Yandicoogina Baseline Hydrology Page 1 of 60 Contents Page

Resource Development Surface Water Management

Baseline hydrology assessment for Yandicoogina discharge 02 April 2012 (Update to Report – Baseline hydrology assessment for Marillana Creek discharge released 4 May 2010)

Future expansion at RTIO Yandicoogina has the potential to increase the volume of surplus water generation and discharge into Marillana and Weeli Wolli Creeks. A baseline hydrological/hydraulic assessment was carried out to access the existing situation and movement of discharged water along the creek systems and to predict the likely behaviour of the released water for various discharge scenarios. Surplus water is discharged by BHPBIO and RTIO Yandicoogina mine operations at several locations along Marillana Creek (BHPBIO discharge outlet is located 2 km up gradient of the RTIO Oxbow deposit; RTIO discharge network is located adjacent to the Junction Central mine) and two outlets by RTIO Hope Downs 1 and Yandicoogina operations in Weeli Wolli Creek (Hope Downs 1 discharge outlet is located 500 m up gradient of the Weeli Wolli Spring; RTIO Discharge Outlet 6 is positioned adjacent to the Junction South East mine). In December 2009, the total average discharge rate to the creek systems from all three mining operations was 116 ML/day or 42 GL/year.

The assessment demonstrated that historically discharged water would not have extended past the Marillana Creek catchment outlet at the confluence with Weeli Wolli Creek; hence anecdotally no flow contribution to Weeli Wolli would have been expected. This suggests the wetting front in Weeli Wolli Creek is likely to have resulted from surplus water discharged from the Hope Downs 1 mine operation.

The average maximum steady state inundation or discharge footprint produced from the total average discharge, from 1998 to 2009, was expected to extend approximately 2.5 km down gradient from the confluence of Weeli Wolli and Marillana Creeks. On the other hand, the discharge footprint would extend 5.5 km downstream from the confluence if 60 GL/year (peak discharge from 1998 to 2009) of surplus water was released at a constant rate into the creek systems.

A discharge footprint of 35.4 km from the BHPBIO discharge outlet and 36.1 km from the Hope Downs 1 discharge outlet or 16.3 km down gradient from the Weeli Wolli – Marillana Creek confluence was estimated for the maximum modelled 110 GL/year regional surplus discharge (based on existing infrastructure). An option to relocate the discharge location in Marillana Creek down gradient from the mine operations was also investigated. Modelling indicated that the footprint distance would extend from approximately 6.7 km to 17.3 km down gradient from the Weeli Wolli – Marillana Creek confluence for modelled volumes 55 GL/year to 110 GL/year.

Due to the dynamic nature of the Weeli Wolli Creek system, the creek channel and in particular the section that drains the alluvial plain is capable of changing course during large flood events. This type of event would modify the existing drainage flow path of the discharged water and alter the course of the discharge footprints.

Yandicoogina baseline hydrology Page 1 of 60 Contents page

Introduction 3 1. Issue 3 2. Objectives 3

Catchment characteristics 4 3. Hydrology 4 4. Rainfall 5 5. Hydrogeology 7 6. Alluvium characteristics 8 7. Riparian vegetation 11 7.1 Mapped vegetation 11 7.2 Evapotranspiration 14

Discharge modelling 16 8. Modelling approach 16 8.1 Defining the discharge footprint 16 8.2 Surface water – groundwater connectivity 18 9. Discharge water balance calculations 20 9.1 Methodology 20 10. Modelling scenarios 28 10.1 Existing discharge regime 28 10.1.1 Scenario 1: Comparison of observed and predicted wetting fronts 28 10.1.2 Scenario 2: Average discharge between 2007 and 2009 29 10.1.3 Scenario 3: Peak discharge between 1998 and 2009 29 10.2 Proposed discharge scenarios 29 10.2.1 Scenario 4: Discharge rate options – 60 GL/year 29 10.2.2 Scenario 5: Discharge rate options – 90 GL/year 29 10.2.3 Scenario 6: Relocation of Marillana Creek discharge outlets 29 11. Modelling results 30 11.1 Existing discharge footprints 30 11.2 Proposed discharge footprints 33 11.2.1 Scenarios 4 and 5 33 11.2.2 Scenario 6 35

Conclusion 40

Appendix A – Base case output 42

Appendix B – Scenario output 47

Addendums– Scenario 7 to 9 including BHPBIO Jinidi 52

References 60

Yandicoogina baseline hydrology Page 2 of 60 Introduction

1. Issue Surplus water is generated as a result of mining below the groundwater table. The volume and rate of surplus water generation will be determined by the difference between the rate at which site and other parties can use the water and the rate of abstraction. The current total abstraction rate for Yandicoogina Junction Central (JC) and Junction South East (JSE) is 35 GL/year, with the potential to increase to a maximum 55 GL/year as a result of expansion and development of the Junction South West (JSW) and Oxbow deposits.

Management of water on Rio Tinto sites follows strict environmental and water use standards (refer to Rio Tinto Environmental Standards). These standards align with the Western Australian State Government Department of Water hierarchy of disposal options informal regulatory guidelines (Bessan Consulting Services, 2007) that recommend (in order of preference):

 Use on site;

 Transfer to another site or industrial location;

 Re-injection;

 Controlled discharge to surface (irrigation); and

 Uncontrolled discharge to surface (creek discharge).

Any surplus water not utilised in the first four strategies is currently being discharged into Marillana and Weeli Wolli Creeks.

Discharge of surplus water from the BHPBIO Yandicoogina mine operation into Marillana Creek began in May 1992. In 1998 RTIO started releasing surplus water into Marillana Creek and by December 2006 the combined operations were discharging at an average rate of 34 ML/day. Release of surplus water into Weeli Wolli Creek began in 2007 with expansion of the JSE mine and development of the Hope Downs 1 operation up gradient of Yandicoogina. By December 2009, the combined average discharge rate to Marillana and Weeli Wolli Creeks from all three operations was 116 ML/day.

2. Objectives The purpose of this study was to predict the hydrological reaction of the creek systems to artificial discharge. The specific objectives of the assessment were:

 To characterise the stream morphology of sections of Marillana and Weeli Wolli Creeks downstream of the discharge outlets. This was accomplished by reviewing the stream pattern, river/floodplain geometry, soil profile/geological logs, vegetation patterns and community distribution, and other characteristics of the receiving creeks to establish representative “reaches”.

 To determine the hydraulic characteristics associated with different volumes of water released into the system. This work was accomplished in order to determine the capacity and reaction (water movement) of the creeks at different discharge volumes.

 To establish the area over which the released water could travel (or discharge footprint).

Yandicoogina baseline hydrology Page 3 of 60 Catchment characteristics

The dearth of hydrological data in the Pilbara, especially related to small and medium sized catchments, their stream flow and rainfall distribution patterns, makes it impossible to use standard hydrology assessment methodologies to determine surface water flow characteristics in local Pilbara catchments. To overcome this limitation and to provide a methodology for estimating the potential flow conditions of artificial discharge into ephemeral Pilbara creeks, hydroecology techniques for evaluating water movement have been adopted.

Hydroecology is the inter-disciplinary study of the interactions between ecological processes and water movement. For the purpose of this study, information that could be extracted from the Pilbara landscape to help describe baseline hydrological characteristics, in the absence of historical stream flow or climate series data, included: vegetation patterns and communities in the riparian zone, pool location/absence and water quality, geomorphology of the creek bed, banks and floodplain, and soil/regolith geology properties and patterns (particularly as recorded in satellite remote sensing imagery). These catchment characteristics are described below and are subsequently used to define the inputs to the discharge modelling.

3. Hydrology The Weeli Wolli Creek regional catchment covers an area of approximately 4,000 km2. The upper Weeli Wolli Creek catchment, up gradient of the Hope Downs 1 mine, is characterised by relatively wide, flat plains of gentle gradient, surrounded by rugged hills of outcropping Marra Mamba Iron and Brockman Iron Formation. The Creek and its tributaries drain in a north easterly direction past the Hope Downs 1 mine site, converging at a narrow valley system. Weeli Wolli Spring is located at the mouth of the valley, approximately 10 km down gradient from the Hope Downs 1 mine site. The Creek continues its path downstream into the lower Weeli Wolli Creek catchment, joins with Marillana Creek to the west and drains onto a wide alluvial floodplain 20 to 30 km across in the Fortescue Valley, producing a meandering channel that can alter its course following large flood events. The flows terminate at the Fortescue Marsh, an internally draining basin of the Upper Fortescue River catchment.

Marillana Creek, a major tributary of the Weeli Wolli Creek system, has a total catchment area of 2,230 km2. The headwaters rise from the high relief areas of Hamersley Range where the Creek drains in an east and north easterly direction into the Munjina Claypan. The Claypan, an internally draining basin, has a total area of approximately 274 km2. It is subject to periodic inundation following rainfall events and has the potential to retain surface water flows for lower flood events, ≤ 1 in 10 year annual recurrence interval (ARI). Surface water exceeding the internal holding capacity of the basin spills south east into the lower Marillana Creek catchment. The lower Marillana Creek drains in an easterly direction through the existing BHPBIO and RTIO Yandicoogina operations before merging with Weeli Wolli Creek.

The Weeli Wolli regional catchment contains four flow gauging stations: 1) Flat Rocks on Marillana Creek (WRC number 708001), approximately 27 km up gradient of the current RTIO Yandicoogina mine operation; 2) Weeli Wolli Spring (WRC number 708016); 3) Tarina on Weeli Wolli Creek (WRC number 708014), approximately 5 km downstream from Weeli Wolli Spring and 4) Waterloo Bore on Weeli Wolli Creek (WRC number 708013), 7 km downstream from the Weeli Wolli/Marillana intersection. Daily flow data for the gauging stations are available from 1970s to present, with occasional missing data.

Yandicoogina baseline hydrology Page 4 of 60 The regional hydrology of the Marillana Creek catchment assessed in 2008 (RTIO) estimated the natural peak flow volumes at Oxbow, the intersection between the BHPBIO and RTIO Yandicoogina operations, to be 70 m3/s for a 2 year ARI event and greater than 2,000 m3/s for a 100 year ARI flood. Gauging information from the Tarina and Waterloo Bore gauging stations on Weeli Wolli Creek were extracted and flood frequency analysis performed (RTIO, 2009). Peak flow volumes for Weeli Wolli Creek at Tarina are expected to exceed 120 m3/s and 2,200 m3/s for a 2 year and 100 year ARI flood events, while the full Weeli Wolli Creek at Waterloo Bore (including flow contribution from Marillana Creek) is expected to reach 180 m3/s and 10,000 m3/s for 2 year and 100 year ARI floods.

Figure 1: Weeli Wolli Creek regional catchment

4. Rainfall Using the Köppen climate classification scheme1 based on temperature and rainfall, the Weeli Wolli Creek regional catchment is described as grassland: hot (persistently dry). Rainfall records are available from Flat Rocks (1972 – present), Munjina (1969 – present), Tarina (1985 – present), Waterloo Bore (1985 – present) and Wonmunna (1984 – present); locations of the gauging stations are illustrated in Figure 1. Average monthly rainfall for the region is provided in Figure 2. The average annual rainfall for the catchment is estimated to be 402 mm. Rainfall is episodic and highly variable between years (Figure 3), with annual recorded rainfall for the region between 180 mm and 810 mm.

1 http://www.bom.gov.au/lam/climate/levelthree/ausclim/koeppen2.htm

Yandicoogina baseline hydrology Page 5 of 60 120 Flat Rocks Munjina Tarina Waterloo Bore Wonmunna

100

60 Rainfall(mm)

0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Figure 2: Average monthly rainfall for Weeli Wolli Creek regional catchment.

Flat Rocks Munjina Tarina 1200 Waterloo Bore Wonmunna Average annual rainfall

1000

800

600 Rainfall(mm) 400

200

1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008

Figure 3: Annual rainfall data series (1969 – 2008) for gauging stations within the Weeli Wolli Creek regional catchment.

The majority of rainfall occurs during the hottest months, between December and March, resulting from cyclonic lows. Winters are dry and mild in comparison with lighter, winter rainfall expected in June/July each year. Larger than average annual rainfall were recorded in the Weeli Wolli Creek catchment particularly in 1973, 1975, 1995 - 2000 and in 2006, potentially under the influence of significant cyclonic activities. Seven major cyclones have passed in vicinity of the catchment for the period 1970 to present; Kerry in January 1973, Joan in December 1975, Bobby in January 1995, John in December 1999, Norman in February 2000, Clare in January 2006 and Emma in February 2006.

The annual average evaporation (dry bulb) rate recorded in Yandicoogina is 1791 mm/year, which exceeds the mean annual rainfall, keeping the landscape typically arid. The average annual pan evaporation for the region (from Department of Agriculture Western Australia,

Yandicoogina baseline hydrology Page 6 of 60 2003) is approximately 3500 mm. Due to the low rainfall (brief wet season) and large evaporation, water courses flow, if at all, for only brief periods.

5. Hydrogeology Hydrogeology of the Yandicoogina region is dominated by three types of aquifer:

 Unconfined, superficial/Quaternary formations of alluvial deposits;

 Unconfined, fractured Channel Iron Deposits (CID);

 Confined, fractured bedrock.

These aquifers are recharged primarily by direct infiltration of rainfall and via creek bed alluvials as a result of surface water flows during and/or following a storm event. The latest hydrogeological conceptual model for the Yandicoogina region (Yandicoogina Hydrogeological Field Program Report, RTIO-PDE-0071209) highlights the hydraulic connection between the superficial alluvium and the CID.

The natural depth to groundwater table (pre-mining) in the Yandicoogina region varies from 3 to 20 m below ground level with the general flow direction to the east within the Marillana Creek catchment and to the northeast along Weeli Wolli Creek. The groundwater flow system has since been modified as a result of abstraction for mine development, reinjection and/or permanent release of surplus water into the Marillana and Weeli Wolli Creek systems.

The existing surplus water discharge outlets along Marillana and Weeli Wolli Creeks are illustrated in Figure 4. BHP Billiton originally released surplus water into Marillana Creek at the discharge outlet at Anniversary Drive, approximately 2 km up gradient of the Oxbow deposit. This outlet was relocated in May 2007 and is now positioned 500 m downstream from the BHP railway bridge. Excess water from the Junction Central (JC) mining operation is discharged into Marillana Creek, via several outlets, adjacent to the mine. With the expansion of the Junction South East (JSE) deposit in 2006, two additional outlets, DO5 and DO6, were constructed to release surplus water into Marillana and Weeli Wolli Creeks. Discharge from the Hope Downs 1 mine into Weeli Wolli Creek is released, approximately 500 m up gradient of the Weeli Wolli Spring, 12 km upstream from the JSE DO6 outlet.

Response of the groundwater table, for the period 1991 to 2010, to natural cyclonic events, mine dewatering and surplus discharge in the Yandicoogina region are illustrated in Figure 5 and Figure 6. Bore locations of where the water level data were extracted are provided in Figure 4. It was demonstrated that impacts resulting from surplus water discharge are minimal compared to the natural fluctuations of the water table in response to storm and/or cyclonic events in the region.

Weeli Wolli Spring is the only groundwater fed naturally permanent pool identified in the study area. It provides a baseflow component to Weeli Wolli Creek at a rate of 4.2 ML/day. Other evidence of pools within the lower Weeli Wolli Creek catchment are transient and dependent on rainfall and surface water, with some now sustained by the surplus water discharge.

Yandicoogina baseline hydrology Page 7 of 60

Figure 4: Existing surplus water discharge outlets along Marillana and Weeli Wolli Creeks. The CID boundary (brown polygon) highlights the current RTIO Yandicoogina mine areas (Junction Central and Junction South East) and undeveloped deposits, including Oxbow, Junction South West and Billiard North/South. Groundwater levels as shown in Figures 5 and 6 were extracted from bores represented as blue dots in the figure.

6. Alluvium characteristics Alluvial and colluvial regolith characteristics, used as a surrogate for detailed soil information, govern the infiltration rate and storage capacity of the creek. These characteristics also influence the type and densities of vegetation communities developed within and adjacent to the creek, and subsequently influence evapotranspiration within the system. In general, the creek alluvium is comprised of interbedded layers of clays to sands and gravels to cobbles. The coarse alluvium at the surface of the creek bed is highly permeable, hence would rapidly recharge during creek flows (Australian Bore Consultants, 1997).

Based on geological sequences extracted from the Rio Tinto Iron Ore drillhole database, alluvial depth within the creeks range from approximately 5 m to 30 m along Marillana Creek and 9 m to 40 m along Weeli Wolli Creek. The alluvium is thin (possibly < 5 m thick) along a small section of Marillana Creek, adjacent to the JC mine. This indicates shallow CID and/or basement rocks of the Weeli Wolli Formation in and around the creek bed in this area. Drilling in the alluvium at Weeli Wolli Creek in 1997 intersected thick sequences of tight alluvial clay, resulted in premature termination of the monitoring bore at 4 m below ground level (the bore is located 1.4 km up gradient of the Weeli Wolli/Marillana confluence). If laterally continuous, the presence of this clay layer may cause perching of the watertable in particular following significant rainfall or flood events.

Yandicoogina baseline hydrology Page 8 of 60 520 Junction South East and Junction Central YJ-P92 YJ-P99 515 YJ-DD119 YM117

510

505

500

495

February1998

October2002

Water Level (m RL) (m Level Water January toApril 2006

490 -

May 2007 May -

485

480

December 1998

March2009

January1997

February1995

February2001

March2004

December1999

- -

475

Creeksflooded

BHPBMonthly Discharge quadruples

CyclonesClaire, Emma,Glenda and Hubert

PermanentandSacrificial Borefields Commissioned

CycloneThelma

CycloneBobby

CycloneWylva

CycloneRachel

CycloneJohn

CycloneMonty HairpinandPhil's CreekBorefields Commissioned 470 Dec-90 Dec-92 Dec-94 Dec-96 Dec-98 Dec-00 Dec-02 Dec-04 Dec-06 Dec-08 Dec-10 Date

Figure 5: Response of groundwater levels to natural cyclonic events, mine dewatering and surplus water discharge at JSE and JC

Yandicoogina baseline hydrology Page 9 of 60 Billiard North and South - Weeli Wolli Creek 500

99YJWB01 99YJWB02 99YJWB03 490 99YJWB04 YM119

480 August2006 -

470

injectioncommences

- January Aprilto 2006

460 -

Water Level (m RL) (m Level Water

March2010

- February2007

450 -

December2007

December2002

December 1998

January1997

February1995

February2001

March2004

December1999

- -

440

CycloneJohn

UnnamedTropical Low

CycloneRachel CycloneWylva CycloneBobby CycloneThelma

SouthernBorefiled Upgrade

CycloneMonty

HopeDowns Discharge 1

UnnamedTropical Low SouthernBorefield Commissioned; Billiard Re CyclonesClaire, GlendaEmma, andHubert 430

420 Dec-90 Dec-92 Dec-94 Dec-96 Dec-98 Dec-00 Dec-02 Dec-04 Dec-06 Dec-08 Dec-10 Date

Figure 6: Response of groundwater levels to natural cyclonic events, mine dewatering and surplus water discharge at Billiard North and South along Weeli Wolli Creek

Yandicoogina baseline hydrology Page 10 of 60 7. Riparian vegetation

7.1 Mapped vegetation Vegetation type, distribution and density can be related to the water availability, soil depth and conditions, and the channel morphology of a creek system. Several vegetation and flora surveys have been conducted in the Yandicoogina region, which include the Junction Central area by Mattiske in 1995, the Junction South East area by Biota in 2004 and the Oxbow, Junction South West and Billiard South areas by Biota in 2009. Riparian vegetation in Marillana Creek is dominated by woodlands of Eucalyptus camaldulensis (River Red Gum), E. victrix (Coolibah) over low open woodlands of Melaleuca argentea (Cadjeput) and M. glomerata. M. argentea is a groundwater dependent species, which primarily draws water from the saturated zone below the water table. Masini (1988) suggested the presence of M. argentea is indicative of permanent water. E. camaldulensis obtains its water from groundwater and river flooding, with mature trees more reliant on groundwater than young. Stands of River Red Gum are intimately associated with the surface flooding regime of the watercourses and related groundwater flow (CSIRO, 2004). Earlier study conducted by AGC Woodward-Clyde in 1992 concluded that the depth to groundwater is crucial to the distribution of M. argentea within the Marillana Creek system and suggested the likely maximum rooting depths of M. argentea is less than 5 m and that of E. camaldulensis is less than 10 m.

