Mangorei Hydroelectric Power Scheme - Hydrology ReportHydrology Report
Trustpower Ltd
November 2020 (Final)
Job No: 1008726.200
Table of contents
1 Introduction 1
1.1 Context 1
1.2 Scope of assessment 1
1.3 Scheme description and key locations 1
2 Catchment characteristics and water resources 5
2.1 Waiwhakaiho catchment 5
2.1.1 Drainage and geology 5
2.1.2 Catchment area and cover 5
2.1.3 Rainfall 6
2.2 Hydrometric data 6
2.3 Water use in the catchment 7
2.4 Waiwhakaiho River flows
page
Monthly Year to Date
Hydro_Sites # days >
0.5 mm
Total
Rainfall
(mm)
% of
typical
month
Total to
date (mm)
% of typical
year to date
% of typical
full year
Records
Began
North Egmont at
Visitors Centre 17 713.0 112.0 2257.0 99.2 33.6 1991
Dawson Falls 16 555.0 120.1 2196.5 139.5 48.8 1933
Kahui Hut 20 563.5 125.2 1665.0 101.3 34.5 2006
Mangorei Upper at
Forest Hill 17 450.5 118.6 1512.0
during the 2021-2022 monitoring year, with south Taranaki
commencing irrigation in November and the rest of the region beginning in January. Irrigation concluded
late April through to early May across the region. Rainfall recorded at the Council’s monitoring locations
over the summer irrigation period ranged between 82% and 203% of historical mean values. Even though
rainfall volumes were higher than previous years, the irrigation season was longer with total irrigation water
usage of 6,960 ML
page
Doc. No: 2955756
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR December 2021
Provisional Data Only
Note: some sites record a number of parameters
Table 1: Rainfall at 27 sites throughout the region
Station Sub-region
Monthly Year to Date
Records Began Number of rain
days (>0.5mm)
Total Monthly
Rainfall (mm)
% of Monthly
Normal (%)
Maximum December
RF (year occurred)
(mm)
Total to date (mm)
% of Normal for year
to
Quarries independent groundwater monitoring (blue) and flow gauging sites (orange) 10
Figure 4 Discharge rates from Civil Quarries stormwater system plotted against rainfall in 10 minute
interval totals. The red line is the consented discharge rate limit 14
Figure 5 Abstraction rates from Pond A which is where groundwater from the excavation pit is pumped
into (1 July 2022 to 30 June 2023) 15
page
iii
Figure 6 Biomonitoring sites in the Kurapete Stream in relation to
page
Doc. No: 2788783
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR May 2021
Provisional Data Only
Note: some sites record a number of parameters
Table 1: Rainfall at 27 sites throughout the region
Station Sub-region
Monthly Year to Date
Records Began Number of rain
days (>0.5mm)
Total Monthly
Rainfall (mm)
% of Monthly
Normal (%)
Total to date
(mm)
% of Normal for
year to date
% of average full
calendar year
Nth Egmont
page
Doc. No: 3033222
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR March 2022
Provisional Data Only
Note: some sites record a number of parameters
Table 1: Rainfall at 27 sites throughout the region
Station Sub-region
Monthly Year to Date
Records Began Number of rain
days (>0.5mm)
Total Monthly
Rainfall (mm)
% of Monthly
Normal (%)
Total to date
(mm)
% of Normal for
year to date
% of average full
calendar year
Nth
page
Doc. No: 2906170
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR October 2021
Provisional Data Only
Note: some sites record a number of parameters
Table 1: Rainfall at 27 sites throughout the region
Station Sub-region
Monthly Year to Date
Records
Began Number of rain
days (>0.5mm)
Total Monthly
Rainfall (mm)
% of Monthly
Normal (%)
Total to date
(mm)
% of Normal for
year to date
% of average full
calendar year
Nth
also be a potential indicator of intensive land use
impact where fertiliser is applied to land (Rosen, 2001).
- - - - - -
Chloride (Cl)
Chloride is relatively unaffected by geochemical processes which makes it a good indicator of general
groundwater quality. The primary source of chloride in groundwater is marine sourced rainfall recharge to
an aquifer. However, saltwater intrusion and land use activities, such as wastewater and effluent
discharges, can contribute chloride to …
page
Doc. No: 2882775
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR October 2021
Provisional Data Only
Note: some sites record a number of parameters
Table 1: Rainfall at 27 sites throughout the region
Station Sub-region
Monthly Year to Date
Records Began Number of rain
days (>0.5mm)
Total Monthly
Rainfall (mm)
% of Monthly
Normal (%)
Total to date
(mm)
% of Normal for
year to date
% of average full
calendar year
Nth