3 North East Coast - Bureau of Meteorology · 23.1 Intr1Io3tr1 2 23.1 IntIrodI1u ocu.i3 Tu.o2..u..hur1osaps 3 North East Coast 3.1 Introduction This chapter examines water resources

North East Coast3 North East Coast ....................................................... 2

3.1 Introduction ........................................................ 2

3.2 Key information .................................................. 3

3.3 Description of the region .................................... 4

3.3.1 Physiographic characteristics.................. 6

3.3.2 Elevation ................................................. 7

3.3.3 Slopes .................................................... 8

3.3.4 Soil types ................................................ 9

3.3.5 Land use ............................................. 11

3.3.6 Population distribution .......................... 12

3.3.7 Rainfall zones ....................................... 13

3.3.8 Rainfall deficit ....................................... 14

3.4 Landscape water flows ................................... 15

3.4.1 Rainfall .................................................. 16

3.4.2 Evapotranspiration ................................ 19

3.4.3 Landscape water yield ......................... 22

3.5 Surface water and groundwater ....................... 25

3.5.1 Rivers ................................................... 25

3.5.2 Streamflow volumes ............................. 27

3.5.3 Streamflow salinity ................................ 27

3.5.4 Flooding ............................................... 30

3.5.5 Storage systems ................................... 32

3.5.6 Wetlands ............................................. 34

3.5.7 Hydrogeology ....................................... 40

3.5.8 Watertable salinity ................................. 40

3.5.9 Groundwater management units ........... 40

3.5.10 Groundwater status of

selected aquifers .................................. 44

3.6 Water for cities and towns ................................ 48

3.6.1 Urban centres ....................................... 48

3.6.2 Sources of water supply ....................... 50

3.6.3 Southeast Queensland ......................... 50

3.7 Water for agriculture ......................................... 58

3.7.1 Soil moisture ......................................... 58

3.7.2 Irrigation water ...................................... 59

3.7.3 Irrigation areas ...................................... 59

3.7.4 Burdekin River Irrigation Area ................ 62

North East Coast

2 Australian Water Resources Assessment 2012

3 North East Coast3.1 Introduction

ThischapterexamineswaterresourcesintheNorthEastCoastregionin2011–12andoverrecentdecades.Itstartswithsummaryinformationonthestatusofwaterflows,storesanduse.Thisisfollowedbydescriptiveinformationincludingthephysiographiccharacteristics,soiltypes,population,landuseandclimateoftheregion.

Spatialandtemporalpatternsinlandscapewaterflowsarepresented,andsurfaceandgroundwaterresourcesexamined.Thechapterconcludeswithareviewofthewatersituationforurbancentresandirrigationareas.TheTechnicalSupplementdetailsthesourcesandmethodsusedindevelopingthediagramsandmaps.

3Australian Water Resources Assessment 2012

3.2 Keyinformation

Table3.1givesanoverviewofthekeycomponentsofthedataandinformationinthischapter.

Table 3.1 Key information on water flows, stores and use in the North East Coast region

Landscape water flows

Evapo-transpiration

Landscapewater yield

Rainfall

Regionaverage Differencefrom1911–2012long-termannual

mean

Decilerankingwithrespecttothe1911–2012record

1,041mm +22% 9th—aboveaverage

814mm +18% 9th—aboveaverage

223mm +42% 9th—aboveaverage

Streamflow (at selected gauges)

Annualtotalflow: Predominantlyaveragetoaboveaverageflowthroughouttheregion

Salinity: Annualmedianelectricalconductivitypredominantlybelow1,000μS/cmthroughouttheregion

Flooding: Majorfloodsinmanypartsoftheregion

Surface water storage (comprising about 92% of the region’s total capacity of all major storages)

Totalaccessiblecapacity

30June2012 30June2011 Change

accessiblevolume

%oftotalcapacity

accessiblevolume

%oftotalcapacity

accessiblevolume

%oftotalcapacity

9,516GL 9,301GL 98% 9,135GL 96% +166GL +2%

Wetlands inflow patterns (for selected wetlands)

BowlingGreenBay: Averageflowsthroughouttheyear,butverymuchaboveaverageflowsinMarch

FitzroyRiverfloodplain: VerymuchaboveaverageflowsduringFebruaryandMarch2012

GreatSandyStrait: VerymuchaboveaverageflowsovertheJanuarytoMarch2012period

MoretonBay: VerymuchaboveaverageflowsinJanuaryandMarch2012

Groundwater (in selected aquifers)

Levels: Predominantlyrisingtrendsintheselectedwatertableaquifersoverthe2007–08to2011–12period

Salinity: Scatteredareasofsalinegroundwater(≥3,000mg/L)throughouttheregion

Urban water use (Brisbane and Gold Coast)

Totalusein2011–12 Totalusein2010–11 Change Restrictions

176GL 180GL –4GL(–2%) PermanentWaterConservationMeasures

Annual mean soil moisture (model estimates)

Spatialpatterns: Predominantlyaboveaverageannualmeansoilmoisturewithlargeinlandareasofverymuchaboveaveragesoilmoisture

Temporalpatternsinregionalaverage:

Aboveaveragetoverymuchaboveaveragesoilmoisturethroughouttheyear

North East Coast


Tropical landscape with tree ferns and rain forest, Queensland Tablelands | Dirk Ercken, Dreamstime

3.3 Descriptionoftheregion

TheNorthEastCoastregionisa451,000km²areainQueenslandsurroundedbytheGreatDividingRangeinthewest,theCoralSeaintheeast,TorresStraitinthenorthandtheQueensland–NewSouthWalesborderinthesouth.

Riverbasinsintheregionvaryinsizefrom400–143,000km².MajorriverbasinsincludetheBurdekin,Fitzroy,Burnett,Brisbane,MaryandJohnstone,Mulgrave,Barron,Daintree,BloomfieldandNormanby.

ThelargestriverbasinsaretheBurdekinandtheFitzroy(Figure3.1),whichtogethercomprise64%oftheGreatBarrierReefcatchmentareaandimpactupontheoffshorereef’secosystemsthroughdischargesofsedimentsandnutrients.

TheregionincludessomeofthemosttopographicallydiverseterraininAustralia,includinghighaltitudesassociatedwithcoastalrangesandtablelandsandaretreatingescarpmentwithoutcropsonthecoastalalluvialplains.ThehighestmountainsinQueenslandandthehighestrainfallareasinAustraliaarenorthofInnisfail.Subsections3.3.1–3.3.4givemoredetailonthephysicalcharacteristicsoftheregion.

Withapopulationinexcessof4millionpeopletheregionishometojustover19%ofallAustraliansand92%ofallQueenslandresidents(AustralianBureauofStatistics[ABS]2011b).MajorpopulationcentreswithintheregionincludeBrisbane,theGold

CoastandtheSunshineCoastaswellastheregionalcentresofHerveyBay,Bundaberg,Gladstone,Rockhampton,Mackay,TownsvilleandCairns(Figure3.1).Furtherdiscussionoftheregion’spopulationdistributionandurbancentrescanbefoundinsubsection3.3.6andsection3.6respectively.

Mostoftheregionoutsidetheurbancentresisusedforgrazing.Inthenorththisoccursonnativerangelandswithfewermanagementinputsandpastureimprovementthanoccurinthesouthernriverbasins.Drylandandirrigatedagricultureaccountsforapproximately0.4%ofthelanduseofthearea.Areasofintensivelandusesuchasinurbanareasaccountfor0.2%ofthearea.Section3.7hasmoreinformationonagriculturalactivities.

Theregion’sclimateissubtropicaltotropicalwithhot,wetsummersandcooler,drywinters.Themonsoonalsummerrainfallismorepredictableinthenorththaninthesouth.Subsections3.3.7and3.3.8provideinformationontherainfallpatternsacrosstheregion.

Alargeareaofoutcroppingfracturedbasementrockdominatesthehydrogeologyoftheregion.Thegroundwatersystemsinfracturedrocktypicallyofferrestrictedlow-volumegroundwaterresources.Incontrast,largegroundwaterresourcesarelocalisedinalluvialvalleysystemsandcoastalsanddeposits.Thestatusofsurfacewaterandgroundwaterispresentedinsection3.5.


Figure 3.1 The North East Coast region

North East Coast


Figure 3.2 Physiographic provinces of the North East Coast region

3.3.1 Physiographiccharacteristics

Figure3.2isaphysiographicmapindicatingareaswithsimilarlandformevolutionaryhistories(Painetal.2011).Thesearerelatedtosimilargeologyandclimaticimpactsdefiningtheextentoferosionprocesses.

Theareashavedistinctphysicalcharacteristicsthatinfluencehydrologicalprocesses.

TheNorthEastCoastregionhasfourphysiographicprovinces.Thesearedescribedinthefollowinglistwiththeproportionoftheregiontheycovershowninbrackets.

• BurdekinUplands(21%):mixtureofhills,plateausandplainswiththehighlandschieflyongraniteandmetamorphicrockswithsomeyoungbasalticplateaus;

• FitzroyUplands(43%):mixtureofhills,plateausandplainswithhighlandsofsandstone,basalt,graniteandmetamorphicrocks;

• NewEngland–MoretonUplands(23%):sandstoneandigneoushighlandswithsedimentaryandmetamorphiclowlands;and

• PeninsularUplands(13%):mixtureofhills,plateausandplainswithhighlandsofsandstoneaswellasvolcanic,graniticandmetamorphicrocks.


Figure 3.3 Ground surface elevations in the North East Coast region

3.3.2 Elevation

Figure3.3presentsgroundsurfaceelevationsintheNorthEastCoastregion.InformationwasobtainedfromtheGeoscienceAustraliawebsite(www.ga.gov.au/topographic-mapping/digital-elevation-data.html).

TheNorthEastCoastregionhasaverydiversetopographyandincludeshighaltitudesassociatedwithcoastalrangesandtablelands,andaretreatingescarpmentwithresidualoutliersonthecoastalalluvialplains.

TheregioncontainsmanymountainsfrompartoftheGreatDividingRange.Italsocontainslargeplateausandlow-lyingcoastalareas.

ThehighestmountainsintheregioncanbefoundsouthofCairns,withpeaksreachingaltitudesof1,600mabovesealevel.

Furthersouth,thepeaksofvariouscoastalmountainrangesformwaterdividesbetweenthesmallercoastalriverbasinsandthefewinlandriverbasins.

ThecrestoftheGreatDividingRangeformsthewesternborderoftheregion.Altitudesonthisboundaryvaryfromlessthan200mtomorethan1,200m.

www.ga.gov.au/topographic-mapping/digital-elevation-data.html

www.ga.gov.au/topographic-mapping/digital-elevation-data.html

North East Coast


Figure 3.4 Surface slopes in the North East Coast region

3.3.3 Slopes

Table3.2summarisestheproportionsofslopeclassesfortheregionwhileFigure3.4showsthespatialdistributionofthesurfaceslopes.Areaswithsteepslopesprovidehigherrun-offgeneratingpotentialthanflatareas.TheNorthEastCoastregionhashighslopevariabilitywithlargerexpansesofsteeperslopesthanmostotherpartsofAustralia.Theslopeswerederivedfromtheelevationinformationusedintheprevioussection.

