Geography - created from Mind Map

Página 1

Mekong River

Source Zone

Transfer Zone

Geomorphic Process: interactions between the Earth's surface and the natural forces acting upon it to produce landforms

Sink Zone

Rup-sa Pass in Tibet

Highlands of Central Asia

~5000m high

Tibetan Plateau, China

Cold and desolate - contains glaciers

Flows for 2100km

Manwan Dan 1000km from Source

Headwaters: upper tributaries of river

Watershed: boundary b/w 2 river systems

Hill-slopes: sloping hill

Hills and channels but no river flats

Quarrying: breaking up of sediment particles

Abrasion:: like sandpaper scraping along sediment and rocks

+Suspension, solution, saltation & traction

Boulders, waterfalls & rapids

Ranges from narrow slots to U-shape & open valleys

Trapeziodal Cross Section

Point bars

Gravel bars

Many ridges and valleys that run N-S

Many waterfalls, rapids and canyons (up to 4km deep)

Pine forests and deciduous woodlands

River is v-shaped and tributaries look like ribs

Fast-flowing water

Chinese plan to build 7 more

WATER MANAGEMENT

- Natural seasonal flows have been altered due to water being stored and released when irrigators require it. o Floods increase in size, number and changed in timing o The occurrence of small and medium floods has reduced altering fish population and ecology

3 IMPACTS OF DAMS AND WEIRS ON NATURAL FLOWS: flood storage and release hydroelectricity and irrigation, physical barrier to fish irrigation, cold-water pollution

90% of Mr's load is carried in suspension

Meandering

Oxbow Lakes

Talus Creep - widespread and slow movement of rock and debris throughout r river

Determined by natural environmental variables: geology, climate, vegetation - no human influence - shape of a river

Delta: triangular

Net receiver of sediment

Lockyer Creek Catchment

WATER QUALITY ISSUES

LAND USES

MAJOR TOWNS

TIRBUTARIES

iNCREASES IN SALINITY

INCREASES IN PHOSPHATE

Riparian Habitat

Due to tree clearing: tree planting projects

Due to sewage and irrigation farming - fertilisers washed into water

Planting dense, deep-rooted, salt tolerant buffer strips

Forestry

Agriculture

Grazing

Sugarcane

Nature Conservation

Mining

Water

Toowoomba

Gatton

Withcott

Coominya

Laidley

Grantham

Sheep Creek

Tenthill Creek

Murphy's Creek

Redbank Creek

Ma Ma Creek

Blackduck creek

Flagstone Creek

Plain Creek

Rocky Creek

Buaraba Creek

Murray-Darling Basin

5 Significant Rivers:

South-east of SA, Southern Qld, more than half of Vic and much of NSW

Land Uses

Issues

The annual flow of the MDB is equal to the daily flow of the Amazon

Source Zone is located in Mt. Kosciusko

The amount of water flowing out of the Murray Mouth is a quarter of its natural flow

Albury-Widonga is a major town on the Murray River - 97 000

Covers about 14% of Australia

Referred to as Australia's food bowl

Over 2 million person living in Basin in 2006 - majority in NSW (39%) and Vic (29%)

~40% of Australian farmers lived in the Basin

In 2005-06, 66% (7720 gigalitres) of Aust.'s agricultural water was consumed for agricultural production in the Basin

Climate is very dry compared to other regions

Natural Features

Natural Processes

River Regulation & Fish Population

Murray River

Darling River

Murrumbidgee River

Warrego River

Lachlan River

Food Producing - Sunbeam, Berri, Uncle Toby's

72% irrigated farms for the nation

43% all farms

50% all crops

50% all sheep

34% all wheat

34% all dairy

25% all cattle

Recreation

Recreational, Forestry, Urban - Industrial & Residential, Mining, Fishing - Commercial, Agriculture - Grazing, Irrigation

Lake Hume

Used for skiing

Most important water storage dam on the Murray

37% of Murray water comes upstream of Lake Hume

Purpose: to prevent damaging floods and for irrigation use

- A gigalitre is 1 billion litres – 500 gigalitres has been kept for environmental flows – experts say we need 1500 gigalitres

- 500 gigalitres per year needs to be preserved as an environmental flow; would have to be purchased back from irrigators as they use most of the water  water would no longer be removed from system

60% of fish are extinct in the lower Murray

Excrement from cattle and horses enters the stream at the source zone and encourage Giardia (parasite)

The water released from the lake is up to eight degrees colder than the surface – negatively impacts native fish – Golden Perch, Murray Cod and freshwater Catfish cannot be found between (due to habitat change) Albury and Lake Hume due to change in habitat (temp) – affects recreational fisherman, tourism and food webs

Treatment of sewage effluent

3 competing uses: irrigation, recreation and tourism, environmental (natural) flows

Clearing

Water Management

Cold-water Pollution

Experiences a highly variable rainfall with periods of floods and extended dry periods

Major flooding can affect areas of the Basin because it is made up of huge expanses of low-lying floodplains

Rainfall is subject to high evaporation rates leaving a small % to drain into the ground or flow across the surface as runoff

20 yr average rainfall in MDB form 1980-99 was 350-650mm

Over-bank flows inundate floodplains and cause widespread damage to communities while at the same time replenishing wetlands and river systems

Tributaries

Sand bar

Point bar

Vegetation

Oxbow Lakes

Flooding

Talus Creep

Ecology

Drought

Health of fish = indicator to health of river

populations of native fish species in the Basin have suffered serious declines in distribution and abundance in last 100 yrs

- River regulation (dams, weirs and diversions) has changed the natural flooding and drying cycles of the river systems and the health of river habitats and native fish populations

- Natural seasonal flows have been altered due to water being stored and released when irrigators require it. o Floods increase in size, number and changed in timing o The occurrence of small and medium floods has reduced altering fish population and ecology

- Cold-water pollution: much colder water entering the waterway as a result of water being released from dams etc.  artificial decrease in temperature of water in a natural ecosystem

- Fish movements may be localised where they access food, shelter or avoid predators - At certain times of the year, usually aligned to rising water levels or temperature, fish species cover significant distances moving downstream and often returning with one or two days - This migration is thought to coincide with their breeding cycle

- Problems of salinity, alien fish species and blue-green algal blooms as well as declining native fish populations

3 IMPACTS OF DAMS AND WEIRS ON NATURAL FLOWS: flood storage and release hydroelectricity and irrigation, physical barrier to fish irrigation, cold-water pollution

- Large volumes of cold water disturb the delicate ecological balance by creating an unseasonal environment that ecologists have compared to an ‘eternal winter’

- Release of cold water from a major dam can suppress spawning for up to 300km downstream o Ability of native fish to reproduce, grow and maintain sustainable members is reduced o Carp flourish as they compete with native species for food and habitat o Some species may disappear from sections of the river

Geography