Inland waters and wetlands: Introduction
Fresh water and the habitats that depend on it are some of Queensland's most precious resources and must be managed well to ensure economic and social prosperity while maintaining a healthy and sustainable environment. Increasing pressures of drought, major floods, climate change and Queensland's increasing population mean that competing needs must be balanced and water efficiency must be improved to protect this resource and its associated habitats.
'Wetlands' is a broad term that encompasses diverse areas, such as those shown in Figure 5.1. Included in this definition are marine areas, lacustrine areas (lakes), palustrine areas (swamps, bogs and fens), estuaries, groundwater, rivers and artificial water bodies such as dams and water storages.
The State and Commonwealth governments have adopted an integrated approach towards wetland management and conservation, and have defined these areas as 'areas of permanent or periodic/intermittent inundation, whether natural or artificial, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres'.
Wetlands support diverse plant and animal communities that are reliant on water availability, quality and natural water flow cycles, including groundwater fluctuations that affect the watertable. Rivers and streams are generally flowing water habitats, although they may dry out seasonally.
Lacustrine and palustrine areas are found throughout the catchment: along rivers, on floodplains and in coastal areas. Lacustrine and palustrine areas generally comprise standing water rather than flowing water. They can be permanently, seasonally or episodically full, with periods of complete drying. They become ephemeral particularly where there are seasonal fluctuations.
Groundwater is any water located beneath the earth's surface in underground streams or aquifers. Groundwater is recharged from and may eventually flow to the surface, where natural discharge occurs through springs and streams.
The Great Artesian Basin (GAB) is one of the world's largest underground reservoirs and underlies approximately 70% of Queensland. Water for agricultural purposes has been extracted from this resource since the late 1800s, and water from the Basin is increasingly being used for urban and industrial use.
To gain a full understanding of the extent and condition of all the state's wetland systems, it is important to read this chapter in conjunction with the information on wetlands in the biodiversity and coastal zone chapters. The six issue papers presented here are:
- the extent and condition of wetland systems;
- condition of rivers;
- surface water quantity;
- subartesian groundwater levels;
- artesian bore pressure; and
- groundwater quality.
Although the different wetlands are discussed separately, the reader should keep in mind that they are interdependent; impacts on one affect all the others to some degree.
The extent of Queensland's estuarine, lacustrine, palustrine and riverine wetlands is relatively well documented. However, data on the condition of some of these areas and associated ecosystems are currently minimal. The paper on extent and condition of wetland systems provides an overview of the available information, while the condition of rivers is covered separately.
The paper on the condition of rivers discusses the quality of surface water and river ecosystems throughout Queensland. Water quality covers physico-chemical measures such as nutrient concentrations, electrical conductivity and turbidity. Ecosystem condition and health are measured by assessing macroinvertebrate and fish populations, riparian zone changes, and land management and clearing practices within the associated regions.
The paper on surface water quantity examines the pressures on surface water supplies, the impact of the drought on these supplies, water use and the programs in place to manage water use.
The three issue papers on groundwater provide information on subartesian water levels, artesian bore pressure and groundwater quality, including a discussion on current pressures and government initiatives to manage them.
Major pressures on wetlands include land use, rural and urban development, land clearing, water extraction and land management practices, all of which can adversely affect lakes, swamps, bogs, fens, river and groundwater water quality, flow regimes and ecosystem biodiversity and health.
Drought conditions have been a feature of Queensland's climate during the four years since the last report. This has affected surface water and groundwater quality and quantity. The impact has been most obvious on the surface, with extensive anecdotal reports of drying-up of rivers and lakes that have been continuously wet for many years. Drought and the resulting lack of surface water have increased rural and urban demand for and dependency on supplementation of water supplies through extraction of surface waters and groundwater. Thus, in a time of low rainfall, added pressure is put on wetland systems to replenish water extracted by the many users.
If not managed properly, this pressure will affect the reliability of surface water and groundwater supplies and overall water quality and water flow. Potential adverse impacts include increased pollution, salinity and incidences of iron bacteria attacking bore casing in groundwater systems, diminished water quality, increased frequency of toxic algal blooms, and further losses of biodiversity.
Wetland areas have declined in number and extent since before European settlement to 2003. Between 1997 and 2003 wetland was lost at more than 7000 ha/year. This problem varies across Queensland and from area to area. The greatest losses have occurred in the Murray-Darling Basin, North East Coast drainage division, and in palustrine and riverine wetland systems.
Differences in wetland loss from one catchment to another are even more pronounced. Between 1997 and 2003, some catchments lost more than 1000 ha, while others have lost only minimal wetland areas.
In contrast to wetland extent, the statewide condition of wetlands is not well known or well monitored, and this represents a gap in knowledge for managing wetlands. Significant wetlands continue to be recognised and mapped by various mechanisms. However, recognition of their significance does not necessarily lead to higher levels of protection.
It is not enough to assess wetland status by using extent alone. Many of the values of a wetland are dependent on its condition: the wetland may still exist but may not be functioning properly; consequently the values associated with it may be compromised.
The Queensland Government in collaboration with the Australian Gove rnment has implemented a number of initiatives since the last report to address wetland management and protection. This report documents the government programs under way to improve understanding and protection of our wetlands.
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Last reviewed 16 May 2011
Last updated 13 February 2008