Wetland Classification
The broad diversity of wetlands means that it is often necessary to divide them into “groups” or “types” which are more closely related to one another. This may be done for a number of reasons, including the identification of wetlands for uniqueness within a catchment or conservation estate, for the identification of monitoring needs, for management purposes etc.
The process of grouping similar types of wetlands is termed wetland classification and different classification systems may be required for different purposes. All wetland classifications are based on describing attributes which may be measured and which, when combined, help to define the nature of a specific wetland and distinguish it from others.
Many wetland classification systems are in use within Queensland and Australia. Most are hierarchical and based on biophysical or physicochemical features.
Before deciding on a classification system for wetlands it is important to establish the purpose for the classification, and to establish the data required to classify the wetlands according to their inherent characteristics. There is no point in establishing an elaborate classification system if that system requires a level of inventory data that is unavailable.
The Directory of Important Wetlands in Australia (DIWA) provides a classification system for wetlands which has been adopted across Australia for wetlands of national significance. It is based on the Ramsar wetland classification for use at a national and international level. It broadly separates wetlands into Marine/ Coastal Wetlands; Inland Wetlands and Human – made wetlands and has identified 42 wetland types under these 3 major headings.
While the DIWA classification system is acceptable for nationally important wetlands where good inventory data is available, a more robust method is required for other wetlands. Recently there has been agreement at an Australian national level to accept a wetland classification based on broad wetland ecosystems (Cowardin et al. (1979) as follows:
- marine (coastal wetlands including rocky shore);
- estuarine (including deltas, tidal marshes and mangrove swamps); riverine (wetlands along rivers and streams);
- lacustrine (wetlands associated with lakes);
- palustrine (marshes, swamps and bogs) wetlands.
- reservoirs (including water storage areas, excavations, wastewater ponds, irrigation channels, rice fields, canals) and
- subterranean (inland subterranean wetlands) are also identified as wetland types.
At the landscape, and local wetland, scale the number of classification systems and wetland sub-types increases exponentially. Of specific note for Queensland is the comprehensive classification system, based on the Cowardine et al 1979, developed by Blackman (1992) and the recent classification system, based on many of the elements in the Blackman system, used to classify wetlands for the Queensland Wetlands Programme mapping project.
Table 1 provides examples of wetland classifications and a summary of category types currently in use in Australia and overseas.
Table 1: Wetland classification systems.
|
Classification |
Details |
|
42 sub-types identified under three major headings (marine and coastal zone wetlands, inland wetlands, and human-made wetlands). |
|
|
42 sub-types identified under three major headings (marine and coastal zone wetlands, inland wetlands, and human-made wetlands). |
|
|
Cowardin et al. (1979) (North America) |
5 wetland types: (marine, estuarine, riverine, lacustrine and palustrine). 56 wetland classes. |
|
Hydrogeomorphic (HGM (Brinson 1993)) (North America) |
1 wetland type: palustrine. |
|
New Zealand Framework (Johnson and Gerbeaux 2004) |
9 wetland types: marine, estuarine, riverine, lacustrine and palustrine, inland salt, plutonic (ie karst), geothermal and nival (ie alpine). |
|
Blackman (1992) (Queensland) |
5 wetland types: (marine, estuarine, riverine, lacustrine and palustrine) |
|
Wetland International – Oceania (Queensland’s south-western wetlands) (Jaensch 1999) |
3 wetland types: riverine, lacustrine, palustrine. |
|
Kingsford and Porter 1999 (Paroo River, Qld) |
7 wetland categories. |
|
Timms 1999 (Currawinya, Qld) |
5 wetland categories. |
|
Casanova 1999 (Paroo Rivers, Qld) |
6 wetland categories. |
|
Timms and Boulton (2001) (Paroo River, Qld) |
5 wetland types: (marine, estuarine, riverine, lacustrine and palustrine). |
|
71 wetland categories under the headings: basins (17 types), flats (4 types), channels (21 types), springs (18 types), subterranean (1 type), and artificial (10 types). |
|
|
14 wetland categories under the headings: coastal, tableland, inland. |
|
|
13 wetland categories. |
|
|
Victorian Index of Wetland Condition (uses Corrick and Norman 1980) |
2 wetland types: palustrine, lacustrine. |
Wetland description tool
A major requirement of a contemporary classification system to be used at a State or national level is that different wetland types be identified using desktop techniques such as remote sensing and data trawling. It is also critical that information collected on wetlands using different classification systems can be “translated” for the purpose of establishing a more complete picture of different wetland types for monitoring purposes, and to provide for a level of data comprability once assessments have been undertaken.
Under the Queensland Wetlands Programme and as part of the National Project on National Wetland Indicators Final Report (Conrick et al. 2007), attributes have been identified addressing characteristics of wetlands at increasingly specific scales (continental, ecosystem, landscape, and local) which can be used for classification purposes (Table 2). Each category has specific layers to identify different features of wetlands that can be used in classification systems.
Table 2: Wetland description layers to assist in classifying wetlands in Queensland.
|
Resolution |
Level |
Category |
Attribute |
|
Continental |
Primary |
Equatorial |
|
|
Ecosystem |
Primary |
Marine |
|
|
Landscape |
Primary |
Soils (permanently inundated areas) |
Peat (organic) |
|
|
Primary |
Floodplain |
|
|
|
Secondary |
Igneous |
|
|
Local |
Primary |
Forested |
|
|
|
Primary |
Commonly wet |
|
|
|
Primary |
Saline |
Layers are identified as either primary or secondary. The secondary layers are those layers that are not essential but that may fine-tune the wetland classification, or that are currently difficult to source.
Last updated: 19 October 2007
