Water resources and management overview ... - NSW Office of Water

Water resources and management overview Namoi catchment

Leading policy and reform in sustainable water management

Publisher NSW Office of Water Level 17, 227 Elizabeth Street GPO Box 3889 Sydney NSW 2001 T 02 8281 7777 F 02 8281 7799 [email protected] www.water.nsw.gov.au The NSW Office of Water is a separate office within the Department of Environment, Climate Change and Water. The Office of Water manages the policy and regulatory frameworks for the State’s surface water and groundwater resources to provide a secure and sustainable water supply for all users. The Office of Water also supports water utilities in the provision of water and sewerage services throughout New South Wales. Water resources and management overview: Namoi catchment February 2011 ISBN 978 1 74263 158 5 This report may be cited as: Green D., Petrovic J., Moss P., Burrell M. (2011) Water resources and management overview: Namoi catchment, NSW Office of Water, Sydney Cover photo: Namoi River upstream of Wee Waa (courtesy of Dayle Green) © State of New South Wales through the Department of Environment, Climate Change and Water, 2011 This material may be reproduced in whole or in part for educational and non-commercial use, providing the meaning is unchanged and its source, publisher and authorship are clearly and correctly acknowledged. Disclaimer: While every reasonable effort has been made to ensure that this document is correct at the time of publication, the State of New South Wales, its agents and employees, disclaim any and all liability to any person in respect of anything or the consequences of anything done or omitted to be done in reliance upon the whole or any part of this document. Maps: The maps are to be used as a general guide for regional and local scale natural resource planning and management only, not for the assessment of specific sites which can only be assessed by investigation specific to those sites. The maps are published by the NSW Office of Water. While every reasonable effort has been made to ensure the accuracy of the information contained in the maps, you should only satisfy yourself as to the accuracy of the information before relying on it.

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Water resources and management overview – Namoi catchment

Contents 1

Introduction.................................................................................................................................... 1

2

Climate .......................................................................................................................................... 4 2.1

Rainfall ................................................................................................................................ 4

2.2

Evaporation ......................................................................................................................... 5

3

Land use........................................................................................................................................ 6

4

Environment .................................................................................................................................. 8

5

4.1

Native vegetation ................................................................................................................ 8

4.2

Parks and reserves ............................................................................................................. 8

4.3

Wetlands ............................................................................................................................. 9

4.4

Significant biodiversity ...................................................................................................... 10

Surface water .............................................................................................................................. 11 5.1

Upper Namoi River............................................................................................................ 11

5.2

Peel River.......................................................................................................................... 12

5.3

Keepit Dam to Narrabri ..................................................................................................... 12

5.4

Lower Namoi ..................................................................................................................... 13

5.5

Stream flow characteristics ............................................................................................... 14

6

Groundwater................................................................................................................................ 17

7

River operations and management ............................................................................................. 20 7.1

Major storages and regulating structures ......................................................................... 20

7.2

Licensed water use ........................................................................................................... 22 Peel River surface water................................................................................................... 22 Peel River groundwater .................................................................................................... 23 Namoi River surface water................................................................................................ 23 Namoi River groundwater use .......................................................................................... 24

7.3

Water sharing plans .......................................................................................................... 25 Combined water sharing plans ......................................................................................... 26 Regulated surface water sharing plans ............................................................................ 27 Unregulated surface water sharing plans ......................................................................... 27 Groundwater sharing plans............................................................................................... 28 Plans in preparation .......................................................................................................... 29

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References .................................................................................................................................. 30

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NSW Office of Water, February 2011


Tables Table 1: Land use statistics for the Namoi catchment .......................................................................... 6 Table 2. Threatened aquatic species of the Namoi catchment ........................................................... 10 Table 3: Mean daily flow for selected Namoi gauge sites ................................................................... 14 Table 4: Major storages of the Namoi catchment ............................................................................... 21 Table 5: Peel Regulated River water entitlements as at 30 June 2010 .............................................. 23 Table 6: Peel catchment groundwater share component as at 1 July 2010 ....................................... 23 Table 7: Namoi Regulated River share components as at 30 June 2010........................................... 24 Table 8: Namoi catchment groundwater entitlements (2009) ............................................................. 25

Figures Figure 1: The Namoi catchment ............................................................................................................ 2 Figure 2: The Peel catchment ............................................................................................................... 2 Figure 3: Topography and elevation of the Namoi catchment .............................................................. 3 Figure 4: Average annual rainfall in the Namoi catchment ................................................................... 4 Figure 5: Average monthly rainfall at Gunnedah................................................................................... 4 Figure 6: Class A pan average annual evaporation in the Namoi catchment ....................................... 5 Figure 7: Mean daily pan evaporation at Gunnedah ............................................................................. 5 Figure 8: Land use in the Namoi catchment.......................................................................................... 7 Figure 9: Annual flows in the Namoi River at Gunnedah 1892-2010.................................................. 15 Figure 10: Daily flow histogram and cumulative deviation from the mean for Namoi River at Gunnedah .......................................................................................................................... 16 Figure 11: Groundwater aquifer types in the Namoi/Peel ................................................................... 18 Figure 12: Groundwater Management Areas in the Namoi catchment............................................... 18 Figure 13: Groundwater quality and suitability in the Namoi catchment ............................................. 19

