River Basin Management

Question 1

• What is the PHYSICAL CHARACTERISTIC (CLIMATE) of the Colorado River? 🏞️

Answer 1

• Climate in the drainage basin
  ➞ characteristic of a hot desert 🏜️
  ↳ with low rates of precipitation (below 250mm per annum)
• The rain that falls is unpredictable ❔
  ➞ resulting in seasonal flow in the river
• When precipitation does fall, ⛈️
  ➞ thunderstorms are common
  ↳ resulting in a risk of flooding (caused by a rapid increase and change in the amount of water within the basin.)
• Temperatures can rise above 40°C 🌡️
  ➞ leading to high evaporation rates (particulary in the summer)
  ↳ Water loss from vegetation is also high, but species have adapted to minimise water loss

Question 2

• What is the PHYSICAL CHARACTERISTIC (SOIL/VEGETATION) of the Colorado River? 🌱

Answer 2

• Poor soils are common, 🌰
  ➞ which limits the breadth of vegetation found in the basin.
  ↳ This reduces interception & results in rapid transfer of rainwater into the river.

Question 3

• What is the PHYSICAL CHARACTERISTIC (RIVER FLOW/DISCHARGE) of the Colorado River? 🌊

Answer 3

• The meltwater from snow at higher altitudes in the upper course of the basin
  ➞ (Wyoming and Colorado)
  ↳ feeds the river. ❄️
• Snowmelt
  ➞ provides the majority of water in the basin. 🌊

Question 4

• What is the NEED FOR WATER MANAGEMENT (CLIMATE) for the Colorado River? 🏞️

Answer 4

• As the Colorado River Basin has low annual rainfall 📉
  ➞ (in the lower basin states, e.g. Arizona, Nevada, California and New Mexico)
  ↳ there is a need for management to ensure these areas get water.
• As the rainfall is extremely variable and unpredictable ❔
  ➞ (in the upper basin states, e.g. Wyoming, Utah and Colorado)
  ↳ there is a need to manage the river to ensure these states have enough water from one year to the next.
• As temperatures reach over 40°C 🌡️
  ➞ (in certain areas of the basin)
  ↳ there is a need for water management as evaporation occurs very quickly, therefore they need to make sure there is enough water for all the people living within the basin.

Question 5

• What is the NEED FOR WATER MANAGEMENT (DOMESTIC WATER SUPPLY) for the Colorado River? 💦

Answer 5

• Cities found within the Colorado RIver Basin (such as Las Vegas and Phoenix)
  ➞ are some of the fastest growing cities in the USA
  ↳ therefore, they need to have a steady supply of water to continue their development. 🏙️🌊
• Water in such areas
  ➞ are needed for swimming pools, flushing toilets and drinking water 🏊🚽🚰

Question 6

• What is the NEED FOR WATER MANAGEMENT (POWER SUPPLY) for the Colorado River? ⚡

Answer 6

• Cities found within the Colorado River Basin (such as Las Vegas and Phoenix) 🏙️
  ➞ also need more and more power for industrial and domestic use as they grow 🏭
• Hydroelectric Power (HEP) ⚡
  ➞ is a cheap and clean source of power
  ↳ which comes with managing the flow of the Colorado River basin using dams. 🌊

Question 7

• What is the NEED FOR WATER MANAGEMENT (FOOD DEMANDS) for the Colorado RIver? 🥪

Answer 7

• As populations continue to rise within the Colorado Basin,
  ➞ there is a greater demand for food production to support this increasing population. 🌾
• However,
  ➞ due to variable and unpredictable rainfall along the west coast
  ↳ this area needs 10x more irrigation water than the east coast
  (therefore the Colorado River needs to be controlled) 💦

Question 8

• What is the NEED FOR WATER MANAGEMENT (FLOOD CONTROL) for the Colorado River? 🌊

Answer 8

• As a result of damming the Colorado River,
  ➞ developments could take place along the river without the risk of flooding ❌🌊
• Before damming the river,
  ➞ it contained a lot of reddish sediment, making the water dirty
  ↳ Today, the dams act as a huge trap for the sediment, thus the water is cleaner as it flows downstream.

Question 9

• What is the NEED FOR MANAGEMENT (POLITICAL TENSIONS) for the Colorado River? 💥

Answer 9

• The Colorado River
  ➞ flows through 7 states and 2 countries.
  ↳ As a result of this, each state and country feels it is entitled to the most water. thus fuelling many political arguements. 🌎🗯️
• River basin management
  ➞ helps to control the amount of water that each state recieves,
  ↳ thus providing a fairer allocation of the Colorado’s water 🤝

Question 10

• What impact does the PHYSICAL factor ‘ROCK TYPE’ have on the SELECTION & DEVELOPMENT of SITES? 🪨

Answer 10

• The dams
  ➞ should have solid foundations
  ↳ to support their great weight.
• The rock beneath the reservoir and the dam
  ➞ needs to be impermeable
  ↳ to reduce water loss through seepage.

CASE STUDY:
* The canyon walls and the sandstone bedrock
➞ of the Glen Canyon Dam
↳ can safely support a large 10 million tonne dam.