Table 3.2 Proportions of slope classes for the region

Slopeclass(%) 0–0.5 0.5–1 1–5 >5

Proportionofregion(%) 19.0 16.4 43.8 20.8

Slopesareparticularlysteepalongthecoastalescarpment.Riversinboththenorthandsouthoftheregionoftenhaveflashfloodingunderhighintensityrainfall.TheJanuary2011floodintheBrisbaneRiverandMarch2012floodintheHaughtonRiverareexamplesofsuchevents.

Furtherinland,slopesarerathergentle(Figure3.4).Atsomelocationslargelakeshaveformed,bothnaturallyaswellasthroughtheconstructionofdamsforwatersupply.

Intheflattercoastalareasmanylargerriversformextensivefloodplains.Theseareoftenidentifiedaswetlandareasofconservationsignificance.


Figure 3.5 Soil types in the North East Coast region

3.3.4 Soiltypes

Soilsplayanimportantroleinthehydrologicalcyclebydistributingwaterthatreachestheground.Watercanbetransportedtoriversandlakesviathesoilsurfaceasrun-offorenterthesoilandprovidewaterforplantgrowthaswellascontributingtogroundwaterrecharge.

Thenatureofthesehydrologicalpathwaysandthesuitabilityofthesoilsforagriculturalpurposesareinfluencedbysoiltypesandtheircharacteristics.

SoiltypeinformationwasobtainedfromtheAustralianSoilResourceSystemwebsite(www.asris.csiro.au).

Figures3.5–3.6showthedistributionofsoiltypeswithintheNorthEastCoastregion.About80%ofthelandsurfaceiscoveredbyfivesoiltypes,namelysodosols,kandosols,kertosols,tenosolsandchromosols.Withtheexceptionofvertosols,thesesoilsarewidespreadacrosstheregion,arelowinfertilityandaremostlyusedforgrazing,drylandagriculture,horticultureandforestry.

Soiltypeswithcleartexturecontrastsinthisregionaresodosolsandchromosols.Thesesoilscanhaveapropensitytobecomewaterlogged.

Sodosolshaveimpermeable,sodicsubsoilduetoelevatedsodiumconcentrations.Theyaresusceptibletodrylandsalinityaswellaserosionifvegetationisremoved.Chromosolsalsohaveanimpermeablesubsoilthatisnotstronglysodicoracidic.

Vertosols,onlydistributedthroughthemiddlepartoftheregion,aresoilswithahighclaycontent.Thesearebrown,greyorblacksoilswithlargewater-holdingcapacity,butcandeveloplargecrackswhendrying.Theyarehighlyfertileandself-mulching.

Soilswithlittleornochangesinsoiltextureintheregionarekandosolsandtenosols.Kandosolsareusuallyred,yellowandgreymassiveearthysoilswithalowwater-holdingcapacity;however,awiderangeofcropscanbegrownonthemwhererainfallishighorirrigationisavailable.Similarly,tenosolshaveaweakprofiledevelopment.Theiragriculturaluseislimitedduetotheirlowwater-holdingcapacityandtheiroftenshalloworstonymaterial.Soiltypeswithsmallareacoverageintheregionarerudosols,dermosols,ferrosols,hydrosols,kurosols,andpodosols(1–6%).

http://www.asris.csiro.au

North East Coast


Figure 3.6 Soil type distribution in the North East Coast region


Figure 3.7 Land use distribution in the North East Coast

Figure 3.8 Land use in the North East Coast region

3.3.5 Landuse

MostoftheNorthEastCoastregionisusedforgrazing.Inthenorththisoccursonnativerangelandswithfewermanagementinputsandpastureimprovementsthaninsouthernriverbasins.

Figure3.7presentslanduseintheregion.Drylandandirrigatedagricultureaccountforapproximately

4%oflanduse,whileintensivelandusessuchasthatofurbanareasaccountfor1%oftheregion(informationfromdata.daff.gov.au/anrdl/metadata_files/pa_luav4g9abl07811a00.xml).

AsseeninFigure3.8natureconservationareas,suchasthoseonCapeYorkareanimportantpartofthelandcoverinthenorth,wherethelargestareasofunspoiltrainforestsinAustraliacanbefound.

http://data.daff.gov.au/anrdl/metadata_files/pa_luav4g9abl07811a00.xml

http://data.daff.gov.au/anrdl/metadata_files/pa_luav4g9abl07811a00.xml

North East Coast


Figure 3.9 Population density and distribution in the North East Coast region

3.3.6 Populationdistribution

Figure3.9showsthepopulationdensityanddistributionintheNorthEastCoastregion.Urbanareasaccountforlessthan1%ofthetotallandareaofthisregion.SouthEastQueensland,whichincludesBrisbane,GoldCoast,andtheSunshineCoast,isthemostheavilyurbanisedandpopulatedareaandconstitutesover65%oftheregion'stotalpopulation.

Agriculture,fishing,miningandtourismarethemajordriversforthemanypopulationcentresinthe

northandlargelyalongthecoastalfringes,estuariesandalluvialplainsoftheregion.CoalminingintheBowenbasininthecentraleasternpartoftheregionhasbeenamajordriverformanysmallinlandtownsaswellasthelargercoastalregionalcitiesthatlieonoradjacenttoitseasternboundary(Gladstone,RockhamptonandMackay).

Furthernorth,thecoastalcitiesofTownsvilleandCairnsprovidethefocalpointsforthemajorpopulationconcentrationsoftheregion’snorthernpopulation.


Figure 3.10 Rainfall zones in the North East Coast region

3.3.7 Rainfallzones

Figure3.10representsmedianrainfallzonesintheNorthEastCoastregion,whichhasasubtropicaltotropicalclimateandreceivesmostofitsrainfallinsummer.Medianrainfallexceeds350mmthroughouttheregion.

Thenorthernhalfoftheregionreceivessummerdominantrainfallwithamarkedwetsummeranddrywinteraswellmedianrainfalldecreasingwestwards

fromover1,200mmperannumalongthecoasttobetween350mmand650mminland.

Thesouthernpartoftheregionhasasummerrainfallseason(wetsummerandlowwinterrainfall)withlocalisedareasalongthecoastnorthofBrisbanehavingaverageannualrainfallsofover1,200mm.Formoreinformationonthisandotherclimateclassifications,visittheBureauofMeteorology's(theBureau's)climatewebsite:www.bom.gov.au/jsp/ncc/climate_averages/climate-classifications

http://www.bom.gov.au/jsp/ncc/climate_averages/climate-classifications

http://www.bom.gov.au/jsp/ncc/climate_averages/climate-classifications

North East Coast


Figure 3.11 Rainfall deficit distribution in the North East Coast region

3.3.8 Rainfalldeficit

Therainfalldeficitindicator,thatis,rainfallminuspotentialevapotranspiration,givesageneralimpressionaboutwhichpartsoftheregionarelikelytoexperiencemoisturedeficitsovertheperiodofayear.TheNorthEastCoasthasadistinctrainfalldeficitpattern.

AsshowninFigure3.11,seriousdeficitscanbeexpectedinlargepartsoftheinlandareaswherethemajorlanduseisgrazing.

Alongthecoast,someareasexperienceabundantwaterovertheyear.RiverscarrythiswatertotheCoralSeaandareanimportantsourceoffreshwaterformanyestuarinewetlands.

Formoreinformationonrainfallandevapotranspiration,seetheBureau’smapsofaverageconditions:www.bom.gov.au/climate/averages/maps.shtml

http://www.bom.gov.au/climate/averages/maps.shtml


Figure 3.12 Landscape water flows in 2011–12 compared with the long-term record (July 1911– June 2012) for the North East Coast region

3.4 Landscapewaterflows

Thissectionpresentsanalysesofthespatialandtemporalvariationoflandscapewaterflows(rainfall,evapotranspirationandlandscapewateryield)acrosstheNorthEastCoastregionin2011–12.Nationalrainfallgridsweregeneratedusingdatafromanetworkofpersistent,high-qualityrainfallstationsmanagedbytheBureau.

Figure3.12showstheregionhasahighlyseasonalrainfallpatternwithawetperiodfromDecember–MarchandaparticularlydryperiodfromJuly–September.Evapotranspirationinthedryperiodgenerallyexceedsrainfall.Afterthewetperiodthesoilsnormallycontainmoisturethatisavailableforevapotranspiration.

Themonthlylandscapewateryieldhistoryfortheregionshowsastablepatternofverylowyieldinthedryperiod.Itgraduallyincreasesduringsummermonthsandsubsidesduringautumn.

The2011–12yearwasrelativelywet,particularlybetweenDecember2011andMarch2012,whenrainfallwasmuchgreaterthanthehistoricmedian.AnactivemonsooninthenorthoftheregioncontributedtoparticularlyhighrainfalltotalsforMarch2012.

Withwetsoilconditionspresentatthestartoftheyear,evapotranspirationrateswerehigherthanrainfallratesforthefirstfivemonthsof2011–12.WiththeexceptionofJanuary2012,evapotranspirationratesremainedabovethe75thpercentilefortherestoftheyearasaresultofthehigherthanusualrainfallinmostpartsoftheregion.

Thelandscapewateryieldfor2011–12closelyfollowedthehistoricpatternwiththeexceptionofMarch2012,whenveryhighrainfallgeneratedamuchhigherlandscapewateryieldthanthehistoricaverage.

North East Coast


Figure 3.13 Spatial distribution of (a) annual rainfall in 2011–12, and (b) their decile rankings over the 1911–2012 period for the North East Coast region

3.4.1 Rainfall

RainfallfortheNorthEastCoastregionfor2011–12isestimatedtobe1,041mm.Thisis22%abovetheregion’slong-termaverage(July1911–June2012)of853mm.Figure3.13ashowsthatthehighestrainfalloccurredalongthecoastalareaswithannualtotalsexceeding2,400mminmanyareasfor2011–12.Themajorityoftheinlandareashadrainfallrangingfrom600–900mmfor2011–12.However,insomeareasalongthewesternborder,rainfallexceeded900mm.

Rainfalldecilesfor2011–12indicateaveragetoaboveaveragerainfallfortheentireregion(Figure3.13b).Mostoftheinlandpartsoftheregionreceivedaboveaveragerainfallwithsomepartsinthewestreceivingverymuchaboveaveragerainfall.ThesoutherncoastalareanorthofBrisbane,includingFraserIsland,alsoreceivedverymuchaboveaveragerainfall.