Riparian vegetation species, such as Eucalyptus victrix and Acacia citrinoviridis (Black Mulga), are commonly found in Weeli Wolli Creek within the Billiard South area. These tree species are believed to rely on water available within the vadose zone of the soil profile above the water table. This suggests these species prefer unsaturated soil conditions with periods of drought broken by groundwater recharge from surface flows and/or direct infiltration of rainfall.

Figure 7 illustrates the locations along Marillana and Weeli Wolli Creeks where photos were taken during the helicopter trip on 22 April 2010; Figures 8 to 15 illustrate the different vegetation types as observed during the site visit.

Riparian vegetation distribution and density within the study area are likely to vary depending on the fluctuations of the groundwater table as a result of mining activities. Figure 16 illustrates the change in vegetation pattern in a stretch of Marillana Creek, adjacent to the current JC mine, between 1994 and 2009. There is photographic evidence of increased density of riparian vegetation distribution within the creek system as a result of prolonged release of surplus water. The change in vegetation pattern is generally confined to areas adjacent to the discharge outlets and pools, identified as local depressions filled by discharged water.

The increase in riparian vegetation density associated with surplus water discharge could be exacerbated by increased creek flows and runoff at times where above average annual rainfall were recorded, in particular during the period 1995 to 2000 and in 2006. 2006 was a cyclone prone year with four cyclones passing through the region, between January and March, bringing heavy downpour to the catchment. This would enhance recharge, from rainfall and surface flows, of the superficial aquifer and would likely sustain the water level in the creek alluvium.

Yandicoogina baseline hydrology Page 11 of 60

Figure 7: Photo locations (illustrated as yellow triangles) along Marillana and Weeli Wolli Creeks during the helicopter trip on 22 April 2010. M1 to M3 illustrate photo locations along Marillana Creek and WW1 to WW5 along Weeli Wolli Creek.

Figure 8 (M1): Marillana Creek adjacent to the Figure 9 (M2): Marillana Creek – evidence of surface BHPBIO Yandi camp water expression on the creek bed (south western corner) as a result of BHP discharge

Yandicoogina baseline hydrology Page 12 of 60

Figure 10 (M3): Marillana Creek adjacent to the JSW- Figure 11 (WW1): Weeli Wolli Creek immediately C deposit downstream from the JSE Discharge Outlet 6

Figure 12 (WW2): Weeli Wolli Creek at Grey’s Figure 13 (WW3): Weeli Wolli Creek/Marillana Creek crossing, approximately 1 km upstream from the confluence – a wide floodplain of Coolibah woodlands confluence with Marillana Creek. This photo shows flooding of the access road by Hope Downs 1 and JSE discharged water.

Figure 14 (WW4): Weeli Wolli Creek showing Figure 15 (WW5): Weeli Wolli Creek at the alluvial progression of the wetting front plain

Yandicoogina baseline hydrology Page 13 of 60

Figure 16: Comparison between 1994 and 2009 aerial imagery showing vegetation change along a section of Marillana Creek, adjacent to the RTIO Yandicoogina JC mine.

7.2 Evapotranspiration Little is known of the water uptake and transpiration rate of riparian vegetation in the Pilbara but they are likely to vary with vegetation types and distribution within the creek system. High water use (groundwater dependent) species, such as Cadjeput and River Red Gums, are likely to transpire more than species that are adapted to drought conditions. Hydrological measurements conducted by Peck et al (1997) on a stretch of Marillana Creek, adjacent to the JSW deposit, revealed that evapotranspiration from the creek pools and riverine vegetation is approximately 25 to 35 % of the rate of evaporation from a standard pan. Based on these findings and the average annual pan evaporation 3500 mm estimated for the Yandicoogina area, the local evapotranspiration rates would vary between 875 and 1225 mm/year. Using Peck‟s estimations, information from available vegetation surveys and visual inspection during the site visit on 22 April 2010, the evapotranspiration rates of vegetation commonly found in Marillana and Weeli Wolli Creeks were estimated and summarised in Table 1.

Table 1: Estimated evapotranspiration rates of vegetation found in Marillana and Weeli Wolli Creeks

Evapotranspiration Photo location2 Main vegetation types (ET) rate (mm/year)

Eucalyptus camaldulensis (River M1 – dense and well Red Gum) 1050 established trees Eucalyptus victrix (Coolibah) Melaleuca argentea (Cadjeput)

M2 – dense and well Eucalyptus camaldulensis (River established trees with Red Gum) 1050 evidence of surface water Eucalyptus victrix (Coolibah) pools Melaleuca argentea (Cadjeput)

2 As of the locations of the photos taken during the helicopter trip on 22 April 2010, as illustrated in Figure 7

Yandicoogina baseline hydrology Page 14 of 60 Eucalyptus camaldulensis (River 700 - despite the same M3 – vegetation vigour Red Gum) vegetation types as evidently declines in this Eucalyptus victrix (Coolibah) above, ET rate was stretch of Marillana Creek lowered due to decline in Melaleuca argentea (Cadjeput) vegetation vigour

WW1 – narrow riparian Eucalyptus victrix (Coolibah) vegetation corridor; larger Acacia citrinoviridis (Black Mulga) 600 trees lined the banks of Weeli Wolli Creek

WW2 – wide floodplain with Eucalyptus victrix (Coolibah) 700 extensive vegetation growth Acacia citrinoviridis (Black Mulga)

WW3 – Weeli Eucalyptus victrix (Coolibah) Wolli/Marillana Creek Eucalyptus camaldulensis (River confluence; wide floodplain Red Gum) 1050 with extensive vegetation growth

WW4 – wide floodplain with Eucalyptus victrix (Coolibah) 700 extensive vegetation growth Acacia citrinoviridis (Black Mulga)

WW5 – alluvial plain Mulga species supporting smaller plant Shrublands/grasslands 530 species

Yandicoogina baseline hydrology Page 15 of 60 Discharge modelling

8. Modelling approach

8.1 Defining the discharge footprint How creeks behave and where water moves and pools when water is artificially added to a creek system are dependent on many interconnected variables, including discharge volume, creek bed topography, alluvial/colluvial thickness, evaporation, evapotranspiration and recent rainfall. Thus creek behaviour will vary over time, with season, changes in weather and along the length of the creek. This makes it difficult to map when and where changes to the system may occur and when those changes may impact other aspects of the creek ecology.

However, two important characteristics of the artificial discharge that can be quantified for a specified discharge rate in order to provide a basis for an assessment of the creek ecosystem reaction are (Figure 17):

 the minimum distance surface water will consistently flow along the surface of the creek bed, where the creek bed will be constantly saturated, and

 the maximum possible extent of surface water expression of any artificial discharge downstream of the outlet (maximum surface water inundation) or “discharge footprint”, where the creek bed may become saturated after a period of continuous discharge once steady state conditions are established.

Figure 17: Reactions states to creek discharge.

Yandicoogina baseline hydrology Page 16 of 60 As illustrated in the creek cross section in Figure 18, water discharged to a creek will flow along the surface of the creek, losing water via infiltration or evaporation; until the volume of water dissipates into the creek bed or is dammed by a small change in the creek bed topography (see Figure 17 – initial conditions).

As the creek bed becomes saturated, there is less room (pore space) for water to infiltrate into the creek bed. Infiltration rates will subsequently reduce as the wetting front moves through or around creek bed materials with lower porosity, i.e. clays, calcretes and even roots. When the volume of water flowing down the creek exceeds the volume of water removed from the creek via storage, recharge (loss beyond the root zone), evaporation and evapotranspiration, water will then start to flow across the creek bed again and the distance the surface water is seen to flow down the creek increases (see Figure 17 – transient conditions).

Evapotranspiration

Evaporation

alluvial

bedrock Infiltration

Recharge

Water balance equation:

Footprint = discharge volume (m3/s) length (m) evaporation x flow top width (m) + (evapotranspiration+recharge)(m/s) x riparian zone width (m)

Surface water = discharge volume (m3/s) expression (m) evaporation (m/s) x flow top width (m) + infiltration (m/s) x wetted perimeter (m)

Figure 18: Stylised water balance cross section and equations for estimating discharge impact.

Water will also move obliquely through the creek bed, albeit at a slower rate, if the effort required for the water to move vertically is greater than the effort to move horizontally. This can be the case if the pore space rapidly decreases vertically, for example with buried clay lenses, calcrete or shallow bedrock, or if there is a preferential pathway (micro-scale) of higher porosity within the alluvial sediments, such as those generated by plant roots, sand seams or rock fractures. This oblique water movement, also referred to as through-flow or interflow, enables water to return to the surface as surface water flow when the depth to the buried barrier decreases or the creek bed slope suddenly increases (break-of-slope); creating streams, increasing stream flow and/or creating pools.

Thus the degree of creek bed saturation, and the potential for water to be seen to flow over the creek bed, is influenced by creek bed topography and transient variations in climate, e.g. daily

Yandicoogina baseline hydrology Page 17 of 60 evaporation rates, seasonal evapotranspiration variations, rainfall and humidity. As a result, transient flow conditions dominate; such that the discharge may not be seen to continuously flow over the creek bed, although water may continue to flow through it.

Eventually, given relatively static environmental and atmospheric conditions, the system reaches equilibrium; when the volume of water entering the system is equal to the volume of water leaving the system through evaporation, evapotranspiration and losses beyond to root zone (recharge) (Figure 18). The length of the creek over which the discharged water is lost to the environment for these generalised “static” environmental and atmospheric conditions is described as the maximum3 surface water inundation or „discharge footprint‟ (see Figure 17 – steady state conditions).

8.2 Surface water – groundwater connectivity “In connected water resources4, the flow of water between the surface water feature and the aquifer is called the seepage flux. The convention is that positive seepage flux indicates upwards groundwater flow to the stream.” On a regional or creek system scale, surface water and ground water interactions are broadly described as (after Winter et. al., 1998):

 Gaining groundwater inflow (Figure 19) where seepage flux is positive. In the Pilbara gaining creek systems are characterised by permanent to semi-permanent water features such as pools or springs.

 Losing water to the underlying aquifer (Figure 20) where seepage flux is negative, however there is a connection (hyporheic zone) between the surface water and groundwater systems. In the Pilbara losing creek systems are characterised by semi- permanent pools, dense riparian vegetation, and shallow groundwater tables.

 Indirectly connected (or disconnected) losing stream (Figure 21) where seepage flux is negative with no hyporheic zone. In the Pilbara indirectly connected creek systems are characterised by the absence of surface water features and poorly defined riparian vegetation.

Figure 19: Schematic representation of surface water – groundwater interaction for a gaining system (after Winter et al., 1998).

3 The minimum distance of surface water expression is differentiated from the distance of maximum surface water inundation through the use of surface infiltration rates instead of evapotranspiration and recharge rates.

4 Sourced from http://www.connectedwater.gov.au/processes/index.html accessed 5 May 2010, defining a connected water resource as the combination of surface water feature(s), such as a river, estuary or wetland, and the groundwater system(s) that can directly interact in terms of movement of water.

Yandicoogina baseline hydrology Page 18 of 60

Figure 20: Schematic representation of surface water – groundwater interaction for a losing system with saturated connection (after Winter et al., 1998).

Figure 21: Schematic representation of surface water – groundwater interaction for an indirectly connected losing system demonstrating unsaturated connection with the groundwater aquifer (after Winter et al., 1998).

Some creek systems may always gain groundwater, or alternatively always lose water to groundwater. In most cases the water exchange direction varies significantly along a creek and water movement can alter in very short timeframes or seasonally in response to flooding or evapotranspiration (Winter et. al., 1998). Thus the average seepage flux condition is used to characterise the creek system.

However, in the ephemeral creek systems of the Pilbara, the effect (or impact) of creek discharge on a creek system is observed on a local scale. Thus it is necessary to characterise and predict the more complex, local scale behaviour of the water movement in order to appreciate and subsequently assess the impact of discharge within the discharge footprint.

On a local scale, water movement within a creek can be observed to:

 Flow over the creek bed (surface flow);

 Move in and out of creek bed and bank alluvial materials (interflow), changing the volume of surface flow without changing the total volume5 flowing down the reach;

 Mix with groundwater in the hyporheic zone, changing water chemistry6 without changing total flow volume;

 Gain volume from confined or unconfined groundwater aquifer discharge, changing water chemistry7;

5 Total flow volume is the proportion of the original discharge plus any additional groundwater discharge defined as the input discharge rate for the reach. 6 Applicable when groundwater chemistry is different from surface water chemistry 7 Applicable when groundwater chemistry is different from surface water chemistry

Yandicoogina baseline hydrology Page 19 of 60  Lose volume to the atmosphere and riparian vegetation; or

 Lose volume to recharge into groundwater aquifers.

Within our model it is necessary to establish whether a reach is gaining or generically losing (losing or indirectly connected), to define the recharge rate. Converse to seepage flux, recharge is positive when water volume is lost from the reach and negative when water is gained, due to the mathematical equation employed. Specific gaining or losing behaviour conditions for the reaches are subsequently established through observation of the local catchment conditions.

However, by differentiating between surface infiltration rates from the surface water expression equation and recharge plus evapotranspiration loss rates from the discharge footprint equation, it is possible to determine whether total flow volume loss is limited by surface creek bed conditions or from subsurface geological constraints.

Water movement that is limited by surface infiltration is generally associated with indirectly connected losing reaches. The saturation footprint is generally limited to the area directly beneath the surface flow. While this water can be accessed by riparian vegetation, unless the flows flood the riparian vegetation the increased plant available water will result in a general increase in vegetation vigour and recruitment.

Water movement that is limited by subsurface geological constraints is most likely to encourage water to move in and out of the creek bed, creating transient pools and associated saturated bank conditions within the reach. Sustained discharge into ephemeral creek reaches with subsurface geological constraints is likely to produce the greatest degree of change in the reach, with saturated bed and bank conditions potentially resulting in bank degradation/collapse and decreased vegetation vigour or death in plants adverse to saturated soil conditions.

9. Discharge water balance calculations Definitive spatial data and temporally varying climate, infiltration, evapotranspiration and soil information is generally not available for Pilbara creek tributaries. This makes it impossible to use two-dimensional or numerical models to accurately map catchment and creek response. As an alternative, an empirical methodology was developed employing the simple, conservative water balance equations from Figure 18 to estimate the length of the creek over which the discharge is lost to the environment.

9.1 Methodology Each branch of the creek below the discharge outlet is divided into sections or “reaches” with similar catchment characteristics. Estimates of evaporation, evapotranspiration and infiltration beyond the soil root zone (recharge) are then assigned to the reach based on the catchment characteristics or information inferred from the catchment characteristics (refer to Sections 4 to 7). A description of how the input values were determined is summarised in Table 2.

Reach geometry inputs including the wetted perimeter (the cross section of the creek under water) and top width (the water surface exposed to evaporation) were determined using the Manning formula, which is an empirical formula for open channel flow. From the reach input values the potential out flow, or loss to environment, was determined. By subtracting the outflow from the inflow, the balance of the flows was distributed to the next downstream reach, until no flow remained. The surface water expression estimate (Figure 18) calculates the minimum distance downstream from the discharge outlet that will be constantly saturated.

Yandicoogina baseline hydrology Page 20 of 60 The discharge footprint is defined as the length of creek over which all loss activities could take place, representing the area where alluvial saturation conditions (increased available water) will vary. For example, saturation conditions and associated pools, in between the minimum and maximum lengths will vary with vegetation growth (season) and climate conditions.

A 19 km section of Marillana Creek was modelled from the current BHPBIO discharge location to the catchment outlet and a 39 km section of Weeli Wolli Creek was modelled from the existing Hope Downs 1 discharge outlet to Puggs Bore (738293 E; 7492847 N). Both creeks were subdivided into six reaches with similar creek morphology, soil conditions and vegetation type and patterns (Figure 22). Average reach characteristics used as input into the water balance equation are presented in Table 3 and Table 4.

Table 2: Model simulation inputs Input value Description

Reach geometry Channel dimensions including channel base width and bank (side) slopes, reach length and bed slope were estimated based on 1:5000 scale spot height and 1 m contour data, with accuracy of +/- 0.2 m horizontal and +/- 0.17 m vertical. In the most downstream section of Weeli Wolli Creek regional 1:50,000 scale spot height data was available, suitable for 10 m contour data only.

Manning’s roughness Manning’s roughness coefficients were estimated according to the Guide coefficient n for selecting Manning’s roughness coefficients for natural channels and floodplains, (USGS 1990) in consideration of channel irregularities, variation in cross section, obstructions, vegetation density and meandering of the reach.

Flow conditions The Manning formula was used to calculate the wetted perimeter, top width, velocity, and water depth of the flow. The average reach value was then used in the water balance equation.

Vegetation width Estimated from 1: 10,000 geological mapping, available vegetation and flora surveys and aerial photographs, the extent of riparian vegetation growth is averaged for each reach. The vegetation width is used to estimate both the area of evapotranspiration and recharge as horizontal movement of water beyond the riparian zone is considered to be minimal.

Evaporation Estimated from average annual pan evaporation for the Yandicoogina area, 3500 mm/year (from Department of Agriculture Western Australia, 2003).

Evapotranspiration The local evapotranspiration rate was estimated to range from 530 to 1050 mm/year based on vegetation types and density (Table 1).

Recharge rate The recharge rates represent the estimated loss of water to below the root zone. Due to the lack of knowledge on the rate of recharge in the area, regional estimates for the Pilbara, 1 x 10-7 m/s for clay materials and 2 x 10-7 m/s for sandy materials, were used. These estimates are used by the Bureau of Rural Science for ‘loss’ or ‘recharge’ estimation (Raupach et al., 2001). However, loss of water to below the root zone does not necessarily represent groundwater recharge. If used for groundwater recharge estimation, these values will overestimate recharge in groundwater fed creek systems and underestimate recharge rate over deep alluvial/sedimentary geology.

Surface infiltration rate An estimate of the soil infiltration rate for a typical sandy to loamy Pilbara floodplain alluvial of 10 mm/h was used for both creeks.

