of material in any kind of information retrieval system. The copyright for the
data, maps, figures and tables in this report is held by NIWA.
page
Contents
Executive Summary iv
1. Introduction 1
2. Present Climate 3
2.1 Taranaki regional environment 3
2.2 Climate of Taranaki region 4
2.3 Storms and high intensity rainfall 6
2.3.1 Methods 6
2.3.2 Observed trends in daily extremes 8
2.4 High winds and tornadoes 13
2.4.1 Winds 13
2.4.2 Extreme winds 15
page
Groundwater quantity
Rainfall or river water that seeps from soils into the pore
spaces between fractures of solid rock or sediments, like
sand or gravel, is known as groundwater. Groundwater is
the largest source of accessible freshwater in the world,
accounting for around 98% of freshwater available for use
on Earth. While groundwater is generally hidden beneath
the land surface, many of the region’s springs, rivers and
lakes are sustained by groundwater
levels GND2102 and rainfall (July 2020-June 2021) 9
Figure 5 Observed groundwater levels GND2102 and abstraction (July 2020-June 2021) 10
Figure 6 Observed groundwater levels GND2103 and rainfall (July 2020-June 2021) 10
Figure 7 Observed groundwater levels GND2103 and abstraction (July 2020-June 2021) 11
Figure 8 Historical groundwater level response and abstraction (2009-2021) 11
page
1
1 Introduction
1.1 Compliance monitoring programme reports and
page
Doc. No: 2813485
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR June 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
Motukawa Hydroelectric Power Scheme - Hydrology Report
Trustpower Ltd
November 2021
Job No: 1008726 Phase 100
Table of contents
1 Introduction 1
1.1 Context 1
1.2 Scope of assessment 1
1.3 Scheme description 1
1.4 Hydrological nodes 3
2 Catchment characteristics and water resources 6
2.1 Waitara catchment 6
2.2 Manganui catchment 6
2.3 Rainfall 6
2.4 Hydrometric data 7
2.5 Water use in the catchment 8
2.6 Manganui River flows 12
2.6.1 Derivation of Manganui River flows at the intake
rainfall events and display a greater range of seasonal water level variation than
the region’s deeper aquifers. In general, groundwater levels across the region appear
relatively stable; however five sites are displaying statistically significant trends in water
level change. Three of these sites display positive trends, meaning water levels are
increasing at these sites. The remaining two sites, GND0508 (Taranaki volcanics aquifer) and
GND0708 (Whenuakura aquifer) display negative trends,
page
Doc. No: 2747617
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR March 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
forming a tributary of the much larger Mimitangiatua awa
catchment. It runs from south-east to north-west. Almost the entire valley formed by the Stream is owned
by the Company, and consists of steep eroded hillsides, multiple side gullies, and small river flats distributed
along its length. The area receives more rainfall than the northern Taranaki coastline to the south-west. Soils
are generally poor and highly erodible. Patches of bush and planted trees cover most of the hillsides, with
the
components including site
inspections, the collection as assessment of abstraction data, residual flow monitoring, water quality
analysis, data review and compliance assessments. The specific range of monitoring carried out for each
consent is dictated by the water source, weather and flow conditions, and system design.
A total of 56 irrigation consents were exercised during the 2020-2021 monitoring year, with most
commencing irrigation in mid-December and concluding late March. Rainfall
page
Doc. No: 2835178
TARANAKI REGIONAL COUNCIL MONTHLY RAINFALL AND RIVER REPORT FOR July 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