Transcript

Geography Yearly Notes

Land and Water Management
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Land management has focused on meeting the needs of people
through industries, such as agriculture, urban development,
transport, industry and recreation
Based off traditional European approach to land management
Nowadays, there is a growing appreciation of the important
contribution ecosystems play in providing clean water, clean air and
healthy soils, as well as maintain biodiversity.
Many current management practices still place enormous pressure
on the land.

Aboriginal Approaches
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Evidence is mounting to show that early Aboriginal people hunted
many species to extinction, including many mega fauna. Also when
they used fire as a management tool, the fire-tolerant species
replaced those that weren’t
After these changes, the Aboriginal people settled into a pattern of
life that was in harmony with the changed environment.
They moved from place to place to take advantage of changing
environmental populations and regulated their population sizes so
that they exceed the land’s capacity to support them. This was a
sustainable lifestyle.

Early European Approaches
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The land management practices of early settlers, did not take into account
the fragility of Australian soils and the unreliable rainfall.
They used agricultural approaches that were suited to the fertile soils of
Europe. They planted European crops, introduced sheep/cattle/horses and
cleared vast amounts of land due to their lack of knowledge of Australian
land.
They believed they need to master and exploit the environment to
produce for the people. This thinking led to a lot of irreversible damage to
the environment.

Contemporary Approaches
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Farmers adopting sustainable farm-management practices that minimise
land degradation:
Limiting stocking rates to ensure that adequate ground cover is
maintained
Reducing the amount of tillage (the agricultural preparation of soil by
mechanical agitation of various types, such as digging, stirring, and

Cost of land degradation increases consistently Types and causes of land degradation: Wind and water erosion: Once soil is stripped of vegetation.2 million ha of productive land are affected by dryland salinity. This brings dissolved salts to the surface. Examples of human-powered tilling methods using hand tools include shovelling. Occurs wherever the natural balance in the landscape is changed by human activity. it can result in in increased salinity in waterways. This makes the soil unstable when it is wet. salinisation and waterlogging. about 2. Soil structure decline: Cultivation of land changes structure of the soil. Results in loss of land stability and usefulness. picking. Soil Acidification: Results from the use of superphospates in fertilisers and the growth of nitrogen-fixing legumes like clover. pesticides and herbicides Excluding stock from river banks. urban and industrial use. causing landslips. rill erosion and sheet erosion. Total Catchment Management   Best way to protect water quality in waterways is to manage the whole catchment. Replacement of natural vegetation with pasture: Results in rising water tables. In addition to tree and crop loss. Acidification can lead to decline in productivity of land. and raking) required. groundwater is gradually drawn towards the surface by evaporation. for example through the use of direct drilling techniques for planting crops Managing the use of fertilisers. killing trees and crops. and also reduces the nutrients in the soil. In Australia. hoeing. Makes it more susceptible to erosion and soil compaction. Loss of native trees and shrubs: Mainly due to land clearing for agriculture. Dryland salinity: When the land is cleared of its natural vegetation. through misuse and overuse. it is easily blown or washed away. Issues in Land Management Land Degradation            Any change in land that reduces its existing or potential productivity. Clearing of natural vegetation: Clearing on steep sloping land has resulted in penetration of water in the soil.      overturning. Sources of pollution need to be identified and pollutants need to be intercepted and treated before they end up in waterways The amount of water taken from waterways meeds to managed for irrigation. steeply sloping lands and other areas prone to land degradation Placing watering points where land degradation will be minimised Rotating crops to minimise land degradation Fencing off areas of natural vegetation Mulching or retaining the stubble of crops to add organic content to the soil and to minimise erosion. mattock work. Includes gullying. Irrigation Salinity & Waterlogging: This occurs when the water table is raised by excessive irrigation. .

Can be provided by irrigating (irrigation salinity) or by clearing vegetation (dryland salinity) Extensive removal of deep rooted native vegetation and its replacement with crops and pasture leads to rising water tables. Also causes a reduction in vegetation cover. Land Clearing     Within 200 years of European Occupation. Strategies for reducing soil erosion: minimising the length of time that soil is left bare. Water table rises. Human-induced salinity is known as secondary salinity. area of Aus covered by eucalyptus has halved and area of rainforests has been reduced by 75% Originally land was cleared for land for industry. waterlogging. Overgrazing: Causes a loss of biodiversity. and is caused by land use activities that change water balance of a catchment. Wind erosion is greatest in areas where rainfall is low and soils are sandy. This is known as rill erosion. Downhill slopes make erosion more severe because of more energy. rain seeps into soil. raising water table. not down. particularly in areas where strong winds and drought occur maintaining plant cover by reducing stocking rates eliminating pests. Removal of trees has led to rising water tables. Soil erosion and salinity                    Water erosion: Removal of soil by rainfall or running water Water erosion is greatest in places with low vegetation cover. which leads to further erosion and runoff. If water moves evenly. Layer of leaf matter (humus) absorbs rainfall and reduces the runoff that can carry away soil in small rivulets. Wind erosion: Soil particles are detached from soil and blown away by wind. Old growth forests (ones that haven’t been affected by human activities) are cleared to make woodchips for wood industries. Eventually most eroded material ends up in the sea/ocean. Nowadays. If water flows into channels or rivulets. bringing dissolved salts to the roots of trees. called contour banks. Occurs when salt stored in the soil or groundwater is mobilised by extra water provided by human activities. slopes or avoiding the cultivation of sloping land planting trees to form windbreaks Natural salinity in arid climates in known as primary salinity. land is cleared for paper products. which can strip an area of its vegetation building raised areas of soil. such as rabbits. dryland salinity. killing them. bringing with it dissolved salts (dryland salinity) When trees are cleared. across slopes to reduce the movement of water down slopes ploughing across. soil erosion and a decline in water quality. . the soil is washed with it. stripping soil over a broad front it is called sheet erosion.

