ENV100 Chapter 11: Freshwater Systems + Water Resources

Fresh water

Water that has low salinity (generally, less than about 500 ppm dissolved salts)

• only 2.5% of water in the world

Residence times

Storage times in reservoirs in the hydrologic cycle

WHat is the largest reservoir in the hydrosphere?

The ocean

Tributary

A smaller river that flows into a larger one

Drainage basin

Area of land drained by one river and its tributaries; sometimes called a catchment

Watershed

The boundaries that delineate a drainage basin; the drainage basin and all of its component parts, including the physical (abiotic) resources, ecological communities, and human occupants and uses of the area

Floodplain

The region of land over which a river has historically wandered, and which is periodically inundated

Riparian

Relating to a river or the area along a river

Upstream area

Near the source of the stream

Downstream area

Farther along the river’s course

Wetland

A system that combines elements of fresh water and dry land; usually there is standing water for at least part of the year

• biologically productive systems include freshwater marshes, swamps, peatlands, fens, bogs, and shallow-water wetlands such as vernal pools

Environments in which wetlands occur

• palustrine (inland)

• fluvial, riparian, or riverine (related to a river)

• lacustrine (related to a lake)

• estuarine (related to an estuary)

• coastal or marine (related to an oceanic coastal zone)

Canadian Wetlands Classifcation System

System where wetlands are grouped into five classes based on their broad characteristics and the environment in which they occur

Five classes are:

1. Marsh

2. Swamp

3. Bog

4. Fen

5. Shallow open water

Form

Specific characteristics of the specific vegetation communities that they host

• wetland classification

Type

Each form/combination can be described according to the specific vegetation communities that they host

• wetland classification

Marsh

A type of wetland in which shallow water allows grasses and seasonal herbaceous plants to grow above the water’s surface

Swamp

A type of wetland consisting of shallow water rich with vegetation, occurring in a forested area

Bog

A type of wetland in which a pond is thoroughly covered with a thick, floating mat of vegetation

• peatlands

• mineral-poor and slightly acidic

Shallow-water wetlands

A wetland with some open, flowing, or standing water

• includes ponds, sloughs, oxbows, and vernal pools

Fen

A type of wetland covered with a thick mat of vegetation, and fed by ground water

• mineral-rich from their association with ground water (typically contains lots of dissolved minerals)

Freshwater marshes

Riverine marshes, lacustrine marshes, wet meadows

Marshes that contain brackish water

Tidal and estuarine marshes

Salt water marsh

Salt marsh

Ephemeral

Short-lived or seasonal

Limnetic zone/photic zone

In a water body, the layer of open water through which sunlight penetrates

• open, sunlit water where photosynthesis takes place

• supports phytoplanton + zooplankton (both are eaten by fish)

• sunlight intensity/water temperature decreases with depth

• clear water allows sunlight to penetrate deeply, turbid water does not

Profundal zone/aphotic zone

In a water body, the volume of open water that sunlight does not reach

• only present in the deepest lakes

• lacks plant life, is lower in dissolved oxygen and supports fewer animals

Benthic zone

The bottom of a water body, including the lowermost layer of water and the bottom sediments

• muddy, rich in detritus and nutrients, and low in oxygen

• many invertebrates live in the mud on the bottom, feeding on detritus/preying on one another

Littoral zone

The region ringing the edge of a water body

• emergent plants grow in shallow water around the shoreline

• rich in invertebrates (insect larvae, snails, and crayfish)

• fish, birds, turtles and amphibians feed

Oligotrophic

Term describing a water body that has low-nutrient and (typically) high-oxygen conditions

Eutrophic

Term describing a water body that has high-nutrient and (typically) low-oxygen conditions

Groundwater

Water held in aquifers underground

Aquifer

An underground reservoir of water, typically a permeable rock or sediment unit

Water table

The upper limit of ground water held in an aquifer

Zone of aeration

An aquifer’s upper layer that consists of rock or sediment in which the pore spaces are only partly filled with water

Zone of saturation

An aquifer’s lower layer where the spaces are completely filled with water

Confined aquifer/artesian aquifer

A water-bearing, porous, and permeable layer of rock, sand, or gravel that is trapped between an upper and lower layer of less permeable substrate, such as clay or unfractured rock

• the water is under pressure because it is trapped between two impermeable layers

