lennard river 2,072 980 352 0.4 west kimberley grain project projects/1) west... · west kimberley...

West Kimberley Grain Project

Summary

The rivers of the West Kimberley region have considerable potential for irrigation

based on capturing the wet season flows. Based on a 1964 report updated for long

term rainfall data, this region could produce 8.4 million tonnes per annum of grain – a

production level equivalent to that of WA’s wheat crop. The fully developed capital

cost will be less than the cost of cropland in the State’s southwest in terms of capital

cost per annual tonne of production. Fully developed, the Kimberley region has the

potential to double WA’s agricultural production.

Catchment Area Rainfall Yield Grain

sq. km. mm. GL/annum mtpa

Barker River 2,253 1125 529 0.6

Isdell River 4,662 1234 1357 1.6

Lennard River 2,072 980 352 0.4

Fitzroy River 16,835 1052 3172 3.6

Central Fitzroy 10,619 744 786 0.9

Leopold River 5,439 762 471 0.5

Margaret River 12,303 635 670 0.8

Total Grain Production 8.4

Table 1: West Kimberley Catchments, Water Yield and Potential Grain

Production

This table is derived from a report by John Lewis in 1964 for the Public Works

Department of Western Australia entitled “The Fitzroy River Plan (W.A.)”. Rainfall

records used in that report have been superseded by modern rainfall data. Grain

production is based on irrigated sorghum yielding 8 tonnes/ha with a water

requirement of 7 megalitres/ha. To grow 8.4 million tonnes per annum on two crops

per year would require an irrigated land area of 524,000 ha. This area is equivalent to

a square with sides of 71 km. Each crop requires 700 ml of irrigation. This

requirement might be reduced by the first crop utilising soil moisture from the wet

season. Sorghum is used as the example as it is already grown in the West Kimberley

region. Wheat and cotton are also likely to be successfully grown.

West Kimberley Grain Project David Archibald, December 2011

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Figure 1: West Kimberley River Catchments


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Figure 2: Ord River Scheme Lake Argyle Storage Levels 1980 – 2011

A dam on the Ord River in the East Kimberley was completed in 1972 to provide

irrigation water downstream. A expansion of the irrigated area of the scheme is

currently underway. There is considerable potential for further expansion of the area

under irrigation. This graph shows the last 30 years of storage history for Lake

Argyle. The Ord River is approximately 650 kilometres long and drains a catchment

area of approximately 55,000 square kilometres. The mean annual flow of the Ord

River at its mouth is estimated to have been 4,500 GL before the river was dammed.

Water demand for Ord Stage 1 was only 300 GL per annum.

A weir on the spillway of the Lake Argyle dam was installed in 1996 in order to make

possible a 30 MW hydro power station. The power from this dam has displaced most

diesel use for power generation in the Kununurra area.


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Irrigation Area Capital Grain Capital Cost/ Capital Cost/

Cost of Production Tonne Hectare

Dams mtpa inc. centre pivot inc. centre pivot

Lennard Group $900 m. 2.6 $602 $9,630

Fitzroy Group $600 m. 4.5 $383 $6,122

Leopold + Margaret $900 m. 1.3 $940 $15,041

Total $2,400 m. 8.4 $536 $8,571

Table 2: Capital Costs and Capital Intensity of the Wester Kimberley Grain

Project

The proposed dams in the West Kimberley naturally group into three areas. Dams on

the Isdell, Barker and Lennard Rivers would service the broad, flat plain of the

Lennard River downstream from Lennard Gorge. The dam with the greatest potential

because of the size of its catchment and rainfall is the Dimond Gorge Dam on the

Fitzroy River upstream from Fitzroy Crossing. Combined with a barrage on the

Fitzroy River just downstream from Fitzroy Crossing, this system will produce grain

at a rate equivalent to half the WA wheat crop at a modest capital costs. The capital

costs in the table above only include the cost of the dams and do not include the cost

of water distribution and centre pivot irrigation. Including indicative costs for the

latter, the capital cost per annual tonne of grain production will be about half of the

cost of prime wheat growing acreage in the southwest of WA.

The Dimond Gorge Dam will provide water as far downstream as Camballin, as well

as completely mitigating the flood risk from Fitzroy Crossing to Camballin. The

prime irrigation area for the dams on the Fitzroy River will be Alexander Island,

produced by the River bifurcating just south of Fitzroy Crossing. The Island is 48

km. long.

Dams on the Leopold and Margaret Rivers would irrigate the black soil plains on

Fossil Downs station in the first instance.


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Figure 3: Grain Prices 2001 – 2011

Rice has steadily increased in price over the last ten years relative to the other major

grain crops and could very well be a high margin crop in the West Kimberley region.

Figure 4: The Dimond Gorge Damsite on the Fitzroy River


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Figure 5: Barker River Damsite

Figure 6: Idsell River Damsite

The Idsell River flows north to be waste in the Timor Sea. A dam at this location and

a 5 km diversion tunnel will turn its waters south to the Barker River.


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Figure 7: Damsites in the Catchment of the Leopold River

Building two dams upstream on gorges will be cheaper than one downstream just

above the irrigation areas. The Leopold River does need to be dammed for flood

mitigation as well as irrigation.


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Figure 8: Lennard River Damsite

A dam on this popular sightseeing spot will significantly enhance its amenity.

