Embedded Files
Precipitation patterns
Precipitation patterns
Source 1:A map showing the average annual rainfall for NSW.http://www.bom.gov.au/climate/maps/averages/rainfall/
Source 2:A map of NSW showing the location of Longneck Lagoon. https://www.google.com/maps/search/longneck+lagoon/@-33.575685,150.8874628,16z/data=!3m1!4b1?entry=ttu
Catchment functioning
Catchment functioning
A catchment area is an area of land where water collects when it rains. As the water flows over the landscape it finds its way into streams and creeks and down into the soil, eventually feeding a water body such as a river, lake or wetland.
The Longneck Catchment is approximately 1269 hectares in size. It has two main tributaries, Longneck and Llewllyn Creeks, which flow in a north-west direction into Longneck Lagoon. The lagoon is also influenced by runoff from the whole of its catchment as well as flooding from the Hawkesbury River.
The hydrology of the lagoon comprises of groundwater and surface flows. The groundwater supply consists of a complex system of aquifers which have formed as a result of the variety of soil layers and the underlying geology of the area.
Flooding
Flooding
The size of the Hawkesbury-Nepean Catchment with the substantial number of tributaries draining into the Hawkesbury River makes the surrounding region, including Longneck Lagoon, susceptible to severe flooding. The largest flood on record occurred in June 1867 when flood waters reached approximately 19.7m at Windsor. Many lives were lost during this flood. The most recent flood of July 2022 was the worst flood to occur in the Hawkesbury region in 44 years reaching 13.93 metres at Windsor.
The number and intensity of floods experienced across the east coast of Australia is expected to increase with climate change. These extreme events have the potential to alter the physical and biological conditions of the Hawkesbury-Nepean Catchment and pose a greater risk to the increasing number of settlements in flood prone areas in the catchment.
Source 4:A photograph of the toilet block during the July 2022 flood. Courtesy Longneck Lagoon EEC.
Source 3:A map showing an estimation of the Longneck Lagoon catchment. https://landcare.nsw.gov.au/groups/hawkesbury-landcare-network/resources-and-report/wetlands of_the_hawkesbury_fullreport.pdf/view
Source 5:A photograph of the Longneck Lagoon EEC classroom during the July 2022 flood. Courtesy Longneck Lagoon EEC.
Catchment land use and development
Catchment land use and development
The health of wetlands are greatly affected by the land use and development in their catchment areas.
In areas with natural forests, rainwater is filtered and slowed down by the trees and vegetation. This means that when the water flows into the wetland and its tributaries, it carries fewer sediments and pollutants, resulting in better water quality. However, in urban or agricultural areas, where there's a lack of natural vegetation and a large amount of hard surfaces like roads and buildings, rainwater rushes off quickly. This can lead to erosion, carrying more sediments and pollutants into water bodies effecting water quality.
Historically, the land within the Longneck Lagoon Catchment has seen significant land clearing. Today, the majority of the Longneck Lagoon Catchment is classified as nature conservation and is protected land within Scheyville National Park. However, approximately 30% of the catchment contains rural and residential properties and some small farms.
Due to the various human activities that have occurred over time in the Longneck Lagoon Catchment area, water quality in the Lagoon has deteriorated. The causes of this decline in water quality include land clearing and pastoral farming which has increased runoff into the lagoon. Introduced species such as European Carp have increased the turbidity of the water. Animal waste, fertilisers, detergents and sewage systems on residential properties have contributed to nutrient enrichment and salt levels that exceeds the healthy range for the lagoon.
Source 6:A diagram of the urban and natural water cycle.https://resinbondedaggregates.com/blog/uk-flooding-what-is-causing-it-and-what-is-being-done-about-it
Source 7A satellite photograph of Longneck Lagoon showing land uses in the catchment. https://geo.seed.nsw.gov.au/Public_Viewer/index.html?viewer=Public_Viewer&locale=en-AU
Suggested learning activity
Suggested learning activity
What is the average annual rainfall for Longneck Lagoon EEC? (Use Sources 1 and 2 to assist you.)
2. Using the embedded worksheet below, construct a precis map showing the different land uses around Longneck Lagoon.
Land use in the Longneck Lagoon Catchment precis map.pdfSources:https://sites.google.com/education.nsw.gov.au/earths-natural-systems/pre-visit/hydrological-systems
https://landcare.nsw.gov.au/groups/hawkesbury-landcare-network/resources-and-report/wetlands_of_the_hawkesbury_fullreport.pdf/view Geology and Water Quality of the Longneck Catchment (date unknown), Cattai Catchment Management Committee and Hawkesbury Nepean Catchment Management Trust.
https://geo.seed.nsw.gov.au/Public_Viewer/index.html?viewer=Public_Viewer&locale=en-AU
https://landcare.nsw.gov.au/groups/hawkesbury-landcare-network/resources-and-report/wetlands_of_the_hawkesbury_fullreport.pdf/view Geology and Water Quality of the Longneck Catchment (date unknown), Cattai Catchment Management Committee and Hawkesbury Nepean Catchment Management Trust.
https://geo.seed.nsw.gov.au/Public_Viewer/index.html?viewer=Public_Viewer&locale=en-AU
https://www.infrastructure.nsw.gov.au/media/vl3jdi3t/hnv-river-mar-jul-2022-floods-review.pdf
Geology and Water Quality of the Longneck Catchment (Date unknown), Cattai Management Committee and the Hawkesbury Nepean Catchment Management Trust.
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