Water Cycle Case Studies

Question 1

The Big Dry

Answer 1

A climatic phenomenon in Australia in the Murray-Darling Basin from 2000-2009.

This was caused partly by changing climates and partly due to the El Nino effect

This dropped water levels in the basin to 21% capacity, causing crop failures which hurt the livelihoods of farmers and caused crop prices to rise (rice production fell to 2%)

Question 2

The Sahel

Answer 2

Human causes of desertfication: Population Increase –> Overgrazing, Deforestation –> Soil Erosion (and climate change)

Overgrazing is estimated to account for 65% of desertification

Positive Feedback Loop (Aridness):
Global temperatures rising 50% faster in Sahel than elsewhere, which dries out the soil faster, increasing soil erosion which creates dust storms which increase temps and reduces precipitation

Positive Feedback Loop (Poverty):
Lack of money means farmers can’t afford much land so they try and overcultivate on smaller plots. The soil erosion means these plots become infertile faster so farmers have lower yields and make even less money

Question 3

Amazon Rainforest

Answer 3

Contains 10% of all species on earth and 40 million humans, absorbs 2 billion tonnes of CO2 per year

20$ destroyed in the last 50 years, largely for cattle ranches, biofuel production, illegal logging and urbanisation

Reduced the % of water returned from evapotranspiration from 75% to 25% increasinf desertification

Estimated 30-45% biodiversity loss by 2030

Question 4

The Nile

Answer 4

257 million people across 11 countries are dependent on the NIle, including 95% of the population of Egypt

In 1929, colonial powers signed a treaty allocating 86% of the Nile water’s use to Egypt and Sudan and gave Egypt veto rights on Nile projects

In 1959, the colonial allocation of Nile water Egypt and Sudan could use was increased to 55.5 billion cubic metres and 18.5 billion cubic metres respectively which, taking evaporation into account, left no water for any other Nile country

The Nile Basin Initiative (NBI) was founded in 1990 to improve international water cooperation but has been relatively unsuccessful due to overlapping demands of water

The Grand Ethiopian Renaissance Dam, built between 2011-2023, highlighted conflict in the Nile as Egypt feared it would reduce water flows downstream while Ethiopia demanded it was vital for economic development

The GERD Dam has led to a 2% reduction in water to Egypt which affects 200,000 acres of irrigated land

Question 5

Colorado River

Answer 5

Provides water to 40 million people across 7 states and Mexico and accounts for $9 billion revenue across 16 million jobs

People are dependent on it like in Las Vegas which uses the river for 90% of its water

There are 29 dams on the Colorado River which reduces downstream access to states like California which increases tensions

Overextraction is leading to decreasing levels of water in the river (19% fall since 2000)

IWRMs have led to increased cooperation and states have pledged to reduce their water usage (eg California by 20% from 2007)

Question 6

South-North Water Transfer Project

Answer 6

A project in China started in 2003 and estimated for completion in 2050 that will transport 44.8 billion cubic tonnes of water from the water surplus south to the water deficit north (Beijing region has 35% of population with only 7% of water)

It costs $100 billion to build, 40% of which is paid by local governments which increases pressure on locals as a result

Critics fear worsening water quality and forced resettlement of up to 345k people, but it will reduce groundwater abstraction and water shortages up north

Question 7

The Three Gorges Dam

Answer 7

Estimated $25 billion cost with net profits of around $3 billion a year

Rehomed 1.3 million people and submerged 632km2 of land but can power 5.4 million homes for a month at full capacity

Question 8

Helsinki Convention

Answer 8

Adopted by UNECE in 1992 and put into effect in 1996

Encouraged international cooperation on managing trans-boundary water sources in Europe (and outside of Europe from 2013)

It established the concept of IWRMs (water treaties which assess trans-boundary basins rather than just water within one country), encouraged sustainable use and collaborative data monitoring

It was successful as it encouraged cooperation which reduced water conflicts and is flexible enough to be globally applicable, but its main shortcoming is that there are limited enforcement mechanisms and not enough members which means conflicts still occur