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Figure 22: Reach locations along Marillana and Weeli Wolli Creeks

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Table 3: Reach characteristics used to model different discharge volumes at Marillana creek. Marillana Creek – Reach 1

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Marillana Creek Reach 1 starts from the current BHP discharge outlet, 500 m down Reach length (m) 1,336 gradient from the BHP railway bridge. Water is released into a defined, relatively stable floodplain Low flow channel – base drainage channel, with minor meandering planform and active floodplain of 12 width (m) approximately 140 m wide. Vegetation is well established within the reach and evenly floodplain distributed across the floodplain. Vegetation is dominated by woodlands of Eucalyptus

Riparian width (m) 140 Lowchannelflow camaldulensis (River Red Gum), E. victrix (Coolibah) and Melaleuca argentea (Cadjeput). Bed slope (m/m) 0.00257 The groundwater table has risen by approximately 8 m along this reach (the 2008 Manning’s roughness 0.065 ~ 522 mRL groundwater table is approximately 1 – 2 m below the creek bed), with photographic ~ 15 m evidence of surface water expression as a result of prolonged surplus water discharge. Infiltration rate (mm/h) 10 ~ 514 mRL It is likely that, during a flood event, the alluvium would rapidly saturate, resulting in groundwater discharging into the creek for weeks or months until the water table Recharge rate (m/s) 2 x 10-7 Not to scale recedes to its preceding level. This reach is recognised as a losing system and subsurface geological constraints are identified as the likely limiting factor for the Evaporation (mm/year) 3500 0 50 100 150 200 250 300 350 400 450 500 volume of water lost from the system. ET (mm/year) 1050

Marillana Creek – Reach 2

Reach characteristics Typical cross section Riparian vegetation corridor Summary

The channel within Reach 2 is more incised and braided than Reach 1 with greater Reach length (m) 2,660 degree of meandering. While the width of the floodplain and riparian zone is slightly Low flow channel – base wider than in Reach 1, vegetation appears to be less dense except at locations where

16 floodplain width (m) floodplain the CID aquifer is intersected (as highlighted in the aerial imagery). The inner section of the reach where the CID is absent, vegetation vigour declines. Vegetation is mainly Riparian width (m) 150 comprised of woodlands of Eucalyptus camaldulensis (River Red Gum), E. victrix Lowchannelflow (Coolibah) and Melaleuca argentea (Cadjeput). Bed slope (m/m) 0.00209 The groundwater table has risen by approximately 5 m along this reach (the 2008 groundwater table is approximately 2 m below the creek bed), with photographic Manning’s roughness 0.065 ~ 518 mRL evidence of surface water expression as a result of prolonged surplus water discharge. ~ 12 m Infiltration rate (mm/h) 10 ~ 513 mRL It is likely that, during a flood event, the alluvium would rapidly saturate, resulting in groundwater discharging into the creek for weeks or months until the water table -7 Recharge rate (m/s) 2 x 10 recedes to its preceding level. This reach is recognised as a losing system and Not to scale subsurface geological constraints are identified as the likely limiting factor for the Evaporation (mm/year) 3500 volume of water lost from the system. 0 50 100 150 200 250 300 350 ET (mm/year) 1050

Marillana Creek – Reach 3

Reach characteristics Typical cross section (for the lower section of Reach 3) Riparian vegetation corridor

Reach 3 is characterised by a meandering creek with less defined banks, but wider and Reach length (m) 3,129 flatter floodplain. Water will be distributed across a wider area during floods in this Low flow channel – base floodplain reach than Reach 1 or 2, hence reduces the average flood water levels and velocities 17 width (m) and allows deposition of sediments along this reach. Common riparian vegetation

floodplain found in this reach includes Eucalyptus camaldulensis (River Red Gum), E. victrix

Riparian width (m) 200 Lowflowchannel (Coolibah) and Melaleuca argentea (Cadjeput) but vegetation vigour and density evidently decline in this reach than Reach 1 or 2.There was a 10 m difference in Bed slope (m/m) 0.00247 groundwater table between the upper and lower section of Reach 3, as observed in 2008. This was likely attributed to the effects of drawdown resulted from groundwater Manning’s roughness 0.045 ~ 506 mRL ~ 16 m abstraction at the adjacent JC mine. ~ 500 mRL Infiltration rate (mm/h) 10 There is evidence of surface water expression and pools along the upper section of Reach 3 while absent in the lower section, indicating the progression of the wetting front Recharge rate (m/s) 2 x 10-7 Not to scale of discharged water from the BHPBIO operation. Reach 3 is recognised as a losing system and subsurface geological constraints are identified as the likely limiting factor Evaporation (mm/year) 3500 0 50 100 150 200 250 300 350 400 450 500 for the volume of water lost from the system. ET (mm/year) 700

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Marillana Creek – Reach 4

Typical cross section (for the section of Reach 3 where the CID Reach characteristics Riparian vegetation corridor Summary intersects the creek bed) 510 Reach 4 characterises a section of Marillana Creek that drains adjacent to the JC Reach length (m) 5,172 floodplain 508 mine. It is defined by a braided creek system with incised banks and recognisable Low flow channel – base width secondary flow channels. Creek alluvium is notably thinner in this reach. 20 (m) 506 Surplus water from the mine operations (JC and JSE) are released at several locations along this reach producing surface flows and pools. Increased riparian vegetation Riparian width (m) 120 504 channelSecondary density and vigour were observed in areas adjacent to the discharge outlets and along

Bed slope (m/m) 0.00214 Lowflowchannel the fringe of surface water pools. Common vegetation includes Eucalyptus

502 camaldulensis (River Red Gum) and E. victrix (Coolibah). Manning’s roughness 0.05 < 5m Reach 4 is located within the cone of depression and influenced by groundwater 500 abstraction at the JC mine. The groundwater table at this reach is likely to fluctuate Infiltration rate (mm/h) 10 ~ 490 mRL locally depending on the abstraction rate and regime. The 2008 water table was at 485 -7 Recharge rate (m/s) 2 x 10 498 ~ 485 mRL mRL, approximately 15 m below the pre-mining water level. Reach 4 is recognised as a losing system and subsurface geological constraints are identified as the likely Evaporation (mm/year) 3500 Not to scale 496 limiting factor for the volume of water lost from the system. 0 100 200 300 400 500 600 700 800 900 ET (mm/year) 600

Marillana Creek – Reach 5

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Reach 5 is differentiated from Reach 4 by a significantly wider floodplain. During Reach length (m) 3,664 floods water is likely to spread across the floodplain, hence reduces the flood levels Low flow channel – base and velocities and allows deposition of sediments along this reach. However the inner 32 floodplain floodplain width (m) section of the reach (highlighted) is flanked north and south by outcropping Weeli Wolli Formation, which constricts flow such that water is likely to back up during large flood

Riparian width (m) 280 events. Lowchannelflow Vegetation density increases slightly in this reach than Reach 4; common vegetation Bed slope (m/m) 0.00257 includes Eucalyptus victrix (Coolibah) and Acacia citrinoviridis (Black Mulga).

Manning’s roughness 0.055 ~ 489 mRL The groundwater table has risen by approximately 10 m along this reach, with photographic evidence of surface water expression as a result of prolonged surplus Infiltration rate (mm/h) 10 ~ 18 m ~ 479 mRL water discharge. Increased vegetation density was observed along the fringe of surface water pools. Reach 5 is recognised as a losing system and subsurface Recharge rate (m/s) 2 x 10-7 Not to scale geological constraints are identified as the likely limiting factor for the volume of water

Evaporation (mm/year) 3500 lost from the system. 0 100 200 300 400 500 ET (mm/year) 600

Marillana Creek – Reach 6

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Reach 6 illustrates the mouth of Marillana Creek. This reach is characterised by a Reach length (m) 3,106 floodplain braided creek system within a wide floodplain that extends several hundred metres Low flow channel – base width across, with multiple, secondary active and inactive flow channels. During floods, 28 (m) water is likely to distribute across the floodplain, hence reduces the flood water levels and velocities within the reach.

Riparian width (m) 460 channelSecondary Lowchannelflow Vegetation is dense within this reach and dominated by woodlands of Eucalyptus camaldulensis (River Red Gum) and E. victrix (Coolibah). The dense vegetation assists Bed slope (m/m) 0.00236 to increase the evapotranspiration rates and recharge by increasing plant roots uptake. Manning’s roughness 0.05 ~ 485 mRL These conditions are likely to enable more discharged water to be accommodated in the system than the channel geometry alone allows. Infiltration rate (mm/h) 10 ~ 30 m ~ 471 mRL The groundwater table has risen by approximately 15 m along this reach. There is -7 evidence of surface water expression and pools along the upper section of Reach 6 Recharge rate (m/s) 2 x 10 Not to scale while absent in the lower section, indicating the progression of the wetting front of Evaporation (mm/year) 3500 0 200 400 600 800 1000 discharged water from the JC and JSE mine operations. Reach 6 is recognised as originally indirectly connected now functioning as a losing system and the channel ET (mm/year) 1050 wetted perimeter is identified as the likely limiting factor for the volume of water lost

from the system.

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Table 4: Reach characteristics used to model different discharge volumes at Weeli Wolli Creek. Weeli Wolli Creek – Reach 1

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Weeli Wolli Creek Reach 1 starts from the existing Hope Downs 1 discharge outlet, 10 Reach length (m) 4,500 floodplain floodplain km down gradient from the mine operation. Water flows down a relatively stable creek Low flow channel – base with minor meandering planform and active floodplain of approximately 200 m wide. 22 width (m) Weeli Wolli Spring is located 500 m down gradient from the discharge outlet. The groundwater table has intersected the sloping creek bed at the spring and groundwater Riparian width (m) 200 discharge is providing a base flow component to the pools located along the reach.

Lowchannelflow Reach 1 is recognised as a groundwater gaining system with Weeli Wolli Spring Bed slope (m/m) 0.00660 discharging at a rate of approximately 4.2 ML/day. Manning’s roughness 0.045 ? ? Riparian vegetation is well established within the reach; increased vegetation density was observed along the fringe of the permanent/semi-permanent pools. Insufficient Infiltration rate (mm/h) 10 ~ 30 m information was available to define the vegetation types within Weeli Wolli Creek Reach 1, but plant species are likely to associate with groundwater, such as Eucalyptus Recharge rate (m/s) -8 -5 x 10 camaldulensis (River Red Gum) and Melaleuca argentea (Cadjeput). (Weeli Wolli Spring Baseflow) Not to scale

Evaporation (mm/year) 3500

ET (mm/year) 700

Weeli Wolli Creek – Reach 2

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Reach 2 is characterised by a meandering creek with more incised banks and an active Reach length (m) 8,270 floodplain that varies in width. There are sections along the reach (sections that are floodplain floodplain Low flow channel – base width defined by narrow floodplain), that may experience high flow velocity during floods. 22 (m) Potential scouring and increased sediment loads may be experienced within these sections. Deposition of these sediments will occur whenever flow velocities reduce. Riparian width (m) 150 While Reach 1 is dominated by woodlands of large tree species these trees are generally absent in Reach 2. This vegetation pattern change may attribute to change in Bed slope (m/m) 0.00233 Lowchannelflow water availability within the reach. Plant species in Reach 2, which may include Manning’s roughness 0.045 Eucalyptus victrix (Coolibah) and Acacia citrinoviridis (Black Mulga), are likely to source ? ? their water requirements from the soil layer rather than groundwater.Groundwater Infiltration rate (mm/h) 10 ~ 30 m elevations are unknown along the reach but are expected to have risen since surplus Recharge rate (m/s) 2 x 10-7 water discharge began in 2006 from the Hope Downs 1 operation. Reach 2 is recognised as a indirectly connected losing system although subsurface geological Evaporation (mm/year) 3500 constraints are identified as the likely limiting factor for the volume of water lost from the Not to scale system. ET (mm/year) 600

Weeli Wolli Creek – Reach 3

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Weeli Wolli Creek Reach 3 is a relatively short reach, characterised by a stable and Reach length (m) 2,350 floodplain straight channel with well defined banks. This reach is likely to experience high flow Low flow channel – base velocity during floods. Potential scouring and increased sediment loads may be 27 width (m) expected within the reach. The riparian vegetation corridor is narrow in this reach but larger trees were observed to line the creek banks. Common plant species include

Riparian width (m) 77 Eucalyptus victrix (Coolibah) and Acacia citrinoviridis (Black Mulga). Lowchannelflow The JSE reinjection borefield is located east of the creek system. Reinjection and Bed slope (m/m) 0.00231 discharge of surplus water from the JSE mine, as well as discharge from the Hope Manning’s roughness 0.045 Downs 1 operation, have resulted in the rise of the groundwater table by approximately ~495 mRL 20 m. It is likely that, during a flood event, the alluvium would rapidly saturate, resulting Infiltration rate (mm/h) 10 ~ 10 m in groundwater discharging into the creek for weeks or months until the water table recedes to its preceding level. Reach 3 is recognised as originally indirectly connected Recharge rate (m/s) 2 x 10-7 ~475 mRL Not to scale now functioning as a losing system and subsurface geological constraints are identified as the likely limiting factor for the volume of water lost from the system. Evaporation (mm/year) 3500

ET (mm/year) 600

Yandicoogina baseline hydrology Page 26 of 60

Weeli Wolli Creek – Reach 4

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Reach 4 is defined by a meandering creek within a relatively narrow floodplain, but widens Reach length (m) 4,620 floodplain floodplain towards the confluence with Marillana Creek. Low flow channel – base width The riparian vegetation corridor widens slightly in this reach than Reach 3 with larger trees, 26 (m) such as Eucalyptus victrix (Coolibah) and Acacia citrinoviridis (Black Mulga) lined the banks of the creek channel. Riparian width (m) 80 Lowchannelflow The groundwater table has risen by approximately 20 m along this reach, with photographic Bed slope (m/m) 0.00274 evidence of surface water expression as a result of reinjection and surplus water discharge from both the JSE and Hope Downs 1 mining operations. As a result it is likely that, during ~485 mRL Manning’s roughness 0.05 a flood event, the alluvium would rapidly saturate, resulting in groundwater discharging into ~ 26 m the creek for weeks or months until the water table recedes to the pre-flood level. This Infiltration rate (mm/h) 10 ~465 mRL reach is recognised as originally indirectly connected now functioning as a losing system -7 and subsurface geological constraints are identified as the likely limiting factor for the Recharge rate (m/s) 2 x 10 volume of water lost from the system. Not to scale Evaporation (mm/year) 3500

ET (mm/year) 600

Weeli Wolli Creek – Reach 5

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Weeli Wolli Creek Reach 5 is located immediately downstream from the Marillana Creek Reach length (m) 8,069 floodplain floodplain intersection. The reach is characterised by a braided, meandering creek system dominated Low flow channel – base by multiple active and inactive flow channels that are capable of changing course during a 40 width (m) channel large flood event. The floodplain stretches from 300 m at the mouth to over 800 m across Secondary in the central section of the reach. The floodplain narrows again towards the end of Reach

Riparian width (m) 500 5, where the channel is constrained between outcropping Weeli Wolli and Brockman Iron Lowchannelflow Formation. This will constrict flow and cause water to back up during large flood events. Bed slope (m/m) 0.00229 Vegetation is dense in Reach 5, dominated by woodlands of Eucalyptus victrix (Coolibah). Manning’s roughness 0.055 Groundwater level varies from 3 m at the mouth to approximately 23 m (the pre-mining ~470 mRL water level) at the end of the reach. Insufficient information was available to define the soil Infiltration rate (mm/h) 10 ~ 32 m and alluvial conditions in Reach 5 to enable characterisation of the mechanisms that

-7 ~455 mRL sustain the extensive vegetation growth, in particular in the central section of the reach, Recharge rate (m/s) 2 x 10 where the groundwater table drops to > 15 m below ground level. The alluvials in Reach 5 may contain more clay and the presence of this clay layer may cause perching of the Evaporation (mm/year) 3500 Not to scale watertable thus provide a water source for vegetation growth. Reach 5 is recognised as originally indirectly connected now functioning as a losing system and subsurface ET (mm/year) 700 geological constraints are identified as the likely limiting factor for the volume of water lost from the system. Weeli Wolli Creek – Reach 6

Reach characteristics Typical cross section Riparian vegetation corridor Summary

Reach 6 is located within a wide, flat alluvial fan system that stretches 20 to 30 km across, Reach length (m) 10,728 characterised by a meandering creek system that is capable of changing its course during Low flow channel – base width floodplain large flood events. Reach 6 terminates at Puggs Bore, approximately 11 km up gradient of 37 (m) the BHP railway line. Groundwater elevations are currently unknown but are likely to be deep (20 – 30 m below Riparian width (m) 280 ground level), hence riparian vegetation maintained within this reach is unlikely to be Bed slope (m/m) 0.00188 Lowchannelflow groundwater reliant but sustained by water available within the unsaturated zone of the soil layer, recharged by surface flows and rainfall infiltration. Reach 6 was observed to support Manning’s roughness 0.045 smaller plant species, including some Mulga species over open shrubland and grassland. Reach 6 is recognised as an indirectly connected losing system and the channel wetted Infiltration rate (mm/h) 10 ~ 30 - 40 m perimeter is identified as the likely limiting factor for the volume of water lost from the Recharge rate (m/s) 2 x 10-6 ? ? system.

Evaporation (mm/year) 3500 Not to scale ET (mm/year) 530

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10. Modelling scenarios

10.1 Existing discharge regime The volume and rate of surplus water discharge on site is variable, depending on the mining schedule, season, occurrences of storm and cyclonic events and rate at which site can use the surplus water. Figure 23 illustrates the variability in surplus water discharge within the study area from 1998 t0 2009. The total discharge, from all three mine operations (BHPBIO Yandi, RTIO Yandicoogina and RTIO Hope Downs 1 operation), varies between 15,000 kL/day (May 2005) and 160,000 kL/day (February 2009). A steady increase in total discharge was observed from 1998 to 2000, predominantly resulted from water released from the BHPBIO operation, then a slow decline before a steep rise from 2006 attributed to the development and release of surplus water from the Hope Downs 1 and JSE operations. Based on the existing discharge regime of the sites, three scenarios were generated and modelled to assess the existing situation and movement of water along Marillana and Weeli Wolli Creeks.

DO3 (kL/d) DO4 (kL/d) DO5 (kL/d) HD (kL/d) BHP (kL/d) 180000 DO1 (kL/d) DO2 (kL/d) DO6 (kL/d) DO8 (kL/d) Total (kL/d)

160000

140000

120000

100000 kL/d 80000

60000

40000

20000

1998 1999 2001

2000 2002 2003 2004 2005 2006 2007 2008

Figure 23: Variability in surplus water discharge within the study area from 1998 to 2009

10.1.1 Scenario 1: Comparison of observed and predicted wetting fronts The wetting front associated with the discharge observed as a series of disconnected pools along Weeli Wolli Creek was monitored from March 2007 to February 2009. The distance extended downstream from the Hope Downs 1 discharge outlet was measured in October 2007 (22 km), December 2007 (23.5 km) and August 2008 (24 km). Under this scenario, the discharge regimes associated with the measured extents were investigated to assess the accuracy of the discharge footprint methodology:

a) 126 ML/day in October 2007

b) 125 ML/day in December 2007

c) 138 ML/day in August 2008

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10.1.2 Scenario 2: Average discharge between 2007 and 2009 Figure 23 revealed that surplus water discharge within the study area peaked during the period 2007 and 2009. The average discharge rate, 116 ML/day or 42 GL/year, between 2007 and 2009 was investigated in this scenario to assess the average maximum discharge footprint that could be expected along the creek systems between 1998 and 2009.

10.1.3 Scenario 3: Peak discharge between 1998 and 2009 In this scenario we investigate the response of the creek systems through continual discharge of 163 ML/day or 60 GL/year, the total peak rate recorded from the mine operations during the period 1998 and 2009. Discharge footprint was determined based on the assumption that steady state conditions were established.

10.2 Proposed discharge scenarios With future expansion and development of the JSW and Oxbow deposits, the total groundwater abstraction rate for the RTIO Yandicoogina operation may increase from 35 GL/year (currently licensed) to maximum 55 GL/year. This may increase the rate of surplus water generated and discharged into Marillana and Weeli Wolli Creeks. Hence discharge scenarios are used to investigate the potential changes to the creek systems resulting from different discharge rates and varying input locations.

10.2.1 Scenario 4: Discharge rate options – 60 GL/year Similar to Scenario 3, continual discharge of 60 GL/year is released into the creek systems. However in order to accommodate additional surplus water that may be generated from JSW and Oxbow, four options are modelled to investigate the response of the creek systems by increasing the current total peak discharge by 5, 10, 15 and 20 GL/year. Hence the modelled options in this scenario include:

a) 60 GL/year – current total peak discharge

b) 65 GL/year – current total peak discharge plus additional 5 GL/year from JSW and Oxbow

c) 70 GL/year – current total peak discharge plus additional 10 GL/year from JSW and Oxbow

d) 75 GL/year – current total peak discharge plus additional 15 GL/year from JSW and Oxbow

e) 80 GL/year – current total peak discharge plus additional 20 GL/year from JSW and Oxbow

10.2.2 Scenario 5: Discharge rate options – 90 GL/year In this scenario we assume the worst case where all feasible options for surplus water disposal have been exhausted and continual discharge to surface drainages becomes the remaining option for surplus water management. Under this scenario, all abstracted groundwater, 90 GL/year (15 GL/year from BHPBIO Yandi operation, 35 GL/year from RTIO Yandicoogina operation and 40 GL/year from Hope Downs 1 operation), plus additional 5, 10, 15 and 20 GL/year of surplus water that may be generated from JSW and Oxbow are discharged into the creek systems.

10.2.3 Scenario 6: Relocation of Marillana Creek discharge outlets In this scenario we investigate the option of relocating the discharge outlets along Marillana Creek down gradient form the mine operations, with the exception of the BHPBIO outlet and DO3 which will remain in their original locations. DO3 will be used for environmental water provisions to sustain creek ecosystem that may be impacted by dewatering. As shown in Table

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5, discharge rate options varying from 55 GL/year, the current average discharge rate from the mine operations, to 110 GL/year8 were investigated. Surplus water from BHPBIO Yandi outlet and RTIO Yandi DO39 are released at Reach 1 and 4, respectively, and the remaining RTIO Yandi water is released at Reach 6 along Marillana Creek. Discharge locations along Weeli Wolli Creek remain unchanged.

Table 5: Modelled discharge options for Scenario 6

Scenario Discharge rate (GL/year)

BHPBIO Yandi Current RTIO JSW + Oxbow Hope Downs 1 Total Yandi

7a - current 5 25 25 55

7b 5 30 5 30 70

7c 10 30 10 30 80

7d 15* 35* 5 35 90

7e 15* 35* 5 40* 95

7f 15* 35* 10 40* 100

7g – peak 15* 35* 15 40* 105

7h 15* 35* 20 40* 110

*Note: current licensed maximum abstraction rate

11. Modelling results

11.1 Existing discharge footprints The estimated wetting front footprints along Marillana and Weeli Wolli Creeks under existing discharge condition are summarised in Table 5 and are depicted in Figure 24. The water balance results are provided in Appendix A. A comparison between the observed and estimated footprints along Weeli Wolli Creek showed that the differences range from -2.7 % to 2.0 %. This suggested the discharge footprint methodology was able to predict the footprint distance (steady state) with accuracy better than ±3 %.