Unconfined aquifer

A water-bearing, porous, and permeable layer of rock, sand, or gravel that lies atop a less-permeable substrate

• the water is not under pressure because there is no impermeable upper layer to confine it

Recharge zone

An area where precipitation falls and infiltrates the ground, percolating downward to eventually join and replenish ground water in an aquifer

Discharge zone

An area where ground water emerges from the subsurface and flows out on the surface to become or join a surface water body

Diversion of water

Removing water from a river system or changing its flow for use in another location

Consumptive use

When we remove water from an aquifer or surfacewater body and do not return it

Nonconsumptive use

Use of water that does not remove, or only temporarily removes, water from the aquifer or surfacewater body

Channelization

Modification of a river’s channel or banks by straightening, widening, or concrete-lining, usually for the purposes of navigation, flood control, or diversion for irrigation or water supply

Dam

Any obstruction placed in a river or stream to block the flow of water so that water can be stored in a reservoir

• built to prevent floods, provide drinking water, facilitate irrigation, and generate electricity

Sinkhole

An area where the ground has given way with little warning as a result of subsidence

• especially in areas underlain by soluble carbonate (limestone) bedrock, and often associated with depression of the water table or depletion of an underlying aquifer

Transboundary waterways

Waterways that cross or flow along national borders + disagreements are common

Desalinization

The removal of salt from sea water or from soil

Reverse osmosis

A method involves forcing water through membranes to filter out salts

Product lifestyle analysis

Concept in which all of the environmental inputs into a product, from beginning to end, are taken into consideration

Pollution

Any matter or energy released into the environment that causes undesirable impacts on the health and well-being of humans or other organisms

• can be physical, chemical, biological, or thermal, and can affect water, air, or soil

Point source

A specific spot—such as a factory’s smokestacks—where large quantities of pollutants are discharged

Nonpoint source

A diffuse source of pollutants, often consisting of many small sources

Eutrophication

The process of nutrient enrichment, increased production of organic matter, and subsequent ecosystem degradation

• abundant algae + high nutrient content

• pollution of freshwater bodies by excess nutrients accelerates this process

Hypoxia

A state of oxygen deficiency

• clear and low nutrient content may eventually become a eutrophic water body

Oligotrophic

Term describing a water body that has low-nutrient and (typically) high-oxygen conditions

Water quality

The suitability of water for various purposes (such as drinking or swimming), as determined by comparing the water’s physical, chemical, and biological characteristics with a set of predetermined standards

End-of-pipe

A response to pollution that deals only with effluents as they emerge from the “end of the pipe,” rather than reducing or eliminating the pollution at its source

Waste water

Water that is used in households, businesses, industries, or public facilities and is then drained or flushed down pipes, as well as polluted runoff from streets and storm drains; effluent

Septic system

A wastewater disposal method, common in rural areas, consisting of an underground tank and series of drainpipes

• waste water runs from the house to the tank, where solids precipitate out

• water proceeds downhill to a drain field of perforated pipes laid horizontally in gravel-filled trenches, where microbes decompose the remaining waste

Primary treatment

At a treatment facility, the physical removal of contaminants in settling tanks or clarifiers, generally removes about 60% of suspended solids from waste water

Secondary treatment

At a treatment facility. when water is stirred and aerated so that aerobic bacteria degrade organic pollutants

Effluent

Water that flows out of a facility such as a wastewater treatment plant, mine, or power plant

Grey water

Water that has been through some treatment, or was only lightly soiled to begin with

Remediation

Removing pollutants from contaminated ground water; cleaning or restoring a degraded habitat, environment, or ecosystem

Pump-and-treat

An approach to groundwater remediation that involves pumping out contaminated ground water, cleaning it in a surface facility, and then (typically) pumping it back into the aquifer

Constructed wetlands (artificial or engineered)

A wetland that is built, usually for the purpose of stormwater runoff management or wastewater management

What percentage of Earth's water is readily available for human use, and how is its availability characterized?

• Only about 1% of all water on Earth is readily available for human use

• Water availability varies spatially and temporally and is often mismatched with population distribution

What are the major human uses of fresh water?

• Agriculture (70% of the fresh water globally)

• Industry

• Residential purposes

Why is a functioning hydrologic cycle vital?

• crucial not only for human needs

• also for maintaining ecosystem integrity

• performs many essential environmental services

How might climate change impact the hydrologic cycle?

