National Wilderness Inventory

Australia: Our national stories
Australian Heritage Commission, 2003
ISBN 0 642 23561 9

4. Creating The Wilderness Database (continued)

4.2 Distance-based Indicators
(Remoteness from Access, Remoteness from Settlement, and Apparent Naturalness)

As discussed in Section 2.1, wilderness survey work is implemented by measuring variation in wilderness quality across the landscape using four wilderness quality 'indicators' that represent the two essential attributes of wilderness: remoteness and naturalness.

Three of these 'indicators' are derived in a similar manner and get their collective name, distance-based 'indicators', from the process used to derive them.

These indicators are:

  • Remoteness from Settlement
    remoteness from places of permanent occupation;
  • Remoteness from Access
    remoteness from established access routes;
  • Apparent Naturalness
    the degree to which the landscape is free from the presence of permanent structures associated with modern technological society;

This section of the handbook describes the processes used to create the results for these three distance-based indicators used in the wilderness analysis. The process of creating these results are similar, and standardised across Australia. Because of this, any variation in the quality and consistency of results for these indicators generally relates back to characteristics of the primary data which are described more fully in other parts of this handbook.

4.2.1 Grades of Impact

For each of the distance-based indicators primary data is graded according to its associated amount of impact. Remoteness from Access and Remoteness from Settlement take into account four grades of impact whilst three grades are used in determining Apparent Naturalness. Descriptions of these grades are presented in Table 4.1. The primary data codes and associated grouped feature coverages are detailed in Section 3.4.

Table 4.1: Description of Distance-Based Indicator Grades
  Grade Primary data description Grouped Primary Data Coverage
Remoteness from Access Major Major two-wheel drive roads: generally sealed or at least surfaced to ensure regular and continuous public use ACC1
Medium Minor roads: generally unsurfaced, or, if surfaced, then irregularly used and maintained. Also included are constructed and maintained airstrips and operating railways. ACC2
ACC2PT
Low LowVehicle tracks (usually four-wheel drive). ACC3
Very Low Established but unconstructed vehicle access routes (e.g. beach access) and cleared lines; established walking tracks; cleared land. ACC4
CULTURAL
Remoteness from Settlement Major Built-up areas and commercial and/or service location with 100 permanent residents or more. SET1
BUILTUP
Intermediate Commercial and/or service location with more than ten but fewer than 100 permanent residents. SET2
Minor Commercial and/or service location with ten permanent residents or fewer. SET3
Residential Residential location only. SET4
Apparent Naturalness Major Intrusive infrastructure (including medium and high grade access routes) and cleared land boundaries AES1LN
AES1PT
ACC1
ACC2
SET1
SET2
SET3
SET4
ACC2PT
CULTURAL
BUILTUP
Medum Small-scale infrastructure (including four-wheel drive AES2LN
AES2PT
ACC3
Minor Minor Structures. AES3LN
AES3PT
ACC4

4.2.2 Deriving Indicator Values.

The analysis process for deriving the three distance-based indicators is outlined below, as a sequence of four steps.

i) Grading primary feature impacts:
Point, line and polygon primary data features are drawn from the appropriate layer in the library manager and grouped in coverages according to feature type and indicator impact grade (outlined in Table 3.6). The association between these grouped coverages and each indicator grade is outlined in Table 4.1.

ii) Distance Calculation:
Euclidean distance (in metres) is calculated from each sample point to the nearest feature within each grouped feature coverage. The nearest distance, in each case, is assigned to each sample point in the database as a permanent attribute.

iii) Minimum Weighted Distance Calculation:
Raw distance values are processed to produce a single indicator distance measure for each sample point. This distance is calculated by weighting the distance values for each grouped feature according to its associated grade of impact so that all distances are represented in units equivalent to a high grade feature. The equation for determining high grade equivalence takes the form:

The equation for determining high grade equivalence

Note: refer to Table 4.2

Table 4.2: Feature Weightings for Remoteness from Settlement, Remoteness from Access, and Apparent Naturalness
Feature Grade Weighting Factor
Remoteness from Settlement
Major Settlement
Intermediate Settlement
Minor Settlement
Residential Settlement
 
1.00
0.80
0.74
0.66
Remoteness from Access
High Access
Medium Access
Low Access
Very Low Access
 
1.00
0.71
0.33
0.20
Apparent Naturalness
Major Structure
Medium Structure
Minor Structure
 
1.00
0.40
0.16

The minimum value for each indicator (mHGE) is recorded for each sample point and recorded as permanent attributes in the wilderness database (refer to Table 4.9).

iv) Indicator Classification:
Minimum high grade feature distances are classified to produce a standardised Remoteness from Settlement, Remoteness from Access, and Apparent Naturalness class according to the following equation:

Formula to produce a standardised Remoteness from Settlement, Remoteness from Access, and Apparent Naturalness class

The resultant classification of the three indicators is shown in Figure 4.3. These distance-based classifications are recorded as continuous floating point variables thus showing variation within class groupings as well as class values beyond the class 5 notional maximum. Remoteness from Settlement, Remoteness from Access, and Apparent Naturalness index values are assigned to sample points in the database as permanent attributes (refer to Table 4.9).

 The classification of distance-based indicator values