Concepts Flashcards
what is a model
simplification of reality with essential features
no model is 100% accurate or else it would not be a model, it would be reality
Advantages of modelling
- test knowledge and answer questions of physical phenomena
- integration of knowledge and disciplines
- quantification of variables
- interpretation of data
- ease of scenario analysis
- creation of projects/policies
- predictive capability
knowledge, questions, integration, quantification, interpretation, scenarios, policies, predictions
disadvantages of modelling
- overparameterized
- measurability and generalizations
- may be too inaccurate
- can’t include everything
- uncertainty of predictions
types of models
- empirical
- physical-based
- numerical
- analytical
- deterministic
- stochastic
- fully-distributed
- semi-distributed
empirical based model
- relationships of different variables based on measurements in a specific area
- unique to specific conditions designed for
- correlational and only predict yield
includes extreme events and conditions of one specific area
physical-process based
- real physical relationships based on proven physical laws
- universal and predictive
- not linked with local resources and their relationships
mostly not calibrated or validated
numerical
- approximations
- good for environmental sciences because allows for uncertainties
analytical models
- math that gives exact examples
- bad for earth science because there are no single right answers or solutions
deterministic models
- one single solution given
- bad for es because no room for uncertainty
stochastic
range of solutions given
fully-distributed
- predicts variation across time and regions
- delineate water shed all the way down to grid cells
- lots of computation power required
semi-distributed
- delineates watershed across topographic map into hru’s/subbasins
- delineates watershed across map, not delineates across watershed
model selection based on what?
- objectives
- details and robustness
- cost (incl time)
- literature review to avoid trial and error
importance of modelling
- status (state of water basin)
- trends (historical changes, seasons, etc)
- find relationships between variables
- predictions
- decisions
SWAT
soil water and assessment tool
- watershed scale
- semi-distributed
- physical process based
- hydrologic but cannot simulate groundwater flow and connectivity between watersheds
world water supply distribution
ocean vs fresh water
freshwater distribution
ocean: 96.5%
fresh: 2.5
- glaciers: 69%
- groundwater/aquifers: 30% (mostly permafrost and ice)
- surface/other: 1% (lakes, atmosphere, soil moisture, etc)
renewable water
- 0.4% of freshwater
- snowfall, snowmelt, rainfall
fossil water
- non renewable (not controlled by melt or precipitation)
- 99.6% of freshwater
- glaciers, ice, permafrost, groundwater feeding rivers
overland processes
surface flow outside of a river channel
- evap, et, precip, infiltration
- surface runoff
- lateral/subsurface flow
- groundwater recharge/percolation
T/F: there can be both fossil and renewable water in the same aquifer
true
what are the boundaries of a watershed
highest elevation that can drain int a catchment/basin
- not governed by political borders, topographic
what type of boundaries do transboundary rivers flow across
political borders
Canada water distribution
freshwater, renewable, fossil
- 20% of world’s freshwater
- 7% of that is renewable
- 13% is fossil
we have large internal water availability and inflow
Alberta water trends
- lowest precipitation in south and drier in south due to wter demand for economy
- most snowfall/BW along mountains
- ET is similar or higher than blue water in most river basins
Alberta economy
- oil and agriculture
- athabasca, and bow and oldman river basins respectively - dams and irrigation is seasonally regulated and above 80% efficiency
water scarcity indiators and alberta
water distirbution varies across canada, lots gets used up in economy as opposed to iran where most is domestically consumed, how does this factor into indicators
why should we manage our ET loss
60% of water resources lost to ET, but 80-90% of water for crop production is from soil moisture. If we can anage losses than we can utilize green water better and less has to be rainfed
Water scarcity
no commonly accepted definition but essentially when an individual does nto have the access to enough safe ad affordable water to meet their needs
qualifications of water scarcity depend on
- how needs are defined
- water availability
- socioeconomics
variations in calculating water scarcity
- methods
- models
- assumptions
- reliability and robustness of data
- spatial/temporal resolution/variation
disagreements on water scarcity
- water needed for food security
- water needed to sustain natural ecosystems
- whether or not the earth has enough resources to meet human and natural needs
is water scarcity a supply or demand problem
both and also economic
water scarcity indicator definition
how much water of a specified quality is needed vs how much is/can be made available
water withdrawal
water diverted or withdrawn from a source
doesn’t always mean water gets used
water use vs consumptive use
use of water by a certain sector/industry/household vs water completely removed from water resource avilability through evaporation, ET, etc
water scarcity indicators list
- falkenmark
- shiklomanovs (water resources vulnerability)
- alcamo
- physical and economic scarcity indicators
- water poverty index
- bos water scarcity index
falkenmark indicator
water per capita
1700m3/person = good
- easy to understand and data is available
- doesn’t account for temporal changes, assumes all water will be used domestically, generic and not local
shiklomanov
water resources vulnerability index
annual withdrawal (of ag, indust, and domestic)/total available water
- if above 20-40% = bad
alcamo’s index
withdrawal/total renewable water
- doesn’t account for what can be made available and what can be recycled
physical and aconomic scarcity indicator
supply of what is and can be made available
demand for consumptive use
- differentiates between economic and physical water scarcity
water poverty index
5 dimensions
- access to water
- water quality, quantity, variability
- water uses
- water management
- environmental aspects
good for small scale, not global and complex and not easy for public understanding
bos water scarcity index
total outflow/total inflow
- if B index is below .2 = bad, .1 is worse
- thresholds are bad
- only addresses surface water
overall index limitations
- only consider blue water
- no suffiecient consideration to spatial and temporal variations
- all relative
green water is main source of food production in most countries
