Hydrology of Canada & Envr changes Flashcards
Wet agricultural regions location, problem and solution & benefit
location: some areas of Qc, Ontario and Prairies
problem: high water table, with soil too wet for heavy machinery and excess water causing plant growth stress
solution: subsurface water drainage (tile drainage) to lower water table by installing pipes parallel to ground surface
benefit: allow denser & deeper root for crops -> increasing yields
impact of tile drainage on watershed
-an extra flow pathways
-changes runoff pathways = less SSSF and SOF
-Decreases GW recharge
-can enhance nutrient export to streams
flat agricultural region peculiarities and seasonal dynamics
peculiarities:
-flat topography
-winter dynamics
-soils at variable depths
-fractured bedrock
- man-made drains & reservoirs
seasonal dynamics:
-early spring: infiltration excess -> frozen soil have low infiltration
-wet summer: saturation excess -> soils are water saturated
-dry summer & fall /late spring: less overland flow -> better infiltration
permafrost definition
ground that remains at or below 0 degree Celsius at least 2 consecutive years
active layer definition and runoff generation
def: soil layer above permafrost that freezes & thaws seasonally
runoff: SSSF depending on depth of soil & vegetation
permafrost hydrologic cycle
some infiltration excess when surface is frozen
crack between talik & active layer -> some water going below permafrost and recharging GW
Canadian wetlands definition and 5 types
def: land seasonally or permanently covered by shallow water, including land where water table is at or close to the surface, causing the formation of hydric soils and favorizing the dominance of hydrophytic plants
-5 types: marshes, swamps, bogs, fens, shallow open water
peatlands definition, types and layers
-def: terrestrial wetlands in which waterlogged conditions prevent plant material to fully decompose -> net accumulation of peat
-2 types:
Fens: minerotrophic
bog: ombrotrophic
-layers:
Acrotelm: above water table with active decomposition and higher hydraulic conductivity (more SSSF)
Catotelm: below water table with dead plant material and lower hydraulic conductivity
peat accumulation process
waterlogged anoxic condition slowing decomposition rate AND peatland plants being less favorable to decomposition
Prairie Pothole Region definition and characteristics
def: small depressional wetlands left by glacier retreat
characteristics:
-subject to temp between -40 and 40 (extreme temp)
-subject to long period of droughts & deluges
-periodically dry, frozen and exhibiting steep salinity gradients
-geographically isolated from streams
pothole wetlands ecosystem services
-floodwater retention
-water quality improvement -> trap nutrients
-carbon sequestration
-biodiversity islands and corridors
why caring about pothole wetlands
help mitigate flooding and water quality issues BUT human alteration of close basin by drainage lead to export of water and nutrient downstream (flooding & water quality issues)
effect of deforestation on hydrology in Canada
decrease evapotranspiration depending on climate
decrease infiltration depending on management
increase runoff
effect of urbanization on hydrology in Canada
amplified fast runoff because impervious surfaces
chemical and thermal pollution from households and industries
Phosphorus pollution from domestic detergents
effect of agriculture on hydrology in Canada
-IMP: Depends on agricultural techniques
irrigation changing water balance (tile drainage modifying dominant runoff)
export nutrients and pollutants (N & P from fertilizers)
Runoff increase AND worse water quality from wetland drainage
Expected effect of temperature changes on hydrology
increase potential evapotranspiration
smaller proportion of precipitation as snow
earlier snowmelt
reduce freezing of lakes & rivers AND earlier ice break-up
increased melting glaciers and permafrost
expected effects of precipitation changes on hydrology
more global runoff with strong regional and temporal differences
complex change in magnitude, duration, variability and frequency of flow events
more extreme precipitation event affecting dominant runoff generation process
high altitudes region hydrology
glaciers & snow dynamics dominate through melt dynamics
GW flow potentially significant depending on local geology
effect of increase temp at high altitudes
earlier snowmelt & glacier ablation
short term: larger meltwater -> higher river flow in summer
long-term: more snowmelt than snowfall -> glacier retreat/ disappearance
high latitude region hydrology
sub-arctic region dominated by snow cover & permafrost with sparse vegetation
effect of increase temp in high latitude
permafrost melt changing subsurface flow & GW storage
earlier snowmelt changing river flow regimes and flooding patterns
climate-change induced vegetation stress = changes evapotranspiration
higher energy demands leading to more river harnessing for hydropower -> threat to ecological flow
wetlands and lakes hydrology
dominated by high evapotranspiration and GW
climate change effect on wetlands & lakes hydrology
higher evapotranspiration -> lake shrinking into smaller wetlands
small wetlands permanently loss -> loss of nature-based water pollution and flood mitigation AND natural habitat
climate change effects on highly anthropized areas
drier climate -> depleted soil & GW storage requiring more irrigation to support food prod
more withdrawal from river or GW for irrigation causing threat to ecological flow
existing water reservoir becoming less sustainable because higher evaporation
change in flood recurrence interval, rendering some flood control infrastructure obsolete (e.g. shift from snowmelt to rainfall dominated system)
human impact on infiltration
land cover change reducing infiltration rates and defining runoff pathways mechanisms
human impact on precipitation regime
affect fog water input with air pollution -> affect amount & water quality
