People and the Environment 5
Terms in this set (75)
Water covers around ___% of the Earth's surface
Uses of water
residential. agricultural. industrial.
Important roles of water
sculpting the earth's surface. moderating climate. removing and diluting wastes and pollutants.
Water resource is one of the most poorly managed resources on the earth...
Water is wasted and polluted. Water is charged too little for its availability, which encourages the waste and pollution of water.
Water as a global health issue
The lack of safe water for drinking and sanitation causes illness
Water as an economic issue
Water is significant for reducing poverty and producing food and energy
Water as an environmental issue
Excessive withdrawal of water from rivers and aquifers and the pollution of water results in lower water tables, lower river flows, shrinking lakes, loss of wetlands, declining water quality, declining fish populations, species extinctions, and degradation of ecosystem services provided by aquatic systems
Available liquid fresh water only covers ____% of the earth's total water supply. Ex:
.024% Lakes, rivers, streams, ground water deposits
salty ocean, frozen polar ice caps and glaciers, deep underground water
Unbalanced freshwater supply among different continents due to differences in both physical and socioeconomic conditions
average annual precipitations, economic resources, and population density
.5% of the world's population. 20% of the world's liquid fresh water
20% of the world's population. 7% of the world's liquid fresh water
60% of the world's population. 30% of the world's liquid fresh water.
the movement of water in the seas, the air, and on land with a changing state among liquid, vapor and ice. Driven by solar energy and gravity. Helps to collect, purify and recycle the fresh water continuously
Human activities can change the hydrological cycle in a negative way:
Waste of water. withdrawal of the ground water and surface water supplies faster than it is replenished. The destruction of wetland and forests which store and slowly release water
We get fresh water from...
groundwater and surface water
Precipitation infiltrates the ground and percolates downward through spaces in soil, gravel, and rock until an impenetrable layer of rock stops it. The water in these spaces is called ground water.
The spaces in soil and rock close to the earth's surface hold little moisture. Below a certain depth, there is a zone of saturation. The top of this groundwater zone is the water table. It falls in dry weather and rises in wet weather.
The geological layer deeper down. They are the underground caverns and porous layers of sand, gravel, or bedrock through which groundwater flows. Groundwater normally moves from high elevation and pressure to low elevation and pressure.
Most aquifers are replenished naturally by precipitation that percolates downward through soil and rock.
The recharge from nearby rivers and streams
Most of the aquifers are recharged very slowly because of...
urbanization, which increases the paved impervious land on the surface so that water can no longer penetrate into the ground to recharge the aquifers
the freshwater from precipitation and snowmelt that flows across the earth's land surface and into rivers, streams, lakes, wetlands, estuaries, and eventually to the oceans
precipitation that does not infiltrate the ground or return to the atmosphere by evaporation
the land that surface water drains into a particular river, lake, wetland, or other body of water
Reliable surface runoff
the amount of surface runoff that can be counted as a source of freshwater from year to year, which is about 1/3 the total amount of the annual surface runoff. The remaining 2/3 of surface runoff in rivers and streams is lost by seasonal floods and is not available for human use
The withdrawal of reliable surface runoff is increasing due to...
the increasing world population. Water resources are also used unsustainably in many areas.
Connection between groundwater and surface water
Most of the groundwater naturally flows into rivers, lakes, estuaries, and wetlands. The disruption of the hydrologic cycle by removing groundwater faster than it is replenished can cause the drying up of nearby streams, lakes, and wetlands. This process also degrades the aquatic biodiversity and other ecological services.
the rough measure o the volume of water that we use directly and indirectly to keep ourselves alive and support our life styles
water that is not directly consumed but is used to produce food and other products
Uneven distribution of renewable freshwater in the US
Eastern states usually have affluent precipitation. Many western and southwestern states have little precipitation.
A large number of water resources are consumed by agricultural and industrial practices
energy production. power plant cooling and manufacturing
The upcoming water shortage problem in the US
Almost half of the water used in the US comes from groundwater resources. The rest comes from the surface water such as rivers, lakes, and reservoirs. The water table drops quickly as the increasing of farm lands and urban areas depletes the surface water.
According to the projection of USGS, in the year 2013, at least ___ US states will possibly face water shortages, resulting in a combination of effects including....
36. Drought, climate change, population growth, urban sprawl, and excessive consumption and waste of water
Long-term projection shows that by 2050...
60 countries, especially those in Asia, are likely to face water stress
__ of the Chinese cities are facing water shortages.
In Egypt, most of the people live in big cities such as Cairo, and the severe water shortage is anticipated to happen around the year...
The accessibility to freshwater is another problem
The UN 2005 report shows that 1.1 billion people lacked regular access to enough clean water. 2.6 billion did not have access to basic sanitation. Most of these situations happen in developing countries where there is fast population growth and urbanization.
Drought is usually caused by...
an extended period of below normal rainfall. Can also result from the reducing of groundwater due to the falling water table, climate change, or the reduction of freshwater availability
Environmental consequences of severe drought:
Dries out soils. reduces stream flows. decreases tree growth and biomass. reduces crop yields.
Between 1979 and 2008...
the areas of the earth experiencing extreme and severe drought became tripled
Currently, approximately __% of the earth's land areas are in drought
Long term projection shows that by the year ____, as much as ___% of the earth's land surface could suffer from extreme drought, mostly as a result of ___________________.
2059. 45. Climate change.
Since _____, except for several wet years, much of the US, particularly the southwest, has experienced...