Figure 9: Margaret River Damsite

This is another ideal damsite in the West Kimberley region.


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Fertiliser Demand

Taking wheat as an example, nutrient removal from a farm per tonne of wheat is

~23kg/t nitrogen, 3kg/t phosphorus and 4kg/t potassium and 1.5kg/t sulphur.

Nitrogen application is at the rate of 25 kg per tonne of wheat. At that rate, the urea

requirement for the Kimberley Grain Project would be 450,000 tonnes per annum.

That demand level would justify building a urea plant on one of the coal deposits of

the region. The capital cost of that plant would be of the order of $900 million,

taking the total investment for the project to beyond $5.5 billion.

Recommendation

The West Kimberley Grain Project will be of enormous benefit to Western Australia

and the Nation. This project, if it resulted in producing 8.4 mtpa of rice at the current

rice price, would increase national income by $5.0 billion per annum.

Planning for this project should begin immediately. Construction of the roads into the

major damsites should also begin immediately.

David Archibald

Perth, December 2011


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Appendix 1

THE FITZROY RIVER PLAN W.A.

PRELIMINARY REPORT JAN. 1964

Contents PAGE

1. Introduction 2

2. The Camballin Scheme 3

3. Topography 4

4. Hydrology 4

(a) Annual Flows 4

(b) Floods 6

(c) Sediment 7

5. Land Resources 7

6. Order of Development 8

7. Details of Damsites 10

(a) Dimond Gorge Dam 10

(b) Go Go Barrage 12

(c) Margaret River Dam 12

d) Leopold River Dam 13

(e) Mt. Krauss Barrage 13

8. Current Investigations 14

9. Associated Schemes in West Kimberley 15

10. Conclusions 16

Plans

1. Catchment Areas, Isohyets, Water Resources

2, Damsites and Irrigation Areas,

5. Detail of Camballin Irrigation Area.


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THE FITZROY RIVER PLAN W.A.

PRELIMINARY REPORT JAN. 1964

1. Introduction

Over a period of years there has been interest in the development of the Fitzroy River

as a multipurpose project primarily for irrigation, but with some benefits in both flood

control and hydro-electric power.

The plan proposed in this report consolidates current Departmental thinking and

would harness all the natural resources of the Fitzroy. It involves building a large

multiple purpose dam on the main branch of the Fitzroy at Dimond Gorge, two lesser

dams on the Margaret and Leopold Rivers, and two diversion dams near Go Go

Station on the Fitzroy and near Mt. Krauss below the confluence of the Margaret and

Watery Rivers. The plan can be implemented in stages with progressive development

of the irrigation areas over a period of time. Flood control and power generation

would also increase progressively as the head works are developed.

This report is purely an engineering and agricultural feasibility plan. Insufficient data

is available to attempt any estimates of cost nor any discussion of likely crops and

economics. The plan has been prepared at this stage for guidance and use of

Departmental personnel engaged in various phases of investigation and design. The

plan would also be useful to officers of CSIRO and Department of Agriculture in their

phases of investigation and development. It is to be hoped that various suggestions

and improvements can be made if all Departments are working towards a known

objective in a definite order of priority,

The first real attempt to utilise the Fitzroy waters was by Mr. K.M. Durack who set up

a small property at Camballin on behalf of Northern Developments Pty. Ltd.

Originally water was simply pumped from a large billabong on Uralla Creek, which is

a branch of the Fitzroy. This scheme was begun in 1951, and has been improved and

enlarged over the years. A statement of the present position follows in Section 2.

The proposal to place a weir on the Fitzroy to divert water into Uralla Creek by

gravity came from Departmental and Consulting Engineers in about 1954 and

construction was completed in 1961.

In about 1952 the late Mr, C.M. Dimond, then Engineer for the North West, initiated a

survey of the Margaret River Damsite and in 1955 flew over and selected the damsite

on the Fitzroy River now bearing his name. The late Mr. W. MacDonald of Fossil

Downs knew the river extremely well and was a keen advocate of damming both the

Margaret and Fitzroy Rivers and gave much help to Departmental Engineers.


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2. The Camballin Scheme

A small irrigation scheme has been developed at Camballin some 75 miles from the

port of Derby. This scheme derives its water from the Fitzroy River by means of a

diversion structure known as the Fitzroy Barrage which is a weir equipped with

shutters capable of collapsing automatically in flood time and being raised

mechanically to divert streamflow into an improved natural channel, leading to the

irrigation area. Something like £l,000,000 has been invested in this weir and

associated distribution structures such as the Uralla Creek Dam and spillway,

channels, levees, measuring structures, pumps, roads, etc.

The Camballin scheme suffers two major deficiencies. Firstly, the area is located on a

flood plain and all structures and crops are liable to damage of varying severity each

wet season according to the intensity of flooding. Secondly, the gross storage of the

Fitzroy Weir and Uralla Creek Dam is only about 7,700 ac. ft. of which a great deal is

lost in evaporation. Since the river normally ceases to flow in about May or June

depending on the season, the Camballin Scheme is limited largely to wet season run

of river operation. When storage is built upstream and water can be released down the

river, this trouble will be overcome.

The first problem of seasonal sheet flooding at Camballin can be partly overcome by

building large flood control storages upstream and partly by building an extensive

levee from Nura Nura Ridge to Grant Range to keep the river out. The latter measure

is too expensive to consider at the present stage of development at Camballin.

