Otago Alluvial Fans Project - Supplementary maps and information on fans in selected areas of Otago - GNS Science Consultancy Report 2009/052 - April 2009

Oct 26, 2026

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Otago Alluvial Fans Project documentation provides supplementary maps and reference information for alluvial fans in selected areas of Otago. The report defines alluvial fans and highlights key hazards, focusing on fast-moving sediment-laden floods and debris slurry-like flows. It details methods for mapping and classifying fans, presents selected case examples across multiple Otago locations, and culminates in regional synthesis and hazard considerations. It concludes with references, acknowledgements, and supporting appendices including GIS data outlines, assessments, and a glossary.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages155

Reading Time6 h 31 min

AccessFree to download

Executive Summary

Introduction

Mapping and Classification of Alluvial Fans in Otago

Mapping of alluvial fans

Classification of alluvial fans

Selected examples of alluvial fans

Fans at Makarora

Fans at Hawea Flat

Fans at Queenstown

Fans in the Roxburgh area

Regional Synthesis

The wet mountains of northwest Otago

The ranges and basins of inland Otago

The hills, valleys and plains of coastal Otago

Hazard considerations

Conclusions

Acknowledgements

References

Appendices

Appendix A: Glossary

Appendix B: GIS data outline

Appendix C: Summary assessments and maps

Otago Alluvial Fans Project: Supplementary maps and information on fans in selected areas of Otago GNS SCIENCE CONSULTANCY REPORT 2009/052 April 2009 D.J.A. Barrell, S.C. Cox, S. Greene, D. B. Townsend Otago Alluvial Fans Project: Supplementary maps and information on fans in selected areas of Otago D.J.A. Barrell, S.C. Cox, S. Greene, D. B. Townsend GNS Science Consultancy Report 2009/052 April 2009 LIMITATION This report has been prepared by the Institute of Geological and Nuclear Sciences Limited (GNS Science) exclusively for and under contract to Otago Regional Council. Unless otherwise agreed in writing, all liability of GNS Science to any party other than Otago Regional Council in respect of this report is expressly excluded. The data presented in this Report are available to GNS Science for other use from April 2009 BIBLIOGRAPHIC REFERENCE Barrell D.J.A.. ; Cox, S.C. ; Greene, S. ; Townsend, D. B. 2009: Otago Alluvial Fans Project: Supplementary maps and information on fans in selected areas of Otago. GNS Science Consultancy Report 2009/052 . Prepared for Otago Regional Council. 19 pages, 3 tables and 3 appendices. David Barrell, Simon Cox, GNS Science, Private Bag 1930, Dunedin Shane Greene, Opus International Consultants, Private Bag 1913, Dunedin Dougal Townsend, GNS Science, PO Box 30-368, Lower Hutt Project Number: 440W1203 CONTENTS EXECUTIVE SUMMARY ......................................................................................................... II 1. INTRODUCTION .......................................................................................................... 1 2. MAPPING AND CLASSIFICATION OF ALLUVIAL FANS IN OTAGO....................... 5 2.1 Mapping of alluvial fans ................................................................................................. 5 2.2 Classification of alluvial fans ......................................................................................... 7 2.3 Selected examples of alluvial fans ................................................................................ 9 2.3.1 Fans at Makarora ............................................................................................. 9 2.3.2 Fans at Hawea Flat .......................................................................................... 9 2.3.3 Fans at Queenstown ...................................................................................... 12 2.3.4 Fans in the Roxburgh area ............................................................................. 13 3. REGIONAL SYNTHESIS ........................................................................................... 15 3.1 The wet mountains of northwest Otago ...................................................................... 15 3.2 The ranges and basins of inland Otago ...................................................................... 16 3.3 The hills, valleys and plains of coastal Otago ............................................................. 16 3.4 Hazard considerations ................................................................................................. 17 4. CONCLUSIONS ......................................................................................................... 17 5. ACKNOWLEDGEMENTS .......................................................................................... 18 6. REFERENCES ......................................................................................................... 18 FIGURES (in text) Figure 1: An example of an alluvial fan in Otago......................................................................................................2 Figure 2: The Otago region, with locations of alluvial fan assessment areas presented in this report......................3 Figure 3: Concept diagrams illustrating three types of alluvial fan described in this investigation............................8 Fig

FAQs

What are the main hazards associated with alluvial fans discussed in the report?

The report identifies fast-moving sediment-laden floods and slurry-like flows of debris as the most serious hazards.

How does the report approach mapping and classification of alluvial fans in Otago?

It covers mapping of alluvial fans, then classifies them using criteria related to fan stability and landform characteristics, supported by selected examples.

Which areas of Otago are included as selected examples of alluvial fans?

Selected examples include fans at Makarora, Hawea Flat, Queenstown, and in the Roxburgh area.

Oct 26, 2026

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