Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. THE LOCATION AND ORIENTATION OF COASTAL PARABOLIC SAND DUNES IN NEW ZEALAND A thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Geography at Massey University Christine Ann Muckersie 1989 ii ABSTRACT No previous research into either the spatial diversity of different coastal sand dune types, or the factors influencing the location and morphology of any particular dune type has been done in New Zealand. Vertical aerial photographs were used to locate Holocene dunefields around the New Zealand coastline. The locations of dunefields in general and the spatial diversity of dune types are able to be explained by identifying the conditions most suitable for sand dune development and examining the spatial variation in these conditions. One particular dune type, parabolic, was examined in more detail in order to discover the relative importance of different variables to the development of that dune type. The relationship between wind climate and the location and morphology of coastal parabolic sand dunes was examined in detail. Wind data from coastal sites around New Zealand were used to compute sand transport vectors using two methods - one proposed by Landsberg (1956) and the other by Fryberger (1979) - and these were compared with dune orientations obtained from aerial photographs. Although Fryberger's method has never previously been applied to coastal sand dunes, the two methods were found to produce very similar results. Spatial variation of other aspects of dune morphology, such as the shape of parabolic dunes, were also compared to wind climate characteristics. Such comparisons were permitted by applying further calculations proposed by Fryberger which allow the directional variablity of wind to be expressed in exact terms. The results of these studies indicate that morphological characteristics of parabolic sand dunes, such as orientation, shape and size, are largely controlled by the strength and frequency of onshore winds and the directional variability of winds. Sand transport resultants computed using the Fryberger method were found to be closely aligned to dune orientations in most cases. This study provides some insight into the processes and variables affecting spatial variation of coastal sand dune development in New Zealand but also highlights the need for more detailed geomorphic studies of coastal dunefields in New Zealand. :.:..l ACKNOWLEDGEMENTS I would like to express my gratitude to my supervisor Dr Mike Shepherd for all his help, advice and support during the complet1on of this dissertation. Thanks are also due to Val and Mooreen of the Map Shop at DOSLI in Wellington for the patience and friendliness they displayed during the weeks I spent in their company. I am also grateful tor the accomodation provided for me in Wellington by Bill Ogier (and flatmates) and by Tom and Joan Ashworth. Steve Reid of the N.Z. Meteorological Service and the farmers in th e vicinity of Porangahau are thanked for their efforts to provide information used in this thesis. Of the many people who offered words of comfort and encouragement. special thanks must be made to Richard Heerdegen. Geoff Duller. Or Patrick Hesp, Professor Andrew Goudie. Professor John Flenley and Greer Robertson-Brown. Thanks also to Rachel, Helen and Glynnis for help with various technical matters. This thesis is dedicated to my father. Robert Muckersie. TABLE OF CONTENTS ,\ck n o wledgement: s Tuble o t Cco cenc~ Li.st: 1..) f figures ·;i i List: c t T.:i.bl·.::s ·,; l l l. Chapcer l - Intr oduc c~ o n Aims and Scope or Study Ch apt:er format: Methods Us e o f Aerial Phocographs Wind Data ·I Literature Review 5 Dunes in Ge neral 5 Coastal Du nes 5 Orientation o f Parabolic Sand Dunes 6 Other Methods of Wind Data Analysis 7 Chapt:er 2 - The Coastal Settioq and Location Qf Coast.al Duoef ii=>ld1 in Ne w :::.ealaru:i Introduce ion 8 Qu at:ernary Hi.scary Tectonics 10 Locatio n and Wave Cli~a te L 1 Longshore Drift L 1 Nea r shore Bathymet:ry 13 Dune Areas o f N•:! W Z·.=alund 14 ·.:: hapt.e.!:" ~ ;and T::- J,n s po rt 11:0 :s::pc;;u:.i:;n - the Ro le ,, : 'li in'-i c.:-: ..J ·;,~ gecati.:n Aeolian Transport. e r Sand 1.8 Mechanics o r .C..eolic,n i::ir.