The area resumed for irrigation at Camballin is only 20,000 acres but surveys have

shown that this could probably be doubled at least. Actual irrigation results so far

have been disappointing for a number of reasons in addition to the two problems

already mentioned. The development of the irrigation area itself is in the hands of a

single private Company under an agreement for joint co-operation with the State

Government. This Company showed great courage in being the first to pioneer

irrigation development on farm scale in the Kimberleys. The risks were great and the

unknowns on the agricultural side proved a formidable barrier. The Company chose to

base its efforts on rice growing and milling for export. If yields of two tons or more to

the acre could have been achieved consistently, the enterprise may have succeeded,

but yields have never approached this figure over the whole crop. Often the crops

have looked promising but some new trouble has occurred each year.

In recent years with development of other crops on the Ord, Camballin has turned to

cotton, linseed, safflower, sudan grass and others on a small scale to gain wider

experience and improve the adverse economic situation. The Company has also

bought a controlling interest in Liveringa Station and is having some success with

broad irrigation of natural grasses for grazing sheep. While this may prove a good

solution to the Company's problems, it is of little assistance in developing an intensive

irrigated agriculture which must be proved if costly major projects are to be justified.

It is essential for full scale agricultural research to proceed in conjunction with the

engineering investigations now being carried out. Without this, no plan can succeed

and it would be foolish to rely too heavily on results coming from the Ord.


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3. Topography

The main tributary of the Fitzroy is the Hann River which rises within fifty miles of

the sea in very rugged and inaccessible country. From here the river flows inland

making a wide semicircular sweep of almost 500 miles before it finally reaches the

sea in King Sound at Langey Crossing near Derby.

The attached plans show the Fitzroy River and its major tributaries the Hann, Adcock,

Traine, Leopold, O‘Donnell, Margaret and Mary Rivers and Christmas Creek. Also

shown are the respective catchment areas at known damsites and potential irrigation

areas. It cannot be readily shown in the plan, but the Fitzroy Catchment is broken up

into two very distinct topographical areas by the Oscar, Sparke and other small

Ranges all running more or less north west to south east across the catchment. The

Fitzroy above the Oscar Range and the Margaret above the Sparks Range, both have

rugged catchments characterised by parallel ridges of quartzite mostly very bare

supporting only spinifex and a few stunted trees. In the valleys between the ridges,

there is some heavier country with a sparse cover of trees and natural perennial

grasses.

The upper perimeter of the catchment is at an elevation between 1500 and 2500 feet

and as the river level at the storage damsites is of the order of 400 feet, there are

considerable slopes from the ridges into the tributary streams. The lower part of the

Fitzroy below the Oscar Range and the Nargaret below the Sparks Range and

Christmas Creek further south all traverse extremely flat country with very little

topographical relief apart from the watercourses. The fall of the Fitzroy River from

Fitzroy Crossing to Langey Crossing near Derby is only 280 feet in a distance of 212

miles or just over one foot per mile. There are no obvious sites for storage dams in

these lower catchments, although if it proved feasible and economic to store water at

Go Go Barrage, this would be most valuable.

The Fitzroy and Christmas Creek have flood plains up to 50 miles wide at their

confluence and the greater part of all the best irrigable soils are subject to sheet

flooding under several feet of water. The rivers meander through the flood plain and

have many anabranches and billabongs indicating old watercourses or new courses

developing. In locating a diversion structure on this flood plain, great care has to be

taken to avoid disturbing the natural regime of the river too much and causing a

sudden switch in its course. This was the main reason for the automatically collapsing

shutter weir at Camballin.

4. Hydrology

(a) Annual Flows

The water resources of the Fitzroy River are only vaguely known at present due to the

small number of gauges and short term of record. It is unfortunate that major storage

dams can only utilise about l3,400 square miles out of a total catchment of 55,000

square miles, but the runoff characteristics of the mountainous upper catchment would

undoubtedly be better than those of the very flat and generally sandy lower catchment.

The rainfall isohyets in the attached plan show that the Hann River, which is the

farthest upstream tributary of the Fitzroy, rises in a 40 inch rainfall area and most of


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the 6,500 square mile catchment up to the Dimond Gorge Damsite has over 25 inches

of rainfall with the average being about 28.75 inches.

The Ord River by comparison has a catchment of 17,800 square miles at the Main

Damsite, but the average annual rainfall is only 21 inches.

It has been shown on the Ord Catchment that total runoff varies with about the 2.5

power of rainfall so that on direct comparison, the relatively small catchment at

Dimond Gorge could have an annual flow of the order of 0.80 times that of the Ord,

i.e. about 1.8 million acre feet per year, assuming the catchments have similar runoff

characteristics. (Using median rather than arithmetic mean to avoid distortion due to

cyclonic floods, and Ord median 2.25 million acre feet per year.)

Alternatively, a rainfall runoff correlation for Fitzroy Crossing suggests a median

annual flow of 2.43 million acre feet at that point. Again utilising the 2.5 power

relationship to distribute the combined flow, the median annual flow at Dimond

Gorge is estimated at 1.55 million acre feet. However, estimates based on Fitzroy

Crossing gaugings could be low as two anabranches bypass the gauge and higher

flows are no doubt grossly under-estimated.

