Anthropogenic activities

Anthropogenic activities in wetlands

People modify the landscape for a variety of purposes including for food, housing, recreation, transport, energy production, extraction of minerals and others. While many of the activities associated with these purposes are undertaken to maintain economic and social values, they can also put pressure on the environment and reduce its capacity to provide ecosystem services. Anthropogenic activities can also affect the naturalness of a wetland, thereby impacting on biodiversity and the intrinsic values of the wetland. Policies, programs and legislation are in place to reduce the impacts of anthropogenic activities and to assess their impacts.

While there are a very wide range of anthropogenic activities affecting wetlands, those that affect the wetlands hydrology are some of the most important. The information below provides details of the key hydrological modifications to wetlands and has been applied to the wetlands mapping in Queensland.

There are seven main anthropogenic activities that affect wetland hydrological processes (including water flow) and hydrological components (including permanence of water and residence extent).

Bunding

Bunding refers to activities that construct a bund including an embankment (a thick wall of earth), dyke (a thick wall), dam (a wall), levee (a raised bank), or weir (a low barrier), etc. that may restrict water flow over the ground and/or raise water levels. Bunds are often either earthen, rock, or concrete in material.

In channels, bunding often raises or stabilises water levels immediately upstream of the wall by holding back water in the channel. In some cases, the bund may cause water to extend beyond the natural channel boundary.

Outside of channels, bunding often raises or stabilises water levels in the wetland or to create an artificial wetland to capture surface water runoff. This can make the water persist longer in the landscape.

Channel reconstruction

Channel construction refers to activities that construct one or more channels. This activity may also involve excavation and/or bunding. Construction of channels in a riverine or intertidal wetland may alter water flow through the wetland and the residence extent of water. In addition, channel construction where there was no previous wetland is used to create an artificial wetland that may direct water movement through the landscape.

Controlled surface hydrology

Controlled surface hydrology refers to activities where surface hydrological flows are controlled consistent with water storage usage. Typically, wetlands with controlled surface hydrology are semi-enclosed structures with pump facilities that mechanically control flow into and out of the wetland.

Cultivation and cropping

Cultivation and cropping refer to activities to prepare land to plant, tend, improve, and harvest crops including tilling, sowing, etc. This activity usually occurs during drier months or years when the wetland can be accessed and often results in wetland loss. However, sometimes wetland hydrological function persists despite cultivation and cropping which is observed with crop failure due to waterlogging.

Drainage

Drainage refers to activities that construct drainage channels in a wetland that are often intended to remove water from a wetland by gravity. Drainage is often used to decreases residence extent and/or depth of wetlands which may alter water persistence, or completely remove a wetland from the landscape. In some cases, drainage may inadvertently allow tidal inundation to enter a wetland.

Excavation

Excavation refers to activities that remove soil and/or rock often increasing wetland extent and/or depth and water persistence. In intertidal wetlands excavation activities may remove natural tidal barriers enabling tidal inundation.

Excavation activities where there was no previous wetland can create artificial wetlands often intended to capture surface water runoff.

Infilling

Infilling refers to activities that deposit soil and/or rock into a wetland often decreasing wetland extent and/or depth. Infilling is often used to remove a wetland from the landscape.

Vegetation clearing is another anthropogenic activity that affects wetland processes (including bank stabilisation, flooding, nutrient cycles, river processes, runoff, soil processes, etc.) and components (including exotic flora, flora taxonomic and functional breakdown, etc.).

Links

Human impacts on wetlands

Pressures

Pages under this section

References

1. ^ Department of Agriculture and Fisheries, Human impacts on wetlands. [online] Available at: https://www.daf.qld.gov.au/business-priorities/fisheries/habitats/human-impacts-wetlands.

Last updated: 15 August 2023