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1 Introduction The Namoi River is one of the Murray-Darling Basin’s major NSW sub-catchments. It covers a total area of about 42,000 km2 from the Great Dividing Range near Tamworth to the Barwon River near Walgett (Figure 1). The Peel River is a major regulated tributary to the Namoi with a catchment area of around 4,700 km2 (Figure 2). It contributes an average annual volume of approximately 280,000 ML to the Namoi River. The Namoi catchment borders the Gwydir and Castlereagh catchments and is bounded by the Great Dividing Range in the east, the Liverpool Ranges and Warrumbungle Ranges in the south, and the Nandewar Ranges and Mount Kaputar to the north. Elevations range from over 1,500 m to the south and east to just 100 m on the alluvial floodplain of the lower catchment west of Narrabri (Figure 3). Stretching from Bendemeer in the east to Walgett on the western boundary, the Namoi catchment is over 350 km long. Major tributaries of the Namoi River include Coxs, Creek and the Mooki, Peel, Manilla, and McDonald Rivers joining the Namoi upstream of Boggabri with Pian, Narrabri, Baradine and Bohena Creeks joining below Boggabri. Major tributaries of the Peel River are Goonoo Goonoo Creek, Cockburn River, and Dungowan Creek. Streamflows in the Namoi catchment are regulated by Keepit Dam on the Namoi River, Split Rock Dam on the Manilla River and Chaffey Dam on the Peel River. The regulated section of the Peel River has historically been managed as a separate allocation scheme to the Namoi regulated river, and operationally the management of Chaffey Dam is independent of the other storages on the Namoi. The annual regional output is over $1 billion, with dryland and irrigated agricultural production representing approximately half this amount. Major industries include cotton, livestock production, grain and hay, poultry, horticulture and forestry. The regions local councils also depend on the Namoi and Peel Rivers to meet the urban water requirements of many of the regions urban centres with the most notable being the major urban centre of Tamworth whose water supply is provided from the Peel River. Prior to European settlement in the mid-1800s the Namoi and Peel catchments were occupied by the Kamilaroi people. Today, approximately 100,000 people live within the Namoi catchment, mostly along the Namoi River and its tributaries between Tamworth and Narrabri. Tamworth, located on the Peel River, is the largest urban centre in the catchment with a population of nearly 33,500 people living in town. Gunnedah, on the Namoi River, has a population of 7,500 people, and Narrabri, also on the Namoi, has a population of 6,100 people. A number of smaller towns throughout the catchment, such as Barraba, Manilla, Quirindi, Walgett, Wee Waa and Werris Creek, support between 1,000 and 3,000 people. Peel River at Taroona upstream of Chaffey Dam

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Figure 1: The Namoi catchment

Figure 2: The Peel catchment

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Figure 3: Topography and elevation of the Namoi catchment

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2 Climate 2.1

Rainfall

Annual average rainfall varies over the Namoi catchment, from a maximum of 1,300 mm over the ranges in the east to around 400 mm near Walgett (Figure 4). The pattern of rainfall varies throughout the year with the highest monthly rainfall at Gunnedah occurring in summer, and the lowest rainfall occurring from April though September. Figure 4: Average annual rainfall in the Namoi catchment

Source: Hutchinson and Kesteven 1998

Figure 5: Average monthly rainfall at Gunnedah

Source: Bureau of Meteorology Climate Data Online

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2.2

Evaporation

Pan evaporation in the Namoi-Peel catchment has a strong east-west gradient. Average Class A pan evaporation varies from around 1,000 mm per year in the south-east, to over 2,200 mm per year in the north-west (Figure 6). Pan evaporation is also strongly seasonal, varying from around 2 mm per day in June and July at Gunnedah, to around 8 mm per day during December and January (Figure 7). Figure 6: Class A pan average annual evaporation in the Namoi catchment

Source: Hutchinson and Kesteven 1998

Figure 7: Mean daily pan evaporation at Gunnedah

Source: Bureau of Meteorology Climate Data Online

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3 Land use The dominant land use in the Namoi catchment is sheep and cattle grazing which accounts for 61 per cent of land use by area (Table 1). Wheat, cotton and other broad acre crops are grown along the alluvial floodplains (Figure 8). Of the 1,120 km2 irrigated in the year 2000, around 800 km2 (over 70 per cent) was used for cotton production in the Lower Namoi catchment (CSIRO 2007). The Peel catchment supports around 66 km2 of irrigation, most of which is for irrigated pasture or fodder crops (NOW 2010). Extensive areas of land for conservation and forestry occur in the middle of the catchment to the south of Narrabri. Together with other native landscapes these land uses account for over 18 per cent of the catchment. Much of this area comprises the Pilliga Scrub, a significant area of remnant dry sclerophyll forest (see Section 4.2). Table 1: Land use statistics for the Namoi catchment

Extent (km2)

Proportion of catchment (%)

25,727

61.2

Dryland cropping and horticulture

6,810

16.2

Forestry

4,339

10.3

Native landscapes

2,136

5.1

Conservation

1,351

3.2

Irrigation

1,259

3.0

Residential

256

0.6

Lakes, rivers, dams

139

0.3

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