________ controls headwaters of the Nile, thus exerting control over water flow and quality. Sudan has second control of the river. Egypt is vulnerable to both countries because it is dependent on the Nile River.
_____ controls the Jordan River, which supplies it, Joran, and Israel. The 1967 Arab-Israeli war was fought in part over the Jordan River's waters.
______ controls the headwaters of the Tigris and Euphrates rivers. Syria and Iraq also use the rivers.
Water covers this percent of the Earth's surface.
About this percent of our planet's abundant water supply is readily available to us as liquid freshwater in accessible groundwater deposits and in lakes, rivers, and streams.
the movement of water in the seas, in the air, and on land, which is driven by solar energy and gravity
precipitation that infiltrates the ground and percolates downward through voids (pores, fractures, crevices, and other spaces) in soil and rocks. One of our most important sources of freshwater and a key component of the earth's natural capital.
zone of saturation
depth at which voids are filled with water except for an occasional air bubble
boundary between zone of saturation and unsaturation. Rises in wet weather and falls in dry weather.
underground caverns and porous layers of sand, gravel, or bedrock through which groundwater flows.
Groundwater usually moves only a _____ or so per year.
process in which aquifers are replenished naturally by precipitation that percolates downward through soil and rock
process in which aquifers are recharged from the side by nearby rivers and streams
freshwater from precipitation and snowmelt that flows across the earth's land surface and into rivers, streams, lakes, wetlands, estuaries, and ultimately to the oceans
precipitation that does not infiltrate the ground or return to the atmosphere by evaporation
a.k.a. drainage basin, the land from which surface water drains into a particular river, lake, wetland, or other body of water
reliable surface runoff
the amount of surface run-off that we can generally count on as a source of freshwater from year to year; one-third of annual surface runoff
This percent of water volume is fresh.
This percent of freshwater is locked up in ice caps, glaciers, or is buried so deep that it costs too much to extract.
This percent of China's cities are already experiencing water shortages.
aquifer with water table as top
bounded above and below by less permeable beds of rock/clay
a well bored perpendicularly into water-bearing strata lying at an angle, so that natural pressure produces a constant supply of water with little or no pumping; produced when drilling goes to confined aquifer (under pressure)
area of land through which water passes downward or laterally into an aquifer (happens naturally as precipitation percolates downward through soil and rock in natural recharge)
This percent of global surface runoff available is currently used and is projected to double in the next 20 years or so. It is the most ever consumed in humanity.
This percent of the world's reliable runoff is withdrawn.
This percent of water withdrawn annually from rivers, lakes, and aquifers is used to irrigate 16% of crops (much wasted).
This percent of water withdrawn annually from rivers, lakes, and aquifers is used for energy production.
a prolonged period in which precipitation is at least 70% lower and evaporation is higher than normal in an area that is usually not dry
1 out of every _ people lack regular access to enough clean water for drinking, cooking, and washing.
This arid country is water-poor but oil-rich, and it gets 70% of its drinking water at a high cost from the world's largest system for removing salt from seawater, located on its eastern coast.
In the US, groundwater is being withdrawn, on average, _ times faster than it is replenished.
________ Aquifer is the oldest, largest known aquifer. It formed 30,000 yrs. ago as glacier ice melted. It supplies a third of US water and covers part of 8 states.
caused by withdrawing large amounts of water -> sand & rock in aquifers collapse, which causes the land above the aquifer to subside/sink
type of land subsidence. Large craters that form when the roof of an underground cavern collapses after being drained of the groundwater that supports it.
a structure built across a river to control the river's water flow
an artificial lake created by the river's flow behind the dam once it's dammed
Only __ of the planet's 177 longest rivers run freely from their sources to the sea because of dams, excessive water withdrawals, and in some areas, prolonged severe drought
Lake Chad in central Africa has shrunk by this percent since the 1960s.
Three Gorges Dam
This will be the world's largest hydroelectric dam and reservoir.
California Water Project
One of the world's largest water transfer projects; it uses a maze of giant dams, pumps, and aqueducts to transport water from water-rich northern California to water-poor southern California's heavily populated agricultural regions and cities
involves removing dissolved salts from ocean water or from brackish (slightly salty) water in aquifers/lakes for domestic use. It is another way to increase supplies of freshwater.
heating saltwater until it evaporates (leaving behind salts in solid form) and condenses as freshwater
a.k.a. microfiltration; uses high pressure to force saltwater through a membrane filter with pores small enough to remove the salt
This percent of the irrigation water applied throughout the world doesn't reach the targeted crops.
a.k.a. gravity flow, water comes from an aqueduct or nearby river. Delivers more than needed for crop growth. Water loss through evaporation, seepage, and runoff. 50-60% efficiency
a.k.a. trickle irrigation, microirrigation, most efficient method in which above or below ground pipes or tubes deliver water to individual plant's roots. Developed in Israel in 1960s. Too expensive for poor farmers and use on low-value or annual crops, but feasible for high-profit fruit, and small-scale or perennial crops/plants. 80-90% efficiency
a.k.a. low-pressure sprinkler, uses water pumped from underground and sprayed from mobile boom with sprinklers. US farmers in Ogallala Aquifer use this and modified system -> LEPA: 75-95% efficiency, otherwise: 70-80% efficiency