Bay of Plenty Regional Council
River Flow Recording Station
River
Tarawera
Site name
Awakaponga
Site Number
15302
NZTM Reference
1931056
5794184
NZMG Reference
2841185
6355627
Start of Record
May 1948
Data Capture Rate
99.5%
Data Summary From
January 1949
To
December 2010
Data Audited From
May 1948
To
December 2010
Equipment History
01/01/36: Staff gauge installed.
23/08/65: F&P digital recorder.
15/06/92: Backup Foxboro removed.
15/09/99: iQuest logger and Handar.
16/02/09: OTT CBS Bubbler.
16/12/48: Kent chart recorder.
24/08/82: Backup Foxboro chart recorder.
01/07/92: Float with L&S digital recorder.
15/03/05: Sutron pressure transducer replaces Handar.
Comments on Stage/Discharge Ratings
Site has a natural control with the riverbed comprising sandy pumice. Ratings are available to convert stage (mm)
to flow (ℓ/s).
General Comments
Site was operated by NIWA, Rotorua until 01/07/92. Site is now operated by Bay of Plenty Regional Council as
part of its Natural Environmental Monitoring Network.
Station Comments
Tarawera River at Awakaponga. Site Number 15302, on River Number 153000.
The local recording authority is Environment Bay of Plenty.
The site is situated 6.5 kilometres from the mouth. The control is by natural channel. The catchment area includes landlocked
lakes: Rotomahana, Rerewhakaaitu, Okataina, Okareka, Tikitapu, and Rotokakahi totalling 243km 2.
The lower reaches of the Tarawera River where the water level recorder is located has a sandy pumice bed, which causes
cross section changes on an hour by hour basis. The bed load travelling past the recorder site varies from two to four
hundred tonnes per day. The changes in bed level have a direct effect on water levels at the site with the station never
registering smooth recession curves. This combined with water extraction by the pulp and paper mills upstream causes the
stage fluctuations that are apparent when the filed data has three millimetres or less compression applied. Dragline and
earthquake effects are best seen in the variation due to major changes in water level slope through the reach.
28/05/48 - Data from 480528 to 541217 was obtained from weekly staff gauge readings. Some flood events over this period
had an increased frequency of readings to establish peak heights and define hydrograph shapes. The staff gauge used for
these readings was situated downstream of the present recorder location at the Railway Bridge.
01/01/73 - From 730101 the increased water draw off by the pulp and paper mills causes frequent large, rapid, rises and falls
in the stage record. These fluctuations are responsible for a lag between some external and internal readings observed at
the site. The rating change beginning 730723 at 150500 is due to a gradual increase in cross sectional area at the gauging
site and is probably attributable to a reduction in sediment transport during a year which only produced 75% of the mean
annual rainfall. This trend was reversed after a fresh in October, causing the rating curve to revert back to its previous
position.
01/02/75 - Dragline operations observed in channel from February 1975, causing unusual shaped base flow recessions.
10/08/77 - Syphon intake installed on 770810 094500 to enable the recorder to operate below the invert level of the bottom
intake.
02/03/87 - Data from 870302 133000 to 870303 133300 was filed from the Foxboro backup recorder as the digital recorder
was badly affected by an earthquake. The order of the sequence of events between 134200 and 140300 is a guess only as
they appear instantaneous on the Foxboro chart.
01/06/87 - Drag line clearing channel upstream and downstream of recorder from 870601 to 870721. This work appears to
have affected the stage record from 870616.
03/02/88 - Dragline was observed clearing channel 880203 112400. This work appears to have affected the stage data from
880123.
29/04/92 - Missing record 920429 080000 to 920429 143000.
01/07/92 - Site handed over to Environment Bay of Plenty. Instrumentation L&S tape recorder with 1mm resolution,
connected to an Aquitel Remote.
29/11/92 - Reduction in water level while Tasman pulp and paper mill shut effluent outfall gates for approximately 2 hours,
while floating a boat stuck on an effluent pond bar.
15/12/94 - Missing record from 941215 231500 to 941216 084500 due to earthquake affecting recorder.
22/09/95 - Missing record from 950922 113000 to 950925 151500.
07/11/95 - Missing record from 951107 091600 to 951110 130000 due to float tape not being on pulleys.
24/11/96 - Data from 961124 0 to 961130 240000 shows the result of Tasman pulp and paper mill stopping their discharge
into the river at Pipe Bridge.
15/11/ 97 - Missing record from 971115 124500 to 971117 130000.
15/03/2005 - Sutron Gas Purge system installed as replacement for Handar 436B encoder (primary stage recorder). Sensor
has a resolution of +/-5mm and a recording interval of 15 minutes. Tower now sitting above normal water level.
27/11/08 - Missing record from 20081127 120000 to 20081128 070000 due to Sutron Gas Purge system failure.
12/2/09 - Missing record from 20090212 133000 to 20090216 104500 due to Sutron Gas Purge system failure. Replaced by
OTT CBS Bubbler 20090216 104500.
For additional information, please see recording authority.