8 Results from the current hydrogeological modelling suggests a mean groundwater abstraction rate of 10 GL/year and up to 15 GL/year maybe dewater from JSW and Oxbow. Thus the expected peak is 105 GL/year. 9 DO3 was modelled at a constant discharge rate of 2.5 GL/year, the average rate between 2000 and 2009.

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Table 6: Estimated discharge footprints for Marillana and Weeli Wolli Creeks under existing discharge conditions.

Marillana Creek from BHP Weeli Wolli Creek from Hope Footprint discharge outlet Downs 1 discharge outlet distance past the confluence of Scenarios Steady Surface Maximum Steady Surface Maximum state water discharge state water discharge Marillana and distance expression footprint distance expression footprint Weeli Wolli (km) (km) (km) (km) (km) (km) Creeks (km)

1a: 126 ML/d 16.3 16.4 16.4 22.4 22.2 22.4 2.7 in Oct 2007

1b: 125 ML/d 16.0 16.0 16.0 23.2 22.8 23.2 3.4 in Dec 2007

1c: 138 ML/d in Aug 2008 11.2* 11.8* 11.8* 23.3 23.0 23.3 3.6

2: 116 ML/d or 16.3 16.4 16.4 22.3 22.1 22.3 2.5 42 GL/y

3: 163 ML/d or 17.4* 16.7* 17.4* 25.2 24.5 25.2 5.5 60 GL/y

Bold: Marillana Creek footprints that did not extend beyond confluence * Note: no flow contribution from BHPBIO, footprint distances were measured from Junction Central

Table 7: Comparison between the observed and predicted wetting front distances along Weeli Wolli Creek downstream from the Hope Downs 1 discharge outlet. Date Discharge Estimated Observed Error (ML/day) footprint distance (km) (km)

21/10/2007 126 22.4 22.0 2.0%

16/12/2007 125 23.2 23.5 -1.5%

06/08/2008 138 23.3 24.0 -2.7%

Model results from Table 5 suggest there were periods where discharged water would not have historically extended the Marillana Creek catchment outlet at the confluence with Weeli Wolli Creek; hence anecdotally no flow contribution to Weeli Wolli Creek was observed. Thus the progression of the wetting front along Weeli Wolli Creek was likely to be attributed to water released from the Hope Downs 1 operation and the volume discharged from DO6, which ranged from 1 GL/year to 4 GL/year between 1998 and 2009.

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Figure 24: The estimated discharge footprints for Marillana and Weeli Wolli Creeks under existing discharge conditions.

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11.2 Proposed discharge footprints

11.2.1 Scenarios 4 and 5 The footprint distances, measured downstream from the discharge locations and downstream from the confluence of Marillana and Weeli Wolli Creeks, for the modelled discharge scenarios 4 and 5 are presented in Figure 26 and are summarised in Table 7. The water balance results are provided in Appendix B. Under all scenarios (except Scenarios 4a, 4b and 4c) the discharge footprint was less than the surface water expression footprint, suggesting under these discharged water would flow along the surface of the creek bed, with occasional pools forming in topographical depressions within the creek bed.

Table 8: Estimated discharge footprints for Marillana and Weeli Wolli Creeks for different discharge scenarios4 and 5 Marillana Creek – existing Weeli Wolli Creek from Hope

discharge locations Downs 1 discharge outlet

Scenarios

er expression (km) expression er

Steady state distance (km) distance state Steady wat Surface (km) footprint discharge Maximum (km) distance state Steady (km) expression water Surface (km) footprint discharge Maximum of confluence the past distance Footprint (km) Creeks Wolli Weeli and Marillana

4a: 60 GL/y 17.4* 16.7* 17.4* 25.2 24.5 25.2 5.5 4b: 65 GL/y 18.7* 17.7* 18.7* 26.5 25.5 26.5 6.8 4c: 70 GL/y 20.0* 18.8* 20.0* 27.8 26.6 27.8 8.1 4d: 75 GL/y 20.3* 21.4* 21.4* 28.1 29.2 29.2 9.4 4e: 80 GL/y 20.5* 22.6* 22.6* 28.3 30.4 30.4 10.7

5a: 90 GL/y 28.0 31.0 31.0 28.6 31.6 31.6 11.9 5b: 95 GL/y 28.2 32.1 32.1 28.9 32.8 32.8 13.0 5c: 100 GL/y 28.5 33.1 33.1 29.2 33.8 33.8 14.1 5d: 105 GL/y 28.8 34.3 34.3 29.4 35.0 35.0 15.2 5e: 110 GL/y 29.0 35.4 35.4 29.7 36.1 36.1 16.3 * Note: no flow contribution from BHPBIO, footprint distances were measured from Junction Central

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Figure 25: Estimated discharge footprints for Marillana and Weeli Wolli Creeks for different discharge rates.

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11.2.2 Scenario 6 Results for Scenario 6 are presented in Figure 26 and are summarised in Table 9 and Table 10. The footprint distances are provided with respect to reference locations, for example downstream from the discharge locations and downstream from the confluence of Marillana and Weeli Wolli Creeks. The model results suggested that discharged water from BHPBIO outlet and DO3 would not reach the proposed outlet at Marillana Creek. Hence their volumes do not contribute to the footprint distances estimated at Weeli Wolli Creek.

Figure 26: Estimated discharge footprints for Marillana and Weeli Wolli Creeks for Scenario 6.

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Table 9: Estimated footprint distances from BHPBIO discharge outlet and DO3. BHPBIO and DO3 water from the modelled options did not reach the new proposed outlet at Marillana Creek and therefore did not contribute to the footprint distances estimated at Weeli Wolli Creek (as shown in Table 10).

Scenario Total Volume from Volume from Footprint distances from BHPBIO discharge outlet Footprint distances from DO3 discharge BHPBIO DO3 volume

(GL/year) (GL/year) (GL/year) Steady state Surface water Maximum Steady state Surface water Maximum distance (km) expression (km) footprint (km) distance (km) expression (km) footprint (km)

7a - current 55 5 2.5 4.3 4.3 4.3 2.7 1.3 2.7

7b 70 5 2.5 4.3 4.3 4.3 2.7 1.3 2.7

7c 80 10 2.5 7.9 7.5 7.9 2.7 1.3 2.7

7d to 7h 90 to 110 15 2.5 14.0 13.4 14.0 5.2 4.6 5.2

Table 10: Estimated footprint distances from Marillana Creek proposed discharge outlet and Hope Downs 1 outlet. The modelled volumes exclude BHPBIO and DO3 water.

Scenario Total Volume from Volume Footprint distances from Marillana Creek Footprint distances from Hope Downs 1 Footprint distance discharge RTIO Yandi from Hope proposed discharge outlet discharge outlet past the confluence of volume (excluding Downs 1 Marillana and Weeli DO3) Wolli Creeks

(GL/year) (GL/year) (GL/year) Steady state Surface water Maximum Steady state Surface water Maximum (km) distance (km) expression (km) footprint distance (km) expression (km) footprint (km) (km)

7a - current 55 22.5 25 9.8 8.9 9.8 26.5 25.5 26.5 6.7

7b 70 32.5 30 11.7 13.7 13.7 28.3 30.4 30.4 10.6

7c 80 37.5 30 12.0 14.9 14.9 28.6 31.6 31.6 11.8

7d 90 37.5 35 12.2 16.1 16.1 28.9 32.7 32.7 12.9

7e 95 37.5 40 12.5 17.2 17.2 29.1 33.9 33.9 14.1

7f 100 42.5 40 12.8 18.3 18.3 29.4 35.0 35.0 15.2

7g – peak 105 47.5 40 13.0 19.4 19.4 29.7 36.0 36.0 16.3

7h 110 52.5 40 13.3 20.4 20.4 29.9 37.0 37.0 17.3

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Modelling indicated that the footprint distance would extend from approximately 6.7 km to 17.3 km down gradient from the Weeli Wolli – Marillana Creek confluence for modelled volumes 55 GL/year to 110 GL/year. Under all scenarios (except Scenario 7a) the steady state footprint was less than the surface water expression footprint, suggesting there is limited recharge potential beneath the creek, such that discharged water is expected to flow along the surface of the creek, with occasional pools forming in topographic depressions within the creek bed.

Figure 27 and Figure 28 illustrate the relationships between discharge volume and maximum footprint measured from the proposed Marillana Creek discharge outlet, Hope Downs 1 discharge outlet and from the Weeli Wolli – Marillana Creek confluence. It is likely that the footprint distance would increase linearly with discharge.

Max footprint Max (km) 15

0 40 50 60 70 80 90 100 110 Discharge volume (GL/year) Footprints from proposed Marillana Creek outlet Footprints from proposed Marillana Creek outlet (+/- 10%) Footprints from HD1 outlet Footprints from HD1 outlet (+/- 10%)

Figure 27: A plot of discharge volume versus maximum footprint measured from the proposed Marillana Creek discharge outlet and Hope Downs 1 discharge outlet (with +/- 10 % error margin). The plot shows a linear increase in footprint distance with discharge. Please note that volumes discharged from the BHPBIO outlet and DO3 were not incorporated into the plot as modelling suggested the discharged water would not reach the proposed outlet at Marillana Creek.

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8 Max footprint Max (km) 6

0 40 50 60 70 80 90 100 110 Discharge volume (GL/year) Discharge footprints Discharge footprints (+/- 10%)

Figure 28: A plot of discharge volume versus maximum footprint measured from the Weeli Wolli – Marillana Creek confluence (with +/- 10 % error margin). The plot shows a linear increase in footprint distance with discharge. Please note that volumes discharged from the BHPBIO outlet and DO3 were not incorporated into the plot as modelling suggested the discharged water would not reach the proposed outlet at Marillana Creek.

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It is important to note that Weeli Wolli Creek, in particular the section that drains the alluvial fan system, is naturally capable of changing course during large flood events. This may occur during the mine life of the Yandicoogina operation; modifying the existing drainage flow path of the discharged water and altering the course of the discharge footprints (Figure 29).

Figure 29: Existing and previous drainage flow paths of Weeli Wolli Creek within the alluvial plain; the creek system is capable of changing course during large flood events.

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Conclusion

Based on the existing discharge regime of the mine sites (BHPBIO Yandi, RTIO Yandicoogina and RTIO Hope Downs 1), three discharge scenarios (Scenarios 1, 2 and 3) were generated and modelled to assess the existing situation and movement of discharged water along Marillana and Weeli Wolli Creeks (model results are shown in the table below). A comparison between the observed and estimated footprints along Weeli Wolli Creek (Scenario 1) showed that the discharge footprint methodology was able to predict the footprint distance with accuracy better than ±3 %. Through the water balance modelling it was determined that between 1998 and 2009 the average maximum discharge footprint along Weeli Wolli Creek, for modelled volume 42 GL/year (Scenario 2), would extend approximately 2.5 km downstream from the confluence with Marillana Creek. On the other hand, continual discharge of the current total peak rate 60 GL/year (Scenario 3) into the creek systems would result in the discharge footprint extending approximately 5.5 km down gradient from the Weeli Wolli – Marillana Creek confluence.

Based on the model results of Scenarios 1, 2 and 3, it was determined that historically discharged water would unlikely have extended past the Marillana Creek catchment outlet at the confluence with Weeli Wolli Creek; hence anecdotally no flow contribution to Weeli Wolli would have been observed. Thus progression of wetting front as observed along Weeli Wolli Creek would primarily attribute to discharged water from Hope Downs 1 operation.

Future expansion of the RTIO Yandicoogina operation may increase the total groundwater abstraction for the mine, with the potential to increase the volume of surplus water generated and discharged into Marillana and Weeli Wolli Creeks. Three discharge scenarios (Scenarios 4, 5 and 6) were modelled to determine the potential changes to the creek systems resulting from different discharge rates and varying input locations. Modelling indicated (results shown in the table below) the footprint distance would extend from approximately 5.5 km to 16.3 km down gradient from the Weeli Wolli – Marillana Creek confluence for modelled volumes 60 GL/year to 110 GL/year, the maximum volume modelled. Under all scenarios, with the exception of Scenarios 4a, 4b and 4c, the steady state footprint was less than the surface water expression footprint, suggesting there is limited recharge potential beneath the creek, such that water discharged into the creek systems is expected to be seen to flow across the surface of the creek bed, with occasional pools forming in topographical depressions within the creek bed.

Upon relocating the discharge location in Marillana Creek down gradient from the mine operations, modelling indicated discharged water from BHPBIO outlet and DO3 would not reach the proposed outlet at Marillana Creek. Hence progression of wetting front as estimated at Weeli Wolli Creek would be attributed to discharged water from RTIO Yandicoogina operation at the new outlet location and from Hope Downs 1 operation. Modelling indicated that the footprint distance would extend from approximately 6.7 km to 17.3 km down gradient from the Weeli Wolli – Marillana Creek confluence for modelled volumes 55 GL/year to 110 GL/year. It is likely that the footprint distance would increase linearly with discharge.

Weeli Wolli Creek, in particular the section that drain the alluvial fan system, is naturally capable of changing course during large flood events. This type of event would modify the

Yandicoogina baseline hydrology Page 40 of 60

existing drainage flow path of the discharged water and alter the course of the discharge footprints.

Footprint distance Discharge footprint distance (km) past the confluence of Marillana and Scenarios Marillana Creek – Weeli Wolli Creek – Hope Weeli Wolli Creeks (km) existing discharge Downs 1 discharge outlet locations 1a: 126 ML/d in Oct 16.4 22.4 2.7 2007 1b: 125 ML/d in Dec 16.0 23.2 3.4 2007

1c: 138 ML/d in Aug 11.8* 23.3 3.6 2008

2: 42 GL/y average 16.4 22.3 2.5 discharge 2007-2009

3: 60 GL/y Peak discharge 1998 - 2009 17.4* 25.2 5.5

4a: 60 GL/y 17.4* 25.2 5.5 4b: 65 GL/y 18.7* 26.5 6.8 4c: 70 GL/y 20.0* 27.8 8.1 4d: 75 GL/y 21.4* 29.2 9.4 4e: 80 GL/y 22.6* 30.4 10.7

5a: 90 GL/y 31.0 31.6 11.9 5b: 95 GL/y 32.1 32.8 13.0 5c: 100 GL/y 33.1 33.8 14.1 5d: 105 GL/y 34.3 35.0 15.2 5e: 110 GL/y 35.4 36.1 16.3

Footprint distance Discharge footprint distance (km) past the confluence of Marillana and Scenario 6 Marillana Creek – Weeli Wolli Creek – Hope Weeli Wolli Creeks proposed discharge Downs 1 discharge outlet (km) location a: 55 GL/y 9.8 26.5 6.7 b: 70 GL/y 13.7 30.4 10.6 c: 80 GL/y 14.9 31.6 11.8 d: 90 GL/y 16.1 32.7 12.9 b: 95 GL/y 17.2 33.9 14.1 c: 100 GL/y 18.3 35.0 15.2 d: 105 GL/y 19.4 36.0 16.3 e: 110 GL/y 20.4 37.0 17.3

Bold: Marillana Creek footprints that did not extend beyond confluence * Note: no flow contribution from BHPBIO, footprint distances were measured from Junction Central

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Appendix A – Base case output

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REACH 1 Yandi discharge - Marillana Reach 1 (BHP discharge)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 140 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 1336 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 18 ET (m/s) ET = 30% evap 3.E-08 5.E-06 6.E-03 1050mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 3.E-05 4.E-02 Time to saturate alluvials (days) 75 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 15.00 0.0411 0.476 0.18 2.925 27.000 0.15 0.150 27.003 6097.65 1.38E-05 34405.95 6,098 saturation 140.00 13,339 saturation 3.00E-06 4.00E-03 7.50E-05 1.00E-01 7.80E-05 1.04E-01 6.23E-03 3.74E-02 3.57E-05 4.76E-02 3.29 1.50 0.04765 TRUE 2 Feb 2009 (59.59 GL/a) 4.10 0.0112 0.130 0.12 1.085 19.000 0.14 0.070 19.001 2366.52 6.35E-06 20462.57 2,367 saturation 140.00 3,736 saturation 2.11E-06 2.82E-03 5.28E-05 7.05E-02 5.49E-05 7.33E-02 6.23E-03 3.74E-02 3.48E-05 4.65E-02 2.31 1.47 0.04646 TRUE 3 ave vol 07-09 (42.4 GL/a) 6.19 0.0170 0.196 0.13 1.485 21.000 0.14 0.090 21.002 3234.08 8.09E-06 24250.31 3,234 saturation 140.00 5,607 saturation 2.33E-06 3.11E-03 5.83E-05 7.80E-02 6.07E-05 8.11E-02 6.23E-03 3.74E-02 3.50E-05 4.68E-02 2.56 1.47 0.04676 TRUE 4 31/10/2007 (46.1 GL/a) 12.65 0.0346 0.401 0.16 2.405 25.000 0.14 0.130 25.003 5552.53 1.18E-05 33911.82 5,553 saturation 140.00 11,317 saturation 2.77E-06 3.71E-03 6.95E-05 9.28E-02 7.22E-05 9.65E-02 6.23E-03 3.74E-02 3.54E-05 4.74E-02 3.04 1.49 0.04735 TRUE 5 31/12/2007 (45.6 GL/a) 7.41 0.0203 0.235 0.14 1.700 22.000 0.14 0.100 22.002 3698.95 8.99E-06 26143.73 3,699 saturation 140.00 6,697 saturation 2.44E-06 3.26E-03 6.11E-05 8.17E-02 6.36E-05 8.49E-02 6.23E-03 3.74E-02 3.51E-05 4.69E-02 2.68 1.48 0.04691 TRUE 6 31/08/2008 (50.5 GL/a) 3.22 0.0088 0.102 0.12 1.085 19.000 0.14 0.070 19.001 1862.58 6.35E-06 16105.17 1,863 saturation 140.00 2,940 saturation 2.11E-06 2.82E-03 5.28E-05 7.05E-02 5.49E-05 7.33E-02 6.23E-03 3.74E-02 3.48E-05 4.65E-02 2.31 1.47 0.04646 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 4.10 0.0112 0.130 0.12 1.085 19.000 0.14 0.070 19.001 2366.52 6.35E-06 20462.57 2,367 saturation 140.00 3,736 saturation 2.11E-06 2.82E-03 5.28E-05 7.05E-02 5.49E-05 7.33E-02 6.23E-03 3.74E-02 3.48E-05 4.65E-02 2.31 1.47 0.04646 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 4.10 0.0112 0.130 0.12 1.085 19.000 0.14 0.070 19.001 2366.52 6.35E-06 20462.57 2,367 saturation 140.00 3,736 saturation 2.11E-06 2.82E-03 5.28E-05 7.05E-02 5.49E-05 7.33E-02 6.23E-03 3.74E-02 3.48E-05 4.65E-02 2.31 1.47 0.04646 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 4.10 0.0112 0.130 0.12 1.085 19.000 0.14 0.070 19.001 2366.52 6.35E-06 20462.57 2,367 saturation 140.00 3,736 saturation 2.11E-06 2.82E-03 5.28E-05 7.05E-02 5.49E-05 7.33E-02 6.23E-03 3.74E-02 3.48E-05 4.65E-02 2.31 1.47 0.04646 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 4.10 0.0112 0.130 0.12 1.085 19.000 0.14 0.070 19.001 2366.52 6.35E-06 20462.57 2,367 saturation 140.00 3,736 saturation 2.11E-06 2.82E-03 5.28E-05 7.05E-02 5.49E-05 7.33E-02 6.23E-03 3.74E-02 3.48E-05 4.65E-02 2.31 1.47 0.04646 TRUE

