Field excursion
The Peel- Harvey estuary consists of the Peel inlet and Harvey estuary; it’s connected to the sea through a narrow channel that is natural and an artificial channel called Dawesville constructed in 1994. It’s among the largest and is located in the Western Australia coastline. It receives water from three main rivers, Murray, Harvey Rivers and Serpentine including their catchments. The estuary is separated from the Lakes Mealup and Mclarty and Yalgorup lakes by a series of vegetated sand ridges that are 5meter high and 1- 5 km wide and this catchment are is approximately 11300km squared and is by and large cleared.
Most of the estuaries waters have a depth between 0. 4- 2 meters It stretches from Mandurah Ocean channel to the Harvey River Delta. The extensive land between Murray and Harvey also drains its water in to the estuary through artificial or natural channels. The Pell- Harvey has had a history of poor water quality eutrophication that resulted to the 1994 construction of the Dawesville channel to aid in reducing the levels of in phosphorous pollution by providing another opening to the Indian Ocean. The ocean and the Peel- Harvey estuary are separated by limestone and sequence sand dunes.
White sandy Beaches lie along the estuary coastline while the offshore consists of sand and reef that forms a habitat for small invertebrates e. g. worms and crustaceans, fish and marine algae. Eutrophication is a process that leads to overloading of the waters with nutrients. Very little geological activity has taken plan in the western Australia therefore meaning that these soils are ancient, the application of nitrogenous and phosphorous nutrients to make the soil more productive led to eutrophication as these nutrients leached in to the Peel- Harvey estuary.
Soil erosion was the main agent for eutrophication since the sandy soil in the coastline could not absorb these nutrients. The effect of the eutriphication includes the loss of significant habitats, decline in the macro algae in the beaches and a great loss of the wildlife because the increased quantity of algae result to algae bloom which when they die reduces the quantity of oxygen in the water through respirations bacteria decompose the dead algae hence death of the marine life in the estuary and its environment, there is also indirect increase in the outbreak of diseases associated with the rise in eutrophication.
The Dawesville channel was management strategies that was aimed at reducing and controlling the level of phosphorous draining in to the Pell- Harvey estuary and eventually make it healthy, visibly clean and ecologically favorable habitat for the inhabitants of the estuary. An increased macro algae growth and phytoplankton bloom in the 1960’s had a detrimental impact to the human use and the ecology of the Peel- Harvey estuary, this necessitated the cutting of the Dawesville channel that between the Indian ocean and the Peel- Harvey estuary with the main purpose of improving water circulation and flushing in the estuary.
The improved tidal exchange involving the estuary and the ocean led to improvement of the water quality and a saline and stable saline setting that led to the extinction of the lethal phytoplankton noduralia that thrives in fresh water. The channel was to flush the nutrients to the ocean from the estuary. In the first year after opening of the Dawesville channel, between 900- 1100 tonnes nitrogen and 100- 120 tonnes of phosphorous were flushed in the Indian Ocean from the estuary and its catchment.
The other management programmes of the estuary included the management measures of the catchment, monitoring of the water quality appropriately, algae harvesting and incorporation of an integrated catchment managerial plan. The sulphates soils occur when the sediment deposited in the estuaries are decomposed in absence of the oxygen. These soil become harmful when they get exposed to the air, get oxidized by naturally formed iron pyrite and when they can to contact with water, they emit iron, suphuric acid and aluminum in to water which all are harmful to the coastal and estuary ecosystem.
This acidification results to rise in the water table otherwise below the water table, the soils aren’t acidic but benign but problems are evident when the soil becomes exposed as the residents try to drain the water through construction of drains and soil excavation and planting the tress excessively. The South Yunderup Oval lakes though supplied with freshwater by the precipitation and underground water are saline due to the long periods of evaporation leading to concentration of salts since they don’t overflow.
The degree of salinity varies depending on the hydrology of the lakes in the Yunderup. Some lakes in the Yunderup oval have vertical stratification whereas others have got underground seepage leading to different levels of salinity depending on the season. Three is further inverse stratification that results to some lakes becoming saturated with oxygen that favors the growth of the Cynophyta especially in Lake Hayward whereas Lake Clifford has got horizontal salinity gradient depending with the season and this le to the rise in the sulphate accumulation in the soils.
Acidification is a multiplying problem that needs an urgent solution that must include land usage planning. The acidic leachates are having a negative impact on the riparian and aquatic ecosystems an eventually affect the underground water supply. It also diminishes the agricultural production due the metallic contamination and acidic conditions while the infrastructure, mainly the buildings and the metallic structures are subject to corrosion.
The economic impact may include the loss of fresh water supplies and the increased cost for water treatment and for repairing the buildings and the infrastructure. The Peel-Harvey Catchment should adopt a sustainable land use forms that will maintain production levels and the revenues and at the same time avoiding the water pollution. Co-operation is essential of all the landholders and the co-ordination in the land usage by all the landholders is necessary and that is referred to as Integrated Catchment Management.
Implementation of this strategy can have a long term solution to the eutrophication problems since the Dawesville was only a short term solution but a sustainable land management applications need to be adopted to reduce the nutrients getting into the ocean. The farmers in the environment within the Peel-Harvey estuary should be offered with technical advice on how to apply the optimum fertilizer that will fully be utilized by the plant and apply less water soluble fertilizer.
They should further guided to plant blue gum trees that is said to be lowering the water table hence intercept the free phosphorous and nitrogen. Industries such as animal feedlots and piggeries location need to be regulated to minimize the chances of eutrophication whereas the horticultural farms need to apply proper irrigation management. There need to be proper urban planning to deter the sewer from being deposited into the estuary. Proper land usage legislation needs to be put in place to manage the estuary and control or end eutrophication.
REFERENCES
Environmental Regulation Framework for the Peel-Harvey Catchments, retrieved on 20th, October, available at www. epa. wa. gov. au/docs/WQIP/AppendixF. pdf Estuary assessment framework for non-pristine estuaries estuary, retrieved on 20th, October, available at www. dbforms. ga. gov. au/pls/www/npm. ozest. show_mm? pBlobno=9308 Great Lakes Water Quality/Great Lakes Water Pollution Issues, retrieved on 20th, October, available at www. greatlakesdirectory. org/great_lakes_water_quality. htm
John Peel, Peter R. Cox, Eugenics Society, (1972) Population and Pollution, Academic Press publishers, Michigan Peel inlet management council file, retrieved on 20th, October, available at www. portal. environment. wa. gov. au/pls/portal/url/item/0594D36EE32DD0CBE04010AC6E0570D4 Peel-Yalgorup, retrieved on 20th, October, available at www. green. net. au/ppg/peel-yalgorup. html Water Pollution Fact, retrieved on 20th, October, available at www. grinningplanet. com/2005/07-26/water-pollution-facts-article. htm
Sample Essay of BuyEssay.org