1999. severe drought coupled with population increase and urban sprawl. According to the 2007 U.N. Intergovernmental Panel on Climate Change report, the drought will continue.
Four possible solutions to increase the supply of freshwater:
Extracting groundwater. building more dams. transferring water from one place to another. converting salty seawater to freshwater.
Advantages of extracting groundwater:
Available for drinking and irrigation. Available year by year. Exists almost everywhere. Aquifers provide drinking water for almost half of the world's population. No evaporation losses. Cheaper to extract than most surface waters.
Disadvantages of extracting groundwater:
Over-pumping causes the aquifer depletion and the sinking of land. Pollution of aquifer. saltwater intrusions into the aquifer. Reduced water flows into surface waters. increased cost and contamination from deeper wells.
In the US, groundwater is withdrawn...
four times faster than it is replenished
California's central valley
Undergoing serious depletion. SUpplies half of the country's fruit and vegetables.
the world's biggest aquifer. Is overdraft.
Supplies about one third of all ground water used in the US. Has helped to turn the Great Plains into one of the world's most productive irrigated agricultural regions. Very low recharge rate.
Economic consequences of groundwater over-pumping:
The resulting higher pumping costs make it too expensive to irrigate crops in some areas. Over-pumping of aquifers limits future food production and increases the gap between the rich and poor in some areas.
Harmful effects of groundwater over-pumping: Land Subsidence
subside or sink of the land. Once an aquifer becomes compressed from subsidence, recharge is impossible. Sinkholes, another kind of land subsidence, can appear suddenly and unexpectedly.
Harmful effects of groundwater over-pumping: Contamination
Groundwater along the coast areas, where many of the world's largest cities and industrial areas are found, can pull salty sea water into the aquifers, making the ground water undrinkable and unusable for irrigation. Rising sea levels from global warming will increase saltwater intrusion and decrease the amount of groundwater available in heavily populated coastal areas.
Prevention of groundwater depletion:
reduce the wasting of water. subsidize water conservation. limit the number of wells. do not grow water-intensive crops in dry areas.
Controlling groundwater depletion:
raise the price of water to discourage waste. tax water pumped from wells near surface waters. set and enforce minimum stream flow levels. diver surface water in wet years to recharge aquifers.
a structure built across a river to control the river's water flow
an artificial lake behind a dam created by the rivers' flow
The purpose of the dam and reservoir system:
To capture and store runoff and release it when needed to control floods. to generate electricity and supply water for irrigation and for towns and cities. Reservoirs provide a location recreational activities.
Advantages of building more dams:
providing irrigation water above and below dam. providing drinking water. reservoir for recreational activities. producing cheap electricity (hydropower). Reducing downstream flooding.
Disadvantages of building more dams:
Flooded land destroys forests or cropland and displaces people. large losses of water through evaporation. depriving downstream cropland and estuaries of nutrient-rich silt. risk of failure and devastating downstream flooding. disrupts migration and spawning of some fish.
How to transfer water:
Tunnels, aqueducts, and underground pipes can transfer stream runoff collected by dams and reservoirs from water-rich areas to water-poor areas
Advantages of transferring water:
Can greatly increase the water supply in water-poor areas
Disadvantages of transferring water:
Can disrupt the ecosystems
the process of converting salty water to fresh drinking water. involves removing dissolved salts from ocean water or from brackish water in aquifers or lakes for domestic use
Advantages of desalination:
Another way to increase the fresh water supply
Disadvantages of desalination
Costly. The resulting salty brine must be disposed of without harming aquatic or terrestrial ecosystems.
Some areas have too much water due to the natural flooding by streams, caused mostly by heavy rain or rapidly melting snow. A flood occurs when water in a stream overflows its normal channel and spills into the adjacent area (a floodplain).
How to reduce the threat of flooding?
Protecting more wetlands and natural vegetation in watersheds. Not building in areas subject to frequent flooding.
Ways to use water more sustainably
Reduce water waste in irrigation use, industrial use, and at home. Raise water prices. Slow the population growth. Protect aquifers, forests, and other ecosystems that store and release water.
Solutions to reducing irrigation water waste:
line canals ringing water to irrigation ditches. irrigate at night to reduce evaporation. monitor soil moisture to add water only when necessary. grow several crops on each plot of land (polyculture). encourage organic farming. avoid growing water-thirsty crops in dry areas. irrigate with treated waste water. import water-intensive crops and meat.
Solutions for more sustainable water use:
waste less water and subsidize water conservation. do not deplete aquifers. preserve water quality. protect forests, wetlands, mountain glaciers, watersheds, and other natural systems that store and release water. Get agreements among regions and countries sharing surface water resources. raise water prices. slow population growth.
Solutions for reducing water waste:
redesign manufacturing processes to use less water. recycle water in industry. landscape yards with plants that require little water. use drip irrigation. fix water leaks. use water meters. raise water prices. use waterless composting toilets. require water conservation in water-short cities. use water-saving toilets, shower heads, and front-loading clothes washers. Collect and reuse household water to irrigate lawns and non-edible plants. purify and reuse water for houses, apartments, and office buildings.
Reducing flood damage: prevention
preserve forests on watersheds. preserve and restore wetlands in floodplains. tax development on floodplains. use floodplains primarily for recharging aquifers, sustainable agriculture, and forestry.
Reducing flood damage: control
straighten and deepen streams (channelization). Build levees or flood walls along streams. Build dams.
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