What are the two key concepts for this section? Define freshwater. Explain why access to water is a health issue, an economic issue, a national and global security issue, and an environmental issue....

What are the two key concepts for this section? Define freshwater. Explain why access to water is a health issue, an economic issue, a national and global security issue, and an environmental issue. What percentage of the earth’s freshwater is available to us? Describe how water is recycled by the hydrologic cycle and how human activities can interfere with this cycle. Define groundwater, zone of saturation, water table, and aquifer, and explain how aquifers are recharged. Define and distinguish between surface water and surface runoff. What is a watershed (drainage basin)?