1. Describe the path a molecule of water might follow through the hydrologic cycle from the ocean to land and back again.
Answer: water evaporates from the oceans to form clouds that are moved over land by prevailing winds and then rainfall brings it to earth where it is returned to oceans by tributaries and rivers.
2. Describe at least one example of the environmental costs of water diversion from rivers to farms and cities.
Answer: Several consequences of river diversion for irrigation are: downstream river discharge is reduced, the evaporation in the overall irrigation region is increased, the groundwater recharge in the region is increased, the level of the water table rises, and the drainage flow is increased. Just in the first category, reduced downstream river discharge, effects can include reduced flooding, disappearance of wetlands and flood forests, reduced availability of potable water, reduced shipping routes, and reduced fishing opportunities.
3. Explain the difference between point and nonpoint pollution. Which is harder to control? Why?
Answer: Non-point source pollution is pollution that comes from a collective of contaminants that cannot be traced to any one source. These would be run-off from agriculture or dumping into a waterway. A point source is pollution that can be traced to one contributor, such as a particular drain pipe from a factory.
4. What changes might occur in the hydrologic cycle if our climate were to warm or cool significantly?
Answer: Warming results in higher ocean levels and more surface area. This results in increased evaporation. This results in more rain. We should see an increase in usable and livable land.
5. Under what conditions might sediment in water or cultural eutrophication be beneficial? How should we balance positive and negative effects?