05. Water Resources and Aquatic Systems Free Online FlashCards

What is the hydrologic cycle?

The continuous movement of water among the atmosphere, hydrosphere, geosphere, cryosphere, and biosphere, powered mainly by solar energy and gravity.

Where is most freshwater stored?

About 68.7% of freshwater is stored in glaciers, ice caps, and permanent snow; about 30.1% is groundwater.

What is water stress?

Water stress occurs when human and ecological demands approach or exceed available supplies, including because of scarcity, pollution, poor management, or unequal access.

What is the simplified watershed water-budget equation?

P = Q + ET + ΔS, where precipitation equals runoff and stream discharge plus evapotranspiration plus the change in water storage.

What is a watershed?

A watershed is land that drains precipitation and surface water to a common outlet, such as a stream, lake, reservoir, bay, or river mouth.

How do wetlands benefit watersheds?

Wetlands store floodwater, slow runoff, trap sediment, remove or transform nutrients, provide wildlife habitat, and can help recharge groundwater.

What is the water table?

The water table is the upper boundary of the saturated zone, where all connected pore spaces are filled with water.

What is an aquifer?

An aquifer is a permeable layer of sediment or rock that can store and transmit useful quantities of groundwater.

What is an aquitard?

An aquitard is a less-permeable layer that restricts groundwater movement.

What is groundwater overdraft?

Overdraft occurs when groundwater withdrawals exceed long-term recharge.

How can excessive groundwater pumping cause land subsidence?

Land subsidence occurs when excessive pumping lowers groundwater pressure and causes sediments to compact, permanently reducing pore space and storage capacity.

What is consumptive water use?

Consumptive use is withdrawn water that is not returned to its original source because it evaporates, enters products or crops, or is transported elsewhere.