Figure 3.14 Time-series of (a) annual rainfall, and (b) five-year retrospective moving averages for the summer (November–April) and winter (May–October) periods for the North East Coast region

Rainfall variability in the recent past

Figure3.14ashowsannualrainfallfortheregionfromJuly1980onwards.Overthis32-yearperiodtheannualaveragewas851mm,varyingfrom551mm(1992–93)to1,586mm(2010–11).Temporalvariabilityandseasonalpatternssince1980arepresentedinFigure3.14b.Thegraphsindicatethepresenceofcyclicalpatternstypicaloftheregion’sannualrainfalloverthese32years,whichare

particularlynoticeableinthesummerperiod.ThispatterniscloselylinkedtotheoccurrenceofElNiñoandLaNiñaperiodsandcorrelateswellwiththeSouthernOscillationIndex(seeNationalOverviewchapter).

AstrongLaNiñaperiodtypicallydeliversaboveaveragerainfalltothisregion,whichisclearlyhighlightedbytherecent2010–11LaNiñaperiod.

North East Coast


Figure 3.15 Spatial distribution of (a) trends in annual rainfall from 1980– 2012, and (b) their statistical significance at 90% (weak) and 95% (strong) confidence levels for the North East Coast region

Recent trends in rainfall

Figure3.15apresentsthespatialdistributionofthetrendsinannualrainfallforJuly1980–June2012.Thesearederivedfromlinearregressionanalysesonthetime-seriesofeachmodelgridcell.ThestatisticalsignificanceofthetrendsisprovidedinFigure3.15b.

Figure3.15ashowsthatsince1980astrongincreaseinrainfallhasoccurredinlargepartsoftheregion

particularlytowardsthenorth.Thesetrendsarestronglysignificantin22%oftheregion(Figure3.15b).

ThetrendsarelargelyaresultofthecyclicrainfallpatternshowninFigure3.14andtheparticularlyhighrainfallofthepasttwoyears.


Figure 3.16 Spatial distribution of (a) modelled annual evapotranspiration in 2011–12, and (b) their decile rankings over the 1911–2012 period for the North East Coast region

3.4.2 Evapotranspiration

ModelledannualevapotranspirationfortheNorthEastCoastregionfor2011–12isestimatedtobe814mm.Thisis18%abovetheregion’slong-term(July1911–June2012)averageof692mm.

Figure3.16ashowsthatspatialdistributionofannualevapotranspirationin2011–12issimilartothatofrainfallFigure3.13a.Evapotranspirationratesarehighestalongthecoastwithannualtotals

exceeding1,200mminsomeareasfor2011–12.Evapotranspirationaveragedaround750mmfortheinlandpartsoftheregion.

Figure3.16bshowsthatevapotranspirationdecilesfor2011–12indicateaboveaverageorverymuchaboveaveragetotalsacrossmostoftheregion.Thiscoincideswiththeverymuchaboveaveragerainfallobservedlargelyalongthewesternborder(Figure3.15b).Mostcoastalareasareestimatedtohavehadaverageevapotranspiration.

North East Coast


Figure 3.17 Time-series of (a) annual evapotranspiration, and (b) five-year retrospective moving averages for the summer (November–April) and winter (May–October) periods for the North East Coast region

Evapotranspiration variability in the recent past

Figure3.17ashowsannualevapotranspirationfortheregionfromJuly1980onwards.Overthis32-yearperiodtheannualevapotranspirationaveragewas682mm,varyingfrom477mm(1992–93)to1,054mm(2010–11).Temporalvariabilityandseasonalpatternssince1980arepresentedinFigure3.17b.

Summerperiodsshowedconsistentlyhigherevapotranspirationratesthanthewinterperiod.

Thehighertemperaturesandthehigherrainfallamountsduringtheseperiodscontributetothis.Comparedwiththeseasonalrainfall(Figure3.14b),thecyclicaltime-seriesofseasonalevapotranspirationislesspronounced(Figure3.17b).


Figure 3.18 Spatial distribution of (a) trends in annual evapotranspiration from 1980–2012, and (b) their statistical significance at 90% (weak) and 95% (strong) confidence levels for the North East Coast region

Recent trends in evapotranspiration

Figure3.18apresentsthespatialdistributionofthetrendsinmodelledannualevapotranspirationfor1980–2012.Thesearederivedfromlinearregressionanalysesonthetime-seriesofeachmodelgridcell.ThestatisticalsignificanceofthetrendsisprovidedinFigure3.18b.

Figure3.18ashowsthatsince1980trendsaremostlyrisinginthecentralnorthernpartoftheregion.Inthesouth,thetrendsaremoreneutraltoweaklyfalling.

AsshowninFigure3.18b,thetrendsaregenerallyonlystatisticallysignificantinsomeinlandpartsoftheregion.Inthesouthoftheregionthefallingtrendshavenostatisticalsignificance.

Asevapotranspirationisdrivenbytheavailabilityofmoisture,thetrendsarerelatedtothecyclicpatternintherainfallshowninFigure3.14andtheparticularlyhighrainfallof2010–11and2011–12.

North East Coast


Figure 3.19 Spatial distribution of (a) modelled annual landscape water yield in 2011–12, and (b) their decile rankings over the 1911–2012 period for the North East Coast region

3.4.3 Landscapewateryield

ModelledlandscapewateryieldfortheNorthEastCoastregionfor2011–12isestimatedtobe223mm.Thisis42%abovetheregion’slong-term(July1911–June2012)averageof157mm.

Figure3.19ashowsthespatialdistributionoflandscapewateryieldfor2011–12,whichissimilartothatshowninFigure3.14a,annualrainfalldistribution.Thisisaresultofrainfallintensityandvolumebeingthedominantdriversforgeneratinglandscapewateryield.

Thehighestlandscapewateryieldsin2011–12areobservedinareasalongthemid-northandsouthcoast,locallyexceeding1,200mm.Fortherestoftheregion,thelandscapewateryielddidnotexceed400mm.

Figure3.19bisthedecile-rankingmapfor2011–12andshowsaveragetoverymuchaboveaveragelandscapewateryields.

Aboveaveragewateryieldsarefoundacrossmuchoftheinlandareas,withverymuchaboveaverageyieldsalongthewesternborder,aswellasalongthesoutherncoast.


Figure 3.20 Time-series of (a) annual landscape water yield, and (b) five-year retrospective moving averages for the summer (November–April) and winter (May–October) periods for the North East Coast region

Landscape water yield variability in the recent past

Figure3.20ashowsannuallandscapewateryieldfortheNorthEastCoastregionfromJuly1980onwards.Overthis32-yearperiod,annuallandscapewateryieldwas162mm,varyingfrom58mm(2001–02)to481mm(2010–11).

Temporalvariabilityandseasonalpatternssince1980arepresentedinFigure3.20b.

AsshowninFigure3.20b,landscapewateryieldisconsistentlyhigherduringthesummerperiodcomparedtothewinterperiod.

Thesummerperiod’saveragealsoexhibitsagreaterinter-annualandcyclicalvariabilitydrivenbytheregion’srainfalldynamics.

North East Coast


Figure 3.21 Spatial distribution of (a) trends in annual landscape water yield from 1980– 2012, and (b) their statistical significance at 90% (weak) and 95% (strong) confidence levels for the North East Coast region

Recent trends in landscape water yield

Figure3.21apresentsthespatialdistributionofthetrendsinmodelledannuallandscapewateryieldfor1980–2012.Thesearederivedfromlinearregressionanalysesonthetime-seriesofeachmodelgridcell.ThestatisticalsignificanceofthetrendsisprovidedinFigure3.21b.

Figure3.21ashowsthatsince1980risingtrendsoccuralongthecoast,particularlyinareaswhere

annualrainfallnormallyexceeds1,200mm.Intheinlandpartoftheregion,weakerrisingtrendsoccur.

Figure3.21bshowsstronglysignificanttrendsoccurmainlyintheinlandpartsoftheregion.Thehighlandscapewateryieldsbetween2007–08and2011–12(Figure3.20a)contributedappreciablytotheserisingtrends.


The Fitzroy River, east of Rockhampton | John Casey, Dreamstime

3.5 Surfacewaterandgroundwater

ThissectionexaminessurfacewaterandgroundwaterresourcesintheNorthEastCoastregionin2011–12.Ananalysisofrivers,wetlandsandwaterstoragesarediscussedtoillustratethestateoftheregion’ssurfacewaterresources.Theregion’swatertableaquifersandsalinityaredescribedandthegroundwaterstatusisillustratedbyshowingchangesingroundwaterlevelsatselectedsites.

3.5.1 Rivers

AlltheriversinthisregiondraintotheCoralSeawithmanyoftherivershavingoutflowsthatcanimpactontheGreatBarrierReef.

Figure3.22showsthe45riverbasinsintheregion,whichvaryinsizefrom400–143,000km2.

Manyoftherivershavehighsummerflowswithrelativelylongperiodsofloworzeroflowsinwinter,especiallytothemid-northoftheregion.Streamsinthesoutheastoftheregiongenerallyflowallyearroundbutstillshowdistinctseasonalvariation.

TheBurdekinandtheFitzroyriversareamongstthelargestAustralianriversintermsoftheirtotalflowvolumes.TheBurdekinRiverisasouth-flowingephemeralriverwhichoftendriestojustaseriesofdisconnectedwaterholes,andrunsover300kmbeforeturningeasttothesea.

ThelowerreachesoftheFitzroyRiverareperennialbutalargeproportionofthetributariesinthecatchmentareephemeral.

ThelowerBurdekin,NogoaandMackenzieriversrunthroughhighlymodifiedcatchments.TheBurnettRiverbasinisthethirdlargestbasinintheregion.

North East Coast


Figure 3.22 Rivers and catchments in the North East Coast region


3.5.2 Streamflowvolumes

Figure3.23presentsananalysisofflowsat46monitoringsitesduring2011–12relativetoannualflowsfortheperiodfromJuly1980–July2012.Monitoringsiteswithrelativelylongrecordsacross20geographicallyrepresentativeriverswereselected(seeTechnicalSupplementfordetails).

Theannualflowsfor2011–12arecolour-codedaccordingtothedecilerankateachsiteoverthe1980–2012period.TheflowsgenerallyreflectthemostlyaveragetoaboveaveragemodelledlandscapewateryieldresultsshowninFigure3.19b.

Highrun-off,generatedintheupstreamreachesoftherivers,causedaboveaveragetoverymuchaboveaverageflowsinmanyriversinthecentralpartoftheNorthEastCoastregion.

Verymuchaboveaverageflowswereobservedatfivemonitoringsiteslocatedonriversinthewest:thenorthJohnstoneRiverinthecentralnorthandtheGregoryRiverinthesoutheastoftheregion.

Aboveaveragetotalflowswererecordedat23monitoringsites.Theseweremainlylocatedontheriverstothesouth,somecentrallylocatedrivers,andinsomeriverbasinstothecentralnorthoftheregion.

Averageflowsoccurredat17sitesintheregionthatwereontheriversinthesouthwestandfarsouthoftheregion,andamongriverbasinsinthecentralnorthandfarnorthoftheregion.

Therewasonlyonebelowaverageflowrecordedforthe46monitoringsitesexaminedacrosstheregion.ThiswasontheNormanbyRiverinthenorth.

