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F'lONTPI:<":CE. Oblique aerial photograph of the t~o photographic study areas. I.:ain divide of southern Ruahine ~ange runs from centre left to top right. Yo. 1 catchment is in the foreground.
The top half of the large slump in the Raparapawai catchment ana the many other erosion scars are clearly seen. Date of photography is ~.~arch 1 9 1 975.
Photo: N.A. Trustrum
D7TF;:o.:,:n~ATJ.OIT OF PROC1'.:DU?.BS TO ESTABLISH
PRIC'~ITE:S FC:t E~CSIOI'T. COFT:lOL AS
A thesis presented in partial fulfilment of the requirements for the degree of },:astera te in Agricultural Science in Soil Science at Lassey University.
Peter ~obert Stephens.
1975 .
i i
AB~'rRACT.
The aim of this study was to investigate several methods
o~ potential usefulness in identi~ying some of the ~actors causing erosion in two catchments 'typical' of the southern "'luahine Ranges.
The condition of the southern 1luahine :tan._~cs, in the head- waters of the li:analiatu 1liver catchment, is deteriorating. The state
o~ equilibrium vrhich has periodically existed between rock, soil, slope, vegetation, and climate has recently been upset, and the area is now in a state of decline. Unless remedial action is taken
promptly, ~arm land will go out o~ production, public water supplies could be ruined, communications by rail, roo.d, and. telephone severely hindered, and the bene~its o~ both the Pohangina-Oroua and Lower
I.:anawatu Flood Control and Drainage Schemes could be lost. This study attempts to establish a basis from which positive steps to recti~y
the situation can be implemented.
1.~ethodology involved the use of aerial photography and on- the-ground observations and 5easurenents. Colour and colour infrared
~ilm types were compared with standard black-and-white panchro~~tic
film to establish which was the most suitable to use in determining priorities for erosion control. Sequential panch~omatic aerial photographs ':'>e::-e taken in 1946, 1961, 1966, and 1974. In this moun-
tainous area, aerial photographs are essential tools for determining the extent of eroded s~aces and erosion types.
Between 19l~6 and 1974 there has been a 120 percent increase in area of eroded. slopes in the study area. The vrorst erosion in 1946, at which time herbivo:::-ous ma.IIlECals had .had little e~fect on vegetation, and in 1974, occurred in the 700 to 900 m altitudinal zone. 1his zone has the highest ~ault density in the study area, which consists of densely ~aul ted and me1ange-lil--:e rocks. This area has also undergone the most draw~tic vegetation changes since 1946. Herbivorous maiD.Eials are considered to be only partly responsible for such changes. As a corollary, the h~ghest percent increase in erosion has occurred in -the altitudinal zone \;rith t.he most intact vegetative canopy.
A positive relationship between the frequency of medium- sized earthquakes and increase of eroded areas has been tentatively
ii:i,.
established. Further, most erosion has occurred during and
following intense rainstorms. These two fa.ctors are considered to be the main ones causing erosion in the ~rea.
Once factors causing erosion had been established, colour, colour infrared, and panchromatic film types were compared. Photo- graphs used in this comparison were taken periodically throughout
1975 using a 35 mm camera. An assessment was made of the capabil- ities of each film ty-pe to show the following features: alignments, eroded surfaces, erosion types, vegetation ~pes and condition, rock types, pug zones, seepage areas, and drainage pattern. Colour infrared was found to be the most suitable to use when deter:nining priorities for erosion control.
A number of salient procedures that should be tmdertaken to determine priorities for erosion control are outlined. These include aquisition of all sequential photographs, photoGraphy using colour in_frared, or preferably, using colour infrared and panchromatic film, a. sound knowledge of grotmd conditions, and collation of relevant erosion, geological, botanical, ~1d animal ecological data. A system that enables priority for erosion control of subcatchments to be established, using a rating value for
factors causing erosion, is outlined.
I would like to express my sincere thanks to the following who have assisted me in this study:
iv
I.:r.D.G. Bowler my supervisor, for initiating this interest- ing study, for his guidance and discussions on aspects of methodol- ogy, and for his criticism of the text.
Professor J.K. Syers for discussions on presentation of data and constructive criticism of the text.
T)r. V.E. Neall who gave much assistance in the geology section, both for the text and in the field.
Dr.J.H. Kirlman for his assistance in determining the clay mineralogy of fault pug materials.
J.:essrs. F .A. Trustum (r.:inistry of Works and Development), and J. ~. Clouston (Photographic Unit, r.:assey University) for helpful discussions on photography and the use of various film types. To the former for the use of his l ight table, and the latter for the use of his caoera.
I.:essrs. A.H. Leigh and A. Cunningham (Few Zealand Forest Service) with >7hom I had stimulating discussions regarding erosion, vegetation, and herbivorous ma~~als of the scuthern ~uahine ~anges.
I am indebted to the latter for his hospitali~J.
I.:r.C. Stephens for the use of his projector.