By the same reasoning, the Margaret and Leopold River catchments are in much

lower rainfall areas and not only would the total runoff be less, but it would be

considerably less reliable from year to year. Christmas Creek has a fairly large

catchment but flows from semi desert areas of only l4 inch rainfall and its annual

runoff would be fairly small, despite the fact that it produces major flooding every

few years when subject to intense cyclonic rainfall of short duration. Topographically,

there are no known damsites on Christmas Creek (but this has not been thoroughly

investigated) and its water resources have been discounted in this examination.

Unfortunately this means that is ability to cause flood in damage downstream of its

confluence with the Fitzroy cannot be controlled.

The first river gauging station in this basin was established at Fitzroy Crossing in

1956. Flow records commenced in February, 1957 and combine the flow of the

Fitzroy and Margaret Rivers. Another gauging station was set up at Dimond Gorge

and recording began at the end of 1962. The record is too short yet to draw

conclusions.

A gauge was established on the Margaret River at Fossil Downs towards the end of

1957, but was affected by backwater levels from the Fitzroy and never rated.

Investigations are being made to establish a new station in the vicinity of the Margaret

River Damsite.

Thus in the future it will be possible to assess the flow in the Leopold and Margaret

Rivers by subtraction of the Dimond Gorge flow from that at Fitzroy with due

allowance for the catchment in between. So far however it is only possible to split

the Fitzroy flows in accordance with rainfall and catchment areas using the 2.5 power

relationship of rainfalls which seems to be valid for the Fitzroy as for the Ord.

The estimated median annual discharges are tabulated hereunder.


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Fitzroy River at Dimond Gorge 1.80 million acre feet

Leopold River 0.27 million acre feet

Margaret River 0.38 million acre feet

Central Fitzroy 0.45 million acre feet

Fitzroy Crossing Total 2.90 million acre feet

The important conclusion of these preliminary assessments is that the flow at Dimond

Gorge is (64%) of the combined flow at Fitzroy Crossing, although the catchment is

only 37% of the total. On the other hand, the Margaret with 27% of the total

catchment only 13% of the flow.

(b) Floods

Estimation of flood flows presents considerable difficulty because high floods at

Fitzroy Crossing are not contained by the current meter section. It is thought that a

large quantity of flood water by passes the branches on the south side. Furthermore

Dimond Gorge gauging station has not been established for long enough to have

metered significant floods although an extrapolated rating curve indicates a flood

peak of approx. 230,000 cusecs in February, 1961 and again in February, 1963.

It seems that a flood of the order of 300,000 cusecs might be expected at Dimond

Gorge with approximately a ten year recurrence interval. The catchment at Fitzroy

Crossing is some 2.75 times the area at Dimond Gorge and a higher ten year flood

would be expected although bank overflow would have a reducing effect. In the seven

years of recorder operation at the Crossing, the highest flood indicated by the

extrapolated rating curve is 210,000 cusecs.

However the rating curve does not account for flow by-passing the cableway. It seems

unlikely that a ten year flood at Fitzroy Crossing could be much below 400,000

cusecs.

The peak rate of discharge probably decreases down the river from Cherrabun to

Langey Crossing because although the catchment increases, a large amount of flood

storage is provided by bank overflow. The time delay in passage of 5 high flood peaks

down the river between Fitzroy Crossing and Langey Crossing varies between 5 and 7

days which, in storms of normal or short duration, generally allows down-stream local

peak runoff to pass before the main flood comes.

Obviously a great deal of hydrological work needs to be done on this river and its

tributaries before major works can be undertaken, but at present it seems that a

storage dam at Dimond Gorge without.flood control would need to be designed for a

discharge of the order of 1,000,000 cusecs. The Go Go barrage is more difficult to

assess for discharge capacity, but even accepting that flood regulation will be

provided upstream, it would seem that a similar flood peak discharge must be passed

by this structure under maximum design storm. This fortunately is markedly less than

required on the Ord River structures. However the main waterway of the Fitzroy is

relatively shallow and consequently the irrigable levee lands are much more prone to

flooding than on the Ord. It is therefore very desirable that the Dam at Dimond Gorge

should have provision for flood control as well as storage within the limits of normal

economics.


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While the dam at Dimond Gorge can control two thirds of the annual flow (based on

median values) up to Fitzroy Crossing, it is most improbable that this dam could

control two thirds of the flooding problems. This is because large floods result from

intense cyclonic rains of only a few days duration and so far as is known at present

those could occur in almost equal intensity on any part of the catchment and bear little

relation to the pattern of annual rainfall isohyets. On this basis flood control at

Dimond Gorge may only reduce high floods by 20% but smaller floods may be

reduced by greater amounts and the normal three year frequency of flooding now

existing could be greatly decreased.

(c) Sediment

The final important hydrological aspect is that of sediment. There is ample evidence

in the streambed that considerable quantities of sand and shingles are transported as

bedload. It is also evident in flood flows that a considerable amount of suspended

sediment is transported. Despite appearances, depth integrated samples taken from

the cableway at Fitzroy Crossing indicated average suspended sediment of less than

0.2%. This is very much lower than the Ord and is probably explained by the fact that

no serious erosion is occurring on the upper catchments.