AsshowninFigure3.23,decilesinthesummer(November2011–April2012)wereverysimilartototalannualflowsfor2011–12.Thisisnotsurprisinggiventhatthegreatestvolumeofflowsintheregion,particularlyinthecentralnorth,occurredoverthesummermonths.Thereareafewmonitoringsitesthatdidnotshowthispattern,suchastherelativelylowflowsobservedinthesummerperiodontheStewartRiverinthefarnorthoftheregion.

3.5.3 Streamflowsalinity

Figure3.24showsananalysisofstreamflowsalinityfor2011–12at79monitoringsitesthroughouttheNorthEastCoastregion.Monitoringsiteswithatleastafive-yeardatarecordwereselectedforanalysis.Theresultsareshownaselectricalconductivity(EC,μS/cm).ThisisacommonlyusedsurrogateforthemeasurementofwatersalinityinAustralia.StandardEClevelsfordifferentapplications,suchasfordrinkingwaterortypesofirrigationareprovidedintheTechnicalSupplement.ThemedianannualECvaluesareshownascolouredcircles.ThecirclesizedepictsthevariabilityinannualEC,shownasthecoefficientofvariation(CV),beingthestandarddeviationdividedbythemean.

ThemedianECvaluesformostoftheselectedmonitoringsitesfallintherange0–1,000μS/cm,anamountthatissuitableformostirrigationuses.SomeresultsforsmallriversandcreeksintheFitzroyRiverbasinandtheLoganRiverbasinfalloutsidethisrange(seeFigure3.24).Ofthe79monitoringsites,53%hadmedianECvaluesbelow500μS/cmand33%werebetween500–1,000μS/cm.Only14%ofthemonitoringsiteshadamedianECabove1,500μS/cm.

Riverswithhigher(>1,000μS/cm)mediansalinitiesalloccurinthesouthernhalfoftheregion.Theyaretypicallyassociatedwithlowannualflows.Medianstreamsalinitywasabove2,000μS/cmatthreeofthe79monitoringsites.ThesewerefromonemonitoringsiteontheDeeRiverthatisatributaryoftheDawsonRiver,andtwocreeksintheFitzroyRiverbasin.HighsalinityintheDeeRiverisinfluencedbythedecommissionedMountMorgangoldmine,fromwhichleachatesentertheDeeRiver.

ThesalinityCVvaluesvarywidelyacrosstheNorthEastCoastregion.TheCVishighatafewmonitoringsitesinthesouthandnorthwest,andintheDeeRiverintheeast.Incontrast,theCVisrelativelylowformostriversinthesouth,northeast,andcentralpartsoftheregion.TheCVofsalinityistypicallyrelatedtothevariabilityinannualflowatthemonitoringsite.

North East Coast


Figure 3.23 Average annual and summer period flow volumes of selected gauges for 2011–12 and their decile rankings over the 1980–2012 period in the North East Coast region


Figure 3.24 Salinity as electrical conductivity and its associated coefficient of variation for 2011–12 in the North East Coast region

North East Coast


Ofthe79monitoringsites,27%hadacoefficientofvariationbelow20%;67%ofthesiteshadCVbetween20%and60%;andonly6%ofthesiteshadCVabove60%.ThesewereontheSuttorRiverintheBurdekinRiverbasininthecentreoftheregion,DeeRiverinthecentraleastandPurgaCreekintheBrisbaneRiverbasininthesouthoftheregion.

Streamsalinityvariationwasabove80%atoneofthe79monitoringsites.ThiswasontheSuttorRiverintheBurdekinRiverbasininthecentreoftheregion.

3.5.4 Flooding

FloodsintheNorthEastCoastregionaremainlycausedbytworainfalltypes.Thesearelocalisedhighintensityrainfall(forexample,thunderstorms)orprolongedperiodsofrainfall(forexample,frontalrainfall,monsoon,tropicalstorms).Whilethefirstrainfalltypeoftenresultsinlocalisedflashflooding,theprolongedrainfallcancausesustainedfloodsoverlargeareas.

Theregionhasaseasonalpatternofrainfall,withmostrainfalloccurringinsummer,inwhichbothrainfalltypesoccurfrequently.

Figure3.25showsthelocationswheretheBureaumonitorsriverlevelsintheregionaspartofitsfloodforecastingservices.Thehighestfloodlevels

experiencedduring2011–12areshownintermsofthefloodclassificationlevelsestablishedinconsultationwithemergencymanagementandlocalagenciestodescribefloodimpactsateachlocation(seeTechnicalSupplement).

Alargenumberofmajorfloodsoccurredin2011–12(Figure3.25).InlargeriverstothecentralwestoftheregionmajorfloodswereobservedduringJanuaryandFebruary2012.TheprolongedrainfallinthelastweekofJanuaryresultedinhighwaterlevelsinthesoutherntributariesoftheBurdekinRiverandmostoftheupstreamtributariesoftheFitzroyRiver.

TheprolongedJanuaryrainfallalsoimpactedtheriversaroundBrisbaneinthesouthernpartoftheregion.AlthoughnotassevereastheJanuary2011floods,someareasintheBrisbaneandLoganriverbasinsexperiencedmajorflooding;howevertheimpactsinsuburbanBrisbaneandsurroundswerelessseverewithonlyminortomoderateflooding.

InMarch,themonsooninthenorthernpartoftheregiondeliveredlargeamountsofrainfalltothecoastalareasofnorthQueensland.Majorfloodingoccurredinmanysmallrivers.FloodingalsooccurredfurthersouthinsomeriversbetweenBrisbaneandRockhampton,whererainfallforthismonthwasupto400mm.


Figure 3.25 Flood occurrence in 2011–12 for the North East Coast region, with each dot representing a river level monitoring station and the colour of the dot representing the highest flood class measured

North East Coast


Table 3.3 Major public storage systems in the region as identified in the Bureau’s water storage website (August 2012), with ‘non-allocated’ accounting for the storages not allocated to a particular system

System name System type System capacity Accessible volume at 30 June 2011 Accessible volume 30 June 2012

Brisbane urban 2,220GL 1,882GL—85% 2,093GL—94%

BurdekinHaughton rural 1,868GL 1,866GL—100% 1,868GL—100%

NagoaMackenzie rural 1,305GL 1,296GL—99% 1,297GL—99%

Bundaberg rural 909GL 908GL—100% 906GL—100%

Proserpine rural 490GL 490GL—100% 480GL—100%

MareebaDimbulah rural 438GL 433GL—99% 437GL—99%

BoyneTarong rural 196GL 195GL—100% 196GL—100%

UpperBurnett rural 187GL 182GL—97% 182GL—97%

Callide rural 148GL 140GL—95% 105GL—71%

Pioneer rural 147GL 146GL—99% 146GL—99%

BarkerBarambah rural 134GL 134GL—100% 134GL—100%

BowenBroken rural 116GL 115GL—99% 116GL—100%

ThreeMoonCreek rural 88GL 88GL—100% 88GL—100%

Warrillvalley rural 86GL 83GL—97% 82GL—95%

Eton rural 62GL 61GL—98% 62GL—100%

Maryriver rural 56GL 56GL—100% 56GL—100%

Loganriver rural 44GL 44GL—100% 44GL—100%

Non-allocated — 1,022GL 1,016GL—99% 1,009GL—99%

Total 9,516 GL 9,135 GL—96% 9,301 GL—98%

3.5.5 Storagesystems

Thereareover100major,publicly-ownedwaterstoragesintheNorthEastCoastregionwithatotalaccessiblecapacityinexcessof10,400GL.

TheBureau’swaterstorageinformation(asatAugust2012)coversapproximately92%oftheregion’spubliclyownedstoragecapacity.Storagessupply17irrigationareasaswellasthecityofBrisbane.

Table3.3givesasummaryofthemajorstoragesystemstogetherwithanoverviewofthestoragelevelsattheendof2010–11andtheendof2011–12.ThelocationofallthesystemsandassociatedstoragesareshowninFigure3.26.

Totalaccessiblestorageintheregionforthe2011–12yearincreasedmarginally,withmoststoragesclosetofullcapacity.ThemajorincreasewasintheBrisbanesystem,wherevolumeswentupfrom85to94%.TheonlysubstantialdropinstoragelevelswasintheCallidesystem.

MoredetailsontheBrisbaneandBurdekinHaughtonsystemsisprovidedinthe‘Waterforcitesandtowns’and‘Waterforagriculture'sectionsinthischapter.

FurtherinformationonthepastandpresentvolumesofthestoragesystemsandtheindividualstoragescanbefoundontheBureau’swaterstoragewebsite:water.bom.gov.au/waterstorage/awris/

http://water.bom.gov.au/waterstorage/awris/

http://water.bom.gov.au/waterstorage/awris/


Figure 3.26 Storage systems in the North East Coast region (information extracted from the Bureau of Meteorology's water storage website in August 2012)

North East Coast


Woodhouse Lagoon | NQ Dry Topics

3.5.6 Wetlands

Important wetlands

AsseeninFigure3.27,therearealargenumberofwetlandsofnationalandinternationalimportanceintheNorthEastCoastregionthatencompassawidediversityofwetlandtypes,fromcoastalfloodplainstohigheraltitudefreshwaterstreamsandwaterfalls.ThewetlandscreateamosaicoftemporallyandspatiallydynamichabitatswithinthispartofAustralia.Themostspatiallyextensivewetlandtypesintheregionareartificialfreshwaterstoragesandthemarine-influencedcoastalflatsandmangroves.

Theartificialwetlands,despitebeingconstructedfromdammedwatercoursesforurbanandruralwatersupplyandfloodretardationpurposes,providerecreationalandecosystemvaluessuchasaquatichabitatforanumberofimportantfloraandfaunaspecies.Thebrackishtosalinecoastalwetlandsinthisregionprovideecosystemservicessuchasmangroveandsalt-marshhabitataswellasactingasfiltersreducingsedimentdischargestotheGreatBarrierReef.

Inflows to selected wetlands

Thestateofthebiodiversityinawetlandislinkedtothewaywaterisstoredwithintheareaandthetemporalvariabilityofinflows.Ananalysisofhistoricandrecentinflowsintowetlandsformsaninformativepictureofpotentialchanges.

Threeinternationally-recognisedRamsarwetlandsites(BowlingGreenBay,GreatSandyStraitandMoretonBay)andonenationally-listedfreshwaterwetland(theSouthernFitzroyRiverwetlandcomplex)wereselectedforhydrologicalanalysisofmajorinflows.Moreinformationabouttheregion'swetlandsisavailablefromtheAustralian Directory of Important Wetlands(www.environment.gov.au/water/topics/wetlands/database/diwa.html)

Sevenupstreammonitoringgaugeswereselectedtoenabletheanalysesandinterpretationofinflowstothesefourwetlands.Thegaugesusedintheanalysesaretheclosestupstreamgaugesthathavelargelycontinuousdischargerecordssince1980.

