water case studies Flashcards
1
Q
Amazon river regime
A
- Rainforest climate
- Seasonal precipitation, rain every month but has high and low seasons
- Very high evapotranspiration levels
- High flow in wetter season
- Low flow in dry season
- Moderate seasonal variation - fed by Andean rivers outside rainforest region
- Human influence is increasing, large dams used by Brazil’s major cities for irrigation and HEP
2
Q
Yukon river regime
A
- Tundra, taiga and mountain climates
- Higher summer temperatures, rainfall and snowfall coincide
- High flow in spring and summer caused by snowmelt
- Low flow in winter as precipitation frozen
- Very large seasonal variation
- Low human influence as most of landscape is wilderness with some HEP use for mining industries
3
Q
Murray-Darling river regime
A
- Seasonal sub-tropical climate, monsoon climate in northern tributaries of Queensland, feeding Darling and temperate climate in south which feeds the Murray
- Most of the basin lays in a rain shadow and undergoes long periods of drought
- High flow in wet season
- Low flow in dry season
- High seasonal variability
- Human influences: Waters are drawn by Australia’s major cities and farms for irrigation.
4
Q
California drought
A
- It was a prolonged period of water scarcity that affected the state of California in the United States. It began in 2012 and lasted until 2017, making it one of the most severe and long-lasting droughts in California’s history
- An area of high pressure blocked low pressure areas from bringing winter rainfall.
In 2013, rainfall was 34% less than expected, California’s statewide precipitation during three separate winters ranked the second lowest since official measurements began in 1895. - A high pressure ridge just off the West Coast diverted storms during all three winters.
- California relies on the Sierra Nevada snowpack as a major source of water. In the years leading up to the drought, the snowpack was well below average due to warmer temperatures
- Over-extraction of groundwater for agricultural, industrial, and domestic use
- Population growth exacerbated the strain on water resources during the drought.
- California’s agricultural sector suffered an estimated $5 billion in direct losses due to reduced crop yields and the following fields. This had a ripple effect on the global food supply chain.
- Wetlands have been drained with natural habitats being altered and fish stocks being depleted. This was all done in order to secure water supplies.
- Wildfires: The drought contributed to a series of devastating wildfires, including the Rim Fire (2013) and the Thomas Fire (2017). These fires burned vast areas of forest and shrubland, causing habitat loss.
5
Q
Brazil drought
A
- Rainfall is normally predictable however in 2014/15 a series of high-pressure systems diverted rain-bearing winds further North away from the Amazon causing drought in Brazil.
- Led to water rationing for 4 million people, cut off for days in some towns
- Halted HEP production, led to power cuts
- 17 largest reservoirs depleted severely, some at 1% capacity
- More groundwater abstraction depleting aquifers
- Reduced crop of Arabica coffee beans pushing global coffee prices by 50%
- Deforestation in the Amazon may have reached a tipping point leading to a positive feedback loop where the rainforest ecosystem is becoming less resilient. (reduced soil water capacity and evapotranspiration which could lead to increased carbon in atmosphere)
- Also affected wetland ecosystems, specifically the Pantanal in Central South America where a lot lies within Brazil. The drought increased tree mortality reducing habitats for animals.
6
Q
Australia drought
A
- Decade long drought
- Driest continent in the world
- MDB provides 75% of Australia’s water
- Five-fold increase in water extraction since the 1920s
- Significantly affected by ENSO cycles - El Nino
7
Q
India drought
A
- Depleted Monsoon precipitation impacted agriculture in the North as only a third of the land is irrigated and the other two-thirds is reliant on rainfall. The monsoon had a 40% deficit in rainfall, depleting ground water in the South. This was the worst drought event that they have experienced in over 150 years.
- Affected over 330 million people
- 400 deaths from heatstroke.
8
Q
Pakistan flood
A
- The primary physical cause of the 2010 Pakistan flooding was an extraordinarily heavy monsoon season. The region experienced significantly above-average rainfall from July to September. In some areas, the rainfall was 200% higher than the annual average.
- The exceptionally heavy monsoon rains were exacerbated by glacial meltwater from the Himalayas and Karakoram ranges. Increased glacier melt due to rising temperatures added to the volume of water
- Pakistan’s river system played a role. The Indus River has a vast catchment area, and the excessive rainfall caused it to overflow and flood surrounding regions.
- Deforestation in the region, particularly in the upstream areas, contributed to soil erosion and reduced the land’s ability to absorb excess rainwater. This increased the risk of flash floods and landslides.
- Poorly timed water releases from reservoirs exacerbated downstream flooding. Decisions about when to release water and the lack of coordination among agencies contributed to the problem.
