Current, Innovative, and Standardized Elevation Data for Flood Modeling in Australia: The...

Current, Innovative, and StandardizedElevation Data for Flood Modeling in Australia:The Murray-Darling Basin

Kea M. Beiningen, CFM, GISPIntermap TechnologiesMay 19, 2010

© 2009 Intermap Technologies. All rights reserved.2

Water Act 2007

The purpose of the Basin Plan is to provide for the integratedmanagement of the Basin water resources in a way that promotesthe objects of this Act, in particular by providing for:

(a) giving effect to relevant international agreements (to the extent to which those agreements are relevant to the use and management of the Basin water resources); and

(b) the establishment and enforcement of environmentally sustainable limits on the quantities of surface water and ground water that may be taken from the Basin water resources (including by interception activities); and

(c) Basin-wide environmental objectives for water-dependent ecosystems of the Murray-Darling Basin and water quality and salinity objectives; and

(d) the use and management of the Basin water resources in a way that optimizes economic, social and environmental outcomes; and

(e) water to reach its most productive use through the development of an efficient water trading regime across the Murray-Darling Basin; and

(f) requirements that a water resource plan for a water resource plan area must meet if it is to be accredited or adopted under Division 2; and

(g) improved water security for all uses of Basin water resources.


Intermap’s Core Products

ORI Orthorectified Radar ImageImage pixel size of 0.62 Meters

DSM Digital Surface ModelDTM Digital Terrain Model

4 © 2010 Intermap Technologies. All rights reserved.

Pixel Size (m) RMSE (m)

1.25 2.0


Travellers Lake, Australia

Google Earth, Spot Image DSM on top of image


NEXTMap Specs

Measures of Accuracy (Meters)

Product Type

RMSE 95% Mean and Standard Deviation

I 0.7 1.5 0.5 0.5

II 1.0 2.0 0.7 0.7

DTM:

Measures of Accuracy

Product Type

RMSE 95% Mean Standard Deviation

I 0.5 1.0 0.3 0.3

II 1.0 2.0 0.7 0.7

III 3.0 6.0 2.0 2.0

DSM:


Source Data Used

Base data provided by MDBA568 tiles of NEXTMap data from IntermapMGA Zone 54 projection (same as UTM 54

South)GDA 1994 datumEach tile

• 10 km by 10 km• Array of 2000 x 2000 5-meter cells

Vertical datum is AUSGeoid98Vertical and horizontal units are meters

Orthorectified radar images (ORI)


Overview

Analyzed basin: ~46,000 sq kmHydrology: Regression equations function of drainage area in square kilometersRiverine-Like Hydraulics: 2-, 10-, 50-, 100-, and 500-year return intervals for riverine areasNon-Riverine Hydraulics: Pits and pondsFloodplain Mapping: Pits & Ponds + RiverineArcHydro data model


Assumptions & Limitations

Pilot-level study, test purposes onlyHighly automated, minimal human interventionBroad assumptions in certain input valuesVery short production time frame (December 2009)Used best available input data at time of work


Riverine-like Portions of Study Area

Steady flow hydraulic models and mapping developed where: Drainage areas 20 sq km or moreContributing area completely

contained by the supplied topography.

Where the reaches somewhat riverine in nature

PBS&J Rapid Floodplain Delineation (RFD) tool usedStep-backwater computationAbility to write HEC-RAS files


Topography Used

Common industry standard for hydrologic analysis is 30-meter cells used to develop basins and flowpaths for hydrology. For this project, topography resampled to 25-

meters (slightly smaller than typical 30-meter cell size)

HydraulicsResampled to a 10-meter cell size for speed of

analysis reasonsFlowpaths were "splined" to smooth them out


Regression Equations for Flows

Annual peak flow gage data available for portions of regionGage annual maximum peak flow series fitted to the Gumbel (Type 1) Extreme Value distribution. 2-, 10-, 50-, 100-, and 500-year

Flow equation developed where drainage area was only variable


Cross Sections (XS)

Cross SectionsRFD has several parameters that

impact XS placementFor this pilot study, values set

reach-by-reach in GISVery minimal manual

manipulation of XS for this study

Standard Manning n value used


Dry Lakes and Pits / Ponds

Only about 25% of the basin riverine-likeRest appears has few or no discernable channels—is not riverine flow. “Ponding" layer shows ponds & pits In excess of about 0.3 meters in depth And, approximately 1 hectare in surface area.

Over 50,000 polygons in the study areaUse pits-ponds layer from riverine models in conjunction with the ponding layer.

Greater extent of two layers is estimated floodplain


Murray and Darling Rivers

Murray and Darling RiversMajority of contributing basins

outside the study area Effects of regulationModeled using historic peak

flows from early 1990sFor Murray RiverFlows roughly equal to 1956

flooding extents also used ~2,265 cms U/S of the Darling ~2,549 cms D/S of the Darling


Murray and Darling Rivers


Floodplain MappingFlow Contained


Floodplain MappingMurray River + Pits and Ponds


Floodplain MappingOverlaid With Basin Boundaries


ArcHydro

Arc Hydro Tools version 1.3 used Created after H&H modeling completeArc Hydro preprocessing workflow usedIn this case, workflow begins with the flow direction grid


ArcHydro

Drainage, Hydrography, and Network feature datasets

• These are standard feature datasets in the Arc Hydro schema

Drainage feature dataset • watershed, catchment, and drainage

line featuresNetwork dataset

• connectivity of the systemHydrography dataset

• Monitoring point features (gauges)Channel feature dataset

• Not included, no channel data available


What’s next???

Intermap continuing to collect IfSAR for the rest of Murray Darling Basin & now for the Eastern part of New South Wales.

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