8. Not allocated (reserved for fold mountains) 9. Drainage systems
9.8 Swamp or marsh 9.9 Sink hole
140 Terrain evaluation: cost-effective mapping
Table 9.4 Numerical system for nomenclature of terrain units in the PUCE terrain classification system
Topography Soils dominantly Vegetation dominantly
1. Flat to undulating or sloping smooth surfaces, usually with 0. Rock outcrop, pockets shallow 0. Bare, sparse grass, occasional tree relatively deep soil soil and gravel or shrub
¡1 f^^^^^^r^^^^ \ Clay soils (Ug) 1. Grassland, occasional tree or 1.2 Gently undulatmg surface (to 2°) J \ t>^ h h
1.3 Moderately undulating surface (to 5°) 2. Clay soils (U or G )
1.4 Undulating surface (to 10°) ^ soils (D) 2. Shrubland, occasional tree 1.5 Sloping surface (to 2°) . ay soi s ( ;
1.6 Sloping surface (to >2°) 4. Silty soils ^· ^ P ^ " ^^^^^^"^
1.7 Undulating sloping surface ^^^^ ^^.^^ 4. Woodland 1.8 Strongly undulatmg surface (to > 10°) ^ ν ; O n e n f n r e^ t
, , , ^ ^ . , ^ , . ^ ^ Γ 6. Sand over clay soils ( D ) ^· ^ P ^ " ^^^^^^
2. Irregular sub-horizontal to undulatmg eroded surfaces, r i Η f t usually with rock outcrop or shallow soil 7. Sandy soils (U or G ) ^· ^'^^^^ ^^^^^^
2.1 Flat surface o c.^of o^i 7. Rainforest
^ ^ r: J J f 8. Stratified soils
2.2 Eroded surface « i- i . r . 2.3 Benched surface 9. Organic soils '^'-^* "'^'^^ ^"'^'"P 2.4 Undulating eroded surface 9. Salt water swamp forest 2.5 Strongly undulating eroded surface
2.6 Moderately dissected surface
PUCE system for terrain analysis 141
Table 9.5 Terrain parameters—class intervals in the PUCE system Classes of lengths and widths of terrain units
to 10 m to 50 m to 100 m to 500 m to 1000 m
to 2000 m to 4000 m to 8000 m Extensive
Classes of lengths and widths of terrain components to 2 m
to 5 m to 10 m to 20 m to 50 m
to 100 m to 500 m to 1000 m Extensive
Classes of relief
1 to 1 m (microtopography) 2 to 3 m
3 to 6 m 4 to 15 m 5 to 30 m
6 to 75 m 7 to 150m 8 to 300 m 9 to>300m
Classes of tree spacings. heights, and girth diameters 1 to 2 m
2 to 3 m 3 to 6 m 4 to 30 m 5 Scattered 6 Occasional
1 to 2 m 2 to 3 m to 6 m to 12m to 18 m to >18 m
1 to 0.05 m 2 to 0.1m 3 to 0.2 m 4 to 0.3 m 5 to 0.5 m 6 to 0.6 m 7 to >0.6m Classes of stream densities
1 <0.5 total streams/1.6 km 2 0.5 total streams/1.6 km 3 1.0 total streams/1.6 km 4 1.5 total streams/1.6 km 5 2.0 total streams/1.6 km 6-9 increasing at 0.5 intervals Classes of slopes
0 Level 5 to 20°
1 to
r
6 to 40°2 to 2° 7 to 60°
3 to 5° 8 to >60°
4 to 10° 9 to vertical
Classes of rubble sizes
1 to 0.025 m 5 to 0.3 m 2 to 0.05 m 6 to 0.6 m
3 to 0.1m 7 to 2 m
4 to 0.2 m 8 to > 2 m
(c) Terrain patterns
These are allocated three digits:
1 the maximum local relief amplitude, classified using significant class intervals;
2 the stream density;
3 serial, if required.
Digits 1 and 2 are classified using significant class inter
vals (see Table 9.5).
(d) Provinces
These are allocated five digits:
1 the geological erathem;
2 the geological system within each erathem;
3,4,5 serial.
The numerical system is listed in Table 9.1.
A n example of the numerical nomenclature used for terrain classification is given in Table 9.7, but for a complete description reference should be made to Grant (1975a,b).
9.2.3 Example of terrain classification description sheet
The example is from the Melbourne area, Victoria (Grant, 1972), Terrain Pattern N o . 46 developed on Devonian granite in Province N o . 34.001 (see Table 9.1).
Characterizing the province are seven terrain patterns each of which is outlined in Table 9.8; pattern numbers are based on relief amplitudes and stream frequencies (see Table 9.2).
Each terrain pattern is illustrated (Figure 9.1) by a characteristic, scaled, cross-section showing the typical location of terrain units, and a diagrammatic block diagram of the topography and the arrangement of terrain units within the terrain pattern. A typical drain
age net for the particular terrain pattern is also given.
Tabulated are descriptions of the constituent terrain units in the terrain pattern, in the prescribed format.
