Chapter 12: Water

Water on Earth

  • Water is an important part of the environment
  • Earth is a blue planet, because on earth there is proof that water exists
  • Water shapes the surface of the earth, it allows for life
  • Makes earth different from all other planets
  • Water exists in 3 states:
  1. Solid
  2. Liquid
  3. Gas
  • Exists in the atmosphere, on the surface, and under the ground


Water in Atmosphere

  • Water is an important component as it moves heat from equator to poles through processes such as evaporation, where water enters the atmosphere as vapour, through which it regulates heat around the earth.
  • It rises as vapour, and falls as rain/snow through precipitation


Water on Surface

  • Ocean currents
  • Sculpts terrestrial landscape
  • Acts as a carrier for many substances

Water in the Mantle

  • Water is locked up in minerals in the earth’s mantle
  • Makes the mantle elastic and flexible, which affects the dynamics of plate tectonics
  • Water, therefore, is a dynamic component of Earth


Hydrology

  • Means ‘water science’
  • Refers to the study of water in the hydrosphere, both on the surface of the earth and underground
  • Includes studying movement, distribution, quantity and quality of water
  • Also includes studying reservoirs, processes, and ecosystems of the hydrosphere


Drinking Water

  • Water is abundant but drinking water is rare
  • Most water one Earth is in oceans, but most fresh water is tied up in ice
  • Fresh water has few dissolved salts
  • Surface fresh water tends to be in lakes mostly
  • Managing and maintain freshwater systems involves:
  • Integrity of freshwater ecosystems
  • Knowing and managing the quantity and quality of water for drinking and other uses
  • Earth is not a 100% closed system, which means our water can be affected from the outside


Hydrologic Cycle from a Systems Perspective

Reservoirs

  • Include oceans, ice caps and glaciers, and then groundwater

Processes

  • Includes precipitation, surface runoff, infiltration, percolation, evaporation, transpiration

Fluxes

  • The global hydrologic cycle maintains mass balance, which means the total amount of water is fixed
  • Local variations affect supply, and cause problems like floods and droughts


Solar Energy & Gravity & the Hydrologic Cycle

  • Solar energy drives and engines processes such as evaporation, transpiration, condensation.
  • Gravity drives precipitation, runoff, groundwater percolation


Surface Freshwater

  • Includes rivers and streams, springs, lakes and ponds, wetlands, etc.
  • Tends to be mostly in lakes


Rivers Shape the Landscape

  • Due to rivers, water from rain, snowmelt, and springs tend to run off over the surface
  • Surface runoff (sheet flow) organizes into rills and gullies, then streams and rivers

Tributary - refers to a smaller river flowing into a larger one

  • Due to the work of erosion, rivers carry remains of water to the ocean

Drainage Basin

  • A drainage basin is a local hydrologic unit
  • Drainage basin or catchment or watershed is the area ordained by one river
  • Catchments are separated from one another by divides


Catchments Inputs & Outputs

  • Inputs == Outputs
  • More specifically: P == R ++ ET ++ S, where:
  • P = precipitation
  • R = runoff (+ infiltration/percolation)
  • ET = evaporation + transpiration
  • S = storage in lakes, aquifers, etc.


Groundwater

  • Groundwater is located beneath the Earth’s surface in soil pore spaces and in fractures of rock formations
  • Largest form of unfrozen freshwater reservoir

Aquifer - Underground reservoir of rock and sediment and is the second largest reservoir of water after glaciers

  • Confined Aquifer - Between impermeable layers
  • Unconfined Aquifer - Water seeps in from above
  • Residence time in an aquifer may be thousands of years
  • Canada has much more water underground than on the surface
  • Aquifers store and transmit water

Porosity- Is the % pore space

Permeability- Refers to the interconnectedness of the pores

Aerated Zone - Includes some air and some water, located at the top (soil moisture)

Saturated Zone - Zone which is the completely filled with water (ex: groundwater)

Water Table - Located on top of the saturated zone

  • Groundwater moves down from the surface to the saturated zone
  • Think of it like a sponge \rightarrow The top part is the zone of aeration, the bottom part is the zone or saturation and everything in the middle is the water table

Groundwater Flow

  • Is controlled by gravity
  • Water table mimics topography because where water table intersects, it equals surface water

Recharge - Water flows into an aquifer (underground reservoir) through precipitation/ infiltration

Discharge - Water flows out of an aquifer into streams, oceans, and springs.

