Wind Erosion in Western Queensland Australia

More documents

Recommendations

Info

Chapter 4 –Modelling Soil Erodibility DynamicsFigure 4.4 A conceptual diagram of the movement of a soil through the erodibility continuum fromminimum (Q min ) to maximum (Q max ) erodibility states. The diagram indicates three phases ofmovement: (i) a condition of minimum erodibility, (ii) a transition phase of increasing erodibility, and(iii) a condition of maximum erodibility. The period of time a soil remains in each phase isdetermined by its textural properties, climate and management conditionsThe second phase (ii) defines the transition of a soil through the continuum from a conditionat Q min to potentially arriving at Q max . This transition phase has a rate of change that isdefined by the complex interaction of soil surface drying/desiccation and trampling bylivestock (disturbance) which induce an increase in erodibility. During this phase rainfallevents may temporarily increase the soil moisture content and aggregation and decreaseerodibility. At the root of this transition phase, soil textural properties (i.e. sand, silt and claycontent) and cohesive agents (e.g. OM, CaCO 3 ) will influence the soil response to the climate112
Chapter 4 –Modelling Soil Erodibility Dynamicsand management factors, the slope gradient or rate of change in erodibility, and therefore theminimum period of time a soil may spend in this phase moving toward Q max .Gillette (1978) reported on the dependence of soils on drought to experience an increase inerodibility to wind (Chapter 2, Figure 2.5). His results show that the erodibility of sandy soilswith 40% clay are highly dependent ondrought to experience an increase in erodibility. This time dependence is driven by the soilparticle size distributions and particle shapes which affect the strength of inter-particle bonds.The final phase in the continuum, (iii) defines the condition of maximum erodibility (Q max ).In order for a soil to reach this condition moisture content (antecedent rainfall) must be at aminimum and disturbance to the soil surface at a maximum. Soils at Q max can be consideredto have an effective grain diameter d of 0.08 mm to position the soil at the u *t minima(Chapter 2, Figure 2.3) reported by Bagnold (1941).Mathematically the phase shifts through the soil erodibility continuum, from i to iii (Figure4.4), can be defined by a logistic (sigmoid) curve. Numerous expressions are available thatcan be used to delineate the shape of this curve (e.g. Richards, 1959; Turner et al., 1976). Thelogistic curve form can be approximated with few parameters, making it a good starting pointfor modelling temporal changes in soil erodibility to wind. The model framework presentedhere uses the Richard’s equation (Richards, 1959), selected for its wide application inmodelling vegetation growth dynamics (Tsoularis and Wallace, 2002) and more recentlydunefield activation and stabilisation (Hugenholtz and Wolfe, 2005). In differential form theRichard’s equation is expressed as:dNdt N = rN 1 (4.7) K where N is the population size, r is the growth rate, β is a positive real number and K is thepopulation carrying capacity reached as lim t→∞ N(t) = K. The integral of Equation (4.7) isthen:113
Page 1:
Modelling Land Susceptibility toWin
Page 4:
AUSLEM was developed as a Geographi
Page 8 and 9:
who joined me on many trips, shared
Page 10 and 11:
Conference Presentations by the Aut
Page 12 and 13:
2.2.5 Soil Moisture Effects........
Page 14 and 15:
Chapter 6: Assessing Land Susceptib
Page 16 and 17:
List of FiguresChapter 1: Introduct
Page 18 and 19:
Figure 2.11 Conceptual model of lan
Page 20 and 21:
hand column) presents trajectories
Page 22 and 23:
List of TablesChapter 1: Introducti
Page 24 and 25:
xxii
Page 26 and 27:
Chapter 1 - Introduction• The abi
Page 28 and 29:
Chapter 1 - Introductionchapter the
Page 30 and 31:
Chapter 1 - Introductionevents yr -
Page 32 and 33:
Chapter 1 - IntroductionFigure 1.2
Page 34 and 35:
Chapter 1 - Introductionsusceptibil
Page 36 and 37:
Chapter 1 - Introductiontemporal pa
Page 38 and 39:
Chapter 1 - Introduction1.5 Researc
Page 40 and 41:
Chapter 1 - IntroductionFigure 1.3
Page 42 and 43:
Chapter 1 - IntroductionMitchell Gr
Page 44 and 45:
Chapter 1 - IntroductionSimpson-Str
Page 46 and 47:
Chapter 1 - IntroductionDowns. Wind
Page 48 and 49:
Chapter 1 - IntroductionChapter 2 p
Page 50 and 51:
Chapter 2 - Land Erodibility Contro
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
Page 76 and 77:
Page 78 and 79:
Page 80 and 81:
Page 82 and 83:
Page 84 and 85:
Page 86 and 87: Chapter 2 - Land Erodibility Contro
Page 93 and 94: Chapter 3 - Modelling Land Erodibil
Page 121: Chapter 3 - Modelling Land Erodibil
Page 124 and 125: Chapter 4 -Modelling Soil Erodibili
Page 154 and 155: Chapter 5 - Land Erodibility Model
Page 182 and 183: Chapter 6 - Field Assessments and M
Page 184 and 185: Chapter 6 - Field Assessments and M
Page 186 and 187:
Chapter 6 - Field Assessments and M
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Chapter 7 - Land Erodibility Dynami
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Chapter 8 - Conclusions• There is
Page 216 and 217:
Chapter 8 - ConclusionsThe third ai
Page 218 and 219:
Chapter 8 - Conclusionswas shown to
Page 220 and 221:
Chapter 8 - Conclusionsland use cha
Page 222 and 223:
Chapter 8 - Conclusionsmodels are n
Page 224 and 225:
Chapter 8 - Conclusionsmultiple ass
Page 226 and 227:
Chapter 8 - Conclusionsthe opportun
Page 228 and 229:
Beadle, N.C.W., 1945. Dust storms.
Page 230 and 231:
Bryan, R.B., Govers, G., Poesen, J.
Page 232 and 233:
Chepil, W.S., 1965. Transport of so
Page 234 and 235:
Fryrear, D.W., Sutherland, P.L., Da
Page 236 and 237:
Gregory, J.M., 1984. Prediction of
Page 238 and 239:
Hugenholtz, C.H., Wolfe, S.A., 2005
Page 240 and 241:
Littleboy, M., McKeon, G.M., 1997.
Page 242 and 243:
Marshall, J.K., 1973. Drought, land
Page 244 and 245:
Assessment Report of the Intergover
Page 246 and 247:
Penner, J.E., et al. , 2001. Climat
Page 248 and 249:
Rickert, K.G., McKeon, G.M., 1982.
Page 250 and 251:
Stokes, C., J., McAllister, R.R.J.,
Page 252 and 253:
Williams, W.J., Eldridge, D.J., Alc
show all

Wind Erosion in Western Queensland Australia

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?