- The floods affected over 20 million people in Pakistan, approximately 2000 people lost their lives
- Women and girls, who are often responsible for fetching water and providing care, were disproportionately affected. They faced increased health risks and the burden of caring for family members in difficult conditions.
- Floods caused habitat loss and land degradation, affecting ecosystems and biodiversity. Wetlands and forests were particularly impacted.
- Floodwaters carried pollutants from urban areas and industries, contaminating water sources and posing a threat to aquatic life and public health.
9
Q
Libya flood 2023
A
- Storm Daniel hit Libya, bringing strong winds and heavy rainfall, causing flooding and destruction in local areas
- The rain brought by the storm swelled the Wadi Derna river, ultimately leading to two of the dams in Derna bursting
- Years of war and lack of central government has meant that a lot of the infrastructure is weak and poorly constructed, which meant that a lot of buildings collapsed during the flood, increasing the amount of destruction
- Potential design flaws and poor maintenance of dams meant that they were more vulnerable to bursting
- Estimated that the 2 dams will cost $76 billion to rebuild
- More than 4000 killed and 10000 went missing
- Flooding increased the quality or arable soil
10
Q
Boscastle, Cornwall flood 2004
A
- The ground was already previously saturated (as a result of heavy rainfall a few days prior) leading the sandstone to act as an impermeable rock causing more surface run-off.
- 125mm of precipitation fell in just a few hours.
- No flood control system in the village
- Deforestation on the valley sides and higher ground to make way for agriculture meant there were fewer trees to intercept the rainwater and absorb surface runoff.
- Damage of the local area had a significant impact on the local economy as tourism was restricted (90% of towns income)
- Damage to infrastructure cost up to £2 million
- Riverbanks were eroded by the weight of river water
11
Q
Nile water conflict
A
- Egypt, Sudan and Ethiopia all depend on inflow from the Blue Nile and Ethiopia announced plans to build the $5 billion GERD. - This will cut off water supply to downstream countries Egypt and Sudan causing water scarcity.
- Population in the Nile basin is expected to grow to 600 million by 2030.
- Unfair allocation of water in the past where Egypt had the vast majority of the water as a result of colonialism, since it is now being taken away, conflict is arising.
12
Q
Mekong water conflict
A
- Large HEP dams being built upstream of Cambodia
- Cascade of HEP dams being built upstream - less water over time in the river. This started in China in the 1990s (they have 11). More are planned. This is restricting flows. Laos Dam - Don Sahong.
- Dams also holding back sediment (nutrients for fish)
- If action not taken sediment net could decrease by 90% by 2040 if action not taken.
- Sand extraction - 60m tonnes per year, dredging an already threatened ecosystem and could lead to irreversible change
- Desperation has led to illegal fishing.
13
Q
Tigris-Euphrates water conflict
A
- Turkey filling Ilisu Dam at the origin of Tigris (altering flow of water into Syria, Iraq and Iran). Has led to lower flows and decreased quality of water.
- Turkey’s GAP project could include as many as 90 Dams
- Reduced water flows into Iraq and Syria by approximately 80 per cent and 40 per cent respectively.
- Syria built dams in response, which led to even less water reaching Iraq. This almost led to war in 1975.
- Low flow rates in Iraq have allowed salt water to infiltrate nearly 150 km inland (saltwater encroachment) from the Persian Gulf
- Earlier this year (2018), Iraq threatened to take its case for an increase in water flows from Turkey and Syria to the UN.
- People in Basra - hospitalised by contaminated water in 2018
- Climate Change - decreasing water supply and making rainfall erratic, June 2019 heatwave
14
Q
Aral Sea water conflict
A
- The Aral Sea has shrunk to a fraction of former size. From 1960 to 1998 volume has fallen by 80%
- Irrigation canals lead to water loss from evaporation or leakage. This has led to less water flowing into the Aral Sea.
- Pollution and increased salinity of water.
- Conditions have improved in North Aral following the construction of the Kokaral Dam but this means the South Aral now receives even less fresh water.
- Positive feedback of impact on climate from drying out of the sea leading to hotter and drier summers.
- High salinity has led to fewer fish in the sea. People have had to move due to impact on livelihoods.
- Countries competing for use of water.
- Been many agreements made following collapse of the USSR however countries are continually failing to uphold their ends resulting in conflict that while has not caused a water war yet, tensions are continuously rising.
15
Q
Three Gorges Dam, China
A
- Electricity generated is vital for China’s growth
- Allows surplus water to build up and be diverted to Northern China via the South-North Water transfer project
- Almost 650km2 of land has been flooded to form the reservoir
- 1.3 million people have been relocated
- Low water quality due to industry, sewage and farm waste from upstream
- Decomposing vegetation in the reservoir produces methane which is released when water passes through turbines.