Hr.C.R. ?..enton (Eanawatu Catchment Board and ":'egional ';'Tater Board) for supplying cl imate information.
1.:r.E.D. Trask (:r-:rew Zealand Aerial J;:apping) fer determining cost comparisons for aerial photography using different film t~~es.
The officers of the Land Use Capability Assessment office and the National Plant l.iaterials Centre. The former for the use of their Abney level and light table, the latter for the use of their camera.
Dr. V.E. Neall, and ~essrs. P.L.Allen, P.G.L. Allen, B.J. Bargh, D.G.B011ler, J .~.Fletcher, R.L.Eathaway, A.H.Leigh,
P. T .r~ankivell,i·: .J .Page, J .F .Stephens, and F .A. Trustum for accompany- ing me in the field. In particular I would like to t.~an.l( F .L.Allen who l ived in the study area with me, and fellov; student B.J. Bargh
who accompanied me o~ a number of occasions.
This study was carried out whilst I was employed by the Y,'ater and Soil Division of the 1anistry of '.''orks and Development, who provided financial assistance for flying, and the purchase of films and photographs.
},~rs.E. Lynch for typing the text.
Christine and Jacqueline.
v
TABLE 0 F C 0 N T E N T S.
Abstract
...
Acknowledgements Table or contents List of rigures List or tables
...
...
...
...
SECTION 1 Il\TT:lODUCTION
...
1 .1 1 • 2 1 .3 1.4-
1 .5
Aim or study
...
Reasons ror investigation
...
Location of study area •••••••••••••••••••••••••••••
Criteria ror choosing study area •••••••••••••••••••
l.:ethodology or the study
...
SECTICI'1 2 OJ'! TEE USE C'Ji' CCNVErTIC·:··.I\1 AR"i.IAL PHOTOG'?~ftPHY FO~ EROSICF A!':D 'lBLATED STUJIES
...
2.1
2.2
2.3
2.4-
2.5 2.6
Introduction
...
Film types in conventional aerial photography
...
Use of conventior~al aerial photography in erosion
studies • . . . • Use of conventional aerial photography in geological studies •••••••••••••••••••••••••••••,••••••••••••••
Use of conventional aerial photography in soil studies. Use of conventional aerial photography in vegetation
studies Summary
...
...
SECTION 3
PHOTOG ~LftPHY
EQUIH.iENT Mm TECHKI (UE USED ~OR AElliAL
3.1 3.2 3.3 3.4-
3.5
Equipment used for aerial photography ••••••••••••••
Conditions governing date of aerial photography ••••
Flight procedure •...•...••...••
Film types 1.1sed ••••••••••••••••••••••••••••••••••••
Focal length of camera •••••••••••••••••••••••••·•••
ii iv vi viii xi
1
1 1
2 2
5
9 9
11
15
20
23
25 29
30 30 30 31 32 34-
SECTIO:f\T
4
FEA'l'UO..ES OF THE STUDY AT.tBA...
4-.1
4 .4 4.5
4.64.7
Regional setting
...
General
...
4.1 .1
4.1 .2 Geology
... ... ...
Physiography Vegetation Climate
. . . . . . . . ...
lt-o 1 .3
lj .• 1 .4 4.1 .5 4.1 .6
. . . . . . . . . . . . . . . ... ...
... ...
Erosion 1/orphometry
4. 2
.1 Area... ... ...
... ...
4 . 2. 2 4. 2. 3 4. 2.4 4 . 2. 5
... ...
Average slope
...
Longitudinal stream-channel profiles Hypsometric analysis •••••••••••••
Slope aspect
...
Geology
.... . ...
...
4.3.1 Lithology of the study area
... ... ...
4 .3. 2
Presence of large rounded boulders4 . 3. 2.1
Characteristics of' these boulders~elationship between distribution and size of boulders
Significance
4. 3.3
~aults and lineationsof' the large boulders
4 .3. 2.3
4 . 3. 3. 1
Use of' aerial photography to map4 .3 .3. 2 4 .3.3.3
f'aults and lineations
....
Field evidence of' faulting Interpretation of' fault pattern
4.3 .l!- Clay mineralogy of' pug material
.. .
Soils Climate Vegetation
... ..
... ...
Erosion
...
Previous erosion phases in study area
...
4. 7.1
4. 7
.24.7.3
Erosion types ...••...•....•...
Increase in area of' eroded slopes since 1911-6
..
4. 7.4
Factors causing erosion4 . 7 . 4 . 1
Variety of' factors... ...
Effect of' herbivorous marru:.als on vegetation, soil, and erosion
Bf'fect of rainfall on erosicn
... .. ...
35 35 35 35 35 36 36 36
38 38 38 39 4141 43 43 45 45
4-547
4-9 49
50 53 54
56
59 62 626l~
75 78 78 78 82
4. 7 .4.4-
Effect of fire on erosion4.7.4.5
~elationship between faults...
and erosion surfaces
...
4. 7 .4.6 Relationship between earthquakes and erosion occurrence
Summary Conclusion
...