• Climate change is expected to alter the hydrologic cycle

• Potentially leading to water shortages in some regions

• Impacting water distribution and availability

What are the characteristics and roles of rivers and streams in freshwater ecosystems?

• Rivers and streams carry water and sediment towards the ocean

• They play a key role in modifying landscapes through erosion and deposition

What are the five main classes of wetlands, and what roles do they play?

• Marshes, swamps, bogs, fens, and shallow-water wetlands

• Occur in various physical environments and provide crucial ecosystem services and diverse habitats

What are the different zones of lake water?

• the littoral (near shore)

• limnetic (open water)

• benthic (lake bottom)

• in large, deep lakes: the profundal zone

What is ground water and how does it function in the freshwater ecosystem?

• Ground water resides in the pore spaces and cracks of subsurface aquifers

• It's replenished in recharge zones by precipitation and infiltration and flows out at discharge zones, joining surface water bodies.

What are the environmental impacts of diverting or withdrawing water from freshwater systems?

Diverting or withdrawing water from river channels, surface water bodies, or aquifers can lead to unintended environmental impacts, often worse in downstream areas

What is the impact of damming on rivers?

• Most of the world's large rivers are dammed, bringing diverse benefits and costs that are environmental, social, and economic

• Other interventions include dikes, floodways, and levees for flood control

How have wetlands been altered by human activities?

• Wetlands have been extensively drained and in-filled for agriculture and coastal development

• The Ramsar Convention is an international agreement to protect wetlands

Why is agriculture the biggest user of water?

• Agriculture is the largest consumer of water

• Primarily due to inefficient irrigation systems which lead to excessive water use

What are the challenges associated with using ground water?

• Ground water, being hidden and hard to monitor, is vulnerable to depletion due to its slow rate of recharge

• Some aquifers are easily depleted

What are the impacts of bottled water on the environment and health?

• Bottled water can contribute to groundwater depletion and generates significant plastic waste

• Bottled water is not necessarily healthier than tap water and may sometimes be worse

What are the primary strategies to address the depletion of fresh water?

• Increasing supply, such as by piping water from abundant areas

• Reducing demand through conservation and efficiency

What role does desalination play in creating fresh water, and what are its limitations?

• Desalination is the only method to "make" more fresh water

• Expensive solution, limiting its widespread application

How can agricultural water demand be reduced?

High-efficiency irrigation, which directs water precisely to plant roots

What personal choices can contribute to water conservation?

• Eating less meat

• Using xeriscaping

• Installing water-efficient toilets

How do water-efficient practices benefit industries?

• Not only conserve water

• Also save money

What are market-based strategies for encouraging water conservation?

• Full-cost pricing

• The virtual water concept includes water use as a critical part of the manufacturing process

What are the two main types of sources of water pollution?

• Point sources (specific, identifiable sources)

• Nonpoint sources (diffuse, often from runoff)

What are common pollutants found in water?

• excessive nutrients

• microbial pathogens

• toxic chemicals

• sediment

• thermal pollution

What indicators are used to monitor water quality?

• biological, chemical, and physical

• the presence of fecal coliform bacteria

• pH and hardness

• turbidity

How does ground water pollution compare to surface water pollution?

• Ground water is subject to many of the same pollutants as surface water

• Ground water pollution can be more persistent and much harder to detect

How has legislation influenced water quality in developed nations?

• Legislation and regulation have significantly improved water quality in developed nations

• Although there are concerns about recent legislative changes weakening aquatic system protections, such as in Canada

What is the status of global access to improved drinking water and sanitation?

• Nearly a billion people worldwide still lack access to improved drinking water and sanitation

• Despite these being goals in the Millennium Development Goals

How are septic systems and municipal treatment facilities used in wastewater management?

• Septic systems treat wastewater in rural areas

• Municipal treatment facilities use physical, biological, and chemical processes

• Treated effluent can be released or reused for urban irrigation or groundwater recharge

What challenges and approaches exist for remediating contaminated ground water?

• Remediation of contaminated ground water is challenging and involves various chemical, physical, and biological technologies

• Either in situ or through pump-and-treat methods

What role do artificial wetlands play in wastewater treatment?

Artificial wetlands can enhance wastewater treatment and simultaneously restore habitat for wildlife