LEC 13: Freshwater Systems and Resources

Freshwater

Water that is relatively pure and free from salts

Ice caps

Frozen freshwater that covers 79% of freshwater systems

Groundwater

Water beneath the surface that resides within pores in soil or rock

Lakes

Bodies of standing surface water in freshwater systems

Water cycle

Renewal and recycling of water as it passes through the atmosphere, land, and bodies of water

Aquifers

Saturated materials that store or transmit sufficient quantities of water for a well

Water table

Upper border of a porous, spongelike formation of rock or sand that contains groundwater

Recharge zone

Area where water can infiltrate through the surface and reach an aquifer

Ogallala Aquifer

Largest known aquifer located under the Great Plains of the United States

Surface water

Water located atop Earth's surface, such as in a river or lake

Runoff

Water that falls from the sky or melts from snow or a glacier and flows over a land surface

Watershed

Area of land drained by a river system and all of its tributaries

Braided river

River that flows as an interconnected series of water courses

Meandering river

River found in flatter regions that forms larger and larger bends

Oxbow river

River with an exaggerated shape due to the shifting course of a meandering river

Freshwater ecosystems

Include streams, rivers, lakes, ponds, and wetlands

Littoral zone

Shallow area along the edges of lakes and ponds where aquatic plants can grow

Benthic zone

Area along the bottom of lakes and ponds

Limnetic zone

Upper layer of water in lakes and ponds that is shallow enough to receive sunlight and allow photosynthesis

Profundal zone

Zone between the benthic and limnetic zone in lakes and ponds that lacks photosynthesis

Oligotrophic lakes

Lakes that are low in nutrients and high in oxygen

Eutrophic lakes

Lakes that have transitioned to high-nutrient, low-oxygen conditions

Wetlands

Systems where the soil is saturated with water, often containing standing shallow water

Freshwater marshes

Wetlands consisting of cattails and bulrushes that grow above the water's surface

Swamps

Wetlands containing standing water and located in forested areas

Bogs

Ponds covered in thick floating mats of vegetation

Vernal pools

Seasonal wetlands that form in the snowmelt of early spring and dry up later in the summer

Water withdrawals

The act of removing water from a source for human use

Aqueducts

Structures that channel water from distant sources to cities or agricultural areas

Dams

Obstructions placed in rivers or streams to block their flow and create reservoirs

Three Gorges Dam

A dam on China's Yangtze River that has complex benefits and consequences

Dam removal

The process of removing dams to restore riparian ecosystems and fisheries

Water scarcity

A condition where the demand for water exceeds the available supply

Desalination

The removal of salt from seawater or other water sources

Water efficiency

Using water more efficiently to reduce demand

Water conservation

Efforts to reduce water use and protect water resources

Water pollution

Changes in the chemical, physical, or biological properties of water due to human activities

Point sources

Discrete locations that release water pollution

Non-point sources

Multiple inputs of water pollution over large areas

Toxic substances

Chemicals released into water sources that can be harmful to organisms

Disease-causing microorganisms

Pathogens that can enter drinking water supplies and cause health problems

Nutrient pollution

Excess nutrients from fertilizers and other sources that cause eutrophication and hypoxia in surface waters

Sediment pollution

Erosion from activities like clear-cutting, mining, and land development that increases sediment in water

Thermal pollution

The addition of warm water to a water source, which can harm native fish species

Biodegradable pollution

Pollution from human waste, animal manure, pulp from paper mills, and yard waste

Wastewater

Water affected by human activities, including water from toilets, sinks, dishwashers, and washing machines

Groundwater pollution

Pollution that affects groundwater, which is slower to decompose contaminants compared to surface water

Clean Water Act

Legislation that set standards for contaminant levels in surface waters and funded construction of sewage treatment plants

Drinking water treatment

Process of treating water from a reservoir or aquifer to remove contaminants before it reaches the tap

Wastewater treatment

Process of treating wastewater to remove contaminants before it is returned to rivers, lakes, or the ocean

Constructed wetlands

Wetlands manipulated or constructed to help cleanse wastewater

Pollution control

Efforts to reduce and prevent water pollution