REACH 2 Yandi discharge - Marillana Reach 2

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 150 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 2660 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 13 ET (m/s) ET = 30% evap 3.E-08 5.E-06 1.E-02 1050mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 3.E-05 8.E-02 Time to saturate alluvials (days) 54 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 13.50 0.0370 0.428 0.15 2.640 28.000 0.13 0.120 28.002 5290.98 1.18E-05 36316.49 5,291 saturation 150.00 11,233 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 2 Feb 2009 (59.59 GL/a) 2.63 0.0072 0.083 0.09 0.925 21.000 0.13 0.050 21.001 1375.32 5.32E-06 15678.71 1,375 2,712 150.00 2,235 3,572 2.33E-06 3.21E-03 5.83E-05 8.02E-02 6.07E-05 8.34E-02 1.12E-02 6.71E-02 3.73E-05 8.14E-02 2.63 2.57 0.08143184 TRUE 3 ave vol 07-09 (42.4 GL/a) 4.71 0.0129 0.149 0.11 1.365 23.000 0.13 0.070 23.001 2249.20 7.11E-06 21019.21 2,249 3,585 150.00 3,980 saturation 2.55E-06 5.74E-03 6.39E-05 1.44E-01 6.64E-05 1.49E-01 1.33E-02 7.98E-02 3.75E-05 9.88E-02 4.71 3.12 0.09881992 TRUE 4 31/10/2007 (46.1 GL/a) 11.15 0.031 0.354 0.15 2.640 28.000 0.13 0.120 28.002 4372.33 1.18E-05 30010.99 4,372 saturation 150.00 9,283 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 5 31/12/2007 (45.6 GL/a) 5.93 0.016 0.188 0.11 1.365 23.000 0.13 0.070 23.001 2832.28 7.11E-06 26468.14 2,832 saturation 150.00 5,012 saturation 2.55E-06 6.79E-03 6.39E-05 1.70E-01 6.64E-05 1.77E-01 1.33E-02 7.98E-02 3.75E-05 9.99E-02 5.57 3.15 0.09986808 TRUE 6 31/08/2008 (50.5 GL/a) 1.76 0.005 0.056 0.09 0.925 21.000 0.13 0.050 21.001 919.37 5.32E-06 10480.82 919 2,256 150.00 1,494 2,831 2.33E-06 2.14E-03 5.83E-05 5.36E-02 6.07E-05 5.58E-02 7.46E-03 4.48E-02 3.73E-05 5.44E-02 1.76 1.72 0.05443514 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 2.63 0.007 0.083 0.09 0.925 21.000 0.13 0.050 21.001 1375.32 5.32E-06 15678.71 1,375 2,712 150.00 2,235 3,572 2.33E-06 3.21E-03 5.83E-05 8.02E-02 6.07E-05 8.34E-02 1.12E-02 6.71E-02 3.73E-05 8.14E-02 2.63 2.57 0.08143184 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 2.63 0.007 0.083 0.09 0.925 21.000 0.13 0.050 21.001 1375.32 5.32E-06 15678.71 1,375 2,712 150.00 2,235 3,572 2.33E-06 3.21E-03 5.83E-05 8.02E-02 6.07E-05 8.34E-02 1.12E-02 6.71E-02 3.73E-05 8.14E-02 2.63 2.57 0.08143184 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 2.63 0.007 0.083 0.09 0.925 21.000 0.13 0.050 21.001 1375.32 5.32E-06 15678.71 1,375 2,712 150.00 2,235 3,572 2.33E-06 3.21E-03 5.83E-05 8.02E-02 6.07E-05 8.34E-02 1.12E-02 6.71E-02 3.73E-05 8.14E-02 2.63 2.57 0.08143184 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 2.63 0.007 0.083 0.09 0.925 21.000 0.13 0.050 21.001 1375.32 5.32E-06 15678.71 1,375 2,712 150.00 2,235 3,572 2.33E-06 3.21E-03 5.83E-05 8.02E-02 6.07E-05 8.34E-02 1.12E-02 6.71E-02 3.73E-05 8.14E-02 2.63 2.57 0.08143184 TRUE

REACH 3 Yandi discharge - Marillana Reach 3

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 200 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 3129 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 16 ET (m/s) ET = 20% evap 2.E-08 4.E-06 1.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 4.E-05 1.E-01 Time to saturate alluvials (days) 67 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 10.30 0.0282 0.327 0.18 1.504 23.660 0.21 0.074 23.662 4778.95 1.20E-05 27163.15 4,779 saturation 200.00 6,940 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 2 Feb 2009 (59.59 GL/a) 0.06 0.0002 0.002 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 200.00 45 4,041 0.00E+00 #VALUE! 0.00E+00 #VALUE! 0.00E+00 #VALUE! 2.00E-04 1.80E-03 4.44E-05 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! 3 ave vol 07-09 (42.4 GL/a) 1.60 0.0044 0.051 0.10 0.551 19.700 0.19 0.030 19.701 889.63 5.79E-06 8747.60 890 4,886 200.00 1,086 5,082 2.19E-06 1.95E-03 5.47E-05 4.87E-02 5.69E-05 5.06E-02 4.82E-03 4.34E-02 4.66E-05 5.02E-02 1.60 1.58 0.05020019 TRUE 4 31/10/2007 (46.1 GL/a) 7.96 0.0218 0.252 0.18 1.504 23.660 0.21 0.074 23.662 3691.77 1.20E-05 20983.71 3,692 saturation 200.00 5,362 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 5 31/12/2007 (45.6 GL/a) 2.79 0.0076 0.088 0.14 0.963 21.500 0.20 0.050 21.501 1422.02 8.65E-06 10212.75 1,422 5,418 200.00 1,886 5,882 2.39E-06 3.39E-03 5.97E-05 8.49E-02 6.21E-05 8.83E-02 8.37E-03 7.54E-02 4.68E-05 8.72E-02 2.79 2.75 0.08721597 TRUE 6 31/08/2008 (50.5 GL/a) 0.04 0.0001 0.001 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 200.00 30 4,026 0.00E+00 #VALUE! 0.00E+00 #VALUE! 0.00E+00 #VALUE! 1.34E-04 1.21E-03 4.44E-05 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 0.06 0.0002 0.002 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 200.00 45 4,041 0.00E+00 #VALUE! 0.00E+00 #VALUE! 0.00E+00 #VALUE! 2.00E-04 1.80E-03 4.44E-05 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 0.06 0.0002 0.002 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 200.00 45 4,041 0.00E+00 #VALUE! 0.00E+00 #VALUE! 0.00E+00 #VALUE! 2.00E-04 1.80E-03 4.44E-05 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 0.06 0.0002 0.002 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 200.00 45 4,041 0.00E+00 #VALUE! 0.00E+00 #VALUE! 0.00E+00 #VALUE! 2.00E-04 1.80E-03 4.44E-05 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 0.06 0.0002 0.002 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 200.00 45 4,041 0.00E+00 #VALUE! 0.00E+00 #VALUE! 0.00E+00 #VALUE! 2.00E-04 1.80E-03 4.44E-05 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!

Yandicoogina baseline hydrology Page 43 of 60

REACH 1 Yandi discharge - Marillana Reach 4 (DO3, DO8, DO1/4 and DO5)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 120 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 5172 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 2 ET (m/s) ET = 17% evap 2.E-08 2.E-06 1.E-02 600mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 2.E-05 1.E-01 Time to saturate alluvials (days) 8 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 35.22 0.0965 1.117 0.27 4.313 27.928 0.20 0.180 27.928 13841.06 2.15E-05 51974.21 13,841 saturation 120.00 37,994 saturation 3.10E-06 1.60E-02 7.76E-05 4.01E-01 8.07E-05 4.17E-01 1.18E-02 1.24E-01 2.94E-05 1.52E-01 13.16 4.79 0.152 TRUE 2 Feb 2009 (59.59 GL/a) 25.88 0.0709 0.821 0.24 3.495 26.600 0.20 0.150 26.607 10675.95 1.84E-05 44654.64 10,676 saturation 120.00 28,060 saturation 2.95E-06 1.53E-02 7.39E-05 3.82E-01 7.69E-05 3.98E-01 1.18E-02 1.24E-01 2.92E-05 1.51E-01 12.54 4.77 0.15124 TRUE 3 ave vol 07-09 (42.4 GL/a) 12.65 0.0346 0.401 0.19 2.220 24.400 0.19 0.100 24.405 5688.30 1.32E-05 30396.55 5,688 saturation 120.00 13,829 saturation 2.71E-06 1.40E-02 6.78E-05 3.51E-01 7.05E-05 3.65E-01 1.18E-02 1.24E-01 2.90E-05 1.50E-01 11.50 4.73 0.14998 TRUE 4 31/10/2007 (46.1 GL/a) 13.41 0.0367 0.425 0.19 2.220 24.400 0.19 0.100 24.405 6029.90 1.32E-05 32221.95 6,030 saturation 120.00 14,659 saturation 2.71E-06 1.40E-02 6.78E-05 3.51E-01 7.05E-05 3.65E-01 1.18E-02 1.24E-01 2.90E-05 1.50E-01 11.50 4.73 0.14998 TRUE 5 31/12/2007 (45.6 GL/a) 12.18 0.0334 0.386 0.19 2.220 24.400 0.19 0.100 24.405 5479.72 1.32E-05 29281.97 5,480 saturation 120.00 13,322 saturation 2.71E-06 1.40E-02 6.78E-05 3.51E-01 7.05E-05 3.65E-01 1.18E-02 1.24E-01 2.90E-05 1.50E-01 11.50 4.73 0.14998 TRUE 6 31/08/2008 (50.5 GL/a) 17.56 0.0481 0.557 0.19 2.220 24.400 0.19 0.100 24.405 7900.43 1.32E-05 42217.47 7,900 saturation 120.00 19,207 saturation 2.71E-06 1.40E-02 6.78E-05 3.51E-01 7.05E-05 3.65E-01 1.18E-02 1.24E-01 2.90E-05 1.50E-01 11.50 4.73 0.14998 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 25.88 0.0709 0.821 0.24 3.495 26.600 0.20 0.150 26.607 10675.95 1.84E-05 44654.64 10,676 saturation 120.00 28,060 saturation 2.95E-06 1.53E-02 7.39E-05 3.82E-01 7.69E-05 3.98E-01 1.18E-02 1.24E-01 2.92E-05 1.51E-01 12.54 4.77 0.15124 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 25.88 0.0709 0.821 0.24 3.495 26.600 0.20 0.150 26.607 10675.95 1.84E-05 44654.64 10,676 saturation 120.00 28,060 saturation 2.95E-06 1.53E-02 7.39E-05 3.82E-01 7.69E-05 3.98E-01 1.18E-02 1.24E-01 2.92E-05 1.51E-01 12.54 4.77 0.15124 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 25.88 0.0709 0.821 0.24 3.495 26.600 0.20 0.150 26.607 10675.95 1.84E-05 44654.64 10,676 saturation 120.00 28,060 saturation 2.95E-06 1.53E-02 7.39E-05 3.82E-01 7.69E-05 3.98E-01 1.18E-02 1.24E-01 2.92E-05 1.51E-01 12.54 4.77 0.15124 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 25.88 0.0709 0.821 0.24 3.495 26.600 0.20 0.150 26.607 10675.95 1.84E-05 44654.64 10,676 saturation 120.00 28,060 saturation 2.95E-06 1.53E-02 7.39E-05 3.82E-01 7.69E-05 3.98E-01 1.18E-02 1.24E-01 2.92E-05 1.51E-01 12.54 4.77 0.15124 TRUE

REACH 1 Yandi discharge - Marillana Reach 5 (DO2)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 280 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 3664 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 18 ET (m/s) ET = 17% evap 2.E-08 5.E-06 2.E-02 600mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 6.E-05 2.E-01 Time to saturate alluvials (days) 75 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 32.26 0.0884 1.023 0.22 4.616 39.025 0.20 0.130 39.025 9072.85 2.50E-05 40848.02 9,073 saturation 280.00 15,574 saturation 4.33E-06 1.59E-02 1.08E-04 3.97E-01 1.13E-04 4.13E-01 1.96E-02 2.05E-01 6.57E-05 2.41E-01 13.03 7.59 0.24063 TRUE 2 Feb 2009 (59.59 GL/a) 22.96 0.0629 0.728 0.20 3.847 37.940 0.19 0.110 37.944 6641.60 2.20E-05 33141.52 6,642 saturation 280.00 11,105 saturation 4.21E-06 1.54E-02 1.05E-04 3.86E-01 1.10E-04 4.02E-01 1.96E-02 2.05E-01 6.56E-05 2.40E-01 12.67 7.57 0.24019 TRUE 3 ave vol 07-09 (42.4 GL/a) 8.70 0.0238 0.276 0.14 2.017 35.240 0.18 0.060 35.242 2709.95 1.39E-05 19795.54 2,710 15,007 280.00 4,228 saturation 3.91E-06 1.06E-02 9.79E-05 2.65E-01 1.02E-04 2.76E-01 1.96E-02 2.05E-01 6.53E-05 2.35E-01 8.70 7.42 0.23536 TRUE 4 31/10/2007 (46.1 GL/a) 8.68 0.0238 0.275 0.14 2.017 35.240 0.18 0.060 35.242 2702.38 1.39E-05 19740.22 2,702 15,000 280.00 4,216 saturation 3.91E-06 1.06E-02 9.79E-05 2.65E-01 1.02E-04 2.75E-01 1.96E-02 2.05E-01 6.53E-05 2.35E-01 8.68 7.42 0.23533 TRUE 5 31/12/2007 (45.6 GL/a) 7.51 0.0206 0.238 0.14 2.017 35.240 0.18 0.060 35.242 2339.75 1.39E-05 17091.28 2,340 14,637 280.00 3,650 15,948 3.91E-06 9.15E-03 9.79E-05 2.29E-01 1.02E-04 2.38E-01 1.95E-02 2.04E-01 6.53E-05 2.33E-01 7.51 7.35 0.23308 TRUE 6 31/08/2008 (50.5 GL/a) 15.87 0.0435 0.503 0.14 2.017 35.240 0.18 0.060 35.242 4943.33 1.39E-05 36109.80 4,943 saturation 280.00 7,712 saturation 3.91E-06 1.43E-02 9.79E-05 3.59E-01 1.02E-04 3.73E-01 1.96E-02 2.05E-01 6.53E-05 2.39E-01 11.76 7.54 0.2391 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 27.96 0.0766 0.887 0.21 4.229 38.484 0.19 0.120 38.484 7974.47 2.35E-05 37711.75 7,974 saturation 280.00 13,511 saturation 4.27E-06 1.56E-02 1.07E-04 3.92E-01 1.11E-04 4.07E-01 1.96E-02 2.05E-01 6.56E-05 2.40E-01 12.85 7.58 0.24041 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 32.96 0.0903 1.045 0.22 4.616 39.025 0.20 0.130 39.025 9270.45 2.50E-05 41737.67 9,270 saturation 280.00 15,913 saturation 4.33E-06 1.59E-02 1.08E-04 3.97E-01 1.13E-04 4.13E-01 1.96E-02 2.05E-01 6.57E-05 2.41E-01 13.03 7.59 0.24063 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 37.96 0.1040 1.204 0.24 5.208 39.835 0.20 0.145 39.835 10459.61 2.73E-05 44054.97 10,460 saturation 280.00 18,302 saturation 4.42E-06 1.62E-02 1.11E-04 4.05E-01 1.15E-04 4.22E-01 1.96E-02 2.05E-01 6.58E-05 2.41E-01 13.30 7.60 0.24096 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 42.96 0.1177 1.362 0.24 5.408 40.106 0.20 0.150 40.106 11757.65 2.81E-05 48512.69 11,758 saturation 280.00 20,703 saturation 4.45E-06 1.63E-02 1.11E-04 4.08E-01 1.16E-04 4.24E-01 1.96E-02 2.05E-01 6.58E-05 2.41E-01 13.39 7.60 0.24107 TRUE

REACH 2 Yandi discharge - Marillana Reach 6

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 460 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 3106 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 30 ET (m/s) ET = 30% evap 3.E-08 2.E-05 5.E-02 1050mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 9.E-05 3.E-01 Time to saturate alluvials (days) 125 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 24.67 0.0676 0.782 0.21 4.096 35.025 0.19 0.130 35.025 7730.69 2.14E-05 36597.17 7,731 saturation 460.00 7,034 saturation 3.89E-06 1.21E-02 9.73E-05 3.02E-01 1.01E-04 3.14E-01 4.76E-02 2.86E-01 1.11E-04 3.45E-01 9.91 10.89 0.31421449 FALSE 2 Feb 2009 (59.59 GL/a) 15.38 0.0421 0.488 0.18 3.070 33.400 0.18 0.100 33.404 5055.17 1.74E-05 28102.59 5,055 saturation 460.00 4,394 saturation 3.71E-06 1.15E-02 9.28E-05 2.88E-01 9.65E-05 3.00E-01 4.76E-02 2.86E-01 1.11E-04 3.45E-01 9.45 10.87 0.29966985 FALSE 3 ave vol 07-09 (42.4 GL/a) 1.28 0.0035 0.041 0.12 1.468 30.700 0.17 0.050 30.702 456.93 1.03E-05 3927.80 457 16,418 460.00 366 16,327 3.41E-06 1.56E-03 8.53E-05 3.90E-02 8.87E-05 4.05E-02 5.61E-03 3.37E-02 1.11E-04 4.08E-02 1.28 1.29 0.04052534 FALSE 4 31/10/2007 (46.1 GL/a) 1.25 0.003 0.040 0.12 1.468 30.700 0.17 0.050 30.702 448.57 1.03E-05 3855.94 449 16,410 460.00 359 16,321 3.41E-06 1.53E-03 8.53E-05 3.83E-02 8.87E-05 3.98E-02 5.50E-03 3.31E-02 1.11E-04 4.01E-02 1.25 1.26 0.03978397 FALSE 5 31/12/2007 (45.6 GL/a) 0.16 0.000 0.005 0.04 0.283 28.540 0.13 0.010 28.540 62.17 3.36E-06 1526.01 62 16,023 460.00 46 16,008 3.17E-06 1.97E-04 7.93E-05 4.93E-03 8.24E-05 5.13E-03 7.11E-04 4.27E-03 1.10E-04 5.18E-03 0.16 0.16 0.00512547 FALSE 6 31/08/2008 (50.5 GL/a) 8.33 0.023 0.264 0.12 1.468 30.700 0.17 0.050 30.702 2978.52 1.03E-05 25603.44 2,979 18,940 460.00 2,386 18,347 3.41E-06 1.01E-02 8.53E-05 2.54E-01 8.87E-05 2.64E-01 3.65E-02 2.19E-01 1.11E-04 2.66E-01 8.33 8.39 0.26416542 FALSE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 20.38 0.056 0.646 0.20 3.749 34.484 0.19 0.120 34.484 6486.08 2.00E-05 32238.61 6,486 saturation 460.00 5,813 saturation 3.83E-06 1.19E-02 9.58E-05 2.97E-01 9.96E-05 3.09E-01 4.76E-02 2.86E-01 1.11E-04 3.45E-01 9.76 10.88 0.30936651 FALSE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 25.37 0.070 0.804 0.21 4.096 35.025 0.19 0.130 35.025 7950.86 2.14E-05 37639.46 7,951 saturation 460.00 7,234 saturation 3.89E-06 1.21E-02 9.73E-05 3.02E-01 1.01E-04 3.14E-01 4.76E-02 2.86E-01 1.11E-04 3.45E-01 9.91 10.89 0.31421449 FALSE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 30.36 0.083 0.963 0.22 4.449 35.565 0.19 0.140 35.565 9370.06 2.27E-05 42410.94 9,370 saturation 460.00 8,652 saturation 3.95E-06 1.23E-02 9.88E-05 3.07E-01 1.03E-04 3.19E-01 4.76E-02 2.86E-01 1.11E-04 3.46E-01 10.06 10.90 0.31906219 FALSE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 35.36 0.097 1.121 0.23 4.808 36.106 0.19 0.150 36.106 10748.89 2.40E-05 46670.26 10,749 saturation 460.00 10,071 saturation 4.01E-06 1.24E-02 1.00E-04 3.11E-01 1.04E-04 3.24E-01 4.76E-02 2.86E-01 1.11E-04 3.46E-01 10.21 10.90 0.32390996 FALSE