From fairly well established data overseas, the bedload is probably less than 20% of

the suspended load. As previously mentioned the gradient of the Fitzroy Crossing is

only just over one foot per mile. Combined with relatively shallow depths of flow,

this means that velocities above six feet per second are uncommon. Such velocities

do not transport large shingle and move small shingle very slowly. Deposits of shingle

for concrete making are very hard to locate in the river bed. Of course larger sizes can

sometimes be found in old courses of the river, presumably laid down when gradients

were higher than at present.

Downstream of Fitzroy Crossing, the catchment has suffered due to poor pastoral

practices and overgrazing by sheep as well as kangaroos. Some bad areas are subject

to erosion by wind and sheet flooding as has been evident in the Camballin Scheme

and once the grass cover is gone, the process is very difficult to stop. On the whole

however, the problem is not nearly as severe as in the Ord River.

5. Land Resources

The CSIRO has made a number of regional soil surveys which have revealed potential

irrigable areas as shown in the accompanying plan amounting to possibly 500,000

acres. All of this area is adjacent to the lower parts of the Margaret, Christmas Creek

and Fitzroy Rivers. A lot of it is subject to sheet flooding and no doubt a considerable

amount cannot be commanded conveniently by gravity from the proposed diversion

dams. Some of the area is dissected by small water courses, anabranches and

billabongs which would render it too rough for irrigation. After making allowances

for these factors it seems there is still about 300,000 acres left and this could be more

than adequate to utilise the water resources of the Fitzroy River system.

The easiest land to irrigate is probably the Alexander Island, Go Go Station and

Lower Christmas Creek areas. This is all quite compact and can be commanded by


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gravity channels from the proposed Go Go Barrage. The gross area surveyed to date

on three mile sections is 200,000 acres and the survey is far from complete. Alexander

Island alone contains 93,000 acres gross. The Department of Agriculture is carrying

out broad soil profiles as the survey proceeds to determine the extent and variation of

the several different soil types, of which there are at least four main classes. The black

soil similar to that occurring at Camballin is very common.

Mention has already been made of possible extensions of the Camballin Scheme and

this has been soil surveyed in some detail by CSIRO. (Churchward and Bettenay

1959). Good strips of land appear to exist at intervals all along the lower Fitzroy

River, one such strip being in the vicinity of Noonkanbah Station. These areas are not

large enough to warrant a large diversion dam but could possibly be served by

pumping or small collapsible weir such as that already built at Uralla Creek.

The remaining large tract of good land, perhaps the best in the whole valley according

to CSIRO is that around Fossil Downs Station mainly on the north side of the

Margaret River. Unfortunately none of this can benefit easily from construction of the

dam at Dimond Gorge or the Go Go Barrage. However it can be served by the waters

of the Margaret and Leopold Rivers, a possible diversion site for which exists in the

vicinity of Mt. Krauss.

Since the damsites on the Margaret and Leopold Rivers are not as good as that at

Dimond Gorge and also since the runoff will be less reliable, the Fossil Downs lands

may have to wait some considerable time for development. A possible alternative is

that the Go Go Barrage is likely to back up the Margaret River some appreciable

distance, and pumping into a channel running back along the Margaret may be

practicable. The gradient of the Margaret is very flat, being about the same as the

Fitzroy. This proposal would involve less pumping if some worthwhile storage can be

held at Go Go Barrage thus raising the expected water level in the Margaret.

It is not inconceivable that water released from Dimond Gorge could be pumped over

the northern end of the Geikie Ranges to the Fossil Downs area.

The passage is long and difficult but the lift may be less than 100 feet. The gross area

of potentially irrigable land around Fossil Downs is about 100,000 acres which is

enough to utilise the waters of the Margaret and Fitzroy Rivers, although this is not an

essential requirement, as any excess can be allowed down to the Go Go Barrage for

use in the main irrigation area commanded from there.

6. Order of Development

Assuming that the financial provisions are not too restricted in the early years, there is

a logical order of development which generally involves building headworks storage

before the diversion structures. This is for a three-fold reason. Firstly, the storage

ensures supply of water all the year round, secondly a considerable measure of flood

control is achieved thus reducing spillway costs and risks to the irrigation area, thirdly

less sediment will be carried into the diversion storage.

On the Fitzroy the second and third points are only partially achieved by a single

headworks storage as the remaining catchment is still uncontrolled. However, control


18

of the major contributor of floods and sediment at Dimond Gorge is still a marked

advantage.

The only point in favour of building Go Go Barrage first is that run of river water can

be supplied immediately without pumping in the wet season and fairly low lift

pumping in the dry season. This applied in the Ord River Project where the Diversion

was built first in order to get the scheme going on reasonable scale at limited cost,

The same may yet apply at Fitzroy but should be avoided if possible.

Bearing the foregoing in mind, the logical order of development is as follows:-

(a) Build the Dimond Gorge Dam on the main branch of the Fitzroy, complete

with gates for flood control. The size has yet to be determined but something

about the same size as the main Ord Dam is envisaged i.e. about 5 - 6 million

acre feet of active storage and at least as much again as flood control

surcharge. This is the heart of the whole Fitzroy Plan as it forms the largest

and most reliable storage in the valley.

(b) Develop an Irrigation Area in the Alexander Island - Christmas Creek

Region complete with channels, drains and flood protection levees. A

pumping station would be needed initially until the Go Go Barrage can be

built. The Ord River Pumps will have become redundant by then and could be

adapted for this purpose quite well. This development, being the primary

object of the Fitzroy Plan, would extend over a large number of years.