~:-: , : :c Effeccs o r \·Jate r Effec c s o r Salt C:ust ~ o r ~ 3t.i~~ .:o Thresho ld Wi nd Ve l oc icy .:o Rate o r Sand T.!::anspo rt 20 Effects o r Topograpr.y .: 1 Effects ot Ve getatio n 21 Sand Dunes ;:3 Unvegetated Sand Dunes 23 Vegetation and Sand Dune Cevelopmenc 24 Parabolic Dunes 25 Chapter 4 - T.hs;_New Zealand Wi nd <1 ; mate and Analysi s o f Wind Data_ New Zealand Wind Climate 27 Previous Methods of Comparing Wind Data to dune orientation 30 Analysis of New Zealand Wind data 32 Landsberg Method 33 Fryberger Drift Potential Calculations 35 Comparison of Landsberg and Fryberger Methods 38 <: hapter 5 - Aeolian Sand Drif::. ?otenti.:1 l ..ii;:_Q _\,m.d the New Zoalaod r ~as tline _ Introd uctio n 4 1 Potentia l Sc.lnd Drift a r ound ". ~e tk~w ;~ .~ al d nd Coastline 41 West c oast tlo rth I :;land 41 \'le.st r;oast :.Ju u th [:; land lj 3 :.Jo ut h coa.s t :Jou th [:;Lind ·l 5 Ea.st coa.st tl o r th r:.;land .ir1' 1 IJ<.1y •> t l'lenr.-1 ·Hi West r.o a::it :;o u t h l:J L.1nd ·18 ·:: hapr.e = _ - :" Jnd T::- .;in s r; on: l r:a ::s:po ;; J.t.i..::n - t:he Ro le •' : ','iind c. :-: d 1., ·e gec1r.i .:: ri Aeolian r::anspo rt. .: I' Sa nd Mecnanic s o r' Ae o ii ~n ~::3n~~o::t Effect.:.> o t \'iater Effec r.s e r' Salt C::us t ~ o r~ 1: ~ c :-: Thre sno ld Wind Velcc i:y .:: o Rar.e o r' Sand T::anspc rt .:: 0 Effecr.s o r' T o p o grap~y Effects o r' Vegetatio n Sand Dunes 23 Unvegetated Sand Dunes 23 Vegetatio n and Sand Dune Cevelopme nr. ;::4 Pa r abolic Dunes :s Chapter: 4 - TM_New Zealand \yind r-1 ;mat.e and Analysis o f Wind Da t~- New Zealand Wind Climate 27 Previous Methods of Comparing Wind Data to dune orientatio n 30 Analysis o f New Zealand Wind data 32 Landsberg Method 33 Fryberger Drift Potential Calculations 35 Comparison of Landsberg and Fryberger Methods 38 r: hapter 5 - Aeolian ::: cind Drir:; ~ o r:-;ntiJ l .Jt;_Q.!JQd the New Z·"aL:rnd <·:ia:.>t L::l..:!_ Int r: oduct ion 4 1 Po tential :1u nd Dr:ift. .J r o und ~. he tl•!W ;',. ~ aLJnd C<) a :;r.L i.ne 4 1 West c oast tl o r:th f:;land 4 1 ':le st r: o .:i s i: :juuth r.;land 'I "3 ~o uth c o a:>t '. )1.) uth [.; lane! ·15 t:ast 1 ~ oa :3t tlorth [:J Ldnd .irl'J 13c1y " t I' Lenty ·Hi ".\lest 1:oast :;1J uth I :.; L:ind 'I H ~ !1 apt. e :: ·· - ·) i: i P n t. a t. :. ~ :: 3 :: ;: ;:i ::: .:. ::-.ens ;. .,; o s <' :; L' arabol; c "'•,, nes · ~ ': ~ w ·,,; aland Int :: ::::: :.: c t:io n '.: l !.:lu ne , ::i.ent:at.io n 1.-Jes::. .:oast: ~! o rt: h ~ .31.:inci West: :oast: 3aut:h Island '.i3 S o ut:~ ~o ast: Sout.h : .3 land SS Ea se. :oa st: tJo rt: h ~.3land .:rnd f3 ay <) t P lent:y Eas t: soast ~o ut:h Island Landsberg Wi nd Resul t.ant:s Dune Cimensions 61 Dune Size 61 Dune Shape 62 Chapt:er 7 - S ummar~ aod Cunc l usion3 65 Appendices 67 Bibliography 70 LIST OF FIGURES ' 1 v t pa raoolic ~ unes "'\ '"'\ ...... 4- P rincipal ways i ~ which tecton ics atfect dunes 2.3 Nearshore bathymetry - North Island :.. 3 - ~ 4 2 . 1\ Nearshore bathymetry - South Island l 3 - l ·I 3.1 Stylised diagr~m er a parabolic dune 'c:. - ~ 6 3. 2 Development o t :inear ridges :s - 26 3.3 Diagram from Hicks (1975) :::: s - 26 4 . 1 Locatio n o f anemometers 35 - 36 4.2 - 4.17 Sand r oses for New Zealand s ites 35 - 36 6.1 - 6.31 Dune o rientatio ns and o nsho re drift resultants for New Zealand locations 51 - 52 7 .1 Relatio nship o f ~hree main dune fo rms t o vegetati on , sand supply a nd wind (Hack 1941) 6 5 - 66 7.2 Relationship of four coastal dune forms to vegetation , ~a n d supply and onshore wind oS - 6 6 LIST OF TABLES T.l\BLE • c; ::2 . l .:..re as <H coast:.J l 3a nd 1-!unes i:'. ::e w .::e a L::.nd 4 . 1 ?ercentage t reaue n ·:: y ·.' t ·: : c-:: n c c : L .:.i~:q :.Jctors i:< ' lew Zea lana ., 4 . "- Anemome ter ~t ati ~ n s ~ s 3t~etc:'. L c~ ast 1 ., ., . .) :orm o ~ daca used ~n this 3 :u ~ y 4 . 4 :ryberge r weighcing :acto rs 35 4.5 Resultants fo r winds >10 knots 3 nd ~ 21 knocs 30 4.6 ?ryberger wind energy classificatio n 37 4.7 DP values for New Zealand stations 37 4.8 Ne w Zealand wind energy classification 37 4.9 ~i recti o nal va riability classification 38 4.10 Directional variability at New Zealand stations 38 4.11 Landsberg vs Fryberger resultants 39 5 .