  • Canada tends to use its water mainly for industrial purposes
  • India \rightarrow agriculture
  • Lithuania \rightarrow  domestic
  • Many areas with high population density are water poor and face serious water shortages
  • Water exceeds supply in many areas of the world, including Canada

Global Water Management Challenges

  • Urban and rural drinking water sanitation
  • Water for industry and agriculture purposes
  • The protection of aquatic ecosystems
  • “Holistic” watershed management
  • Impacts of environmental change on water resources


Environmental Impacts of Human Use of Surface Water

  • Surface water being used by humans has significant environmental impacts:
  • When humans use rivers, the environmental impacts may be downstream and transboundary. Meaning the pollution causes damage to a different place from where it originated
  • Decreased flow of water in such rivers and lakes may be another environmental impact as we take water out from such places
  • Human use of surface water can change how fast erosion might occur and siltation rates as we alter the shape and so forth when we extract water from such places
  • May be changes in water salinity because of humans extracting water it may change how much soil is getting into the water if you change the level of the water, therefore changing salt levels which may have an effect on some organisms
  • Creating reservoirs and increasing irrigation increases evaporation as you are spreading water over a larger area, which therefore leads to loss of water
  • Environmental impacts of human use of surface water also include impacts on habitat, wildlife, ecosystems
  • Also causes pollution and eutrophication
  • In conclusion, whenever we affect flowing water, we are effecting the hydrological cycle and all kinds of things related to it in the whole catchments


Dams

  • We have erected thousands of dams

Dam - Refers to obstruction which blocks the flow of water in a river so the water can be stored in a reservoir

  • Not always constructed for water to be stored in a reservoir, sometimes they are done to create a higher fall of water for hydro-electrical purposes, to extract water easily, for agricultural purposes, etc.

Diversion dam - When water is diverted but is not stored in a reservoir

  • Dams are done to prevent floods provide drinking water, allow irrigation, generate electricity

Problems

Dams are that their affects on large rivers such as changing the flow of water, and affects the hydrologic cycle

Rivers are Ecologically Complex

Different organisms adapted to different areas of rivers, different type of vegetation surrounding the river, etc. if you are making changes to such rivers by creating dams, you are changing the speed of the flow of water in the river, the temperature of the river, the Ph of the river, etc.

Benefits

  • Power generation - less reliant on fossil fuels
  • Emission reduction
  • Crop irrigation
  • Drinking water flood control
  • Shipping
  • New recreational opportunities: artificial lakes created through impoundments, etc.

Drawbacks

  • Dams need to be better planned when made
  • Habitat Alteration - Affects habitats by changing and creating habitats which originally existed
  • Fisheries decline
  • Population displacement
  • Sediment Capture - May cause sediment clogging in river
  • Waterlogged land (saturation of soil with water)
  • Risk of dam failure
  • Lost recreational opportunities

Dam Removal (decommissioning)

  • Removing damns restores riparian ecosystems fisheries river recreation


Inefficient Irrigation Wastes Water

  • Today more water tends to be withdrawn for irrigation purposes, today the amount of irrigated land has doubled

The Aral Sea

  • A case study of diversion
  • It once was the 4th largest lake on Earth
  • Lost 80% of volume due to the diversion of two input rivers
  • Because of this 60k fishing jobs were lost


Environmental Impacts of Groundwater Use

Depletion of Aquifers - Aquifers are underground reservoirs and are charged by runoff, however aquifers commonly recharge from infiltration (penetration) through soils. Aquifers take a while to fill up, which is why if you take more water out; it will reduce the system