Thoughtheanalysesdonotcapturethetotalinflows,theyareindicativeofthetemporalpatternsoffreshwatersurfaceflowstothesewetlands.


Figure 3.27 Location of important wetlands in the North East Coast region

North East Coast


Bowling Green Bay

WetlandscentredonBowlingGreenBay,southofTownsville,formoneoftropicalAustralia’slargestandmostdiversecoastalwetlands.Thewetlandsaremostlycoastalplainscoveredintidalmudflats,mangroveforestandsaltmarshes.Riverchannelsandfreshwatermarshesalsoformpartofthislargewetlandcomplex.

DailydischargedataforthemonitoringgaugesontheHaughtonRiveratPowerlineandontheBarrattaCreekatNorthcotehavebeencombinedtoprovideatemporalpatternoffreshwaterinflowsintoBowlingGreenBay(Figure3.28).

Figure3.29presentsanoverviewofthedistributionofdailystreamflowdecilerankingsfortheperiodbetween1980and2012.Thedataisfairlysparseuntil1987.ThereafteronecanseeapatternofwetperiodsinblueofvaryinglengthusuallybetweenNovemberandMay.From2008–09therehasbeenanincreaseinthelengthoftheperiodofverymuchaboveaverageflows.

Figure3.30comparesmonthlydischargesfrom2011–12withtheflowstatisticsfrom1980onwards.TheMarch2012flowswellexceededtheninthdecileofthe32-yearrecordandcontributedasubstantialamountoffreshwatertoBowlingGreenBay.

Figure 3.28 Location of the monitoring sites in relation to Bowling Green Bay

Figure 3.29 Daily flows of the Haughton River at Powerline and on the Barratta Creek at Northcote between 1980 and 2012, ranked in decile classes

Figure 3.30 Combined monthly flows at Haughton River and Barratta Creek from 2011–12 compared with the 1980–2012 decile rankings


Southern Fitzroy River floodplain complex

TheFitzroycatchmentisthesecondlargestintheregion,atnearly150,000km2,andisdominatedbyagricultureandminingincludingcoalmining.Inter-tidalwetlandsarepresentparticularlyaroundthelowerreachesoftheriverandsouthofthemouth.Thesewetlandstypicallyconsistofextensivesaltpansfringedbymangroves.

DailydischargedataforthemonitoringgaugeontheFitzroyRiveratTheGapprovidesatemporalpatternoffreshwaterinflowsintothesouthernFitzroyRiverfloodplaincomplex(Figure3.31).

Figure3.32presentsanoverviewofthedistributionofdailystreamflowdecilerankingsfortheperiodbetween1980and2012.From1994onwards,flowsweregenerallyverymuchbelowaverageduringthedryperiod,exceptforthelasttwoyears.Additionally,therewereextendedperiodsofverymuchaboveaverageflowsduringthewetmonthsof2009–10to2011–12.

Figure3.33comparesmonthlydischargesfrom2011–12withtheflowstatisticsfrom1980onwards.TheFebruaryandMarch2012flowscontributedasubstantialamountoffreshwatertothefloodplaincomplex.

Figure 3.32 Daily flows of the Fitzroy River at The Gap between 1980 and 2012, ranked in decile classes

Figure 3.31 Location of the monitoring site in relation to the southern Fitzroy River floodplain complex

Figure 3.33 Monthly flows at the Fitzroy River monitoring site at The Gap from 2011–12 compared with its 1980–2012 decile rankings.

North East Coast


Great Sandy Strait

TheGreatSandyStraitisenclosedbetweentheAustralianmainlandandFraserIsland.TheMaryRiverentersthestraitatRiverHeads.TheStraitisacomplexlandscapeofmangroves,sandbanks,inter-tidalsand,mudislands,saltmarshesandseagrassbeds.Itformsanimportanthabitatforbreedingfish,crustaceans,dugongs,dolphinsandmarineturtles.

DailydischargedataforthemonitoringgaugeontheMaryRiveratMiva(seeFigure3.34)provideatemporalpatternoffreshwaterinflowsintotheGreatSandyStrait.

Figure3.35presentsanoverviewofthedistributionofdailystreamflowdecilerankingsfortheperiodbetween1980and2012.Anirregularpatternofhighandlowflowsoccursthroughoutmostyears.Therewereextendedperiodsofverymuchaboveaverageflowsduringthewetmonthsof2010–2012.Extendedperiodsofverymuchbelowaverageflowsoccurredduring2002–03to2006–07.

Figure3.36comparesmonthlydischargesfrom2011–12withtheflowstatisticsfrom1980onwards.TheJanuary–March2012flowswellexceededtheninthdecileofthe32-yearrecordandcontributedasubstantialamountoffreshwatertothewetland.

Figure 3.36 Monthly flows at the Mary River monitoring site at Miva from 2011–12 compared with its 1980–2012 decile rankings

Figure 3.34 Location of the monitoring site in relation to the Great Sandy Strait

Figure 3.35 Daily flows of the Mary River at Miva between 1980 and 2012, ranked in decile classes


Moreton Bay

Becauseoftheexistenceofaseriesofoff-shorebarrierislandsthatrestricttheflowofoceanicwater,MoretonBayactssimilartoalagoon.Thewetlandsinthebayrangefromperchedfreshwaterlakesandsedgeswampsontheoffshoresandislands,tointer-tidalmudflats,marshes,sandflatsandmangrovesontheshoresofthebay’sislandsandthemainland.ThemajorriversflowingintothebaypassthroughBrisbane.

DailydischargedataforthemonitoringgaugesontheBrisbane,LoganandNerangrivers(Figure3.37)havebeencombinedtoprovideatemporalpatternoffreshwaterinflowsintoMoretonBay.

Figure3.38presentsanoverviewofthedistributionofdailystreamflowdecilerankingsfortheperiodbetween1980and2012,rankedindecileclasses.TheWivenhoeDamintheBrisbaneRiverwascompletedin1985andfromthenonwardsflowsintheriverbecameincreasinglyregulated.Prolongedperiodsofverymuchbelowaverageinflowstothebayoccurredbetween2006–07and2010–11.TheBrisbanefloodsofDecember2010brokethispattern.

Figure3.39comparesmonthlydischargesfromJune2011–March2012withtheflowfrom1980onwards.DatawasnotavailablebeyondMarch2012.TheMarch2012flowscontributedasubstantialamountoffreshwatertothewetland.

Figure 3.37 Location of the monitoring sites in relation to Moreton Bay

Figure 3.38 Combined daily flows of Brisbane, Logan and Nerang rivers between 1980 and 2012, ranked in decile classes

Figure 3.39 Combined monthly flows of Brisbane, Logan and Nerang rivers from 2011–12 compared with the 1980–2012 decile rankings

North East Coast


3.5.7 Hydrogeology

AsseeninFigure3.40,theNorthEastCoastregionisdominatedbyfracturedrockgroundwatersystemsthatprovidealow-volumegroundwaterresource.Greaterresourcepotentialisassociatedwiththefollowingaquifergroups:

• Surficialsedimentaquifer(porousmedia—unconsolidated);

• Tertiarybasaltaquifer(fracturedrock);and• Mesozoicsedimentaquifer

(porousmedia—consolidated).

Figure3.40showsthatsedimentsoftheGreatArtesianBasin,whichisoneofAustralia’slargestandmostsignificantgroundwaterbasins,arepresentalongthewesternborderoftheregion;however,thesesedimentsarenotextensiveintheNorthEastCoastregion.

3.5.8 Watertablesalinity

Figure3.41showstheclassificationofwatertableaquifersasfresh(totaldissolvedsolids(TDS)<3,000mg/L)orsaline(TDS≥3,000mg/L).Thesalinitywasinterpolatedfromboreslessthan40mdeepusingthelong-termaveragegroundwatersalinityforallbores.Mostpartsoftheregionhavefreshgroundwater.Saltygroundwateroccursinlocalisedareasinthecentralhighlandsandthecoast.

3.5.9 Groundwatermanagementunits

InQueensland,anumberofgroundwaterareashavebeenestablishedbytheStategovernmenttoprotectundergroundwaterresources.

AgroundwaterareainQueenslandisanareaidentifiedintheWaterRegulation2002asawaterresourceplanorawildriverdeclaration.Withintheseareasauthorisationisrequiredtoaccessgroundwaterorconstructworkstotakegroundwaterforcertainpurposes.

ThegroundwatermanagementunitswithintheregionarepresentedinFigure3.42.ThisdatasetisextractedfromtheBureau’sInterimGroundwaterGeodatabaseascompiledin2009(currentlyunderrevision).

Mostgroundwatermanagementunitsarerelativelysmallinarea.Inlargeareas,groundwaterresourcesareusedoutsideofgroundwatermanagementunits(unincorporatedareas).Thispatternofgroundwaterusereflectsthehydrogeologyintheregion,whichisdominatedbyalargeareaofoutcroppingfracturedbasementrocktypicallyofferingrestrictedlow-volumegroundwaterresources.

Incontrast,significantgroundwaterresourcesarelocalisedinalluvialvalleysystemsandcoastalsanddeposits.


Figure 3.40 Watertable aquifers of the North East Coast region, data extracted from the Groundwater Cartography of the Australian Hydrological Geospatial Fabric (Bureau of Meteorology 2012)

North East Coast


Figure 3.41 Watertable salinity classes in the North East Coast region; data extracted from the Groundwater Cartography of the Australian Hydrological Geospatial Fabric (Bureau of Meteorology 2012)


Figure 3.42 Groundwater management units in the North East Coast region, data extracted from the National Groundwater Information System (Bureau of Meteorology 2013)

http://en.wikipedia.org/wiki/River_Heads,_Queensland

North East Coast


3.5.10Groundwaterstatusofselectedaquifers

ThestatusofgroundwaterlevelsisanalysedateachborethroughouttheNorthEastCoastregion.Thisassessmentevaluatestrendsingroundwaterlevelsoverthefive-yearperiod2007–08to2011–12.

Thetrendsingroundwaterlevelsoverthefiveyearsareinvestigatedusinga5kmx5kmgridacrossdatarichareasusuallyassociatedwiththemajorgroundwatermanagementunits(seeFigure3.42).Thisscalereflectsthemostlylocaltointermediateflowsystemofthealluvialandtertiarybasaltsaquifersintheregion.

Thelineartrendingroundwaterlevelsforagridcellisassessedas:

• decreasing(wheremorethan60%oftheboreshaveanegativetrendinlevelslowerthan–0.1m/year);

• stable(wheremorethan60%oftheboreshaveatrendlowerthan0.1m/yearandhigherthan–0.1m/year);

• increasing(wheremorethan60%oftheboreshaveapositivetrendinlevelshigherthan0.1m/year);and

• variable(wherethereisnodominanttrendingroundwaterlevelsamongsttheboreswithinagridcell).

Exampleborehydrographsarepresentedforeachsub-regionovertheentirerecordlengthandtrendsarediscussedwithafocusonthe2007–08to2011–12period.Theselectedborehydrographsrepresentmostlyboreswithhighdatadensitythatwereusedinthe2010Assessment.