...
SECTION" 5 CO:PAR.Ism: CF COLOUR, COLOU"!l IF"FRAR.ED, AIID
PANCH:tOEA'riC FlU! TYPES
...
5.1 Introduction • • • • • c • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
Considerations relevant to this assessment
...
5.2
5.3 Comparative photo-interpretation
...
5.4
Variation of spectral signatures...
5.5 Cost comparison of aerial photography using each film type
5.6 Conditions most suitable for aerial photography
...
5.7
t:ultispeotral photography5.8 Conclusions
...
SECTIO:t-~ 6 PRCCE:9U1?.ES TC DETEDJ:Il~ P"tl.IORITES "!:"CR
84
84.
85 89
90
92 92 92
94 104
106 107 107 108
E"tl.OnON cn:r'::'RCL I}i THE SCUr;:"h'ETITT "!'1.UAI-"'II'~ TLAJ''GB2 • 109
Selected bibliography
...
Appendix I Aeri8l photographs en study area
-
run andphotograph numbers
...
Appendix I I Glossary of plant names used in text
...
Appendix IJI I.:ineralogy of fault pug material
...
Appendix IV Soil profile descriptions
...
113
135
136
137
139
L I S T Ci F FTGU'Q_;::s
F-:)_CNTPIECE
Fig. 1. Locality map
...
Fig. 2. Oblique aerial photograph of southern Ruahine
Ranges
... ...
Fig. 3. Vertical aerial photograph of ~aparapawai
catchment
...
Fig. 4-. Vertical aerial photograph of Ho. 1 catchment
Fig.
5.
Fl ight path. ... ... .
Fig. 6. Longitudinal stream-channel profiles
. ... .
T<' ig.
7.
P.yp sometric curves... ...
Fig. 8. Geology map
...
Fig. 9. Photograph of largest boulder Fig. 10. Photograph of boulder split in ~no Fig. 11 • :telation.ship betv;een bo'J.lder size and
location in streambed
...
Fig. 12. Photograph of pug zone on fault
.... ... . ...
Fig. 13. Photograph of faulted rocks
. ...
Fig. 14-. '!lose diagram of fault strikes
...
Fig. 15. Tabrpa.ri peaty loam
. ...
Fig. 16. 'lain£' all gauge locations in southern '!) .uarnne ' •
R.ange
...
Fig. 17. R.epeat photographs of Raparapawai catcmaent
....
Fig. 18. Vegetation w~p
... . ...
Fig. 19. Debris slide in upper No. 1 catcl:linent
...
Fig. 20. Debris slide in lovter No. 1 catchment
. ...
Fig. 21. Oblique aerial photograph of Slump A
...
Fig. 22. Deterioration of slopes on SlUI!!p A
. ...
Fig. 23. Debris avalanche which occurred during
3
4- 6 7 33 4-0 42
46 4-6
48 51 51 52
55
57 60 61 65 65 67 69
cyclone Alison ••••••••••••••••••••••••••••••••• 72 Fig. 2l~-o Debris avalanche on fault • • • • • • • • • • • • • • • • • • • •• • 72 Fig. 25.
Fig. 26. Fig. 27.
S{iowing rill erosion
. ...
Showine rock fall debris
. ...
i.elationship between eroded surfaces, altitude, aspect, and time
... ... ...
73 73 76
Fig. 28. Frequency of earthqu~~es
...
Fig. 29. Comparative photo-interpretation. ~aparapawai
catchment
...
Fig. 30. Comparative photo-interpretation. Fo. 1
catchment
...
Fig. 31. Colour, colour infrared, and panchromatic vertical aerial photographs of Ho. 1
catchment
...
Fig. 32. Colour, colour infr~red, and panchromatic vertical aerial photographs of Ra.parapawai
catchment
...
Fig. 33. Showing difference in colour balance of
colour infrared photographs
...
87
95
101
10.2
105
Table I.
Table II.
Table III. Table IV.
Tabl e V.
Table VI. Table VII.
Table VIII.
Table IX. Table X.
Table XI.
Table XII.
Table XIII.
Table XIV. Table XV.
Table XVI.
L I S T 0 F TABLES
Sequential aerial photographs of study
area
...
Days suitable for aerial photography Area and average slope of study area Distribution of slope aspect in
. ...
s tud.;.r area • . . . Average arillual rainfall •••••••••••••••••
~ainfall intensities ',';hari te climate data
. ... .
Increase in eroded slopes between
1946
and1974 ...
Comparing eroded slopes and slope aspect Fault density and erosion severity
Earthquakes and erosion occurrence Length of alignrr.ents mapped in both
. ...
ca tchne nt s •••...••...•...•..••
Spectralsignatures using colour and
colour infrared aerial photographs
...
:?.ank of ease of interpretation ••••••••••
Cost comparison of aerial photography
8 31 39
41 56 58 58
75
77
85 88
98 103
using different film types •••••••••••••• 106
~ating values to determine priorities
for erosion control
...
111