  • When the aquifer is depleted you are going to drop the water table, and if there is no water to fill up the aquifer, it leads to a big empty space which is overburden on top of it such as soils and trees - It will collapse dramatically, leading to ground subsidence.
  • Declining water tables
  • Urban flooding
  • Contamination of the aquifer


Cone of Depression

  • As you are withdrawing water from a well, it leads to a cone of depression as the water table starts to drop because you are extracting water from aquifers
  • If discharge is greater than recharge, water table can become depressed, therefore the water table will drop


Climate Change Water Problems and Shortages

  • Changes in precipitation patterns will occur due to climate changes
  • Shift northward in mid-latitude rain belt
  • More evapotranspiration
  • Drier summers in the interior continental regions
  • Warmer rivers (impacting fish)
  • Lower water levels in the great lakes
  • Higher ocean water levels (salinization)


Quality is as Important as Quantity

  • Major pollution has caused a reduction in the quality for our water today

Superfundacites - Areas which have been rehabilitated

Example \rightarrow Cuyahoga River which was rehabilitated after the fire in 1952

Point Sources - Separate locations where pollutants are generated or located

  • Emissions from factories, slaughterhouses, mines, industry effluent, or sewage outfall pipes
  • You can indicate on a map where the pollution is coming from

Non-Point Sources - Multiple cumulative inputs over a large area. Locate din multiple areas

  • Non-point sources are tiny areas which are hard to locate on a map
  • Many small sources together, such as atmospheric fallout from car emissions.


Types of Surface Water Pollution

Nutrient Pollution - From fertilizers etc. causes eutrophication

Pathogens & Waterborne Diseases - Which occur from improperly treated waste: cause disease and death

Toxic Chemicals - From industrial sources which cause genetic somatic damage

Sediment Pollution From agriculture, mining, clear-cut logging, construction; can lead to degraded aquatic habitat, affects light levels

Thermal Pollution - From heat and hot water; kills fish, affects oxygen levels

Sources of Groundwater Pollution

Natural Sources - Mercury from wet lands, fluoride, sulphate, etc.

Anthropogenic Sources - Landfills and other disposal sites, infected tanks which are stored underground could leak, agricultural pollution – nitrates from fertilizers, hazardous wastes, etc.


Groundwater Pollution Management

  • It's particularly difficult
  • Because contaminated groundwater tends to be hidden it makes it difficult to monitor
  • Groundwater can retain contaminants for decades and longer
  • Slow breakdown due to dissolved oxygen levels

Protecting Lakes and Wetlands

Wetlands

  • Wetlands are combination of terrestrial and aquatic environment
  • Wetlands are systems that combine elements of land and water
  • Considered areas of land whose soil is saturated (inundated) permanently, seasonally or tidally
  • some wetlands may be covered partially or completely by shallow pools of water
  • water may be fresh, saline or brackish (salty) – depends on the environment (quality meaning not polluted and so forth)


Marine & Freshwater

Salt Marsh - Water in these area will be salty

Peat Marsh - Water will contain largely fresh water


Wetland Characteristics

Soils

  • Hydric (water saturated)
  • Anaerobic - Refers to the soils that are wet
  • Anaerobic bacteria break things down
  • Lots of organic matter (doesn’t decompose)

Can be parts of a succession

  • Wetland can be part of a temporal sequence
  • They tend not to be permanent part of landscapes and tend to change over time: they may fill in pond areas where vegetation will start growing, etc.
  • Main idea here is that even without the influence of humans, wetlands change over time (they appear and disappear over time)


Types of Wetlands

Marsh

  • Marsh wetlands refer to wetlands with shallow water, which allow plants to grow above water surface (emergent)

Swamp

  • Swamp is a wetland with shallow water which allows both the emergence of vegetation and trees

Bogs & Fens

  • Both of these wetlands have low productivity (low vegetation)
  • Often mineral nutrients limited due to the hydrology around them (not a lot of nutrients come in because of low decomposition)
  • Collect (accumulate) peat (decaying vegetation)
  • Carnivorous plants: digest things to gain nutrients because they cannot gain nutrients from soils