Northern aquifers

ThemapinFigure3.43illustratesthespatialandtemporaltrendsingroundwaterlevelsinthemajoralluvialaquifersalongthecoast(showninbrown)andinthemaininlandbasaltaquifer(showninpink),overthe2007–08to2011–12period,inthenorthoftheregion.Manyofthegridcellsshowarisingtrendwithaminorityofcellsshowingastabletrend.

SelectedBore1showsastabletrendwhilebores2and3showarisingtrendingroundwaterlevelsoverthelastfiveyears.Thisreflectsthelocalgroundwateruseandtherisingtrendinrainfallforthenorthernpartoftheregion.IrrigationintheBurdekinirrigationareamayalsobeaffectinggroundwaterlevelsinBore2.Groundwaterlevelsinthelastfiveyearsarewithintheshallowestlevelsonrecord.

Central aquifers

ThemapinFigure3.44illustratesthespatialandtemporaltrendsingroundwaterlevelsinthemajoralluvial(showninbrown)andbasaltaquifers(showninpink),overthe2007–08to2011–12period,inthecentralareaoftheregion.Manyofthegridcellsshoweitherarisingorstabletrend.

SelectedBore4showsarisingtrendingroundwaterlevelsovertheanalysisperiod.TheBore4hydrographissimilarinnaturetothebehaviourofgroundwaterlevelsinthenortherncoastalaquifers.Bores5and6,locatedintheinlandalluviumoftheCallidegroundwatermanagementunit,showanincreaseingroundwaterlevelfromend2010toearly2011incontrasttothelong-termdecliningtrendsuggestingrecenthighrechargetogroundwater.Thisreflectsthehighrainfallandfloodingthatoccurredsince2010.

Southern aquifers

ThemapinFigure3.45illustratesthespatialandtemporaltrendsingroundwaterlevelsinthemajoralluvial(showninbrown)andbasalt(showninpink)aquifersinlandandalongthecoast,overthe2007–08to2011–12period.Manyofthegridcellsshowarisingtrendwithaminorityofcellsshowingastabletrend.

Selectedbores7,8and9showarisingtrendingroundwaterlevelsovertheanalysisperiod,especiallyinBore9,representingtheLockyervalleyalluviumaquifer;thisisincontrasttothelong-termdecliningtrend.Itsuggestsrecenthighrechargetogroundwater,reflectingthehighrainfallandfloodingsince2010.


Figure 3.43 Spatial distribution of trends in groundwater levels for the surficial sediments and tertiary basalt aquifers in the northern North East Coast region for 2007–08 to 2011–12 with selected hydrographs showing groundwater levels

North East Coast


Figure 3.44 Spatial distribution of trends in groundwater levels for the surficial sediments and tertiary basalt aquifers in the central North East Coast region for 2007–08 to 2011–12 with selected hydrographs showing groundwater levels


Figure 3.45 Spatial distribution of trends in groundwater levels for the surficial sediments and tertiary basalt aquifers in the southern North East Coast region for 2007–08 to 2011–12 with selected hydrographs showing groundwater levels

North East Coast


3.6 Waterforcitiesandtowns

ThissectionexaminesurbanwaterintheNorthEastCoastregionin2011–12.Thelargeurbancentresintheregion,theirwatersupplysystemsandwaterstoragesituationsarebrieflydescribed.Themainurbanisedarea,southeastQueensland,isaddressedinmoredetailandthehistoryofwaterrestrictionsoverrecentyearsisdiscussed.AbreakdownisprovidedforwaterobtainedforanddeliveredtoBrisbaneandtheGoldCoast.

3.6.1 Urbancentres

StraddlingtheBrisbaneRiver,thecityofBrisbaneisthelargestcityintheregionandwithapopulationofover1.8millionpeopleitisthethirdlargestinAustralia.TheSunshineCoastandGoldCoast,totherespectivenorthandsouthofBrisbane,arehometoafurther743,000people.

Outsideoftheheavilypopulatedsoutheastcoast,theregionhasalargenumberofurbancentresandtowns.Inparticular,anumberofcoastalcitiesthatsupportadjoiningareaswithintheregion.

Cairnsisthenorthernmostandsecondlargestofthesecities.FromnorthtosouthbetweenCairnsandBrisbanethesecitiesincludeTownsville,thelargestregionalcityoutsideofsoutheastQueensland,Mackay,Rockhampton,GladstoneandBundaburg.Thesecities,alongwithBrisbane,TheGoldCoastandtheSunshineCoastareshowninFigure3.46inconjunctionwiththeirpopulationranges.

Table3.4summarisesthemajorurbancentresoftheregionwithpopulationsofover25,000peopleandprovidesinformationonthepopulation,surroundingriverbasinandsignificantwaterstoragesforeachof

themajorurbancentres.

Table 3.4 Cities and their water supply sources in the North East Coast region

City Population1 River basin Major supply sources

Brisbane 1,874,000 BrisbaneRiver Wivenhoe,SomersetandNorthPinereservoirs(partofSEQWaterGrid)

TheGoldCoast 534,000 SouthCoast Hinzereservoir(partofSEQWaterGrid)

TheSunshineCoast 209,000 MaryRiver LakeMacdonald,BaroonPocket,EwenMaddock,CooloolabinandWappareservoirs

Townsville 158,000 RossRiver RossRiverandPalumareservoirs

Cairns 134,000 Mulgrave–RussellRivers

TinarooFallsandCopperlodereservoirs

Mackay 74,000 PioneerRiver TeemburraandKinchantreservoirs

Rockhampton 62,000 FitzroyRiver FitzroyRiverBarrageandEdenBannWeir

Bundaberg 50,000 BurnettRiver BenAndersonBarrage,NedChurchwardWeir,ParadiseandFredHaighreservoirs

HerveyBay 49,000 MaryRiver LakeLenthall

Gladstone 32,000 CalliopeRiver AwoongaReservoir

1 Australian Bureau of Statistics (2011b)


Figure 3.46 Population range of major urban centres in the North East Coast region

North East Coast


3.6.2 Sourcesofwatersupply

Surfacewateristhemajorsourceofsupplyforthecitiesandtownsoftheregion.Ithasover70majorwaterstorages,eachwithacapacityofover1GL,thatsupplyacombinationofurban,agricultural,industrialandminingdemands.

SupplyingBrisbaneandsurroundingpopulations,Wivenhoeisarguablythemostwellknownsurfacewaterstorageintheregion;however,withrespecttosizeitranksthirdbehindFairbairnandBurdekinFalls.Thelatter,beingthelargestsurfacewaterstorageintheregion,suppliesbothirrigationandurbandemands,includingthoseoftheCityofTownsville.

Figure3.47showsmajorsurfacewaterstoragesintheregion,includingWivenhoeandBurdekinFalls,thatarepartlyinuseforurbanwatersupply.

Inadditiontosurfacewaterstoragestheregionutilisesdirectriverextractions(includingextractionsofupstreamstoragereleases),groundwater,desalination,recycledwater,andharvestedstormandrainwatertosupplyitsurbandemands.

3.6.3 SoutheastQueensland

SoutheastQueensland(SEQ)isservicedbywhatisarguablythemostcomplexwatersupplysysteminAustralia.KnownastheSEQWaterGrid,thesupplyareaitcoversisabout22,000km2,extending240kmfromtheShireofNoosainthenorthtotheGoldCoastandtheNewSouthWalesborderinthesouth.ItencompassesthetenlocalgovernmentareasofBrisbane,theGoldCoast,Ipswich,LockyerValley,Logan,MoretonBay,Redland,ScenicRim,SomersetandtheSunshineCoast.

Newinstitutionalarrangementsforthemanagementandoperationoftheregion’swaterservicescameintoeffecton1January2013.SevenseparateauthoritiesandutilitiesarecollectivelyresponsiblefortheSEQWaterGridandarecomprisedofabulkwaterauthority(Seqwater),anetworkcontrollerforbulksupplies(LinkWater)awatergridoperator(SEQWaterGridManager),anoperatorfortheregion’sdesalinationandrecycledwaterplants(SecureWater),andthreeretailsuppliers(UnityWater,QueenslandUrbanUtilitiesandAllconnexWater).

Seqwaterisresponsibleforthecollectionandstorageofsurfacewater,extractionofgroundwater,operationofthedesalinationfacilitiesandthearea’sWesternCorridorRecycledWaterScheme.Inaddition,Seqwateristhecatchmentmanagerforthearea'ssurfacewaterandgroundwatersupplycatchments.

LinkWateroperatesandmaintainsthebulkwatersupplynetworkandisresponsibleforthetransportationofwatersuppliestotreatmentplantsandbetweenstorages.

AstheownerofurbanwaterentitlementsintheSEQregiontheSEQWaterGridManageroperatestheSEQWaterGridtosupplythecouncil-ownedretailauthoritiesandindustrywithpotablewater.

SecureWateroperatestheGoldCoastdesalinationplantandtheWesternCorridorRecycledWaterScheme.

Theregion'surbanwaterutilitiesareUnityWater(MoretonBayandSunshineCoast),QueenslandUrbanUtilities(Brisbane,ScenicRim,Ipswich,SomersetandtheLockyerValley)andAllconnexWater(GoldCoast,LoganandRedland).Inadditiontotheprovisionofwatersupplyservicestheseutilitiesareresponsibleforthecollectionandtreatmentofwastewater.


Figure 3.47 Urban supply storages in the North East Coast region

North East Coast


Supply system

Theregion'swatersuppliesaredrawnfromacomplexnetworkofsurfacewaterstorages,watertreatmentplants,groundwaterborefieldsandrecycledanddesalinatedwaterplants.

Overtenmajorsurfacewaterstorages,includingWivenhoe,SomersetandNorthPine,aseriesofsmallstoragesandweirs,theStradbrokeIslandandBribieIslandborefields,theTugandesalinationplant,theWesternCorridorRecycledWaterSchemeandacomplexnetworkofpipes,servicereservoirs,pumpstationsandtreatmentplantsmakeuptheSEQWaterGrid.

Figure3.48outlinesthemajorwaterinfrastructureinsoutheastQueenslandandillustratesurbanflowpathwaysbetweenlocalgovernmentandothermaincustomers.

Somewaterisexportedtocostumersbeyondthissystem,thelargestbeingtheTarongPowerStation.

Storage volumes

Incombination,theWivenhoe,Hinze,SomersetandNorthPinestoragesprovideover90%ofthetotalaccessiblesurfacewaterstorageforSEQ,withWivenhoecontributingoverhalfofthistotal.

Figure3.49presentsthetotalaccessiblevolumeheldinthesestoragesoverthepast18years(1984–2012)andclearlyillustratestheimpactsofthemillenniumdroughtwithstorageslevelsreachingcriticallylowlevelsin2008.Ashiftinclimaticconditionsin2009andaseriesofwetteryears,includingAustralia’swettesttwo-yearperiodonrecordin2010and2011,sawstoragelevelsrecoverfromtheirhistoriclows.Continuedgoodrainfallintheregion'scatchmentshasseenstoragelevelsmaintainedatornearcapacitythroughout2011–12.

