River Styles Assessment of the Waipā River Catchment, Waikato, New Zealand

TR 2021/01
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Report: TR 2021/01

Author: Will Marson, Nicole Wheeler, Gary Brierley

About this report

Waikato Regional Council contracted the joint venture of Aerialsmiths New Zealand Ltd, Hydrobiology Qld Pty Ltd and The University of Auckland to finalise a River Styles assessment of the Waipā River catchment. This study uses the River Styles Framework (Brierley & Fryirs, 2005) to present a coherent overview of the controls on river adjustment to support geomorphologically-informed appraisals of targeted river management and restoration strategies. The assessment builds on an initial River Styles assessment carried out by Wheeler (2019) and valley confinement assessment by Marson (2019). The study focuses on the main stem of the Waipā River and five of its sub-catchments: the Moakurarua Stream (228 km2), the Mangapū River (445 km2), the Upper Waipā River (458 km2), the Pūniu River (561 km2), and the Mangapiko River (307 km2). Many of these areas contain priority zones that have been outlined in the Waikato and Waipā Restoration Strategy (Neilson et al., 2018). This report assesses the regional and catchment setting, identifies and maps the diversity of River Styles, and interprets controls on river character and behaviour.

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River Styles Assessment of the Waipā River Catchment, Waikato, New Zealand [PDF, 14 MB]

Contents
Executive summary 1
Section 1: Introduction 3
1.1 Aim 3
1.2 Study Area 3
1.3 Report Structure 5
Section 2: Regional Setting 5
2.1 Introduction 5
2.2 Climate and Flood History 7
2.3 Geology, Lithology and Geomorphic History 8
2.4 Land Use History 11
2.5 Sediment Regime 16
2.6 Management Interventions 16
Section 3: Methods 17
3.1 River Style Framework: Background 17
3.2 River Styles Framework: Stage One 18
3.1.1 Step One - Assess Regional and Catchment Setting Controls 19
3.1.2 Step Two - Define and Map River Styles 19
3.1.3 Step Three - Interpret Controls on the Character, Behaviour, and Downstream Patterns of River Styles 22
3.1.3.1 Potential Geomorphic Sensitivity Ranking 22
Section 4: Downstram Patterns of River Styles 24
4.1 Background 24
4.2 Moakurarua Sub-Catchment 25
4.3 Mangapū Sub-Catchment 28
4.4 Upper Waipā Sub-Catchment 33
4.5 Pūniu Sub-Catchment 38
4.6 Mangapiko Sub-Catchment 42
4.7 Waipā Sub-Catchment 46
Section 5: Controls on River Styles 51
5.1 Background 51
5.2 Geology and Geomorphic History (Imposed) 51
5.2.1 Topography and Valley Setting 51
5.2.2 Lithology and Bed Material 51
5.2.3 Configuration and Planform 52
5.3 Climte - Magnitude-Frequency Relationships, Geomorphic Effective Floods (Flux) 52
5.4 Highly Modified Systems - (Imposed) Anthropogenic Controls 53
5.5 Riparian Vegetation (Flux) 53
5.6 Summary 54
Section 6: Implications of this Study 54
6.1 Diversity 54
6.2 Sensitivity 55
6.3 Emerging Techology 57
Section 7: Concluding Comment 58
Reference List 59
Appendix A: River Styles 64
Appendix B: River Style Proformas 68
Appendix C: GIS Data 153