Irrigation Methods (College Board AP® Environmental Science): Flashcards
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What is the largest human use of freshwater?
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What is the largest human use of freshwater?
The largest use of freshwater is irrigation, at about 70% of use.
Freshwater makes up only about % of Earth's total water supply.
Freshwater makes up only about 2.5% of Earth's total water supply.
Define furrow irrigation.
Furrow irrigation is where trenches (furrows) are dug between crop rows and filled with water, which seeps into the soil.
True or False?
Industry uses more freshwater than domestic households.
True.
Industry uses about 20% of freshwater, while domestic use accounts for about 10%.
Define waterlogging.
Waterlogging is when excess water saturates the soil, preventing proper drainage.
How much water is lost to evaporation and runoff in furrow irrigation?
About 1/3 of the water is lost to evaporation and runoff in furrow irrigation.
Why does waterlogging harm plant roots?
Waterlogging reduces air spaces in the soil, limiting oxygen so roots cannot perform respiration properly.
True or False?
Furrow irrigation delivers an even amount of water to every plant.
False.
Furrow irrigation causes uneven water distribution, so some plants receive more water than others.
Define flood irrigation.
Flood irrigation is where water is released to flood entire fields, allowing it to soak into the soil.
How can waterlogging be prevented?
Waterlogging can be prevented by improving drainage systems (such as pipes and ditches), using raised beds, or growing water-tolerant plant species.
Which crops are best suited to flood irrigation?
Flood irrigation suits crops such as rice that thrive in standing water on flat fields.
How much water is lost to evaporation and runoff in flood irrigation?
About 1/5 (20%) of the water is lost to evaporation and runoff in flood irrigation.
How can flood irrigation increase soil salinity?
Water evaporates and leaves mineral deposits behind, increasing soil salinity.
Define spray irrigation.
Spray irrigation is where water is pumped through pipes and sprayed over fields using rotating nozzles or sprinklers.
What are the advantages of spray irrigation over flood and furrow irrigation?
Spray irrigation is more efficient and can be used on uneven terrain.
Spray irrigation is because it needs pumps and pressure systems to operate.
Spray irrigation is energy-intensive because it needs pumps and pressure systems to operate.
Define drip irrigation.
Drip irrigation is where perforated hoses release small amounts of water directly to plant roots.
How much water is lost to evaporation and runoff in drip irrigation?
Only about 1/20 (5%) of the water is lost, making drip irrigation the most water-efficient method.
True or False?
Drip irrigation is the most widely used irrigation method because it is the most efficient.
False.
Drip irrigation is not widely used because of its high initial costs.
How does drip irrigation benefit the soil?
Drip irrigation minimizes soil erosion and prevents waterlogging.
What maintenance does drip irrigation require?
Drip irrigation requires regular maintenance to prevent clogging of the hoses.
Define salinization.
Salinization is the accumulation of salts in the soil, which reduces soil fertility and harms plant growth.
How does evaporation cause salinization?
When water evaporates from the soil, it leaves behind salt deposits.
True or False?
Salinization is most severe in cool, humid regions.
False.
Salinization is most severe in hot, arid regions, such as parts of California, Australia, and the Middle East, where water evaporates quickly.
Define aquifer.
An aquifer is an underground layer of permeable rock or sediment that stores and supplies groundwater.
Why are low-lying agricultural lands prone to salinization?
Low-lying lands have higher groundwater levels, so heavy irrigation can make the water table rise and bring dissolved salts to the soil surface.
Rising groundwater brings dissolved salts to the soil surface through action.
Rising groundwater brings dissolved salts to the soil surface through capillary action.
Why are fields with heavy clay soils prone to salinization?
Clay soils prevent proper water infiltration, trapping water and increasing salt deposits.
Define aquifer depletion.
Aquifer depletion is when groundwater is withdrawn faster than it can be naturally replenished.
How does salt stress affect plants?
Salt stress disrupts plant metabolism, reducing water absorption and nutrient uptake, which causes stunted growth, leaf burn, and reduced yields.
How does a salt crust affect crops?
Salt deposits form a hard crust on the soil, making it difficult for plant roots to penetrate.
How does climate change reduce aquifer recharge?
Droughts and reduced precipitation slow recharge, and higher temperatures increase evaporation, reducing available groundwater.
Periodically flushing soil with excess water removes accumulated salts through .
Periodically flushing soil with excess water removes accumulated salts through leaching.
How does drip irrigation help prevent salinization?
Drip irrigation delivers water directly to plant roots, reducing evaporation and salt buildup.
Define land subsidence.
Land subsidence is the sinking of land as underground water-filled spaces collapse after excessive groundwater withdrawal, as in parts of California's Central Valley.
How can crop rotation reduce soil salinity?
Rotating crops with salt-tolerant plants helps because they absorb excess salts from the soil over time.
How does aquifer depletion cause saltwater intrusion?
In coastal areas, depleted aquifers allow saltwater to seep into freshwater supplies, contaminating drinking water, as in Florida.
True or False?
Aquifer depletion makes groundwater cheaper for farmers to extract.
False.
As wells dry up, farmers must drill deeper and use more energy, which increases water costs.
Why is the Ogallala Aquifer being depleted?
Extensive irrigation for crops such as corn, wheat, and soybeans withdraws water much faster than the aquifer recharges.
How can growing cities deplete aquifers?
Cities extract large volumes of groundwater for drinking water and industrial use, and unregulated pumping removes it faster than it recharges.
How could depletion of the Ogallala Aquifer be reduced?
Solutions include more efficient irrigation (drip irrigation or soil moisture monitoring), growing drought-resistant crops, and water conservation policies.
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