. Changes to seasonal flows: Increases in consumption of water in summer reduces amount of water for aquatic ecosystems. ploughing and burning are used for weeds. as domesticated animals. Irrigation sprays are cheap. Water quality in urban areas can be improved by following these suggestions: •Wash cars on the lawn not in the street.Water table rises further and salt pan forms where water table reaches surface. When domesticated animals escape and become wild they are known as feral. Introduced Species       Exotic species compete with native plants and animals for food and space. Fencing. nutrients. Minimise runoff from construction sites by using straw and plastic barriers to trap silt. trapping. purposefully to curb populations of other invasive species. Many introduced species are domesticated. Water quality in urban areas is affected by sediment. but waste a lot of water. household and industrial uses reduce amount of water for aquatic ecosystems. Can be introduced via ship cargoes. Rural water quality can be improved by: •protecting the vegetation of the stream’s river bank to create a buffer zone Ploughing across slopes rather than down them Taking care when applying fertilisers. oil and rubber from cars. Use lawn fertilisers carefully. pesticides and weedicides Controlling where stock drink from rivers. nutrients from detergents. Banning importation of species is best way to reduce exotic species. killing are used to control feral animals. Fertiliser runoff can cause excessive plant and fungal blooms. Poisoning. Also reduces salinity. Plants that are unwanted are known as weeds. Drip irrigation reduces wastage and delivers water to where it is needed. paint or other toxic substances down stormwater drains. Water Management                  Irrigation accounts for 69% of world water use. Don’t allow them to wash into stormwater drains. Water quality in rural areas are affected by eroded soil. pollutants. Temperature change: Storage of water leads to drop in temperature and industry pollute rivers with very warm water Dam walls can prevent fish from moving upstream to breed Pollution kills aquatic plants and enters the food chain. causing genetic damage. Reduced river flow: Water used for irrigation. Never pour oil. There is also higher runoff in urban areas with hard surfaces. pesticides/weedicides and salt. lawn fertilisers and dog faeces. litter.

Its return is called     backwash. . Rocks such as sandstone and limestone are soft and break down more quickly than more resistant rocks. arches can collapse leaving solitary rocky features in the sea called sea stacks. forming caves that eventually may become arches. Sometimes the more resistant rocks form outcrops. such as shale and granite. When a wave breaks some of the water flows up the beach (known as a swash). Salt-spray weathering breaks up surface or rock because the salt particles expand and contract as they dry in the sun Plant weathering breaks rock and plants send their rooots into rocks Animal weathering break up rock when sea creatures attach to rocks and produce chemicals that erode them. As the weathering process continues. The action of breaking waves also erodes the bases of cliffs.Coastal Management  Waves are the most significant of all agents shaping the coastal zone.

The sand usually returns to the beach within a short period of time. The backwash will then carry the sediment straight back down the slope of the beach to the water. stripping away the sand and rock (see Figure 7. In periods of calm weather constructive waves will gradually deposit sand on the beach. These changes are often dramatic but are usually short term. If waves approach the beach at an angle. This is known as longshore drift. sediment will also be transported across the beach at an angle by the swash of the wave. however. massive destructive waves pound the coast.  O n a beach there is a continual cycle of sand being deposited and taken away. During storms. longshore drift will slowly deposit sediment across the river to form a long finger of sand known as a . The sand is deposited in shallow water in offshore bars.7g). If a beach is next to a river mouth or bay.

When sand spits link islands to the mainland they are known as tombolos. Sand dunes are formed when wind blows dry. agriculture. When moved. Mangroves have salt-excluding root systems and salt-excreting leaves. These plants have adapted to cope with fluctuations in water level and salinity. . brackish (saltier than fresh water but less salty than sea water) or fresh water depending on its proximity to the sea. beach sand inland. Succulents and grasses are common in these areas. They are extremely biodiverse and are home to a vast array of aquatic and terrestrial organisms. The water in a lagoon can be saline (salty). Coastal wetlands act as a water filtering system. Sand is eroded from the beach and transported offshore by storm waves. such as spits. which is found close to the sea.7l). they act as buffers against high-energy waves. Inland from the mangroves are salt marshes (see figure 7. exposing the sand and soil to consequent erosion. The sulphuric acid releases other toxins in the soil and decreases water quality. During storms. Coastal land has been cleared for human settlement. recreation and forestry. the sand is transported back and redeposited on the beaches and dunes. industry. In calm conditions. Dune systems protect low-lying coastal areas. Estuaries are the lower areas of a river and its mouth and often support vegetation. They also protect land-based ecosystems close to the sea from the full impact of destructive wave energy. mining. The most common coastal wetland species is the mangrove. This sand is trapped by specialised plant and grass communities. by removing nutrients and sediments and also recycling chemical and organic matter. A lagoon is a large body of water that sometimes forms behind depositional barriers. which enable them to survive in salty waters. however. These areas are less frequently flooded and the vegetation is more dense and low growing. destroying sensitive ecosystems. The Myall Lakes on the NSW coast are a well-known example of a lagoon system. Acid sulphate soils are relatively harmless and found in most wetlands. loose. In most cases natural vegetation is cleared. They assist with erosion control by binding and stabilising soils and reducing surface flows.      spit. they release sulphuric acid.