(c) Enlarge the Camballin Project to its full extent and split it up into small

farms if necessary to hasten development. Provide flood control by

constructing a levee from Nura Nura Ridge along the Fitzroy River and back

into Grant Range near Liveringa Homestead. This will be about 15 miles long,

constructed of river sand as at Carnarvon and will need provision of inlet and

outlet structures for Uralla Creek. The height of this levee can be reduced

because of the flood control at Dimond Gorge and would be of the order of 10

feet although higher at Liveringa. This levee and structures will be costly but

will allow 50,000 acres of land to be irrigated under secure conditions and

would justify itself, The area has good soil and topography, is close to Derby

and already has considerable capital invested which must be made good. Local

water from Nemille Creek would still be of some nuisance value in the lower

areas. This phase of development could be concurrent with (b).

(d) Build Go Go Barrage to provide gravity command of the main rrrigation area

with left and right bank channels. The left channel runs right down to

Christmas Creek which is uncontrollled and which would need a siphon

crossing if further land had to be served. The right channel does not command

so much land but meets no known obstacles. It could serve Alexander Island

through a large barrel siphon under the Cunningham River which is the lesser

of the two branches of the Fitzroy. Alternatively, it may prove feasible to close

off the Cunningham completely and pass the flood controlled flows down the

Fitzroy alone. This would simplify the supply and access to Alexander Island

and reduce the cost of flood protection levees as these would be confined to

the one river instead of two, although naturally somewhat greater in height.


19

(e) Build the Margaret River Dam complete with gates for flood control. The

size has yet to be determined but something of the order of 0.8 million acre

feet of active storage and at least the same amount of flood surcharge is

envisaged, depending on the nature of the dam and spillway solution in

relation to benefit cost economics.

(f) Build the Leopold River Dam complete with gates for flood control. This

could be constructed concurrently with the Margaret River Dam as both are

relatively small and serve the same irrigation area. The order of` size of this

dam is about 0.6 million acre feet of active storage and a similar amount of

flood surcharge depending on the same factors as above.

(g) Develop an Irrigat1on Area in the Fossil Downs – Mt Krauss Region complete with channels, drains and flood protection levees. A pumping station

would be needed until the Mt. Krauss Barrage could be built or became

economically justified. By this time the Go Go pumping equipment ex Ord

River, if still serviceable, should be available having become redundant at Go

Go after building that barrage.

(h) Build the Mt. Krauss Barrage to provide gravity command of the Fossil

Downs Irrigation Area on both left and right banks. The main supply channels

have n number of substantial creeks to cross and would probably need to

siphon under some of them. A fairly large irrigation area would be necessary

to justify a costly diversion against a small weir with pumping. It could well

be argued that the dam on the Leopold River could wait till last when

irrigation development actually needed it, but against this are the two points

that flood protection in (g) and spillway design in (h) will be more expensive

due to the lack of control on the Leopold River. Detail design and economic

analysis will determine the best order of development.

7. Details of Damsites

(a) Dimond Gorge

This is a magnificent damsite, perhaps the most impressive discovered so far in

the Kimberleys. The geology is simple comprising gently folded quartzite of large

blocky structure with fairly tight jointing. There is no sign of faulting, shear zones,

thin bedding or foreign intrusive in the vicinity of the dam. The foundations are

obviously solid parent rock, being almost completely exposed at the end of the dry

season.

The river bed is more or less flat across the bottom and the walls of the Gorge rise

abruptly and almost vertically. They are only three hundred feet apart at the

damsite and not badly weathered for quartzite. Since the dam will be over two

hundred feet high, a thin arch dam will have to receive serious consideration. In

this case the spillway would have to be cut in a narrow but long natural saddle

which has been located about two miles from the dam. The spillway could include


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the flood control gates or it could be uncontrolled whichever is cheaper. It is

possible that the Kariba-type spillway located in the arch dam some distance

below the crest would give adequate discharge.

An obvious solution is a hollow gravity type concrete dam with spillway gates on

top. It seems a pity to place a gravity dam in such a fine site but spillway problems

have dictated that this be done in similar sites previously.

Due to the high cost of concrete in this remote area (250 miles by road from

Derby) and the relative cheapness of rock excavation and rockfill, it is very likely

that a rockfill dam and rock cut spillway will be the most economic solution as at

the Ord Main dam. Unfortunately the lead from the spillway cut is rather long for

rockfill and it may be more economic to open up a quarry near the damsite.

Comparative designs and estimates for these various types of structure are being

carried out and when the most economic solution is found, a drilling programme

can be laid out for further site investigation in the dry season of 1965. Surveys of

the damsite and reservoir basin have been completed. Since the basin is so large, it

was necessary to cover the area by aerial photography and 10 foot contours have

been drawn by stereo-plotter. Basin volumes at different heights 1% have been

computed.

The effective flood storage has not yet been full determined, but it is fairly certain

that flood storage will be feasible and economic to a degree at least comparable to

the Ord. The damsite is in a most inaccessible part of the King Leopold Ranges.

Access can be made from the south through Fossil Downs to the stream gauging

station which has a light airstrip and store hut nearby. However the four miles

from here to the damsite are accessible only by foot and will require quite heavy

roadworks in due course.

