i+,ìi I f, q2- ?â 'iì:i'i'!ìii¿Ë--?. L lfif{írFl',{ rz,ê'o\t SOIL PATTERN RECOGNITION IN A SOUTH AUSTRALIAN SUBCATCHMENT by INAKWU OMINYI AKOTS ODEH B. S c. Hon. (Ibadan, Nigeria), M. S c. (S a matu-Zaria, Nigeria) Departrnent of Soil Science Waite Agricultural Research Institute The University of Adelaide Australia Thesis submitted to TheUniversity of Adelaide in fulfillment of the requirements for the degree of Doctor of PhilosoPhY November 1990 TABLE OF CONTENTS LIST OF FIGURES...... vll LIST OF PLATES XI LIST OF TABLES.... ABSTRACT... ..xv STATEMENT xvu ACKNOWLEDGEMENTS. XVTTl CHAPTER 1 GENERAL INTRODUCTION 1 1.1 Inûoduction ..... .. 1 1.2 Soil Pattern Recognition...... 5 1.3 The Scope of this Work 8 CHAPTER 2 PHYSICAL CHARACTERISTICS OF TT{E STUDY ARE 4... 10 2.1 lncabonof the Study fuea.. 10 2.2 Gælogy .... 10 2.3 Geonnrphology 16 2.4 Clinnte n 2.5 Yqetafion and I¿nd Use. n 2.6 Soil..... A 2.6. 1 Prevíow w ork and historical dev elnpmenf . .. -.... 24 2.6.2 Soil genesís n lt lll CHAPTER 3 DF^SIGN OF OPTIMAL SAIVIPLING SCTIEMES BY GEOS TATIS TICAL METHODS 3t) 3.1 Inûoduction 30 3.1.1 Methods of soíl ínvenÍory 30 3.1.2 The msin objectives JJ 3.2 Tlansect Survey and l¿boratory procedues JJ 3.2.1 The study (rea-. 33 3.2.2 Ttwtsect sur-vey JJ 3.2. 3 Morphology description 35 3.2.4 Labomtory procedures 'x 3.3 Spatial Analysis and Discussion.. v 3.3.1 The regi.onalízedvøíable fheory .. v 3. 3.2 Dda explomlion...... 47 3. 3. 3 S ønple semív uiognøms.. 48 3.3.4 Soíl øtìsotropy ...:... 49 3.2.5 Desígn of optímal sunplÍng schcmc 52 3.5 Conclusion û CTIAPTER 4 SUL CLASSIFICATION IYITH FVzzY-C-MEAN S: SOIL- I-AND FORM INTERRET,ATIONS HIPS AND OPTIMAL SAMPLING STRATEGMS. 61 4.1 Inûoduction 6r 4.1.1 The need for conlírunus (ftuzy) soil clnsses 62 4.1.2 Thc ryplicdion of fwzy set tlwory to chnter øurl¡'sis . 63 4.1.3 Objectives. & 4.2 Tlne Concept of Fwzy (Continuom ) Clæses (A 4.2.1 Tlrc FCM Algorirhm. 67 iv 4.2.2 Choice of distmce dependenl metríc 6l 4.2. 3 Optímol rutmber of clæses.. (f) {.t Pvzzy Classiflication of Soil for Opfinnl Sampling Scherrres ... ... 13 4.3.1 The soil dda 73 4.3.2 Soìl class mcmberchip semívañogruns øtd optimal satnplíng shúegy.. 81 4.3. 3 S egmentalion along hwtsects.. u 4.4 FCll[ the Problem of Exhagrade Membets. 85 ^Generalized 4.4.1 ApplicaÍion to the soíl dda.. 88 4.4.2 The degree oÍfuzzíness 89 90 4.4. 3 Optimal Combfualion of Q ørd c ..... 4.4.4 The luzzy soíl clss ses 95 4.5 Conclusions.. 1æ CHAPIER 5 ELU CIDATION OF SOILI,A NDFORM IN TERRELATIONS HI P S BY CANONICAL ORDINATTOI{ ANALYSIS.. .. ... 110 5.1 Inûoduction..... ..... 110 5.1.1 Quørlitñive methods in pedolngy ... 110 5. 1. 2 Multiv añafc rypruach to soil-lørdform studies. .. ...t2 5.1.3 Objectíves. ..... 113 5.2 The Principles and Application of Canonical Ordination Analysis 115 5.3 Algorithrns. ......118 5.3.1 Weighlc¡I avemging method (CCA) ...... 118 5.3.2 Weighfcd summdionmethod (PCA and RDA) ......1i9 5.4 Material and lMethods.. ......tn 5.4.I Larulformuulysís ......r21) 5.4.2 The soil d{ún... ... ...124 5.4. 3 Ordíndíon aruly ses. ......r24 v 5.5 Resulß and Discussion .t27 5.5.1 Weíghfcd ot,emgíng based onunimodal models .lTt 5.5.2 Linearmethods. .r32 5.5.3 DdnTrutsþmtúion. .\y 5.5.4 Cønnìcal ordhúion of truaformed soíl daln.. .135 5.5.5 Physical Inlerprctñion . t41 5.6 Conchnions.. 145 CHAPTER 6 SPATIAL MODELLTNG OF FVZry (SOIL) CLAS S MEMBERSHTP VALUES ..146 6.1 Intuoducfion... ..146 6.2 Optinnl Interpotation- Kriging ..t46 6.3 Field Sampling and I¿boratory Procedures. ..r52 6.3.1 Sffiified. sønpling based on prcdetermined sarnpling design ..r52 6. 3. 2 Mo rpholo gy d.e s críptio n and lob o mtn ry analy s ís .. 153 6.4 Fruzy Analysis .. 153 6.5 Kriging Analysis and Resulb ..167 6.5.1 Krìgilrg malysß ..761 6.5.2 Composíte mqs- mq over'lny .. 168 6.5.3 The class cenhoíds ..t74 6.5.4 The extmgmde uniß. 6.5.5 Physícalínturprctñíon- rclñí.ottships of soil ptúturts wítlr landform 175 6.5.6 Relevance to geogmphical information systems (GIS).. t76 6.6 General Rernarks and Conclusiorn .. r17 vl CHAPTER 7 GENERAL SUMMARY AI{D CONCLU SIONS....... 179 7.1 Sumnnry... 119 7.2 General Conchsions tu 7.3 General Rennrt<s and Suggestions forFuûue Researth .. 186 7.3.1 Remøks .. 186 7.3.2 Futue Reseøch. .. 187 APPENDIX: PUBLISHED AND SUBMITTED PAPERS 190 REFERENCES .191 LIST OF F'IGURES Fig. Title Page 2.1 Location of the study area. 11 2.2 Generalised geology of southern South Australia (modified from 1: 1 1000 000 geological map of S. Ausralia, S. Australian Dept. of Mines & Energy, 1980). 