• The sandstone of the Glen Canyon Dam
  ➞ is not totally impermeable
  ↳ so there is some water loss due to seepage.

Question 11

• What impact does the PHYSICAL factor ‘LANDFORMS’ have on the SELECTION & DEVELOPMENT of SITES? ⛰️

Answer 11

• NARROW VALLEY:
  ➞ there must be a narrow cross-section
  ↳ to reduce the length of the dam needing to be built and also reduces the strain upon the structure
  ➜ once the lake behind it is full.
• DEEP VALLEY:
  ➞ a large, deep valley
  ↳ must be available to flood behind the dam
  ➜ to store as much water as possible.

CASE STUDY:
* The Colorado River
➞ has eroded a narrow steep valley at Glen Canyon
↳ which has made it easier to construct a dam and reduce construction costs.

• At the Glen Canyon,
  ➞ the canyon is over 700ft (213m) deep
  ↳ which is an ideal site for a dam and reservoir.

Question 12

• What impact does the PHYSICAL factor ‘WATER SUPPLY’ have on the SELECTION & DEVELOPMENT of SITES? 💦

Answer 12

• There must be sufficient water flow
  ➞ to fill the new lake behind the dam and maintain supplies for all parts of the scheme.

CASE STUDY:
* Water
➞ is supplied from the distant Rocky Mountains
↳ and Lake Powell is dependent on precipitation from outside its area.

Question 13

• What impact does the PHYSICAL factor ‘SOURCE OF AGGREGATE’ have on the SELECTION & DEVELOPMENT of SITES? ✨

Answer 13

• A good source of rock and sand nearby
  ➞ for concrete for building the dam
  ↳ is helpful to reducing construction costs.

CASE STUDY:
➞ Rock and sand source for concrete
↳ was supplied from Waheep Creek only 6 miles from the dam site.

Question 14

• What impact does the PHYSICAL factor ‘GEOLOGICALLY STABLE’ have on the SELECTION & DEVELOPMENT of SITES? 🌎

Answer 14

• A geologically stable area
  ➞ away from earthquake zones/fault lines with a solid foundation
  ↳ will reduce the risk of damage or failure of the dam.

CASE STUDY:
* The sedimentary rocks
➞ are in a fairly stable environment
↳ but the upper Colorado can suffer earthquakes at times.

Question 15

• What impact does the HUMAN factor ‘ACCESSIBILITY’ have on the SELECTION & DEVLOPMENT of SITES? ♿

Answer 15

• The dams
  ➞ shoud be built in areas that are accessible for workers and materials.
• The location of dams and reservoirs
  ➞ should take into account disrupting present transport routes.

Question 16

• What impact does the HUMAN factor ‘LOCAL SERVICES & AMENITIES’ have on the SELECTION & DEVELOPMENT of SITES? 🏬

Answer 16

• The further away the dam is from centres of high population,
  ➞ the further the distance to transport electricity, or water for irrigation to customers.
  ↳ It would need to be determined if the distance was cost efficient.
• Greater distances
  ➞ also mean greater losses for evaporation and seepage.

CASE STUDY:
* The desert cities of Las Vegas and Phoenix
➞ are expanding close enough to provide a market for the electricity supplied from the dams.

Question 17

• What impact does the HUMAN factor ‘LOSS OF LAND’ have on the SELECTION & DEVELOPMENT of SITES? 🪓

‘LOSS OF LAND’ = Farmland and Settlements:

Answer 17

• FARMLAND:
  ➡ It is important
  ↳ to factor in the amount of farmland to be flooded
  ➜ in order to ascertain the cost payable to landowners and if the loss can be balanced by the additional land irrigated.
• SETTLEMENTS:
  ➡ The number of settlements that will need to be flooded
  ↳ will also have to be considered
  ➜ and the likely cost of moving and compensating people and companies.

CASE STUDY:
* Flooding historical sites
➞ for example, the Rainbow Bridge,
↳ should be avoided if possible, as should sacred burial ground.

Question 18

• What are the SOCIAL ADVANTAGES of consequences of Water Control Projects? 🌎🟢

Answer 18

• Improved water supply for drinking
  ➡ as the dam ensures a constant supply.
• Irrigation water
  ➡ allows farmers
  ↳ for example, in California,
  ➜ to grow crops all year round, which increases food supply.
• The availability of water
  ➡ can sustain increasing populations
  ↳ especially in the desert cities of Phoenix and Las Vegas.
• There is a greater availability of electricity
  ➡ (e.g. 4 billion kilowatt hours per year)
  ↳ therefore, more businesses can set up in the area.
• The local populations
  ➡ surrounding the reservoirs
  ↳ (e.g. Lake Powell)
  ➜ now have access to recreational activities, like water sports (e.g. jetskis)
• They can become tourist attractions
  ➡ bringing money into the area.

Question 19

• What are the SOCIAL DISADVANTAGES of consequences of Water Control Projects? 🌎🔴

Answer 19

• Many people
  ➡ were forced to leave their homes
  ↳ to allow the flooding of the valleys to create the reservoirs
  ➜ and often people were resettled in other areas that were not as productive as the land they left.

