2.1.4.2 Statistical analysis and interpolation


Table 7 shows the maximum and the 10th, 25th, 50th (median), 75th and 90th percentile daily flows for the 37 streamflow gauging stations for data available from 1983 to 2012. Half of the catchments have their 10th percentile flow (a flow that is exceeded 90% of time) less than 1 ML/day. Similarly, 19% of the catchments have their 25th percentile flow less than 1 ML/day. About 8% of catchments also have a median flow of zero or close to it (≤1 ML/day) implying flow in the stream occurs for less than half the time in these catchments. The majority of smaller catchments (<1000 km2) have their 10th and 25th percentile flows as zero except for the Peel River downstream of Chaffey Dam (407 km2).

Table 7 Maximum, median, 10th, 25th, 75th and 90th percentile flows for the Namoi subregion using data from 1983 to 2012


Gauge ID

10th

(ML/d)

25th

(ML/d)

Median

(ML/d)

75th

(ML/d)

90th

(ML/d)

Maximum flow

(ML/d)

419001

26

117

416

1338

2661

212,616

419003

15

132

480

1513

2986

137,308

419005

15

50

139

377

1041

93439

419006

19

45

115

305

978

131,450

419007

3

9

26

709

1981

104,397

419012

12

114

426

1397

2844

213,343

419015

29

43

71

133

419

36,637

419016

0

3

19

74

260

23,395

419020

7

13

24

45

185

40,115

419021

5

44

143

425

2510

106,627

419022

35

76

184

543

1521

115,853

419024

16

34

74

232

796

79,426

419026

0

27

109

411

3169

109,948

419027

0

1

12

46

272

134,047

419029

1

2

6

17

81

10,456

419032

0

0

0

4

71

98,478

419033

0

1

5

15

69

31,580

419035

0

1

6

20

70

16,494

419039

20

140

490

1457

3010

182,402

419043

6

12

25

42

115

28,007

419045

4

15

44

92

177

16546

419049

0

0

6

51

229

35,744

419051

0

3

7

15

41

30,239

419053

1

3

13

37

97

57,865

419054

0

0

6

28

116

15,979

419059

7

56

194

559

1726

144,550

419061

0

3

139

425

781

10,719

419068

10

51

171

473

1865

64,038

419072

0

0

0

5

38

16500

419088

0

0

44

158

306

1,731

419089

0

2

11

43

154

25,312

419091

0

3

51

245

2869

159,595

420014

0

0

0

0

1

15,605

420017

2

5

13

49

180

34,272

418014

0

3

16

56

217

31,888

418027

0

0

4

28

129

18,204

418033

0

2

5

17

61

5,002

Data: NSW Office of Water (Dataset 1, Dataset 2, Dataset 3)

This table follows BA convention of assigning percentile values which is different to the NSW Policy Advice Note No. 6 at: http://www.water.nsw.gov.au/__data/assets/pdf_file/0010/548848/plans_notes_policy06.pdf

Last updated:
6 December 2018
Thumbnail of the Namoi subregion

Product Finalisation date

2018
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ASSESSMENT