Chapt. 13

4. a barrier constructed to hold back water and raise its level, forming a reservoir used to generate electricity or as a water supply.
7. water that collects on the surface of the ground.
12. the ability to be maintained at a certain rate or level.
14. a large natural or artificial lake used as a source of water supply.
16. naturally occurring water that is not salty, and is suitable for consumption if clean or processed.
17. an area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.

1. supplies
2. the level below which the ground is saturated with water.
3. a prolonged period of abnormally low rainfall, leading to a shortage of water.
5. a body of permeable rock which can contain or transmit groundwater.
6. the process of removing salt from seawater.
8. a large body of water surrounded by land.
9. a large natural stream of water flowing in a channel to the sea, a lake, or another such stream.
10. an area or ridge of land that separates waters flowing to different rivers, basins, or seas
11. water held underground in the soil or in pores and crevices in rock.
13. a measure of the amount of fresh water utilized in the production or supply of the goods and services used by a particular person or group.
15. the draining away of water (or substances carried in it) from the surface of an area of land, a building or structure, etc.