Access from the north through Glenroy and Mornington is comparatively good,

especially with the new beef road going through. This is the best access for

surveys, drilling and possibly construction, but it will become submerged under

the future reservoir.

Bypassing around the edge of the reservoir would be long and cut into hill slopes

making it very expensive. If permanent access is wanted from the north, a ferry

may be the best solution.

The reservoir will inundate some pastoral country which is not very valuable and

Mornington homestead will be under some 50 feet of water at normal storage

level.

The possible provision of hydro power will need close consideration. The head

will be greater than the Ord, being close to 200 feet at full storage and the

tailwater not nearly as high. Geological conditions appear good for tunnelling and

underground construction. The transmission route to the irrigation area

commencing at Go Go Barrage is 60 miles long and fairly rough, although vehicle

access could be established. In view of this and since the power needs will be

small for a number of years, it seems best to install local diesel plant until the


21

demand builds up enough to justify development of the hydro plant. Diesel power

will be rather expensive in this area because low grade diesel fuel is not shipped

by tanker into Derby and the lead from there is 160 miles.

(b) Go Go Barrage

This site is 8 miles downstream of Fitzroy Crossing. It was located during the

floods of February, 1962 when a survey was made by helicopter to determine the

most suitable place for barrages and the extent of flooding of potential irrigable

lands. The Go Go site joins Alligator Hill on the right bank to Mt. Campbell on

the left bank. It is four miles between the abutments which may seem a long way,

but nevertheless this is the best site on the lower Fitzroy River.

The greater part of the Barrage could be built in earthfill and only the spillway

need be of concrete construction. Insufficient data is available to design the

spillway, but it will need to be about 1,000 feet long and fully gated in a similar

way to the Ord Diversion Dam. With such a narrow spillway there is some

freedom in choosing where it should be placed in the whole length of the barrage.

If the foundation conditions are not good in the existing river channel, then the

spillway can be built in excavation in a more favoured location. The limits to this

are that a new river entry and exit have to be excavated and due regard has to be

given to hydraulic conditions of the new river profile.

Only a single seismic section has been run between the two abutments so far but

this gives promise of finding reasonably competent sedimentary rock at shallow

depths of the order of 20 to 40 feet. More seismic work correlated with check

drilling may show up better profiles in due course. The important point for now is

that the foundations are not sand and shingle extending to great depth.

The Go Go Barrage is ideally situated to serve the main irrigation areas of

Alexander Island, Go Go and Christmas Creek. Mention has already been made of

the left and right bank channels, the possibility of closing off the Cunningham

River and flood protection levees along the Fitzroy downstream of the Barrage.

If possible it would be very desirable to have storage as well as diversion at Go

Go since it commands a lot of good catchment downstream of the three storage

dams. Surveys will show if this is feasible. If Fitzroy Crossing had to be moved,

this is no great problem and its importance would disappear in any event, as the

new highway would use the all weather access provided by the Barrage and a new

town would be needed nearer to the centre of the irrigation areas.

(c) Margaret River Dam

This site is a spectacular gap in the Barramundi Range. It is quite narrow and the

storage basin spreads out well making it an economic location. The rock is mainly

quartzite, strongly folded with some faulting. The joints are more open and the

surface more weathered than at Dimond Gorge. The foundations are no doubt

fairly sound rock, but they are deep as a long pool runs right through the Gorge.


22

Probing and preliminary survey of the damsite has been completed. The basin has

been flown and 10 feet contours are being stereo-plotted. A ground survey to give

a quick guide to capacity was also done some years ago. Nothing of any value

would be inundated by this dam. Access to the site is quite good from Fitzroy

Crossing during the dry season. A light airstrip has been constructed near a

proposed river gauging station just downstream of the Gorge. The site does not

offer very stable control for stream-flow recording and construction of a cableway

has been delayed until alternative sites have been investigated.

No suitable saddles for a spillway cut have been located, but this has not been

proved exhaustively. If it is true, then a rockfill dam is not possible and the choice

of dam would be limited to hollow gravity with gates on top and the Kariba-type

arch with gates some distance below the crest. By the time this dam is built there

may be enough experience to encourage an arch design with deep overflow

springing clear of the crest. At present these designs are limited to shallow

overflows but have been used on quite high dams without excessive vibration.

Due to the lower priority of this dam in current planning, no preliminary designs

or estimates have been carried out nor can attention be given to them for some

years.

(d) Leopold River Dam

This has only been identified as a likely site from the air. No survey has been done

nor is it contemplated at present.

It is a pity that the one dam cannot harness both the Margaret and Leopold Rivers,

but this unfortunately appears to be so. It is also a pity that neither dam will serve

an irrigation area directly by channel or pressure pipeline, but such occurrences

are rare.

(e) Mt. Krauss Barrage

This has only been identified as CI possible site from the air. Others probably

exist and would serve the potential irrigation areas adequately. The right bank

channel would serve the best land around Fossil Downs. The left bank channel

would serve a more broken and lighter soil type down towards Go Go Station.

Both channels will encounter a number of difficult creek crossings probably

involving siphon structures.

Although Mt. Krauss has no obvious attractions as a storage site, this would bear

checking as its combined function of storage for the Margaret, Leopold and

Louisa Rivers plus diversion could be very useful and lead to earlier development

of the non-flooding Fossil Downs Area.