TheobservedstepchangeintheaccessiblevolumesoftheHinzestorageisexplainedbyanincreaseinthestorage’stotalcapacity.ComingintoeffectinDecember2011,theHinzeDamwasraisedtoincreasethetotalaccessiblestoragefrom161GLto311GL.


Figure 3.48 Water supply schematic for southeast Queensland

North East Coast


Figure 3.49 Variation in the amount of water held in storage over recent years (light blue) and over 2011–12 (dark blue) for the Hinze, Wivenhoe, Somerset and North Pine storages, as well as total accessible storage capacity (dashed line)

Gold Coast (Hinze)

Brisbane (Wivenhoe)

Brisbane (Somerset)

Brisbane (North Pine)


Water restrictions

Followingitsformationon1January2013,SeqwaterhastakenoverthewatersecurityandefficiencyresponsibilitiespreviouslyperformedbytheQueenslandWaterCommission.

Waterrestrictionshavebeeninplacesince2005,andappliedthroughoutSEQ,excludingRedland,SunshineCoastCouncilandToowoombauntilDecember2009.TheyareshownwiththecombinedstoragelevelsinFigure3.50.

Between2005and2008combinedstoragelevelssteadilydecreasedresultingintheintroductionofmorestringentwaterrestrictions.

Permanentwaterconservationmeasures(PWCM)wereintroducedinDecember2009acrosssoutheastQueenslandincludingtheSunshineCoast.Althoughthecombinedstoragelevelremainedabove80%during2011–12,PWCMremainedinplace.Thesemeasuresencouragedtheuseofamaximumof200litresperpersonperday.

Figure 3.50 Urban water restriction levels across southeast Queensland since 2005 shown against the combined accessible water volume of Wivenhoe, Somerset and North Pine storages

North East Coast


Sources of water obtained

BecauseofdatalimitationsthefollowingdiscussionofsourcesofwaterobtainedpertainsonlytotheBrisbane,LoganandGoldCoastCityCouncilareas.Forthepurposesofthisandthefollowingsectionsthissupplyareaisreferredtoasthe‘combinedarea’andrepresentsthecentralandsouthernextentsoftheSEQWaterGrid.

Figure3.51showsthetotalvolumeofwatersourcedfromsurfacewaterextractions,groundwater,recycling,andbulkwatertransferstothecombinedareaforthelasteightyears(2005–06to2011–12).

FollowingchangestothemanagementofbulkwaterresourcesinSEQwiththecreationoftheSEQWaterGridin2008,reporteddatanolongerdistinguishes

betweenlocallysourcedsurfacewaterandsurfacewaterimportedtothearea.

Theobserveddownwardtrendinthetotalvolumeofwatersourcedforurbansupplyisattributabletodemandmanagementandwaterconservationmeasuresputinplaceinresponsetodwindlingsurfacewaterstoragelevels.

Ashiftinclimaticconditionsin2009andaseriesofwetteryearshasseenstoragesinSEQrecovertoatornearfullsupplylevelsandresultedinaneasingofwaterrestrictions.Theseconditionshaveseenagradualincreaseinthetotalamountofwatersourcedforurbansupplytotheareaandareductioninthevolumeofrecycledwaterusedtomeettheareasdemand.

Figure 3.51 Total urban water sourced for the combined area from 2005–06 to 2011–12


Categories of water delivered

Asinthepreviousdiscussionthissectionreportsonwaterusageforthe‘combinedarea’comprisingBrisbane,LoganandGoldcoastcouncils.

Figure3.52showsthetotalvolumeofwaterdeliveredtoresidential,commercial,municipal,industrial,andotherconsumers,suchasnurseries,parks,gardensandcemetaries,inthecombinedarea.

Totalwatersuppliedwas220GLin2005–06thatthendecreasedfortwoconsecutiveyearsduetowaterrestrictions.Between2007–08and2009–10,

totalwatersuppliedincreasedslightlyduetotheeasingofwaterrestrictionsandthereintroductionofoutdoorwatering.Thetotalvolumeofwatersuppliedtourbancustomersin2011–12was176GL.Recentwateruseislowcomparedtothatin2005–06.

Averagetotalresidentialwaterconsumptionofthecombinedareain2011–12was297ML/dor158litresperpersonperday(L/p/d).Theresidentialsectoraccountedfor62%oftotalpotablewaterconsumption(similartothepreviousyearwhenresidentialconsumptionwasestimatedtobe59%).Thecommercial,municipalandindustrialsectorsaccountedfor26%ofurbanwaterconsumption.

Figure 3.52 Total urban water supplied to the combined area from 2005–06 to 2011–12

North East Coast


3.7 Waterforagriculture

ThissectiondescribesthewatersituationforagricultureintheNorthEastCoastregionduringthe2011–12yearcomparedwiththepast.Soilmoistureconditionsarepresentedandimportantirrigationareasareidentified.TheBurdekinirrigationareaisdescribedinmoredetailandinformationisprovidedregardingsurfacewaterstorageandgroundwater.

3.7.1 Soilmoisture

Sincemodelestimatesofsoilmoisturestoragevolumesarebasedonasimpleconceptualrepresentationofsoilwaterstorageandtransferprocessesaveragedovera5kmx5kmgridcell,theyarenotsuitableforcomparisonwithlocallymeasuredsoilmoisturevolumes.Thisanalysis,therefore,presentsarelativecomparisononly,identifyinghowmodelledsoilmoisturevolumesof2011–12relatetomodelledsoilmoisturevolumesofthe1911–2012period,expressedindecilerankings.

Figure3.53givesanoverviewofthedecilerankingofmodelledannualaveragesoilmoisturefor2011–12withrespecttothe1911–2012period.Itshowsthatthemajorityoftheregionhadaboveaverageorverymuchaboveaveragesoilmoistureconditions.Thelatterconditionsweremoreprominentinthewesternpastoralandcroppingareasoftheregionwhereverymuchaboveaveragerainfallsoccurredinthatperiod.

AboveaveragesoilmoistureconditionsintheregionweredominantinthewetmonthsofNovember2011–March2012(Figure3.54).Soilmoistureremainedverymuchaboveaverageinallothermonthsoftheyear.Itcreatedbeneficialwaterconditionsfordrylandcroppingacrosstheinlandandwesternpartsoftheregionwhicharenormallydrier.

Figure 3.53 Deciles rankings of annual average soil moisture for 2011–12 with respect to the 1911–2012 period for the North East Coast region

Figure 3.54 Decile ranking of the monthly soil moisture conditions during the 2011–12 period with respect to the 1911–2012 period in the North East Coast region


3.7.2 Irrigationwater

TheDepartmentofEnergyandWaterSupply,establishedinApril2012,providespolicyandregulationforthedeliveryofwatertoQueensland.

SunWaterisagovernment-ownedcorporation,whichisthemainsupplierofbulkwater,bulkwaterstorageanddeliveryofservicesforregionalQueensland.Inthesoutheast,Seqwaterprovidesbulkwatersupplyandservicestoaround1,000ruralcommunitiesinfivewatersupplyschemesintheUpperMary,Logan,CentralBrisbane,WarrillvalleyandLockyervalleyareas.

Acomparisonofwateruseinirrigatedcatchmentsbynaturalresourcemanagement(NRM)regionsintheregionovertheperiod2005–06to2010–11isshowninFigure3.55.Figure3.56showsthemapofthewateruseperNRMregionin2010–11.

AswiththepreviousyearsBurdekinhadthehighestirrigationwaterconsumptionamongotherNRM

regions,butthewateruseduringthe2010–11inallregionshaddroppedduetoincreasedavailabilityofwaterthroughrainfall.Atthetimeofwritingthereportdatawasnotavailablefor2011–12.

TheBurdekinRiverIrrigationAreaisdescribedinmoredetailinsubsection3.7.4

3.7.3 Irrigationareas

MostoftheNorthEastCoastregionisusedforgrazing.Drylandandirrigatedagricultureaccountforonly0.4%ofthelanduseoftheregion.Thegreatestareaofdrylandagriculture,1.8millionhectares,islocatedintheFitzroyRiverbasin.

AsshowninFigure3.57,thelargestirrigationareasarelocatedintheBrisbane,Mary,Burnett,BurrumandKolanriverbasinsinthesouth;theFitzroy,PlaneCreekandPioneerriverbasinsinthecentreoftheregion;andtheHaughtonandBurdekinriverbasinsinthenorth.

Figure 3.55 Total annual irrigation water use for 2005–06 to 2010–11 for natural resource management regions in the North East Coast region (ABS 2006–2010; 2011a)

North East Coast


Figure 3.56 Annual irrigation water use (GL) per natural resource management region for 2010–11 in the North East Coast region (ABS 2011a)


Figure 3.57 Irrigation areas in the North East Coast region

North East Coast


3.7.4 BurdekinRiverIrrigationArea

TheBurdekinRiverbasinislocatedinthedrytropicsontheNorthEastCoastregion,coveringatotalcatchmentareaofapproximately133,000km2.

Thebasin’sassetsincludewater,biodiversity,nationalparks,grazing,fertilesoilandcrops(Figure3.58).

TheLowerBurdekininthebasinisthelargestirrigationareainnorthernAustralia,predominantlygrowingsugarcane.Thispartoftheregioncanreceivemorethan300daysofsunshineeachyear,whichisaprimaryreasonforthehighlyproductiveagriculturalsector.Thiscanbetempered,however,bythetraditionalwetseason,whichrunsfromNovember–MarcheachyearwiththewettestmonthstypicallybeingJanuaryandFebruary.

LowerBurdekincomprisestwoschemes:theBurdekinRiverDelta,andtheBurdekin–HaughtonWaterSupplyScheme.

TheBurdekinDeltadownstreamoftheBurdekinRiverisagroundwater-dominatedscheme,with

morethan35,000haofirrigatedsugarcaneandothercrops.Thissystemoverliesmajorgroundwatersupplies.

TheBurdekin–HaughtonWaterSupplySchemeissurfacewaterdominatedandreceivessignificantvolumesofwaterfromBurdekinFallsstorage.Groundwatersuppliessupplementirrigation.

BurdekinFallsontheBurdekinRiverisoneofthelargestsurfacewaterstoragesinQueenslandcovering22,000haandissuppliedbyanupstreamcatchmentareaofapproximately120,000km2.ThetotalaccessiblestoragecapacityofBurdekinFallsis1,850GL.

TotalwaterdeliveryintheBurdekin–Haughtonschemein2011–12was455GL,whichwas41percentofthewateravailabletothescheme(SunWater2012).

Forthepurposeofthisreport,theBurdekinRiverIrrigationAreawasselectedasanexampleofgroundwateruseforirrigationintheNorthEastCoastregion.

