Module 9 - Chapter 10 - Water: Hydrologic Cycle and Human Use

Describe how water demands might be reduced in agriculture, industry, and households.

Agriculture can use less water by using a surge flow method, in which computers control the periodic release of water or drip irrigation systems. Industry and homes can use less water by using toilets that require less water, putting in xeriscaping, replacing leaking faucets, replacing faucets with low-flow alternatives, and using water displacement devices. Gray water (from showers, sinks, bathroom, and laundry) can be used for irrigation.

How does changing the earth's surface (for example, by deforestation) change the pathway of water? How does it affect streams and rivers? Humans? Natural ecology?

As forests are cleared or land is overgrazed and plants are not there to intercept rainfall, the pathway of the water cycle is shifted from infiltration and groundwater recharge to runoff, and the water runs into streams or rivers almost immediately. This cause floods, surface erosion, sediment, and other pollutants.

Distinguish between renewable and nonrenewable groundwater resources. What are the consequences of overdrawing these two kinds of groundwater?

Groundwater more than 3/4th's that has a recharge rate of centuries or more is considered nonrenewable. Renewable groundwater is replenished by the percolation of precipitation water, so it's vulnerable to variations in precipitation. Groundwater that's use exceeds aquifer recharge, leading to shortages as the water table drops below pump levels.

How do dams facilitate the control of surface waters? What kinds of impacts do they have?

If you dam something up, you control the height of the lake/river/etc. This can have big impacts on the migration patterns of certain animals. If this is a river, perhaps fish try to swim into the dam. Also, if the lake normally dries up, you are eliminating the species who would use the land then. This also has growing effects on the animals that rely on the previous animals I spoke of.

Give a full description of the hydrologic cycle, including each of its three loops—namely, the evapotranspiration, surface runoff, and groundwater loops.

In the evapotranspiration loop (consisting of green water), the water evaporates and is returned by precipitation. In the surface runoff loop (containing blue water), the water runs across the ground surface and becomes part of the surface water system. In the groundwater loop (also containing blue water), the water infiltrates, percolates down to join the groundwater, and then moves through aquifers, finally exiting through seeps, springs, or wells, where it rejoins with surface water.

Define precipitation, infiltration, runoff, capillary water, transpiration, evapotranspiration, percolation, gravitational water, groundwater, water table, aquifer, recharge area, seep, and spring.

Precipitation: any form of water that falls from clouds and reaches Earth's surface. Infiltration: the process of water soaking into the soil. Runoff: is the flow of water that occurs when excess storm water, melt water, or other sources flows over the earth's surface. Capillary water: is water held by surface tension to soil particles, but it can move through pores in response to moisture gradients. Transpiration: the loss of water as it moves from the soil through green plants and exits through their leaf pores. Evapotranspiration: The evaporation of water from soil plus the transpiration of water from plants. Percolation: passage of a liquid through the spaces of a porous material such as soil. Gravitational water: water in a soil that percolates through to the water table. Groundwater: is the water located beneath Earth's surface in soil pore spaces and in the fractures of rock formations. Water table: the upper surface of of ground water. Aquifer: underground places where water collects. Recharge area: area where water enters the aquifer. Seep: pass gradually or leak through or as if through small openings. Spring: a natural flow of ground water.

What are the two processes that result in natural water purification? State the difference between them. Distinguish between green water and blue water.

The processes of evaporation and condensation purify water naturally. When water evaporates only the water molecules leave the surface and when the water condenses again it is thus purified water.

Describe how a Hadley cell works, and explain how Earth's rotation creates the trade winds.

They work as warm air rises, and moves away to a region of low pressure. As the air moves away the air cools, becomes more dense and falls back to earth. As this air nears the ground it is heated again and moves towards the low pressure area caused by the rising air. Trade winds are a result of the earth's rotation relative to the movement of the air cells.

What are the three major uses of water? What are the major sources of water to match these uses?

Uses of Water: agriculture (irrigation), industry, domestic, animal habitat, recreation, power generation, borders and boundaries. Sources of Water: surface water, under river flow, ground water, desalination, and frozen water.

Give examples of the infrastructure that has been fashioned to manage water resources. What are the challenges related to developing countries?

We have built dams, canals, reservoirs, aqueducts, sewer systems, treatment plants, water towers, elaborate pipelines, irrigation systems, and desalination plants. 1.1 billion people still lack access to safe drinking water, 2.6 billion people don't have adequate sanitation services, and more than 1.8 million deaths are traced back to waterborne diseases.