Yandicoogina baseline hydrology Page 44 of 60

REACH 1 HD1 discharge - Weeli Wolli Reach 1

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 200 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 4500 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 30 ET (m/s) ET = 20% evap 2.E-08 4.E-06 2.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) -5.E-08 -1.E-05 -5.E-02 Time to saturate alluvials (days) 125 Weeli Wolli Spring Baseflow 4.2 ML/day Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 2 Feb 2009 (59.59 GL/a) 27.77 0.076 0.880 0.13 25.000 25.000 12191.26 9.39E-06 93778.94 12,191 saturation 200.00 122,047 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 3 ave vol 07-09 (42.4 GL/a) 21.25 0.058 0.674 0.13 25.000 25.000 9328.94 9.39E-06 71761.07 9,329 saturation 200.00 93,392 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 4 31/10/2007 (46.1 GL/a) 19.62 0.054 0.622 0.13 25.000 25.000 8616.14 9.39E-06 66277.98 8,616 saturation 200.00 86,256 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 5 31/12/2007 (45.6 GL/a) 22.28 0.061 0.707 0.13 25.000 25.000 9783.98 9.39E-06 75261.36 9,784 saturation 200.00 97,947 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 6 31/08/2008 (50.5 GL/a) 23.36 0.064 0.741 0.13 25.000 25.000 10254.68 9.39E-06 78882.14 10,255 saturation 200.00 102,659 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 27.77 0.076 0.880 0.13 25.000 25.000 12191.26 9.39E-06 93778.94 12,191 saturation 200.00 122,047 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 27.77 0.076 0.880 0.13 25.000 25.000 12191.26 9.39E-06 93778.94 12,191 saturation 200.00 122,047 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 27.77 0.076 0.880 0.13 25.000 25.000 12191.26 9.39E-06 93778.94 12,191 saturation 200.00 122,047 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 27.77 0.076 0.880 0.13 25.000 25.000 12191.26 9.39E-06 93778.94 12,191 saturation 200.00 122,047 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE

REACH 2 HD1 discharge - Weeli Wolli Reach 2

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 150 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 8270 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 30 ET (m/s) ET = 20% evap 2.2.E-08 3.E-06 3.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 3.E-05 2.E-01 Time to saturate alluvials (days) 125 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 2 Feb 2009 (59.59 GL/a) 28.27 0.0775 0.897 0.13 25.000 25.000 12414.86 9.39E-06 95498.94 12,415 saturation 150.00 24,833 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 3 ave vol 07-09 (42.4 GL/a) 21.76 0.0596 0.690 0.13 25.000 25.000 9552.54 9.39E-06 73481.07 9,553 saturation 150.00 19,108 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 4 31/10/2007 (46.1 GL/a) 20.13 0.0552 0.638 0.13 25.000 25.000 8839.74 9.39E-06 67997.98 8,840 saturation 150.00 17,682 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 5 31/12/2007 (45.6 GL/a) 22.79 0.0624 0.723 0.13 25.000 25.000 10007.58 9.39E-06 76981.36 10,008 saturation 150.00 20,018 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 6 31/08/2008 (50.5 GL/a) 23.86 0.0654 0.757 0.13 25.000 25.000 10478.28 9.39E-06 80602.15 10,478 saturation 150.00 20,960 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 28.27 0.0775 0.897 0.13 25.000 25.000 12414.86 9.39E-06 95498.94 12,415 saturation 150.00 24,833 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 28.27 0.0775 0.897 0.13 25.000 25.000 12414.86 9.39E-06 95498.94 12,415 saturation 150.00 24,833 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 28.27 0.0775 0.897 0.13 25.000 25.000 12414.86 9.39E-06 95498.94 12,415 saturation 150.00 24,833 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 28.27 0.0775 0.897 0.13 25.000 25.000 12414.86 9.39E-06 95498.94 12,415 saturation 150.00 24,833 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE

REACH 1 HD1 + Yandi discharge - Weeli Wolli Reach 3 (DO6)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 77 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 2350 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 10 ET (m/s) ET = 20% evap 2.E-08 2.E-06 4.E-03 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 2.E-05 4.E-02 Time to saturate alluvials (days) 42 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 2 Feb 2009 (59.59 GL/a) 18.86 0.0517 0.598 0.22 2.880 30.600 0.22 0.100 30.606 6763.92 1.95E-05 30610.94 6,764 saturation 77.00 29,164 saturation 3.40E-06 7.98E-03 8.50E-05 2.00E-01 8.84E-05 2.08E-01 4.02E-03 3.62E-02 2.05E-05 4.82E-02 6.55 1.52 0.04819 TRUE 3 ave vol 07-09 (42.4 GL/a) 13.88 0.0380 0.440 0.19 2.275 29.880 0.22 0.080 29.884 5098.97 1.66E-05 26577.02 5,099 saturation 77.00 21,551 saturation 3.32E-06 7.79E-03 8.30E-05 1.95E-01 8.63E-05 2.03E-01 4.02E-03 3.62E-02 2.04E-05 4.80E-02 6.40 1.51 0.048 TRUE 4 31/10/2007 (46.1 GL/a) 14.47 0.0396 0.459 0.19 2.275 29.880 0.22 0.080 29.884 5314.23 1.66E-05 27699.00 5,314 saturation 77.00 22,461 saturation 3.32E-06 7.79E-03 8.30E-05 1.95E-01 8.63E-05 2.03E-01 4.02E-03 3.62E-02 2.04E-05 4.80E-02 6.40 1.51 0.048 TRUE 5 31/12/2007 (45.6 GL/a) 17.10 0.0468 0.542 0.21 2.576 30.245 0.22 0.090 30.245 6206.17 1.81E-05 30018.64 6,206 saturation 77.00 26,495 saturation 3.36E-06 7.89E-03 8.40E-05 1.97E-01 8.74E-05 2.05E-01 4.02E-03 3.62E-02 2.05E-05 4.81E-02 6.48 1.52 0.04809 TRUE 6 31/08/2008 (50.5 GL/a) 17.79 0.0487 0.564 0.21 2.576 30.245 0.22 0.090 30.245 6456.56 1.81E-05 31229.74 6,457 saturation 77.00 27,564 saturation 3.36E-06 7.89E-03 8.40E-05 1.97E-01 8.74E-05 2.05E-01 4.02E-03 3.62E-02 2.05E-05 4.81E-02 6.48 1.52 0.04809 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 18.86 0.0517 0.598 0.22 2.880 30.600 0.22 0.100 30.606 6763.92 1.95E-05 30610.94 6,764 saturation 77.00 29,164 saturation 3.40E-06 7.98E-03 8.50E-05 2.00E-01 8.84E-05 2.08E-01 4.02E-03 3.62E-02 2.05E-05 4.82E-02 6.55 1.52 0.04819 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 18.86 0.0517 0.598 0.22 2.880 30.600 0.22 0.100 30.606 6763.92 1.95E-05 30610.94 6,764 saturation 77.00 29,164 saturation 3.40E-06 7.98E-03 8.50E-05 2.00E-01 8.84E-05 2.08E-01 4.02E-03 3.62E-02 2.05E-05 4.82E-02 6.55 1.52 0.04819 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 18.86 0.0517 0.598 0.22 2.880 30.600 0.22 0.100 30.606 6763.92 1.95E-05 30610.94 6,764 saturation 77.00 29,164 saturation 3.40E-06 7.98E-03 8.50E-05 2.00E-01 8.84E-05 2.08E-01 4.02E-03 3.62E-02 2.05E-05 4.82E-02 6.55 1.52 0.04819 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 18.86 0.0517 0.598 0.22 2.880 30.600 0.22 0.100 30.606 6763.92 1.95E-05 30610.94 6,764 saturation 77.00 29,164 saturation 3.40E-06 7.98E-03 8.50E-05 2.00E-01 8.84E-05 2.08E-01 4.02E-03 3.62E-02 2.05E-05 4.82E-02 6.55 1.52 0.04819 TRUE

Yandicoogina baseline hydrology Page 45 of 60

REACH 2 HD1 + Yandi discharge - Weeli Wolli Reach 4

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 80 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 4620 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 26 ET (m/s) ET = 20% evap 2.22.E-08 2.E-06 8.E-03 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 2.E-05 7.E-02 Time to saturate alluvials (days) 108 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 2 Feb 2009 (59.59 GL/a) 17.34 0.0475 0.550 0.21 2.850 31.000 0.22 0.100 31.004 6138.95 1.91E-05 28789.71 6,139 saturation 80.00 25,915 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE 3 ave vol 07-09 (42.4 GL/a) 12.37 0.0339 0.392 0.19 2.240 30.000 0.21 0.080 30.003 4524.97 1.61E-05 24377.57 4,525 19,645 80.00 18,582 saturation 3.33E-06 1.51E-02 8.33E-05 3.77E-01 8.67E-05 3.92E-01 8.20E-03 7.39E-02 2.11E-05 9.72E-02 12.37 3.06 0.09718998 TRUE 4 31/10/2007 (46.1 GL/a) 12.95 0.0355 0.411 0.19 2.240 30.000 0.21 0.080 30.003 4739.38 1.61E-05 25532.66 4,739 saturation 80.00 19,463 saturation 3.33E-06 1.54E-02 8.33E-05 3.85E-01 8.67E-05 4.00E-01 8.20E-03 7.39E-02 2.11E-05 9.75E-02 12.63 3.07 0.09750638 TRUE 5 31/12/2007 (45.6 GL/a) 15.58 0.0427 0.494 0.21 2.850 31.000 0.22 0.100 31.004 5517.27 1.91E-05 25874.24 5,517 saturation 80.00 23,291 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE 6 31/08/2008 (50.5 GL/a) 16.27 0.0446 0.516 0.21 2.850 31.000 0.22 0.100 31.004 5761.53 1.91E-05 27019.73 5,762 saturation 80.00 24,322 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 17.34 0.0475 0.550 0.21 2.850 31.000 0.22 0.100 31.004 6138.95 1.91E-05 28789.71 6,139 saturation 80.00 25,915 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 17.34 0.0475 0.550 0.21 2.850 31.000 0.22 0.100 31.004 6138.95 1.91E-05 28789.71 6,139 saturation 80.00 25,915 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 17.34 0.0475 0.550 0.21 2.850 31.000 0.22 0.100 31.004 6138.95 1.91E-05 28789.71 6,139 saturation 80.00 25,915 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 17.34 0.0475 0.550 0.21 2.850 31.000 0.22 0.100 31.004 6138.95 1.91E-05 28789.71 6,139 saturation 80.00 25,915 saturation 3.44E-06 1.59E-02 8.61E-05 3.98E-01 8.96E-05 4.14E-01 8.20E-03 7.39E-02 2.12E-05 9.80E-02 13.05 3.09 0.09801912 TRUE

REACH 1 HD1 + Yandi discharge - Weeli Wolli Reach 5

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 500 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 8069 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 32 ET (m/s) ET = 20% evap 2.E-08 1.E-05 9.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 1.E-04 8.E-01 Time to saturate alluvials (days) 133 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 44.80 0.1227 1.421 0.23 6.788 50.500 0.19 0.150 50.504 9737.63 3.33E-05 42655.69 9,738 saturation 500.00 12,173 saturation 5.60E-06 4.52E-02 1.40E-04 1.13E+00 1.46E-04 1.18E+00 8.96E-02 8.07E-01 1.17E-04 9.42E-01 37.13 29.70 0.94173 TRUE 2 Feb 2009 (59.59 GL/a) 20.18 0.0553 0.640 0.18 4.350 47.003 0.18 0.100 47.000 4713.26 2.42E-05 26476.27 4,713 16,655 500.00 5,502 17,443 5.22E-06 2.46E-02 1.31E-04 6.15E-01 1.36E-04 6.40E-01 6.11E-02 5.50E-01 1.16E-04 6.36E-01 20.18 20.05 0.63582 TRUE 3 ave vol 07-09 (42.4 GL/a) 9.30 0.0255 0.295 0.13 2.526 44.200 0.17 0.060 44.202 2310.30 1.65E-05 17897.12 2,310 22,050 500.00 2,543 22,283 4.91E-06 1.13E-02 1.23E-04 2.84E-01 1.28E-04 2.95E-01 2.82E-02 2.54E-01 1.16E-04 2.94E-01 9.30 9.27 0.29386 TRUE 4 31/10/2007 (46.1 GL/a) 9.88 0.0271 0.313 0.13 2.526 44.200 0.17 0.060 44.202 2453.35 1.65E-05 19005.34 2,453 22,193 500.00 2,700 22,440 4.91E-06 1.20E-02 1.23E-04 3.01E-01 1.28E-04 3.13E-01 3.00E-02 2.70E-01 1.16E-04 3.12E-01 9.88 9.84 0.31205 TRUE 5 31/12/2007 (45.6 GL/a) 12.49 0.0342 0.396 0.14 2.972 44.902 0.17 0.070 44.902 3053.88 1.85E-05 21453.13 3,054 22,794 500.00 3,412 23,152 4.98E-06 1.52E-02 1.25E-04 3.81E-01 1.30E-04 3.96E-01 3.79E-02 3.41E-01 1.16E-04 3.94E-01 12.49 12.44 0.39434 TRUE 6 31/08/2008 (50.5 GL/a) 13.18 0.0361 0.418 0.14 2.972 44.902 0.17 0.070 44.902 3222.54 1.85E-05 22637.91 3,223 22,963 500.00 3,601 23,341 4.98E-06 1.61E-02 1.25E-04 4.02E-01 1.30E-04 4.18E-01 4.00E-02 3.60E-01 1.16E-04 4.16E-01 13.18 13.12 0.41611 TRUE 7 Feb 2009 (59.59 GL/a) + 5GL/a JSW 24.87 0.0681 0.789 0.18 4.350 47.003 0.18 0.100 47.000 5807.97 2.42E-05 32625.69 5,808 17,749 500.00 6,780 18,721 5.22E-06 3.03E-02 1.31E-04 7.58E-01 1.36E-04 7.89E-01 7.52E-02 6.78E-01 1.16E-04 7.83E-01 24.87 24.71 0.78349 TRUE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 29.71 0.0814 0.942 0.19 4.824 47.703 0.18 0.110 47.703 6836.15 2.60E-05 36200.37 6,836 18,778 500.00 8,094 saturation 5.29E-06 3.62E-02 1.33E-04 9.06E-01 1.38E-04 9.42E-01 8.96E-02 8.07E-01 1.16E-04 9.33E-01 29.71 29.41 0.93269 TRUE 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 34.54 0.0946 1.095 0.19 4.824 47.703 0.18 0.110 47.703 7949.13 2.60E-05 42094.07 7,949 19,891 500.00 9,411 saturation 5.29E-06 4.21E-02 1.33E-04 1.05E+00 1.38E-04 1.10E+00 8.96E-02 8.07E-01 1.16E-04 9.39E-01 34.54 29.60 0.93859 TRUE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 39.39 0.1079 1.249 0.21 5.792 49.104 0.19 0.130 49.104 8805.18 2.97E-05 42078.99 8,805 saturation 500.00 10,717 saturation 5.45E-06 4.40E-02 1.36E-04 1.10E+00 1.42E-04 1.14E+00 8.96E-02 8.07E-01 1.17E-04 9.40E-01 36.10 29.66 0.94048 TRUE

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 285 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 10728 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 32 ET (m/s) ET = 15% evap 1.70.E-08 5.E-06 5.E-02 536mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-06 6.E-04 6.E+00 Time to saturate alluvials (days) 133 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 15.10 0.0414 0.479 0.18 3.614 43.300 0.20 0.090 43.303 3828.72 2.30E-05 20808.65 3,829 30,965 285.00 826 27,963 4.81E-06 1.84E-02 1.20E-04 4.61E-01 1.25E-04 4.79E-01 4.00E-03 4.71E-01 5.80E-04 4.93E-01 15.10 15.56 0.47893617 FALSE 2 #DIV/0! #DIV/0! n/a 285.00 n/a 5.75E-04 FALSE 3 #DIV/0! #DIV/0! n/a 285.00 n/a 5.75E-04 FALSE 4 #DIV/0! #DIV/0! n/a 285.00 n/a 5.75E-04 FALSE 5 #DIV/0! #DIV/0! n/a 285.00 n/a 5.75E-04 FALSE 6 #DIV/0! #DIV/0! n/a 285.00 n/a 5.75E-04 FALSE 7 #DIV/0! #DIV/0! n/a 285.00 n/a 5.75E-04 FALSE 8 Feb 2009 (59.59 GL/a) +10GL/a JSW 0.29 0.0008 0.009 reach dry #DIV/0! #VALUE! #VALUE! #VALUE! #VALUE! 285.00 16 27,153 #VALUE! #VALUE! #VALUE! 7.87E-05 9.27E-03 5.75E-04 #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! 9 Feb 2009 (59.59 GL/a) +15GL/a JSW 4.95 0.0135 0.157 0.11 1.536 39.801 0.18 0.040 39.801 1363.99 1.27E-05 12396.03 1,364 21,375 285.00 271 20,282 4.42E-06 6.03E-03 1.11E-04 1.51E-01 1.15E-04 1.57E-01 1.31E-03 1.54E-01 5.79E-04 1.62E-01 4.95 5.10 0.15682669 FALSE 10 Feb 2009 (59.59 GL/a) +20GL/a JSW 9.73 0.0267 0.309 0.14 2.346 41.202 0.060 41.202 2592.18 1.70E-05 18177.08 2,592 22,603 285.00 532 20,543 4.57E-06 1.19E-02 1.14E-04 2.97E-01 1.19E-04 3.09E-01 2.58E-03 3.04E-01 5.79E-04 3.18E-01 9.73 10.03 0.30852672 FALSE

Yandicoogina baseline hydrology Page 46 of 60

Appendix B – Scenario output

Yandicoogina baseline hydrology Page 47 of 60

REACH 1 Yandi discharge - Marillana Reach 1 (BHP discharge)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 140 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 1336 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 18 ET (m/s) ET = 30% evap 3.E-08 5.E-06 6.E-03 1050mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 3.E-05 4.E-02 Time to saturate alluvials (days) 75 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 15.00 0.0411 0.476 0.18 2.925 27.000 0.15 0.150 27.003 6097.65 1.38E-05 34405.95 6,098 saturation 140.00 13,339 saturation 3.00E-06 4.00E-03 7.50E-05 1.00E-01 7.80E-05 1.04E-01 6.23E-03 3.74E-02 3.57E-05 4.76E-02 3.29 1.50 0.04765 TRUE 2 Peak max (90 GL/a) - d/s of operation 0.00 0.0000 0.000 0.00 0.000 0.000 0.00 0.000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 140.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.27E-05 0.00E+00 0.00 0.00 0 FALSE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 0.00 0.0000 0.000 0.00 0.000 0.000 0.00 0.000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 140.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.27E-05 0.00E+00 0.00 0.00 0 FALSE 4 Peak max (90 GL/a)+JSW (5 GL/a) 15.00 0.0411 0.476 0.18 2.925 27.000 0.15 0.150 27.003 6097.65 1.38E-05 34405.95 6,098 saturation 140.00 13,339 saturation 3.00E-06 4.00E-03 7.50E-05 1.00E-01 7.80E-05 1.04E-01 6.23E-03 3.74E-02 3.57E-05 4.76E-02 3.29 1.50 0.04765 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 15.00 0.0411 0.476 0.18 2.925 27.000 0.15 0.150 27.003 6097.65 1.38E-05 34405.95 6,098 saturation 140.00 13,339 saturation 3.00E-06 4.00E-03 7.50E-05 1.00E-01 7.80E-05 1.04E-01 6.23E-03 3.74E-02 3.57E-05 4.76E-02 3.29 1.50 0.04765 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 15.00 0.0411 0.476 0.18 2.925 27.000 0.15 0.150 27.003 6097.65 1.38E-05 34405.95 6,098 saturation 140.00 13,339 saturation 3.00E-06 4.00E-03 7.50E-05 1.00E-01 7.80E-05 1.04E-01 6.23E-03 3.74E-02 3.57E-05 4.76E-02 3.29 1.50 0.04765 TRUE 7 Peak max (90 GL/a)+JSW(20 GL/a) 15.00 0.041 0.476 0.18 2.925 27.000 0.15 0.150 27.003 6097.65 1.38E-05 34405.95 6,098 saturation 140.00 13,339 saturation 3.00E-06 4.00E-03 7.50E-05 1.00E-01 7.80E-05 1.04E-01 6.23E-03 3.74E-02 3.57E-05 4.76E-02 3.29 1.50 0.04765 TRUE 8 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 140.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.27E-05 0.00E+00 0.00 0.00 0 FALSE 9 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 140.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.27E-05 0.00E+00 0.00 0.00 0 FALSE 10 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 140.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.27E-05 0.00E+00 0.00 0.00 0 FALSE

