan at 10,873 gigalitres per year (GL/y). This includes 3,468 GL/y for the northern Basin, which establishes a water ‘saving’ of 390 GL/y from water allocations previously set under the Living Murray initiative (MDBA 2011). These savings are available as ‘environmental water’ which is regulated by the Commonwealth Environmental Water Office (CEWO) via the EWP. Water allocations in the northern Basin are currently under review via the Northern Basin Review, which is due for finalisation in mid-2016. This review is expected to improve environmental science in relation to floodplain systems in the Condamine-Balonne and Barwon-Darling River systems, and may recommend changes to the Basin Plan accordingly. A key part of the Review is to improve knowledge about environmental assets within river systems of the northern Basin (e.g. floodplain and wetland vegetation, fish, water birds), and how they respond and interact to fluctuations in surface water flow. Improved knowledge about the native vegetation of inland floodplain systems is fundamental to the Northern Basin Review. To improve information about the distribution and extent of floodplain and wetland vegetation types in the northern Basin, Eco Logical Australia (ELA) was commissioned by the Murray Darling Basin Authority (MDBA) to map the distribution of plant community types (PCTs) within a large section of the Darling floodplain west of Louth, and within the Condamine-Balonne system south of the NSW-Queensland border. An improved knowledge about the distribution and extent of floodplain PCTs will inform how environmental water allocations might be refined, and is thus an important component of the Northern Basin Review. Attributes: PCT_ID = NSW Plant Community Type Code PCT_LABEL = Plant Community Type Label BROAD_VEG = Broad Vegetation Type HYDROL_ECOL = Hydro-Ecological Functional Group VEG_FORMAT = Vegetation Formation VEG_CLASS = Vegetation Class Floodplain = Floodplain vegetation (yes or no) MAP_LABEL = Short vegetation label suitable for display on map products RE = Regional Ecosystem Code RE_LABEL = Regional Ecosystem Label ACCURACY = Attribute accuracy (values 1 to 5) 5 - Verified in the field by either full floristic, rapid or API (observational) site 4 - Not verified in the field but likely to be correct due to extrapolation from similar verified pattern or verified in field but uncertain of boundary 3 - Probably correct although could be one of a few related communities 2 - Possibly correct but might be one of several other communities 1 - Unlikely to be correct For more information please refer to the technical report. Eco Logical Australia 2015. Vegetation of the Barwon-Darling and Condamine-Balonne floodplain systems of New South Wales: Mapping and survey of plant community types. Prepared for Murray-Darling Basin Authority. VIS_ID 4453