Find further information on the Conservation of Freshwater Ecosystem Values (CFEV) Program and its data at www.dpipwe.tas.gov.au/cfev.
TitleKarst hydrology sub-index
CustodianWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment
CreatorSteve Carter, Environmental Dynamics
DescriptionAn index which assess individual karst features according to sediment input, flow change, sediment capture and geomorphic responsiveness.
Input data
Lineage
The hydrology variable for karst was established using an expert rule system (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. The input variables were the regulation index and the abstraction index. Experts developing the expert rule system rated the abstraction index as having a greater influence on hydrology than the regulation index.
The method for assigning a hydrology sub-index score to the karst spatial units is provided below.
Date createdJanuary 2005
Scale and coverage1:25 000; Statewide
Column headingKT_HYDRO
Type of dataContinuous but has been converted to categorical format (see Table 2).
Number of classes5
Assigning values to ecosystem spatial units
A hydrology sub-index score (0 = poor condition – 1 = good condition) was assigned to karst spatial units as KT_HYDRO using the expert rule system shown as a definition table in Table 1 (e.g. if the karst area has a HIGH score for abstraction index and LOW score for regulation index, then assign a score of 0.4). 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 1. Expert rules system definition table for the hydrology sub-index for karst.
Abstraction index (KT_ABSTI) | Regulation index (KT_REGI) | Hydrology score (KT_HYDRO) |
H | H | 1 |
H | L | 0.4 |
L | H | 0.2 |
L | L | 0 |
The karst spatial data layer has the continuous hydrology sub-index data categorised according to Table 2. The categorical data was used for reporting and mapping purposes.
Table 2. Hydrology sub-index categories for karst areas.
Category | Min to max values |
1 | 0 to <0.2 |
2 | 0.2 to <0.4 |
3 | 0.4 to <0.8 |
4 | 0.8 to <1 |
5 | 1 |
CFEV assessment framework hierarchy