REACH 2 Yandi discharge - Marillana Reach 2

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 150 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 2660 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 13 ET (m/s) ET = 30% evap 3.E-08 5.E-06 1.E-02 1050mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 3.E-05 8.E-02 Time to saturate alluvials (days) 54 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 13.50 0.0370 0.428 0.15 2.640 28.000 0.13 0.120 28.002 5290.98 1.18E-05 36316.49 5,291 saturation 150.00 11,233 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 2 Peak max (90 GL/a) - d/s of operation #DIV/0! #DIV/0! n/a 150.00 n/a 3.50E-05 FALSE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC #DIV/0! #DIV/0! n/a 150.00 n/a 3.50E-05 FALSE 4 Peak max (90 GL/a)+JSW (5 GL/a) 13.50 0.037 0.428 0.15 2.640 28.000 0.13 0.120 28.002 5290.98 1.18E-05 36316.49 5,291 saturation 150.00 11,233 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 13.50 0.037 0.428 0.15 2.640 28.000 0.13 0.120 28.002 5290.98 1.18E-05 36316.49 5,291 saturation 150.00 11,233 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 13.50 0.037 0.428 0.15 2.640 28.000 0.13 0.120 28.002 5290.98 1.18E-05 36316.49 5,291 saturation 150.00 11,233 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 7 Peak max (90 GL/a)+JSW(20 GL/a) 13.50 0.037 0.428 0.15 2.640 28.000 0.13 0.120 28.002 5290.98 1.18E-05 36316.49 5,291 saturation 150.00 11,233 saturation 3.11E-06 8.27E-03 7.78E-05 2.07E-01 8.09E-05 2.15E-01 1.33E-02 7.98E-02 3.81E-05 1.01E-01 6.79 3.20 0.10134407 TRUE 8 #DIV/0! #DIV/0! n/a 150.00 n/a 3.50E-05 FALSE 9 #DIV/0! #DIV/0! n/a 150.00 n/a 3.50E-05 FALSE 10 #DIV/0! #DIV/0! n/a 150.00 n/a 3.50E-05 FALSE

REACH 3 Yandi discharge - Marillana Reach 3

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 200 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 3129 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 16 ET (m/s) ET = 20% evap 2.E-08 4.E-06 1.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 4.E-05 1.E-01 Time to saturate alluvials (days) 67 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 10.30 0.0282 0.327 0.18 1.504 23.660 0.21 0.074 23.662 4778.95 1.20E-05 27163.15 4,779 saturation 200.00 6,940 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 2 Peak max (90 GL/a) - d/s of operation 0.00 0.0000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 200.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.44E-05 0.00E+00 0.00 0.00 0 FALSE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 0.00 0.0000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 200.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.44E-05 0.00E+00 0.00 0.00 0 FALSE 4 Peak max (90 GL/a)+JSW (5 GL/a) 10.30 0.0282 0.327 0.18 1.504 23.660 0.21 0.074 23.662 4778.95 1.20E-05 27163.15 4,779 saturation 200.00 6,940 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 10.30 0.0282 0.327 0.18 1.504 23.660 0.21 0.074 23.662 4778.95 1.20E-05 27163.15 4,779 saturation 200.00 6,940 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 10.30 0.0282 0.327 0.18 1.504 23.660 0.21 0.074 23.662 4778.95 1.20E-05 27163.15 4,779 saturation 200.00 6,940 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 7 Peak max (90 GL/a)+JSW(20 GL/a) 10.30 0.0282 0.327 0.18 1.504 23.660 0.21 0.074 23.662 4778.95 1.20E-05 27163.15 4,779 saturation 200.00 6,940 saturation 2.63E-06 8.22E-03 6.57E-05 2.06E-01 6.84E-05 2.14E-01 1.39E-02 1.25E-01 4.71E-05 1.47E-01 6.75 4.64 0.14727943 TRUE 8 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 200.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.44E-05 0.00E+00 0.00 0.00 0 FALSE 9 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 200.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.44E-05 0.00E+00 0.00 0.00 0 FALSE 10 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 200.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.44E-05 0.00E+00 0.00 0.00 0 FALSE

REACH 1 Yandi discharge - Marillana Reach 4 (DO3, DO8, DO1/4 and DO5)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 120 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 5172 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 2 ET (m/s) ET = 17% evap 2.E-08 2.E-06 1.E-02 600mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 2.E-05 1.E-01 Time to saturate alluvials (days) 8 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 35.22 0.0965 1.117 0.27 4.313 27.928 0.20 0.180 27.928 13841.06 2.15E-05 51974.21 13,841 saturation 120.00 37,994 saturation 3.10E-06 1.60E-02 7.76E-05 4.01E-01 8.07E-05 4.17E-01 1.18E-02 1.24E-01 2.94E-05 1.52E-01 13.16 4.79 0.152 TRUE 2 Peak max (90 GL/a) - d/s of operation 0.00 0.0000 0.000 0.00 0.000 0.000 0.00 0.000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 120.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.63E-05 0.00E+00 0.00 0.00 0 FALSE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 0.00 0.0000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 120.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.63E-05 0.00E+00 0.00 0.00 0 FALSE 4 Peak max (90 GL/a)+JSW (5 GL/a) 35.22 0.0965 1.117 0.27 4.313 27.928 0.20 0.180 27.928 13841.06 2.15E-05 51974.21 13,841 saturation 120.00 37,994 saturation 3.10E-06 1.60E-02 7.76E-05 4.01E-01 8.07E-05 4.17E-01 1.18E-02 1.24E-01 2.94E-05 1.52E-01 13.16 4.79 0.152 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 35.22 0.0965 1.117 0.27 4.313 27.928 0.20 0.180 27.928 13841.06 2.15E-05 51974.21 13,841 saturation 120.00 37,994 saturation 3.10E-06 1.60E-02 7.76E-05 4.01E-01 8.07E-05 4.17E-01 1.18E-02 1.24E-01 2.94E-05 1.52E-01 13.16 4.79 0.152 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 35.22 0.0965 1.117 0.27 4.313 27.928 0.20 0.180 27.928 13841.06 2.15E-05 51974.21 13,841 saturation 120.00 37,994 saturation 3.10E-06 1.60E-02 7.76E-05 4.01E-01 8.07E-05 4.17E-01 1.18E-02 1.24E-01 2.94E-05 1.52E-01 13.16 4.79 0.152 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 35.22 0.0965 1.117 0.27 4.313 27.928 0.20 0.180 27.928 13841.06 2.15E-05 51974.21 13,841 saturation 120.00 37,994 saturation 3.10E-06 1.60E-02 7.76E-05 4.01E-01 8.07E-05 4.17E-01 1.18E-02 1.24E-01 2.94E-05 1.52E-01 13.16 4.79 0.152 TRUE 8 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 120.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.63E-05 0.00E+00 0.00 0.00 0 FALSE 9 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 120.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.63E-05 0.00E+00 0.00 0.00 0 FALSE 10 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 120.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 2.63E-05 0.00E+00 0.00 0.00 0 FALSE

Yandicoogina baseline hydrology Page 48 of 60

REACH 1 Yandi discharge - Marillana Reach 5 (DO2)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 280 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 3664 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 18 ET (m/s) ET = 17% evap 2.E-08 5.E-06 2.E-02 600mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 6.E-05 2.E-01 Time to saturate alluvials (days) 75 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 32.26 0.0884 1.023 0.22 4.616 39.025 0.20 0.130 39.025 9072.85 2.50E-05 40848.02 9,073 saturation 280.00 15,574 saturation 4.33E-06 1.59E-02 1.08E-04 3.97E-01 1.13E-04 4.13E-01 1.96E-02 2.05E-01 6.57E-05 2.41E-01 13.03 7.59 0.24063 TRUE 2 Peak max (90 GL/a) - d/s of operation 0.00 0.0000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 280.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6.13E-05 0.00E+00 0.00 0.00 0 FALSE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 0.00 0.0000 0.000 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 280.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6.13E-05 0.00E+00 0.00 0.00 0 FALSE 4 Peak max (90 GL/a)+JSW (5 GL/a) 37.26 0.1021 1.181 0.24 5.208 39.835 0.20 0.145 39.835 10266.03 2.73E-05 43239.64 10,266 saturation 280.00 17,963 saturation 4.42E-06 1.62E-02 1.11E-04 4.05E-01 1.15E-04 4.22E-01 1.96E-02 2.05E-01 6.58E-05 2.41E-01 13.30 7.60 0.24096 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 42.26 0.1158 1.340 0.24 5.408 40.106 0.20 0.150 40.106 11565.37 2.81E-05 47719.33 11,565 saturation 280.00 20,365 saturation 4.45E-06 1.63E-02 1.11E-04 4.08E-01 1.16E-04 4.24E-01 1.96E-02 2.05E-01 6.58E-05 2.41E-01 13.39 7.60 0.24107 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 47.26 0.1295 1.498 0.26 6.015 40.916 0.20 0.165 40.916 12677.66 3.03E-05 49378.45 12,678 saturation 280.00 22,743 saturation 4.54E-06 1.66E-02 1.14E-04 4.16E-01 1.18E-04 4.33E-01 1.96E-02 2.05E-01 6.59E-05 2.41E-01 13.66 7.61 0.2414 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 52.26 0.1432 1.657 0.26 6.015 40.916 0.20 0.165 40.916 14019.06 3.03E-05 54603.08 14,019 saturation 280.00 25,150 saturation 4.54E-06 1.66E-02 1.14E-04 4.16E-01 1.18E-04 4.33E-01 1.96E-02 2.05E-01 6.59E-05 2.41E-01 13.66 7.61 0.2414 TRUE 8 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 280.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6.13E-05 0.00E+00 0.00 0.00 0 FALSE 9 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 280.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6.13E-05 0.00E+00 0.00 0.00 0 FALSE 10 #DIV/0! 0.00E+00 #DIV/0! 0 n/a 280.00 0 n/a 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 6.13E-05 0.00E+00 0.00 0.00 0 FALSE

REACH 2 Yandi discharge - Marillana Reach 6

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 460 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 3106 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 30 ET (m/s) ET = 30% evap 3.E-08 2.E-05 5.E-02 1050mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 9.E-05 3.E-01 Time to saturate alluvials (days) 125 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 24.67 0.0676 0.782 0.21 4.096 35.025 0.19 0.130 35.025 7730.69 2.14E-05 36597.17 7,731 saturation 460.00 7,034 saturation 3.89E-06 1.21E-02 9.73E-05 3.02E-01 1.01E-04 3.14E-01 4.76E-02 2.86E-01 1.11E-04 3.45E-01 9.91 10.89 0.31421449 FALSE 2 Peak max (90 GL/a) - d/s of operation 46.39 0.1271 1.471 0.26 5.915 37.727 0.19 0.180 37.727 13498.30 2.80E-05 52560.32 13,498 saturation 460.00 13,193 saturation 4.19E-06 1.30E-02 1.05E-04 3.25E-01 1.09E-04 3.38E-01 4.76E-02 2.86E-01 1.12E-04 3.46E-01 10.67 10.92 0.33845338 FALSE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 31.39 0.0860 0.995 0.23 4.628 35.835 0.19 0.145 35.835 9615.97 2.34E-05 42612.06 9,616 saturation 460.00 8,944 saturation 3.98E-06 1.24E-02 9.95E-05 3.09E-01 1.04E-04 3.21E-01 4.76E-02 2.86E-01 1.11E-04 3.46E-01 10.14 10.90 0.32148595 FALSE 4 Peak max (90 GL/a)+JSW (5 GL/a) 29.66 0.081 0.940 0.23 4.628 35.835 0.19 0.145 35.835 9084.23 2.34E-05 40255.72 9,084 saturation 460.00 8,450 saturation 3.98E-06 1.24E-02 9.95E-05 3.09E-01 1.04E-04 3.21E-01 4.76E-02 2.86E-01 1.11E-04 3.46E-01 10.14 10.90 0.32148595 FALSE 5 Peak max (90 GL/a)+JSW (10 GL/a) 34.65 0.095 1.099 0.23 4.808 36.106 0.19 0.150 36.106 10535.31 2.40E-05 45742.90 10,535 saturation 460.00 9,871 saturation 4.01E-06 1.24E-02 1.00E-04 3.11E-01 1.04E-04 3.24E-01 4.76E-02 2.86E-01 1.11E-04 3.46E-01 10.21 10.90 0.32391012 FALSE 6 Peak max (90 GL/a)+JSW (15 GL/a) 39.64 0.109 1.257 0.24 5.171 36.646 0.19 0.160 36.646 11874.55 2.53E-05 49599.83 11,875 saturation 460.00 11,286 saturation 4.07E-06 1.26E-02 1.02E-04 3.16E-01 1.06E-04 3.29E-01 4.76E-02 2.86E-01 1.11E-04 3.46E-01 10.37 10.91 0.32875775 FALSE 7 Peak max (90 GL/a)+JSW (20 GL/a) 44.64 0.122 1.416 0.26 5.915 37.727 0.19 0.180 37.727 12989.18 2.80E-05 50577.90 12,989 saturation 460.00 12,696 saturation 4.19E-06 1.30E-02 1.05E-04 3.25E-01 1.09E-04 3.38E-01 4.76E-02 2.86E-01 1.12E-04 3.46E-01 10.67 10.92 0.33845338 FALSE 8 Peak max (90 GL/a)+JSW (5 GL/a) - d/s of operation 51.39 0.1408 1.630 0.27 6.295 38.267 0.19 0.190 38.267 14741.95 2.93E-05 55594.03 14,742 saturation 460.00 14,607 saturation 4.25E-06 1.32E-02 1.06E-04 3.30E-01 1.11E-04 3.43E-01 4.76E-02 2.86E-01 1.12E-04 3.46E-01 10.83 10.93 0.34330102 FALSE 9 Peak max (90 GL/a)+JSW (10 GL/a) - d/s of operation 56.39 0.1545 1.788 0.27 6.295 38.267 0.19 0.190 38.267 16176.21 2.93E-05 61002.82 16,176 saturation 460.00 16,029 saturation 4.25E-06 1.32E-02 1.06E-04 3.30E-01 1.11E-04 3.43E-01 4.76E-02 2.86E-01 1.12E-04 3.46E-01 10.83 10.93 0.34330102 FALSE 10 Peak max (90 GL/a)+JSW (15 GL/a) - d/s of operation 61.39 0.1682 1.947 0.27 6.295 38.267 0.19 0.190 38.267 17610.46 2.93E-05 66411.61 17,610 saturation 460.00 17,450 saturation 4.25E-06 1.32E-02 1.06E-04 3.30E-01 1.11E-04 3.43E-01 4.76E-02 2.86E-01 1.12E-04 3.46E-01 10.83 10.93 0.34330102 FALSE 11 Peak max (90 GL/a)+JSW (20 GL/a) - d/s of operation 66.39 0.1819 2.105 0.29 7.467 39.888 0.20 0.220 39.888 18270.72 3.33E-05 63212.33 18,271 saturation 460.00 18,840 saturation 4.43E-06 1.37E-02 1.11E-04 3.44E-01 1.15E-04 3.58E-01 4.76E-02 2.86E-01 1.12E-04 3.47E-01 11.28 10.94 0.34702281 TRUE

REACH 1 HD1 discharge - Weeli Wolli Reach 1

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 200 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 4500 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 30 ET (m/s) ET = 20% evap 2.E-08 4.E-06 2.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) -5.E-08 -1.E-05 -5.E-02 Time to saturate alluvials (days) 125 Weeli Wolli Spring Baseflow 4.2 ML/day Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 2 Peak max (90 GL/a) - d/s of operation 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 4 Peak max (90 GL/a)+JSW (5 GL/a) 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 8 Peak max (90 GL/a)+JSW(5 GL/a) - d/s of operation 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 9 Peak max (90 GL/a)+JSW(10 GL/a) - d/s of operation 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 10 Peak max (90 GL/a)+JSW(15 GL/a) - d/s of operation 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE 11 Peak max (90 GL/a)+JSW(20 GL/a) - d/s of operation 40.00 0.110 1.268 0.13 25.000 25.000 17563.12 9.39E-06 135100.90 17,563 saturation 200.00 175,824 saturation 2.77E-06 1.25E-02 6.94E-05 3.13E-01 7.22E-05 3.25E-01 2.00E-02 -4.86E-02 -3.59E-06 -1.61E-02 10.25 -0.51 -0.0161 TRUE

Yandicoogina baseline hydrology Page 49 of 60

REACH 2 HD1 discharge - Weeli Wolli Reach 2

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 150 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 8270 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 30 ET (m/s) ET = 20% evap 2.2.E-08 3.E-06 3.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 3.E-05 2.E-01 Time to saturate alluvials (days) 125 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 2 Peak max (90 GL/a) - d/s of operation 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 4 Peak max (90 GL/a)+JSW (5 GL/a) 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 8 Peak max (90 GL/a)+JSW(5 GL/a) - d/s of operation 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 9 Peak max (90 GL/a)+JSW(10 GL/a) - d/s of operation 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 10 Peak max (90 GL/a)+JSW(15 GL/a) - d/s of operation 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE 11 Peak max (90 GL/a)+JSW(20 GL/a) - d/s of operation 40.51 0.1110 1.285 0.13 25.000 25.000 17786.72 9.39E-06 136820.91 17,787 saturation 150.00 35,579 saturation 2.77E-06 2.29E-02 6.94E-05 5.74E-01 7.22E-05 5.97E-01 2.75E-02 2.48E-01 3.61E-05 2.99E-01 18.83 9.42 0.2985812 TRUE

REACH 1 HD1 + Yandi discharge - Weeli Wolli Reach 3 (DO6)

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 77 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 2350 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 10 ET (m/s) ET = 20% evap 2.E-08 2.E-06 4.E-03 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 2.E-05 4.E-02 Time to saturate alluvials (days) 42 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 2 Peak max (90 GL/a) - d/s of operation 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 4 Peak max (90 GL/a)+JSW (5 GL/a) 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 8 Peak max (90 GL/a)+JSW(5 GL/a) - d/s of operation 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 9 Peak max (90 GL/a)+JSW(10 GL/a) - d/s of operation 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 10 Peak max (90 GL/a)+JSW(15 GL/a) - d/s of operation 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE 11 Peak max (90 GL/a)+JSW(20 GL/a) - d/s of operation 34.70 0.0951 1.100 0.28 4.293 32.228 0.23 0.145 32.228 11819.20 2.59E-05 42424.14 11,819 saturation 77.00 53,193 saturation 3.58E-06 8.41E-03 8.95E-05 2.10E-01 9.31E-05 2.19E-01 4.02E-03 3.62E-02 2.07E-05 4.86E-02 6.90 1.53 0.04861 TRUE

REACH 2 HD1 + Yandi discharge - Weeli Wolli Reach 4

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 80 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 4620 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 26 ET (m/s) ET = 20% evap 2.22.E-08 2.E-06 8.E-03 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 2.E-05 7.E-02 Time to saturate alluvials (days) 108 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding 1 Peak max (90 GL/a) 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 2 Peak max (90 GL/a) - d/s of operation 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 4 Peak max (90 GL/a)+JSW (5 GL/a) 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 8 Peak max (90 GL/a)+JSW(5 GL/a) - d/s of operation 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 9 Peak max (90 GL/a)+JSW(10 GL/a) - d/s of operation 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 10 Peak max (90 GL/a)+JSW(15 GL/a) - d/s of operation 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE 11 Peak max (90 GL/a)+JSW(20 GL/a) - d/s of operation 33.17 0.0909 1.052 0.26 4.130 33.000 0.22 0.140 33.006 11030.98 2.50E-05 42117.96 11,031 saturation 80.00 49,059 saturation 3.66E-06 1.69E-02 9.17E-05 4.24E-01 9.53E-05 4.40E-01 8.20E-03 7.39E-02 2.14E-05 9.90E-02 13.89 3.12 0.09904462 TRUE