9.2.4 Example of map and legend for terrain patterns
The terrain classification map of Melbourne (Grant, 1972) is published in colour at a scale of 1:250 000. A part of the map showing Terrain Pattern N o . 46 on Devonian granite has been selected as illustration, together with the complete legend for the seven terrain patterns comprising Province 34.001. With the aid of the legend and the descriptive memoir, the map is particu
larly easy to interpret (Plate 12).
Although the terrain classification is stated to be for engineering purposes in the Melbourne area, nowhere in the report or on the map is there any specific reference to engineering geology. It would appear that the docu
ments provided should be regarded as a basic assessment or evaluation that can be applied for a number of purposes. Finlayson (1984) has enumerated these as including: location o f materials and routes for railway and road construction (Grant and Ferguson, 1979);
water resources (Grant and Ferguson, 1979); military and off-road mobility (Grant and Ferguson, 1979);
engineering geology (Grant, 1976; Finlayson, 1982);
urban and road planning (Grant et al, 1981); regional development (Grant et al, 1982).
9.2.5 Using terrain assessments
Grant and Finlayson (1978), having described the P U C E system of terrain evaluation, consider the appli
cation o f terrain maps in engineering and planning. This involves assessment and evaluation of the geotechnical resource capability o f a terrain. In one particular study (their Appendix I I ) , all soils were selectively sampled to a depth of 2 m.
142 Terrain evaluation: cost-effective mapping
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PUCE system for terrain analysis 143
Table 9.6 Numerical system for nomenclature of terrain components
D Η
Slope profile
Maximum magnitude parallel to major axis Maximum magnitude parallel to minor axis Soil profile
Land-use or surface cover - Vegetation association — A Slope profile
Parallel to
Β C Slope—maximum magnitude parallel to major axis or minor axis
Major axis Minor axis 0 Flat
1 Planar Planar 1 Γ
2 Planar Concave 2 Τ
3 Planar Convex 3 5°
4 Concave Planar 4 W
5 Concave Concave 5 20°
6 Concave Convex 6 40°
7 Convex Planar 7 60^
8 Convex Concave 8 >60°
9 Convex Convex 9 Vertical
D Ε Soil profile—consistent within one class of the Unified Soil Classification and one subdivision of the primary profile form (Northcote, 1974)—numbered serially within each province
Land-use or surface cover where applicable Land-use
0 Unused Forestry Pasture Agriculture Recreation Urban development
Not allocated
Surface cover 0 Not present
1 Silcrete, rounded 2 Silcrete, angular 3 Ironstone, rounded 4 Ironstone, platy 5 Porcellanite 6 Quartzite 7 Calcrete 8 Salt
9 Rock outcrop and rubble of appropriate lithology G Η Vegetation association—numbered serially within each province
Table 9.7 Example of the numerical nomenclature used for terrain classification in the PUCE system
Province 52.009
Terrain pattern 2212
Terrain unit 1.7.11
Terrain component 431032 01 means:
Province Terrain pattern
Terrain unit
Terrain component
52 .009 2 2
¡2 1.7
.1 1 4 3 1 03 2 01
Quaternary
Ninth recognized province of Quaternary age
Relief amplitude to 75 m Drainage density 2 stream-lines per 1.6 km
Second recognized terrain pat- tern with the above parameters in the particular province Undulating sloping surface Clay soils (Ug)
Grassland
Slopes major axis concave, minor axis planar
—major axis to 5°
—minor axis to Γ Soil profile (serial within province)
Land use—pasture Vegetation (serial within province)
The assessments sought were:
• suitability for road sub-base;
• suitability for road fill and/or untreated wearing sur
face;
• suitability for foundations - low buildings and high buildings (shallow and/or deep foundations);
• degree o f limitation for use as sewerage dispersal field or septic use;
• source o f sand and gravel;
• landslide occurrence;
• slope stability;
• suitability for trenching or tunnelling for under
ground facilities;
• suitability for embankments (water and non-water retaining);
• suitability for grassed waterways (comments on wind and/or water erosion).
Assessments o f these matters would be based upon the following tests and observations:
1. Characterization:
(a) depth o f soil profile and depth of water table (where shallow);
( b ) depth to bedrock and type o f rock (residual areas only);
144 Terrain evaluation: cost-effective mapping
(c) grain-size distribution, Atterberg limits, linear shrinkage;
(d) moisture content, density;
(e) p H , dispersivity, soil suction;
( 0 unified soil classification;
(g) on-site assessment of the drainage characteristics.
2. Engineering (where relevant):
(a) simple consoHdation;
(b) simple shear strength (triaxial test);
(c) repeated loading modulus.
Assessments for building foundations were made for small buildings only (footing width 300 mm). It was considered that large buildings would require foun
dation investigations that would be beyond the scope of soil sampling (to 2 m ) planned to be used for the investi
gation.
Assessments for road construction (specification - sub-base) were made for fill material that could be used as sub-base and as sub-grade. The latter assessment was not called for in the original specification, but in view of the natural materials in the area, it was considered important that this assessment should be made.
Although the assessment and evaluation of the geo
technical resource capability of terrain may or may not be conducted concurrently with the terrain classification
stage, it is essentially a separate procedure. Terrain