Bay of Plenty Regional Council
River Flow Summary
Site Number
River
Station name
NZTM Reference
Catchment area (km2)
15302
Tarawera
Awakaponga
2841185
6355627
906
Date compiled
Compiled by
June 2012
Brent Hutchby
NZMG Reference
Period of Summary
2841185
6355627
1949 to 2011
Statistical Summary
Flow (ℓ/s)
15186
Maximum Flow
22866
Mean Annual Maximum Flow
30196
Mean Summer Flow
28916
Mean Autumn Flow
33
Mean Winter Flow
Mean Spring Flow
GEV
Peak Flow Distribution Fit
17079
Peak Flow (5 yr Return)
23315
Peak Flow (10 yr Return)
20174
Peak Flow (20 yr Return)
18947
Peak Flow (50 yr Return)
Peak Flow (100 yr Return)
Minimum Flow
Mean Annual Minimum Flow
Mean Flow
Median Flow
Mean Specific Flow (/km2)
Low Flow Distribution Fit
7 day Low Flow (Minimum)
7 Day Low Flow (Mean Annual)
7 day Low Flow (5 yr Return)
7 Day Low Flow (10 yr Return)
92392
54821
28417
21914
32552
32210
GUMBEL
64078
71607
78828
88176
95180
Annual Summaries
Year
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
Minimum
17752
19116
17985
16936
22908
23094
20691
19185
18614
16478
18107
24023
21550
Flow (ℓ/s)
Mean
28024
27538
23428
22851
31212
28892
25415
24358
22377
21851
28199
30967
27548
Year
Maximum
48989
47410
34225
51708
47289
48101
43023
39691
37221
48445
74188
52184
42957
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
Minimum
20389
23241
22740
21597
21922
20521
20821
21760
23508
20381
19224
21691
19450
Flow (ℓ/s)
Mean
29408
30456
28511
29984
27613
25359
29319
28496
33025
25929
28358
26703
27565
Maximum
68882
60018
52685
67521
50335
56501
70201
59223
73681
38751
54996
46834
62902
Flow Distribution
Percentiles
0
10
20
30
40
50
60
70
80
90
100
0
92392
39355
35100
32597
30604
28916
27409
25908
24214
22306
15186
1
54412
38736
34789
32391
30434
28752
27261
25738
24038
22067
2
50057
38182
34488
32167
30263
28605
27113
25574
23848
21810
3
47558
37689
34203
31958
30089
28449
26980
25401
23669
21537
Flow (ℓ/s)
4
45704
37243
33951
31762
29902
28308
26838
25237
23493
21218
5
44234
36848
33693
31571
29722
28150
26696
25066
23307
20863
6
43182
36445
33470
31375
29534
28006
26545
24898
23134
20521
7
42102
36098
33226
31176
29359
27850
26385
24721
22950
20091
8
40990
35771
33023
30985
29213
27702
26232
24548
22756
19548
9
40136
35437
32815
30793
29072
27553
26068
24379
22538
18672
Maximum Flow
Minimum Flow
5 per. Mov. Avg. (Maximum Flow)
100000
30000
80000
25000
60000
20000
Flow (l/s)
Flow (l/s)
5 per. Mov. Avg. (Minimum Flow)
35000
40000
15000
10000
20000
5000
0
19451950195519601965197019751980198519901995200020052010
0
19451950195519601965197019751980198519901995200020052010
Year
Year
Mean Flow
5 per. Mov. Avg. (Mean Flow)
60000
50000
Flow (l/s)
40000
30000
20000
10000
0
1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Year
Winter
5 per. Mov. Avg. (Autumn)
60000
60000
50000
50000
40000
40000
Flow (l/s)
Flow (l/s)
Autumn
30000
20000
10000
30000
20000
10000
0
19451950195519601965197019751980198519901995200020052010
0
19451950195519601965197019751980198519901995200020052010
Year
Spring
Year
Summer
5 per. Mov. Avg. (Spring)
60000
60000
50000
50000
40000
40000
Flow (l/s)
Flow (l/s)
5 per. Mov. Avg. (Winter)
30000
20000
10000
5 per. Mov. Avg. (Summer)
30000
20000
10000
0
19451950195519601965197019751980198519901995200020052010
Year
0
19451950195519601965197019751980198519901995200020052010
Year
Tarawera at Awakaponga
Karaponga Stream Gaugings
14 November 2015
Gaugings and summary report by L Palmer
Report prepared for Karaponga Hydro Limited
Gauging date 14 November 2015
Overview
The Karaponga Stream is nestled in the hills about 14km inland from Matata heading towards
Kawerau. A small hydro scheme utilises about 90m of fall as the Karaponga Stream emerges from
the Rotoma Hills. The scheme utilises an existing arch weir constructed in the early 1920’s, with the
pipeline and power station rebuilt in recent years. Consents for this scheme are curently being
reviewed, and stream flow gaugings were undertaken to assess stream flow above and below the
Karaponga weir.
Gauging Summary
Three gaugings were undertaken using the Sontek Flow Tracker on 14 November 2015. The weather
was fine and calm. Two gaugings were undertaken either side of the Karaponga weir, and another on
the Karaponga stream further downstream, approximately 80m upstream of the power station.
Figure 1 and Table 1 summarises the gauging locations and gauging results. Appendix 1 provides a
photo of each gauging location, and Appendix 2 the Flow Tracker discharge measurement summary.
The comment column in Table 1 is the approximate stream distance either from the weir, or up from
the station. The gaugings performed are considered good with over 25 verticals per gauging
(Appendix 2).
A visit to the power station around 1400 NZST indicated the station was generating about 115 kW.
Figure 1 – Gauging locations (straight line distance between weir and station approx. 800m)
Table 1 – Karaponga Stream gauging summary (14 November 2015)
Location
Upstream weir
Downstream weir
Upstream station
GPS
38.00610
176.69821
38.00664
176.69879
38.00978
176.70639
Time (NZST)
1021-1056
Flow (l/s)
304.6
1135-1210
30.5
1307-1339
38.1
comments
≈50m upstream weir
≈60m downstream
weir
≈80m upstream
station
Appendix 1 - Site Photos (all photos looking downstream)
Figure A1.1 - Karaponga upstream weir
Figure A1.2 - Karaponga downstream weir
Figure A1.3 - Karaponga upstream station
Appendix 2 : Flow Tracker Discharge Measurement Summary