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TitleLand disturbance adjacent to saltmarshes sub-index
CustodianWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment
CreatorSteve Carter, Environmental Dynamics
DescriptionAn index which rates the relative condition of saltmarshes according to land disturbance impacts (i.e. road/tracks, urban development and landfill) adjacent to the saltmarsh.
Input data
Lineage
An assessment of land disturbance adjacent to saltmarshes incorporated adjacent roads/tracks, urban development and landfill condition variables into an expert rule system to generate an overall score (see ‘Assigning values to ecosystem spatial units’ below). Information on expert rules systems can be found in Appendix 3 of the CFEV Project Technical Report. These input variables were assessed by inspecting aerial photograph and were scored between 0 (disturbed) and 1 (pristine) according to the details in Table 1.
Table 1. Summary of variables assessed using aerial photographs for land disturbance adjacent to saltmarshes condition variable.
Variables | Unit | Other comments |
Roads or tracks | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | |
Urban development | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | Housing adjacent. |
Landfill | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | Apparent landfill associated with industrial, agricultural, housing or other developments inside the saltmarshes was recorded. |
Within the expert rule system, the input variables assessing impacts adjacent to saltmarshes were weighted as follows: urban development adjacent > roads/tracks adjacent > landfill adjacent.
The method for assigning a land disturbance adjacent to saltmarshes sub-index score to the saltmarsh spatial units is provided below.
Date createdNovember 2004
Scale and coverage1:25 000; Statewide
Column headingSM_LDADJ
Type of dataContinuous but has been converted to categorical format (see Table 3).
Number of classes3
Assigning values to ecosystem spatial units
An land disturbance adjacent to saltmarshes sub-index score (0 = poor condition – 1 = good condition) was assigned to saltmarsh spatial units as SM_LDADJ using the expert rule system shown as a definition table in Table 2 (e.g. if the saltmarsh has a HIGH score for roads/tracks adjacent to saltmarshes, LOW score for urban development adjacent and HIGH score for landfill adjacent to saltmarshes, then assign a score of 0.5). Using fuzzy logic enables input data and output results to be continuous rather than categorical as implied here (i.e. inputs and output data can range on a continuous scale between 0 and 1, and the process of executing the expert rule system will determine its membership as being HIGH or LOW) (refer to Appendix 3 of the CFEV Project Technical Report for more information on expert rules systems).
Table 2. Expert rules system definition table for the land disturbance adjacent to saltmarshes sub-index for saltmarshes.
Roads adjacent to saltmarshes (SM_RDADJ) | Urban development adjacent to saltmarshes (SM_UDADJ) | Landfill adjacent to saltmarshes (SM_LFADJ) | Land disturbance adjacent to saltmarshes score (SM_LDADJ) |
H | H | H | 1 |
H | L | H | 0.5 |
L | H | H | 0.55 |
H | H | L | 0.6 |
H | L | L | 0.35 |
L | L | H | 0.3 |
L | H | L | 0.4 |
L | L | L | 0.1 |
The saltmarsh spatial data layer has the continuous impacts within saltmarshes sub-index data categorised according to Table 3. The categorical data was used for reporting and mapping purposes.
Table 3. Land disturbance adjacent to saltmarshes sub-index categories for saltmarshes.
Category | Min to max values |
1 | 0 to <0.2 |
2 | 0.2 to <0.8 |
3 | 0.8 to 1 |
CFEV assessment framework hierarchy