12 2.3 Geology of the study area and its immediate surroundings (modified from 1: 50 000 geological map sheet 6628-tI (Onkaparinga) S. Australian Dept. of Mines & Energy, 1979) 13 2.4 Perspective block diagram of a digital elevation model computed from a 7l x 111 point altitude matrix of the study area; each cell is 20 x 2O m; the view is north east at 5'from the horizontal. 14 2.5 Annual distribution of (a) rainfall for Gumeracha and (b) rainfall and, maximum and minimum temperatures for Mt. Crawford. 19 3.1 A contour map of the study area showing the transects. 32 3.2 A layout of sampling scheme along the nansect 34 J.J (a) Plots of the values of some selected ordinal variables versus distance along transect-W: (i) topsoil structural grade, (ii) subsoil structural grade and (iü) parent material cutan abundance. 38 (b) Plots of the values of some selected numerical variables versus distance along transect-'W: (i) topsoil Vo sand, (11) Vo subsoil Oc and (iii) subsoil Ec (mS m-1). 39 3.4 (a) Plots of the values of some selected ordinal variables versus distance along transect-S: (i) topsoil structural grade, (ii) subsoil structural grade and (iii) parent material cutan abundance. 40 (b) Plots of the values of some selected numerical variables versus distance along transect-S: (i) topsoil Vo sànd, (11) 7o subsoil Oc and (iii) and subsoil Ec (mS m-1). 4r 3.5 (a) Plots of standard deviation of pairs versus distance along transect-W for (i) topsoil 7o [rrel, (ii) subsoil Vo Oc and (iii) subsoil Ec (mS m-1). 42 (b) Plots of standard deviation of pairs versus distance along transect-S for (i) topsoil 7o Sãvel, (ii) subsoil Vo Oc and (iii) subsoil Ec (mS m-1). 43 3.6 Standard deviation-mean plots of (a) topsoil 7o gravel along transect-W, (b) topsoil Vo gravel, along transect -S, (c) subsoil Vo Oc alorrg transect-W, (d) subsoil 7o Oc along transect-S, (e) subsoil Ec (mS --1¡ along transect-W and (f) subsoil Ec (mS --l¡ ulong transect-S. 44 vil v 111 3.7 Sample and model semivariograms showing anisotropic variation in (a) topsoil sand, (b) topsoil gravel and (c) subsoil clay; the gamnra (h) is in (7o)2. 45 3.8 Sample and model semivariograms showing anisotropic variation in (a) topsoil pH, (b) subsoil pH, (c) subsoil organic carbon content (7o) and (d) subsoil electrical conductivity ( mS m-1); the garnma (h) for the soil attributes is in units of measurement squared. 46 3.9 Krigrng conltdence for punctual and block estimation of topsoil srlt (7o) as a function of grid spacing in transect-W direction. 54 3.10 Kriging conhdence for punctual and block estimation of subsoil sand (o/o) as a function of grid spacing in transect-W direction. 55 3.11 Kriging confidence for punctual and block estimation of topsoil sand (7o) as a function of grid spacing in transect-W and transect-S directions. 56 3.r2 Krigrng confidence for punctual and block estimation of subsoil clay (Vo) as a function of grid spacing in transect-W and transect-S directions. 5l 4.r Fuzziness performance index and normalized clasSification entropy against number of classes for whole soil data (Q=1.15) 74 4.2 Anisotropic semivariograms of finzy class membership coefficients for soil class B; the gamma(h) is in membership coefficient squared. 75 4.3 Anisotropic semivariogmms of fuzzy class membership coefficients for soil class G; the gamma(h) is in membership coefficient squared. 76 4.4 Kriging error for punctual and block kriging of luzzy class membership coefficients for soil class A as a function of grid spacings in transect-W and transect-S directions. 77 4.5 Kriging error for punctual and block kriging of fuzzy class membership coefficients for soil class G as a function of grid spacings in transect-W and transect-S directions. 18 4.6 Digital gradient, g of soil classes along (a) transect-W and (b) transect-S as an indicator of Sesrient boundaries. 83 4.7 Fuzzine s s performance index (F' ) and normalized cl as sihc atio n en trop y (^É1) against number of classes for whole soil data (0 = 1.15). 9I 4.8 Fuzziness performance index (F') and normalizcd classification entropy (H) against number of classes for morphological data (@ = 1.13) 91 4.9 Fuzziness performance index (F) and normalized classification entropy (H) against number of classes for particle-size data (Q = l.I2).