As previously mentioned if the Mt. Krauss Barrage proved very expensive, a

fairly large irrigation area would be necessary to justify it compared to the

alternative of a small weir with a pumping station. Also as noted earlier, the Go

Go Barrage may back water up far enough into the Fossil Downs area to render

such a weir unnecessary.


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8. Current Investigations

One of the most serious deficiencies at present is the lack of hydrological data

Fitzroy Crossing gauging station has been fully operative for some time but the

rating is inadequate at higher flows which are not contained. Dimond Gorge

gauge has not been long in operation and it is not yet rated for higher flows. The

gauge at Margaret River Damsite should be completed as soon as possible and a

gauge established on the Leopold River in due course.

Analysis of data already available is needed, especially concerning correlation of

runoff and rainfall for yield studies and production of a design flood hydrograph.

Daily rainfall records are available for some pastoral stations going back more

than 50 years.

For proper flood design of Dimond Gorge Dam at least one gauging station is

required upstream of the structure probably on the Hann River.

Further field information is needed on sediment load at different discharges. This

should not be neglected because the problem is less severe than on the Ord.

The second serious deficiency concerns soil surveys and agricultural research. The

location and extent of the best areas are now fairly well understood, but existing

levelling and sampling on three mile sections is not adequate to determine the best

layout of the irrigation scheme or the extent of each soil type. The next step

should be to level and sample on lines 20 chains apart as on the Ord. Finally this

would have to be closed up to a 5 chain grid for farm layouts, but the 20 chain

sections are adequate for design purposes.

A research station is needed as soon as possible in the Alexander Island -

Christmas Creek Area. This should combine the several predominant soil types

and be close to a large billabong for dry season water supply. A number of sites

have already been suggested and the final choice rests with the soil scientists.

The 20 chain sections will enable the left and right bank channels to be laid out

together with the major drainage system. It will enable a decision to be made as to

whether it is prudent to close off the Cunningham River. Together with

hydrological data and locally determined flood heights, the height and extent of

flood protection levees can be established.

Regarding the damsites, no more field work can be done at Dimond Gorge until

preliminary designs, now current, are prepared. When this is done, a full

geological investigation combined with diamond drilling and seismic testing can

be carried out in the dry season of 1965.

At Go Go Barrage site, only one section is available so far and in the 1964 dry

season a full coverage of levels, seismic testing and auger drilling will be obtained

to establish depths and soil properties of overburden and possible location of the

spillway section.


24

Preliminary designs can then be made in the following dry season of 1965.

Diamond drilling can be carried out to determine the nature of the bedrock

especially in the concrete spillway section.

A suitable pumping station site will have to be selected to serve the irrigation area

in the early years before the Go Go Barrage is built.

As time permits, some design work should be done on an ultimate plan for

Camballin, including the levee from Nura Nura Ridge to Grant Range. The intake

structure for Uralla Creek through this levee could possibly combine a high level

supply channel to serve the full extent of the irrigable area east and north of the

present area. Low lift pumping will probably be required for this extension.

9. Associated Schemes in West Kimberley

The attached plan shows in faint lines some schemes other than the Fitzroy Plan

which are important in West Kimberley Development. These are the Lennard

River Dam and the Isdell River Dam with a tunnel diverting it into the Barker

River and thence to the lower reaches of the Lennard.

The Lennard River Damsite is not particularly good as the left abutment is well

back off the river and an extensive saddle embankment is required in a gap to the

north. The basin area has been flown and 10 foot contours are being produced.

The irrigation area downstream of the Napier Range is small but very attractive. A

preliminary reconnaissance has been made by CSIRO some years ago. Supply of

water to this area would require a diversion dam or pumping.

The Isdell River Damsite has only been identified from the air but is at the head of

a long deep gorge. There is little doubt that this is a good site with an extensive

basin behind it, and that water can be diverted through the King Leopold Ranges

by a tunnel only three or four miles long.

The catchment area of the Isdell is only about 1800 square miles but the annual

rainfall is about 34 inches and the estimated average annual runoff 770,000 ac. ft.

The main reason for diverting the Isdell is that it has no irrigable land in its own

valley whereas the Barker and Lennard are fairly well endowed and relatively

close to Derby.

Although little definite information is available, it is reasonably certain that

neither the Lennard nor the Isdell - Barker schemes would be as economic as the

Fitzroy Plan nor could they compete in scale which is important in northern

development.


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10. Conclusions

1. The first structure to be built in the Fitzroy Plan should be the Dimond Gorge

Dam complete with provision for maximum economic flood surcharge storage.

2. With water available at all times in the river, the main Go Go - Christmas Creek

irrigation area could be commenced in a small way using pumped water until

firmly established. The Ord pumps would suit this purpose on completion of the

main dam.

3. The Camballin Scheme could be brought up to its full potential of 50,000 acres

with all season water available. The area should be subdivided if necessary to

promote close irrigated development. If this is done, a flood control levee to keep

out flood waters would be warranted. (see attached plan)

4. Intensive agricultural research is required at both Camballin and Go Go —

Christmas Creek as soon as possible. Emphasis should be placed on farm scale

problems rather than fundamental research and close liaison should be maintained

with Kimberley Research Station on the Ord.

John G. Lewis

9/1/64

lennard river 2,072 980 352 0.4 west kimberley grain project projects/1) west... · west kimberley...

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