Figure 3.58 Burdekin River Irrigation Area


Surface water storage inflows

Thehighlyseasonalrainfallpatternoftheregion,whichischaracteristicofthetropicsofnorthernAustralia,ishighlightedbythehistoricalstreamflowdischargerecordsofgaugingstationsontheSuttorRiveratStAnns,CapeRiveratTaemasandBurdekinRiveratSellheim(Figure3.59).

TheseasonalrainfallpatternislinkedtotheElNiñoSouthernOscillation,tropicalcyclonesandmonsoonalactivity.

ThemajorityoftherecordeddischargeinthethreecatchmentsupstreamofBurdekinFallsfortheperiod1980–2012occurredduringthemonthsofJanuarythroughtotheendofMarch,whichisthewetseasonintheregion.

Thedischargehydrographsof2011–12showalaginpeakflowcomparedwiththehistoricalpatterns.Thisisconsistentwiththeoverallpatternofrainfallintheregion;showinggradualascentwithapeakinMarchthatsubsidesafterwards.

Figure 3.59 Monthly inflows to Burdekin Falls for 2011–12 with respect to the 1980–2012 decile rankings

North East Coast


Surface water storage volumes

DespitethelargestoragecapacityofBurdekinFalls,thesignificantseasonaldischargefromtheupstreamcatchmentshasresultedinanalmostperiodicspillingofthedameverywetseasonsinceconstruction(Figure3.60).Inwetyears,thespillingcancontinueformonths.In2011–12,thedamoverflowedfromJanuary2012andcontinuedtospillinJune2012.

BetweenJanuaryandJune2012,morethan29,000MLofwaterpassedoverthespillway.Thefullstorageandwetweatherconditionsensured100%ofwaterallocationswereavailabletolocalirrigators.

Local hydrogeology

IrrigationareasintheBurdekinRiverDeltaareunderlainbyarelativelyshallowwatertable.LowerBurdekinWatermanagesagroundwater-dominatedirrigationsystemdownstreamandeastofMountKelly(Figure3.61).Morethan1,400groundwaterpumpsareinoperationapplying10–40ML/ha/yrtocrops(McMahonetal.2002).Thisisequivalentto1,000–4,000mm/year.

Thewatersourceusedforirrigation(groundwaterorsurfacewater)dependsonproximitytotheriverorirrigationchannelsandongroundwatersalinityandyield.

Thecoastalfloodplainismostlyunconfinedandhasupto100mofsedimentsoverlyingthebasement.TheshallowgroundwaterinthissystemisindirecthydraulicconnectionwiththeBurdekinRiver.

Typically,duringthedryseason,groundwaterelevationishigherthansurfacewaterlevelsintheriverupstreamoftheRocksweirallowinggroundwaterdischargeintotheriver.Duringoccasionalhighflowsinthewetseason,thedirectionofflowisreversedallowingsurfacewatertorechargegroundwater(LenahanandBristow2010).Thisactivityindicatesahighconnectivitybetweensurfacewaterandgroundwater.

Lateralgroundwaterflowisnortherlytowardsthecoast.However,groundwaterpumpingcauseslargefluctuationsingroundwaterlevelsthatcanchangethelocalgroundwaterflowdirection.

Figure 3.60 Variation in the amount of water held in storage over recent years (light blue) and over 2011–12 (dark blue) for Burdekin Falls storage, as well as total accessible storage capacity (dashed line)


Figure 3.61 The Burdekin River Irrigation Area showing the location of groundwater bore sites, river gauge and rain gauge

North East Coast


Influences on shallow groundwater

Figure3.62showsthefluctuationsinshallowgroundwaterlevelsatselectedsites.From2003groundwaterlevelsshowarisingtrend.

Figure3.62alsoillustratesthedriversofthegroundwaterlevelbycomparingfluctuationinshallowgroundwaterlevelswiththemonthlycumulativerainfallresidualatAyrandthemonthlydischargeoftheBurdekinRiveratClare(Figure3.62).ThelocationofgaugesandboresisshowninFigure3.61.

Periodsinwhichthecumulativerainfallresidualcurverisesindicatewetterthanaverageconditions.Periodswithafallingtrendindicatedrierthanaverageconditions.

Figure3.62bshowsadrierthanaverageperiodupto2007,followedbyawetterthanaverageperiod.

Bothrainfallandstreamflowappeartobedriversforgroundwaterlevels.Peaksinstreamflowandintherainfallresidualcurvecorrespondtopeaksingroundwater.Thereare,however,someinconsistenciesbetweentherainfallandgroundwaterlevelcycles.Forexample,groundwaterlevelsstartrisingin1995and2003eventhoughtherainfallresidualmasscurveisstillfalling.

Figure 3.62 Comparison of shallow groundwater levels recorded at nested bore sites with rainfall and streamflow in the Burdekin River Irrigation Area to June 2012, showing (a) top panel: Bore 11910262 pipe D (red), Bore 12000202 pipe D (blue), Bore 11900162 pipe D (yellow); (b) cumulative rainfall residual mass at Ayr, Station 33002; and (c) lower panel: Burdekin River discharge at Clare, Station 120006B)


Groundwater level

Groundwaterlevelmeasurementisanimportantsourceofinformationabouthydrologicalandanthropogenicinfluencesonthegroundwaterinanarea,includingrecharge.

Figure3.63presentsgroundwaterlevelsrecordedinboresofdifferentdepthatthesamesite,anestedboresite,intheLowerBurdekinarea.Groundwaterlevelfluctuationsaresimilaratalldepthsindicatingthatdeeperandshallowergroundwaterishydraulicallyconnected.Verticalgroundwatergradientsaremostlydownwardindicatingpossibilityofflowfromthewatertabletothedeepestpartoftheaquifer.

Figure3.64(a)showsthemediangroundwaterdepthsintheuppergroundwateraquiferintheBurdekinRiverDeltain2011–12;Figure3.64(b)

showsthedecileranksof2011–12mediangroundwaterlevelscomparedtoannualmediangroundwaterlevelsinthelast22years(1990–2012).

Ingeneral,intheupperaquifer,groundwaterlevelsvaryfromquiteshallownearthecoasttodeeperthan10mfurtherinland.Mediangroundwaterdepthsintheupperaquiferin2011–12aremostlyabovetheaverageofrecordedlevelswithintheirrigationareaandareamixofaboveaverageandbelowaveragenortheastoftheirrigationareas.

AsshowninFigure3.65(a),groundwaterlevelsintheloweraquiferaregenerallybetweenoneandfivemetersbelowthesurface.Mediangroundwaterlevelsintheloweraquiferin2011–12aremostlyabovetheaverageofrecordedlevelsofthelast22yearsFigure3.65(b).

Figure 3.63 Groundwater levels between 2007 and 2012 recorded at selected nested bore sites in the Lower Burdekin area, depth of the screen interval increases from pipe D (shallow) to pipe A (deep)

North East Coast


Figure 3.64 (a) Upper aquifer median groundwater depths for the Burdekin River Delta in 2011–12, and (b) decile ranks of depth in 2011–12 compared to the 1990–2012 period. Deciles 1–3 are shown as below average (greater depth below surface), deciles 4–7 as average and deciles 8–10 as above average


Figure 3.65 (a) Lower aquifer median groundwater depths for the Burdekin River Delta in 2011–12, and (b) decile ranks of depth in 2011–12 compared to the 1990–2012 period. Deciles 1–3 are shown as below average (greater depth below surface), deciles 4–7 as average and deciles 8–10 as above

North East Coast


Groundwater salinity

Sincethe1960s,whentheQueenslandGovernmentcommencedregularmonitoringofgroundwaterquality,anincreaseinsalinityhasbeenreportedatmanysites.TwomainissueslinkedtodegradinggroundwaterqualityhighlightedbyLenahanandBristow(2010)are:

• anincreaseingroundwatersalinitybeyondirrigatedcroptolerancelevelreducingthegroundwaterresourcevolumeavailableforirrigation;and

• ecosystemsindeclineduetogreaterinfluxofsolutesfromtheaquifersintothesurfacewaterandultimatelyintotheGreatBarrierReef.

Increasinggroundwatersalinityatsomelocationsiscausedbyinfluencesonthehydrologicalcycle,suchaslandclearingandirrigation,whichmobilisesubsurfacesolutestores.

Increasesingroundwaterpumpingcanresultinseawaterintrusionorupwardmovementofdeepersaltygroundwater.Incontrast,decreasinggroundwatersalinitiesintheshallowsystemcanresultfromdilutionbyirrigationdrainageorleakagefromtheriver.

Figure3.66showsgroundwatersalinity,expressedinunitsofelectricalconductivity,atfourdepthsforeachofthreenestedboresitesinthelowerBurdekinRiverDelta(forborelocations,seeFigure3.61).

Groundwatersalinityinthedeepboresisusuallyveryhighcomparedtotheshallowbores.Atthesenestedsites,theshallowgroundwatersalinityismorethananorderofmagnitudelowerthansalinityindeeperbores.

Figure3.66alsoshowsthatgroundwatersalinityatthesesiteshasbeenrelativelystablesince2007.Ingeneralgroundwatersalinityisslowtochange.

Figure3.67andFigure3.68showthemediangroundwatersalinitiesintheupperandlowergroundwateraquifersin2011–12andtherankingofthesesalinitiescomparedto22-yearannualaveragesforthe1990–2012period.

TheBurdekinRiverDeltagroundwaterintheupperaquiferissaltierinthenorth,inthesoutheastnearthecoastandclosetothebedrockoutcropsinthesouth.Mediangroundwatersalinitiesintheupperaquiferin2011–12donotshowanyconsistenttrendfromthelong-termaverages.

Intheloweraquifer,saltygroundwaterappearstodefinethedistancefromthecoastwhereseawaterintrusionmayhaveoccurred.Mediangroundwatersalinitiesintheloweraquiferin2011–12againdonotshowanyconsistenttrendfromthelong-termaverage.

Figure 3.66 Groundwater salinity recorded at selected nested bore sites in the lower Burdekin area between 2007 and 2012, with depth of the screen increasing from pipe D (shallow) to pipe A (deep)


Figure 3.67 (a) Upper aquifer median groundwater salinity for the Burdekin River Delta in 2011–12, and (b) groundwater salinity in 2011–12 compared to the 1990–2012 period. Deciles 1–3 are shown as below average (greater depth below surface), 4–7 as average and deciles 8–10 as above average

North East Coast


Figure 3.68 (a) Lower aquifer median groundwater salinity for the Burdekin River Delta in 2011–12, and (b) groundwater salinity in 2011–12 compared to the 1990–2012 period. Deciles 1–3 are shown as below average (greater depth below surface), deciles 4–7 as average and deciles 8–10 as above average

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3 North East Coast - Bureau of Meteorology · 23.1 Intr1Io3tr1 2 23.1 IntIrodI1u ocu.i3 Tu.o2..u..hur1osaps 3 North East Coast 3.1 Introduction This chapter examines water resources