Question 20

• What are the ECONOMIC ADVANTAGES of consequences of Water Control Projects? 💵🟢

Answer 20

• The dams produce cheap HEP
  ➡ attracting industry into the area,
  ↳ providing jobs,
  ➜ and increasing the standard of living.
• The water and power produced
  ➡ has encouraged the expansion of major cities.
• The facilities in the cities
  ➡ attract many tourists
  ↳ (e.g. Las Vegas)
  ➜ bringing money into the economy.
• The availability of irrigation water for farming
  ➡ means agricultural produce increases,
  ↳ and this extra produce for sale creates more income for the economy.

Question 21

• What are the ECONOMIC DISADVANTAGES of consequences of Water Control Projects? 💵🔴

Answer 21

• The scheme
  ➡ costs a huge amount of money to build and maintain
  ↳ (e.g. $135 million)
• The more irrigation water is used by farmers along the river,
  ➡ the more saline the water becomes.
• To begin with,
  ➡ when the water eventually reached Mexico
  ↳ it was unusable.
  ➜ To solve this problem, a huge desalination plant had to be built, costing over $300 million to build.
• Large amounts of compensation
  ➡ needs to be paid to those that have been relocated for the dam’s construction.
• Water is very cheap for farmers to buy
  ➡ so much is wasted.

Question 22

• What are the ENVIRONMENTAL ADVANTAGES of consequences of Water Control Projects? 🌳🟢

Answer 22

• There is a constant supply of water for domestic use,
  ➡ which benefits health.
• The creation of reservoirs
  ➡ encourages wildlife into the area.
• The reservoirs and dams
  ➡ are seen by some people as improving the scenery and environment.

Question 22

• What are the ENVIRONMENTAL DISADVANTAGES of consequences of Water Control Projects? 🌳🔴

Answer 22

• The original wildlife
  in the area
  ➡ have been forced to move
  ↳ as the habitats have been destroyed by the reservoirs
  ➜ (e.g. there are no longer any wild beavers in Tucson)
• The natural landscape
  ➡ has been destroyed by the development of the dams and associated reservoirs.
• The level of Lake Powell
  ➡ is so high
  ↳ that the Rainbow Bidge, said to be one of the geological wonders of the world,
  ➜ is slowly being dissolved by the water.

Question 23

• What are the POLITICAL PROBLEMS of consequences of Water Control Projects? 🚨

Answer 23

• The Colorado River
  ➡ runs through 7 states of the USA, and Mexico.
  ↳ This can cause many political problems and arguements as to how to divide up the river’s waters.
  ➜ For example, different states have different needs for domestic use, agriculture and industry, and each state can pass laws regarding water, but these can conflict with other states.
• Different states have different laws on water rights.
  ➡ The amount of water allowed to reach the lower areas
  ↳ depends on the cooperation of upstream neighbours.
  ➜ This is also true for the quality of the water, as the areas lower down the valley can often be left with very little, polluted water due to industrial use further upstream.
• The waters can also be used for irrigation
  ➡ and repeated withdrawal of the river water
  ↳ leads to salinity (increase in salt) downstream.
  ➜ This can be costly to treat.
• The legal system in the USA
  ➡ worked in favour of the richest state (California)
  ↳ so it had more power over the water than other states,
  ➜ creating conflict.

Question 24

• What is the effect on EVAPORATION in the Hyrdological Cycle?

Answer 24

• EVAPORATION (the process in which a liquid changes state and turns into a gas)

1. When rivers like the Colorado are dammed,
   ➡ surface runoff is reduced.
2. Dams restrict water flow,
   ➡ so there is less water flowing below the dam and into the sea.
3. Additionally,
   ➡ there is an increase in evaporation
   ↳ from the surface of the massive reservoirs created behind the dam.
4. Less evaporation occurs in the Colorado River
   ➡ as it contains less water due to storage in reservoirs.

Question 25

• What is the effect on INFILTRATION in the Hydrological Cycle?

Answer 25

• INFILTRATION (the process by which water on the ground surface enters the soil)

1. The amount of water infiltrating the ground
   ➡ is increased
   ↳ as a result of storage in reservoirs.
2. Infiltration rates into the ground
   ➡ are also altered
   ↳ as rivers are diverted for irrigation channels
   ➜ such as the Colorado Aqueduct (a bridge to transport water through a valley) which takes water to California.
3. There may be a change in seasonal variations in river levels
   ➡ and the level of water tables may also be changed.

Question 26

• What is the effect on TRANSPIRATION in the Hydrological Cycle?

Answer 26

• TRANSPIRATION (the process of water movement through a plant and its evaporation from ariel parts, such as leaves, stems and flowers)

1. Removing foresty from the dam/reservoir construction sites
   ➡ can lead to less transpiration
   ↳ and less interception.
2. If forestry is then planted after a dam has been constructed,
   ➡ it will then have the opposite effect
   ↳ with an increase in transpiration.
3. An increase in moisture in the air
   ➡ will lead to an increase in rainfall
   ↳ altering the climate of the area.
4. Large lakes
   ➡ can also create their own microclimates
   ↳ by keeping surrounding land cooler or even increasing precipitation.