Yandicoogina baseline hydrology Page 50 of 60

REACH 1 HD1 + Yandi discharge - Weeli Wolli Reach 5

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 width per reach total Stream Alluvials Rates m/s m/s m3/s Base width HECRAS INPUT Riparian veg width (m) 500 Infiltration (mm/h) 10 2.78E-06 Side slopes (1: x) HECRAS INPUT channel length (m) 8069 Evaporation (mm/y) 3500 1.11E-07 Mannings No, n HECRAS INPUT channel depth (m) 32 ET (m/s) ET = 20% evap 2.E-08 1.E-05 9.E-02 700mm/year Slope, Sf HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-07 1.E-04 8.E-01 Time to saturate alluvials (days) 133 Water Balance FLOW CONDITIONS Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zone lossGroundwater loss SW Groundwat Limited Reach peak distance to time peak distance to Surface Riparian Steady footprint er loss per loss to Potential Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per loss per year per next for Scenarios name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s year per reach (GL) reach ponding 1 Peak max (90 GL/a) 44.80 0.1227 1.421 0.23 6.788 50.500 0.19 0.150 50.504 9737.63 3.33E-05 42655.69 9,738 saturation 500.00 12,173 saturation 5.60E-06 4.52E-02 1.40E-04 1.13E+00 1.46E-04 1.18E+00 8.96E-02 8.07E-01 1.17E-04 9.42E-01 37.13 29.70 0.94173 TRUE 2 Peak max (90 GL/a) - d/s of operation 65.76 0.1802 2.085 0.25 7.812 51.900 0.19 0.170 51.905 13907.80 3.69E-05 56496.17 13,908 saturation 500.00 17,845 saturation 5.76E-06 4.65E-02 1.44E-04 1.16E+00 1.50E-04 1.21E+00 8.96E-02 8.07E-01 1.17E-04 9.43E-01 38.16 29.74 0.94298 TRUE 3 Peak max (90 GL/a) - d/s of operation;BHP in JC 51.30 0.1405 1.627 0.22 6.286 49.804 0.19 0.140 49.804 11306.30 3.15E-05 51644.65 11,306 saturation 500.00 13,948 saturation 5.53E-06 4.46E-02 1.38E-04 1.12E+00 1.44E-04 1.16E+00 8.96E-02 8.07E-01 1.17E-04 9.41E-01 36.61 29.68 0.94111 TRUE 4 Peak max (90 GL/a)+JSW (5 GL/a) 49.56 0.1358 1.572 0.23 7.041 50.854 0.19 0.155 50.854 10698.07 3.42E-05 45942.89 10,698 saturation 500.00 13,462 saturation 5.64E-06 4.55E-02 1.41E-04 1.14E+00 1.47E-04 1.19E+00 8.96E-02 8.07E-01 1.17E-04 9.42E-01 37.38 29.71 0.94205 TRUE 5 Peak max (90 GL/a)+JSW (10 GL/a) 54.48 0.1493 1.728 0.24 7.553 51.555 0.19 0.165 51.555 11600.32 3.60E-05 47975.44 11,600 saturation 500.00 14,789 saturation 5.72E-06 4.62E-02 1.43E-04 1.16E+00 1.49E-04 1.20E+00 8.96E-02 8.07E-01 1.17E-04 9.43E-01 37.90 29.73 0.94267 TRUE 6 Peak max (90 GL/a)+JSW (15 GL/a) 59.32 0.1625 1.881 0.25 7.812 51.900 0.19 0.170 51.905 12545.00 3.69E-05 50960.21 12,545 saturation 500.00 16,096 saturation 5.76E-06 4.65E-02 1.44E-04 1.16E+00 1.50E-04 1.21E+00 8.96E-02 8.07E-01 1.17E-04 9.43E-01 38.16 29.74 0.94298 TRUE 7 Peak max (90 GL/a)+JSW (20 GL/a) 64.01 0.1754 2.030 0.27 9.400 54.006 0.19 0.200 54.006 13011.07 4.23E-05 47969.58 13,011 saturation 500.00 17,336 saturation 5.99E-06 4.84E-02 1.50E-04 1.21E+00 1.56E-04 1.26E+00 8.96E-02 8.07E-01 1.17E-04 9.45E-01 39.70 29.80 0.94487 TRUE 8 Peak max (90 GL/a)+JSW(5 GL/a) - d/s of operation 70.61 0.1935 2.239 0.27 9.400 54.006 0.19 0.200 54.006 14351.93 4.23E-05 52913.08 14,352 saturation 500.00 19,122 saturation 5.99E-06 4.84E-02 1.50E-04 1.21E+00 1.56E-04 1.26E+00 8.96E-02 8.07E-01 1.17E-04 9.45E-01 39.70 29.80 0.94487 TRUE 9 Peak max (90 GL/a)+JSW(10 GL/a) - d/s of operation 75.61 0.2072 2.398 0.27 9.400 54.006 0.19 0.200 54.006 15368.20 4.23E-05 56659.92 15,368 saturation 500.00 20,476 saturation 5.99E-06 4.84E-02 1.50E-04 1.21E+00 1.56E-04 1.26E+00 8.96E-02 8.07E-01 1.17E-04 9.45E-01 39.70 29.80 0.94487 TRUE 10 Peak max (90 GL/a)+JSW(15 GL/a) - d/s of operation 80.61 0.2209 2.556 0.27 9.400 54.006 0.19 0.200 54.006 16384.48 4.23E-05 60406.75 16,384 saturation 500.00 21,830 saturation 5.99E-06 4.84E-02 1.50E-04 1.21E+00 1.56E-04 1.26E+00 8.96E-02 8.07E-01 1.17E-04 9.45E-01 39.70 29.80 0.94487 TRUE 11 Peak max (90 GL/a)+JSW(20 GL/a) - d/s of operation 85.49 0.2342 2.711 0.27 9.400 54.006 0.19 0.200 54.006 17376.90 4.23E-05 64065.64 17,377 saturation 500.00 23,152 saturation 5.99E-06 4.84E-02 1.50E-04 1.21E+00 1.56E-04 1.26E+00 8.96E-02 8.07E-01 1.17E-04 9.45E-01 39.70 29.80 0.94487 TRUE

HD1 + Yandi discharge - Weeli Wolli Reach 6

PHYSICAL CREEK CHARACTERISTICS Riparian zone = 1, No riparian = 0 1 wdith per reach total Alluvials Rates m/s m/s m3/s HECRAS INPUT Riparian veg width (m) 285 Infiltration (mm/h) 10 2.78E-06 HECRAS INPUT channel length (m) 10728 Evaporation (mm/y) 3500 1.11E-07 HECRAS INPUT channel depth (m) 32 ET (m/s) ET = 15% evap 1.70.E-08 5.E-06 5.E-02 536mm/year HECRAS INPUT porosity 0.2 loss past roots (m/s) 2.E-06 6.E-04 6.E+00 Time to saturate alluvials (days) 133 Water Balance Data from HECRAS averages Surfacxe water Groundwater Evaporation loss Infiltration loss SW footprint loss ET loss Past root zoneGroundwater loss loss SW footprint Groundwater Reach peak distance to time peak distance to Surface Riparian Steady loss per year loss per year Limited loss Reach volume Reach peak Ave Velocity Ave Flow Ave Top Ave Water Wetted zero volume loss m3 per volume to zero volume water recharge steady state state width per width per width per width per per reach per reach to next reach Potential for name volume GL/y (GL/d) m3/s (m/s) Area (m2) Width (m) Froude no Depth (m) Perimeter (m) second zero (s) (m) footprint influence distance (m) footprint m/s total m3/s m/s total m3/s m/s total m3/s total m3/s total m3/s m/s total m3/s (GL) (GL) (m3/s) ponding Peak max (90 GL/a) 15.10 0.0414 0.479 0.18 3.614 43.300 0.20 0.090 43.303 3828.72 2.30E-05 20808.65 3,829 30,965 285.00 826 27,963 4.81E-06 1.84E-02 1.20E-04 4.61E-01 1.25E-04 4.79E-01 4.00E-03 4.71E-01 5.80E-04 4.93E-01 15.10 15.56 0.47893617 FALSE Peak max (90 GL/a) - d/s of operation 36.03 0.0987 1.142 0.22 4.944 45.403 0.20 0.120 45.403 8709.66 2.88E-05 39640.71 8,710 19,885 285.00 1,970 13,145 5.04E-06 4.39E-02 1.26E-04 1.10E+00 1.31E-04 1.14E+00 9.53E-03 1.12E+00 5.80E-04 1.18E+00 36.03 37.10 1.14235555 FALSE Peak max (90 GL/a) - d/s of operation;BHP in JC 21.62 0.0592 0.686 0.17 3.184 42.602 0.19 0.080 42.602 5570.53 2.10E-05 32583.93 5,571 16,746 285.00 1,183 12,358 4.73E-06 2.63E-02 1.18E-04 6.59E-01 1.23E-04 6.86E-01 5.72E-03 6.74E-01 5.80E-04 7.06E-01 21.62 22.27 0.68555324 FALSE Peak max (90 GL/a)+JSW (5 GL/a) 19.85 0.0544 0.630 0.20 4.050 44.003 0.20 0.100 44.003 4952.78 2.50E-05 25215.46 4,953 32,089 285.00 1,086 28,222 4.88E-06 2.42E-02 1.22E-04 6.05E-01 1.27E-04 6.30E-01 5.26E-03 6.19E-01 5.80E-04 6.48E-01 19.85 20.45 0.62956725 FALSE Peak max (90 GL/a)+JSW (10 GL/a) 24.75 0.0678 0.785 0.22 4.944 45.403 0.20 0.120 45.403 5984.72 2.88E-05 27238.57 5,985 33,121 285.00 1,354 28,490 5.04E-06 3.02E-02 1.26E-04 7.55E-01 1.31E-04 7.85E-01 6.55E-03 7.72E-01 5.80E-04 8.08E-01 24.75 25.49 0.78495405 FALSE Peak max (90 GL/a)+JSW (15 GL/a) 29.58 0.0810 0.938 0.22 4.944 45.403 0.20 0.120 45.403 7151.72 2.88E-05 32549.99 7,152 34,288 285.00 1,618 28,754 5.04E-06 3.60E-02 1.26E-04 9.02E-01 1.31E-04 9.38E-01 7.83E-03 9.22E-01 5.80E-04 9.66E-01 29.58 30.46 0.93801701 FALSE Peak max (90 GL/a)+JSW (20 GL/a) 34.22 0.0937 1.085 0.22 4.944 45.403 0.20 0.120 45.403 8272.24 2.88E-05 37649.88 8,272 35,408 285.00 1,871 29,007 5.04E-06 4.17E-02 1.26E-04 1.04E+00 1.31E-04 1.08E+00 9.05E-03 1.07E+00 5.80E-04 1.12E+00 34.22 35.23 1.08498426 FALSE Peak max (90 GL/a)+JSW(5 GL/a) - d/s of operation 40.81 0.1118 1.294 0.24 5.866 46.804 0.21 0.140 46.804 9571.87 3.26E-05 39666.55 9,572 20,747 285.00 2,231 13,406 5.19E-06 4.97E-02 1.30E-04 1.24E+00 1.35E-04 1.29E+00 1.08E-02 1.27E+00 5.80E-04 1.33E+00 40.81 42.02 1.29417078 FALSE Peak max (90 GL/a)+JSW(10 GL/a) - d/s of operation 45.81 0.1255 1.453 0.24 5.866 46.804 0.21 0.140 46.804 10744.52 3.26E-05 44526.10 10,745 saturation 285.00 2,505 13,680 5.19E-06 5.57E-02 1.30E-04 1.39E+00 1.35E-04 1.45E+00 1.21E-02 1.43E+00 5.80E-04 1.50E+00 45.74 47.16 1.45051155 FALSE Peak max (90 GL/a)+JSW(15 GL/a) - d/s of operation 50.81 0.1392 1.611 0.24 5.866 46.804 0.21 0.140 46.804 11917.17 3.26E-05 49385.65 11,917 saturation 285.00 2,778 13,953 5.19E-06 5.57E-02 1.30E-04 1.39E+00 1.35E-04 1.45E+00 1.34E-02 1.58E+00 5.80E-04 1.65E+00 45.74 52.12 1.45051155 FALSE Peak max (90 GL/a)+JSW(20 GL/a) - d/s of operation 55.70 0.1526 1.766 0.24 5.866 46.804 0.21 0.140 46.804 13062.30 3.26E-05 54131.13 13,062 saturation 285.00 3,045 14,220 5.19E-06 5.57E-02 1.30E-04 1.39E+00 1.35E-04 1.45E+00 1.47E-02 1.74E+00 5.80E-04 1.81E+00 45.74 56.95 1.45051155 FALSE

Yandicoogina baseline hydrology Page 51 of 60

Addendums– Scenario 7 to 9 including BHPBIO Jinidi

Yandicoogina baseline hydrology Page 52 of 60

Scenario 7: Comparison of different discharge rate combinations

This scenario investigates the response of the creek systems by changing the combination of the volume discharged from Hope Downs 1 and RTIO Yandicoogina. The 90, 95, 100 GL/year discharge rate options were investigated, which are equivalent to existing Scenarios 7d, 7e and 7f but with different discharge rate combinations.

Modelling results

A comparison of the discharge volumes and the subsequent estimated footprint distances for the existing and additional scenarios are shown in Table 11. The differences between the estimated discharge footprints for the existing and additional scenarios are less than 0.3 %. Based on the model results, it was determined that changing the combination of the volume discharged from Hope Downs 1 or RTIO Yandicoogina would unlikely to have a notable effect on the footprint distances

Table 11: A comparison of the discharge volumes and estimated footprint distances for the existing and additional 90, 95 and 100 GL/year discharge rate options

Discharge rate (GL/year) Maximum footprint (km)

Total BHPBIO RTIO Hope Proposed Hope Downs Weeli Wolli – Yandi Yandi Downs 1 Marillana Creek 1 outlet Marillana Creek outlet confluence

90 (7d) 15 40 35 16.1 32.7 12.9

95 (7e) 15 40 40 17.2 33.9 14.1

100(7f) 15 45 40 18.3 35.0 15.2

90 15 45 30 16.0 32.7 12.9

95 15 45 35 17.2 33.8 14.1

100 15 50 35 18.3 34.9 15.2

Bold – existing scenarios Italic – additional scenarios

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Scenario 8: Hope Downs 1 discharge rate options

In this scenario we investigate the response of the Weeli Wolli Creek system from Hope Downs 1 discharge alone, at a continual rate of 25 (the current average discharge rate), 30, 35 and 40 (the licensed maximum abstraction rate) GL/year. This scenario investigates the contribution of Hope Downs 1 water on the progression of the wetting front along Weeli Wolli Creek.

Modelling results

The footprint distances, measured downstream from the Hope Downs 1 discharge location and the confluence of Marillana and Weeli Wolli Creeks, for the modelled discharge options are presented in Figure 30 and are summarised in Table 12. Modelling indicated that the footprint distance would extend from approximately 3.2 km to 7.3 km down gradient from the Weeli Wolli – Marillana Creek confluence for modelled volumes 25 GL/year to 40 GL/year, the maximum volume modelled. It is assumed that the creek conditions are uniform for 8 km downstream from the confluence of Marillana and Weeli Wolli Creeks. As all of the footprints for the modelled scenarios terminate within this reach, it is expected that the footprint distance would increase linearly with discharge (Figure 31 and Figure 32).

Table 12: Estimated discharge footprints for Weeli Wolli Creek for different discharge options

Scenario 8 Weeli Wolli Creek from Hope Downs 1 discharge Footprint distance past the outlet confluence of Marillana and Weeli Wolli Creeks Steady state Surface water Maximum (km) distance (km) expression (km) footprint (km) a: 25 GL/year 22.9 22.6 22.9 3.2 b: 30 GL/year 24.3 23.8 24.3 4.6 c: 35 GL/year 25.6 24.9 25.6 5.9 d: 40 GL/year 27.0 25.9 27.0 7.3

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Figure 30: Estimated discharge footprints for Marillana and Weeli Wolli Creeks for different discharge rates.

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From Hope Downs 1 outlet 35

20 Max footprint Max (km) 15

10 10 15 20 25 30 35 40 45 50 Discharge volume (GL/year) Discharge footprints Discharge footprints (+/- 10%)

Figure 31: A plot of discharge volume versus maximum footprint measured from the Hope Downs 1 discharge outlet (with +/- 10 % error margin). The plot shows a linear increase in footprint distance with discharge.

From Weeli Wolli - Marillana Creek confluence 10

4 Max footprint Max (km) 2

0 10 15 20 25 30 35 40 45 50 Discharge volume (GL/year) Discharge footprints Discharge footprints (+/- 10%)

Figure 32: A plot of discharge volume versus maximum footprint measured from the Weeli Wolli – Marillana Creek confluence (with +/- 10 % error margin). The plot shows a linear increase in footprint distance with discharge.

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Scenario 9: Impacts of dewatering discharge from the BHP Jinidi Iron Ore Project

The BHP Jinidi Project is located approximately 12 km east of the RTIO Hope Downs 1 mine. Based on the information provided in their referral document (BHPBIO 2011), groundwater abstraction as required for operation could be up to 7 GL/year. Mine-derived water would be used for construction and operational purposes but there is the potential for surplus groundwater to be discharged into local watercourses in the catchment. The proposed location for disposal of surplus water is to the south of the Project Area, approximately 17 km upstream of the Hope Downs 1 discharge outlet. For the purpose of this study, a „one-reach‟ discharge model was developed to assess the contribution of Jinidi water, at a continual rate of 1, 3, 5 and 7 (the maximum predicted abstraction rate) GL/year, on the progression of the wetting front along Weeli Wolli Creek. (It is important to note that results from the model are preliminary and that additional survey data and reach breakdowns are recommended if more comprehensive assessment of the impacts is required.)

Modelling results

Results for the modelled discharge rates are presented in Figure 33 and are summarised in Table 13. The cumulative effects associated with surplus water discharge from the BHPBIO Yandi, RTIO Yandi and Hope Downs 1 operations (Scenario 6) and from the proposed BHPBIO Jinidi mine along Marillana and Weeli Wolli Creek systems are illustrated in Figure 34.

It was demonstrated that surplus water released from the proposed Jinidi outlet would terminate before the Hope Downs 1 discharge location and therefore would not contribute to the footprint distances estimated at Weeli Wolli Creek. Based on the preliminary modelling results, a discharge footprint of 11.3 km was estimated for the maximum modelled 7 GL/year.

Table 13: Estimated discharge footprints for Weeli Wolli Creek from the proposed BHPBIO Jinidi discharge outlet

Scenario 9 Weeli Wolli Creek from the proposed Jinidi discharge outlet

Steady state distance Surface water Maximum footprint (km) expression (km) (km) a: 1 GL/year 1.6 0.9 1.6 b: 3 GL/year 4.9 2.4 4.9 c: 5 GL/year 8.1 3.9 8.1 d: 7 GL/year 11.3 5.3 11.3

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Figure 33: Estimated discharge footprints for Weeli Wolli Creek from the proposed BHPBIO Jinidi -surface water management area and assumed discharge outlet location

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Figure 34: Estimated wetting fronts as a result of surplus water discharge from the BHPBIO Yandi, RTIO Yandi and Hope Downs 1 operations (Scenario 6) and from the proposed BHP Jinidi mine along Marillana and Weeli Wolli Creeks.

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References

A.J. Peck and Associates Pty Ltd (1997) Yandi (HIY) Mine: Hydrology of Marillana Creek, report no RTIO-PDE-0069444.

Australian Bore Consultants Pty Ltd (1997) Yandicoogina Monitoring Bores – Bore Completion Report, report no GDSR 4171.

BHPBilliton Iron Ore (2011) Jinidi Iron Ore Mine – Environmental Referral Document (Final)

Biota Environmental Sciences Pty Ltd (2004) Yandi Expansion Vegetation and Flora Survey, report no RTIO-HSE-0057589.

Biota Environmental Sciences Pty Ltd (2009) Vegetation and Flora Surveys of the Oxbow and Junction South West Deposits, near Yandicoogina, report no RTIO-HSE-0083283.

CSIRO (2004) Water for a Healthy Country, http://www.anbg.gov.au/cpbr/WfHC/Eucalyptus-camaldulensis/index.html

Ecosystems Research Group, University of Western Australia (2002) Possible impact of hydrological changes to the Marillana Creek System on associated creek-line vegetation, report no RTIO-HSE-0009481.

E.M. Mattiske and Associates (1995) Flora and Vegetation – Yandicoogina Junction Area, report no RTIO-HSE-0057043.

Reid M., Cheng X., Banks E., Jankowski J., Jolly I., Kumar P., Lovell D., Mitchell M., Mudd G., Richardson S., Silburn M. and Werner A. (2009) Catalogue of conceptual models for groundwater – stream interaction in eastern Australia, eWater Cooperative Research Centre Technical Report.

Rio Tinto Iron Ore (2009) Guidelines for the assessment of discharge to natural creeks (Draft), report no RTIO-PDE-0057752.

Rio Tinto Iron Ore (2010) Baseline hydrology assessment for Marillana Creek discharge, report no RTIO-PDE-0074001

Rio Tinto Iron Ore (2008) Marillana Creek Hydrology Report, report no RTIO-PDE- 0047262.

Winter T.C., Havey J.W., Franke O.L. and Alley W.M. (1998) Groundwater and surface water; a single resource, USGS Circular 1139, US Geological Survey, Denver, Colorado. http://www.catchment.crc.org.au/pdfs/technical200305.pdf

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