AP Environmental: Ch. 13
define gray water.
the relatively clean waste water from baths, sinks, washing machines, and other kitchen appliances.
identify the benefits of a flood plan.
Fertile soils; nearby rivers for use and recreation Flatlands for urbanization and farming
explain reliable runoff and its distribution of usage.
Reliable runoff: Remaining ⅓ on which we can rely Distribution: Used of freshwater withdrawn from lakes, rivers, and aquifers Worldwide averages Domestic: 10% Agriculture: 70% Industrial use: 20%
list ways to prevent and control flooding.
Rely more on nature's systems Wetlands Natural vegetation in watersheds Rely less on engineering devices Dams Levees Channelized streams
compare the traditional spray irrigation systems and flood irrigation systems.
Traditional Spray Sprays huge volumes of water onto large fields wasteful, 40% of water is lost Flood Irrigation Water pumped from groundwater or surface water through ditches where it flows by gravity to crops Wasteful; 45% of water is lost to evaporation, seepage and runoff
explain what causes a flood.
Usually caused by heavy rain or rapidly melting snow
list the ways by which to increase our freshwater supply.
Withdrawing groundwater Building dams and reservoirs Transporting surface water Converting saltwater to freshwater
define zone of saturation, water table, and aquifer.
Zone of saturation: Spaces in soil are filled with water Water table: Top of zone of saturation Aquifers: Deeper down underground caverns and porous layers of sand, gravel, or rock through which groundwater flows
identify the advantages and disadvantages of using large dams.
Advantages: Provides irrigation water above and below the dam Provides water for drinking Reservoir useful for recreation and fishing Can produce cheap electricity (hydropower) Reduce downstream flooding of cities and farms Disadvantages: Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Deprives downstream cropland and estuaries of nutrient- rich silt Risk of failure and devastating downstream flooding Disrupts migration and spawning of some fish
list the advantages and disadvantages towards withdrawing groundwater.
Advantages: Useful for drinking and irrigation Exists almost everywhere Renewable if not over pumped or contaminated Cheaper to extract than most surface waters Disadvantages: Aquifer depletion from over pumping Sinking of land from over pumping Some deeper wells are nonrenewable Pollution of aquifers
compare the improved systems of irrigation: center pivot low pressure sprinkler, low energy precision application sprinklers, and drop or trickle microirrigation.
Center-pivot, low pressure Uses pumps to spray water on a crop; more crop per drop & uses low pressure 80% efficiency Drip, trickle, microirrigation Consists of small tubing that delivers drops of water at a slow, steady rate The most efficient Center-pivot, low-energy, precision application Uses pumps to spray water; puts water where it's needed 90% efficiency
explain how water transfers can be inefficient and environmentally harmful.
China South-North Water Diversion Project North China has high urban population which have depleted aquifers and led to pollution in 40% of rivers; 300 million rural residents do not have access to clean water Project diverts six trillion gallons of water per year from Yangtze River in southern China to the thirsty north; serves 440 million Chinese Problems: Quite expensive 350,000 villagers have to relocate to low-grade farms or urban areas Yangtze River ecosystem could be severely damaged, especially with drought California California State Water Project Uses giant dams, pumps, and aqueducts are used to transport water from the High Sierra Mountain of NE Cali to heavily populated cities and agricultural regions in SO Cali Supplies half of US fruits and veggies! Helps San Diego and LA populations, too Problems: Degraded Sacramento River Bay has suffered pollution Flow of freshwater to coastal marshes and other ecosystems has declined
explain the process of desalination and the problems associated with it.
Desalination Removing dissolved salts 1. Distillation: Evaporate water, leaving salts behind 2. Reverse osmosis, microfiltration Use high pressure and filter through membrane to remove salts Problems 1. High cost and energy footprint 2. Keeps down algal growth and kills many marine organisms 3. Large quantity of brine wastes
list the factors leading to water scarcity.
Dry climates Drought Too many people using a normal supply of water Wasteful use of water
explain how human activities can worse a flood.
Levees can break or be over-topped Paving and development increase runoff Removal of water-absorbing vegetation Draining wetlands and building on them Rising sea levels from global warming means more coastal flooding
outline the main goal of a dam and reservoir system.
Main goal of a dam and reservoir system: Capture and store runoff Release runoff as needed to control Floods Generate electricity Supply irrigation water Recreation (reservoirs)
define virtual water.
Not consumed; use to produce food and other products
explain the issues associated with using deep aquifers.
Slow recharge
define surface runoff and watershed.
Surface Runoff: Precipitation that does not infiltrate the ground or return to the atmosphere (39% of all precipitation) Watershed: Land from which surface water drains into a particular stream, lake, wetland