Bogs

  • Bogs tend to be very acidic because most of their water source is rainfall, which can be acidic. Technical term if you are getting you water from rainfall is ambatrophic
  • Bogs water sources is mainly rainfall (ambatrophic)
  • Productivity is lower than fens
  • Elevation is higher than fens
  • Diversity is lower than fens

Fens

  • Fens water source is mainly ground or surface water
  • Have higher productivity than bogs
  • Elevation is lower than bogs
  • Higher diversity than bogs

Peat

  • Forms in acidic, low oxygen conditions, which means decomposition is low
  • Organic matter doesn’t fully decay: builds up
  • The wetter peat is, the faster it accumulates
  • Peat stores massive amount of carbon (due to decaying only partially)
  • Peatlands today are draining (we drain peatlands for agriculture, harvesting purposes)
  • However, draining peatlands is not good for the environment because it drains organic matter and releases massive amounts of carbon dioxide, which has a huge effect on climate change


Wetlands Importance

  • Wetlands are the most biologically diverse and productive ecosystems on Earth (they are the most primary productive ecosystems on Earth)
  • They are considered the ‘kidneys’ of the terrestrial system
  • Also important for breeding and staging ground for migrating species (especially birds)

Environmental Services Performed by Wetlands

  • They slow down runoff and erosions
  • They reduce flooding
  • They buffer shorelines against storms
  • Recharge aquifers
  • Filter pollutants
  • Save sediment and nutrients


Lakes and Ponds

  • Bodies of open, standing water

Lentics - Is a term which refers to slow moving waters

  • Lakes are transient (temporary) features of the landscape
  • For example: no lakes older than 20M years most are a few thousand-year-old. Relatively short-lived components of a landscape
  • Lakes can form through the divergence of plate tectonics, but a lot of lakes form by glaciers (glaciations) as they melt down
  • Formed by recent geological or contemporary processes
  • Kettle lakes are an example of glaciation


Lake Terminology (Different Lake Zones)

The deeper the lake is the more complex its dynamics are

Littoral - Close to shore; emergent vegetation

Limnetic - Light penetrates; high O2

Profundal - No light; lower O2

Benthic - Bottom substrate; low O2


Lakes Variability

Highly variable in space and time

  • Among lakes - differences in productivity
  • Within lakes - Temperature profiles; seasonal variation; spatial variation
  • Vary in temperature and they have seasonal variations (lake frozen in winter but not in summer) as well
  • lakes vary over time, they fill in with sediment over time, whereas they start off with low productivity with a regular clear lake, they start to fill in with natural eutrophication in which more sediment starts to form, resulting in higher productivity (more nutrients entering the lake) in the lake

Lakes Vary in Productivity

  • Oligotrophic - Minimal nutrients
  • Mesotrophic - Intermediate (middle) amount of nutrients
  • Eutrophic - Abundant nutrients


Fertility

  • Related to nutrient availability, age, substrate and climate
  • Young lakes: basin is exposed rock; doesn’t erode quickly; has fewer nutrients
  • Older lakes: more nutrient rich than younger lakes as they have a nutrient rich sediment which washes from watersheds
  • Nutrient levels therefore can provide information to how old a lake may be
  • large lakes tend to function as “inland seas”


Wetlands Drainage Reasons

  • Settlement and development purposes
  • Farming
  • Aquaculture - Raising fishes where wetlands are
  • Drained for mosquito control; seen as useless ‘swamps’
  • Ramsar Site - Refers to the wetlands with international importance


Changes to the National Fisheries Act

  • No longer protects fish habitats
  • Only covers protection of economically important fisheries


Changes to Navigable Water Protection Act

  • Developers and industries building on exempt waterways don’t need to inform the government or require a permit to do so
  • Pipelines are exempted under this law
  • Pipeline impacts on waterways will no longer be subject to environmental assessments


Note Created by
Is this note helpful?
Give kudos to your peers!
00
Wanna make this note your own?
Fork this Note
57 Views