1. Global hydrological cycle and water resources Flashcards
Hydrology
Science concerned with the origin, circulation, distribution of water on earth (freshwater)
Percent of saltwater vs freshwater
97.5% vs 2.5%
The water cycle (def)
Conceptual model describing the storage and movement of water between the biosphere, atmosphere, lithosphere and hydrosphere.
Precipitation
Water condensed in clouds that falls on land as rain, sleet, hail or snow
Evaporation
Liquid water in lakes, oceans, rivers and soils heated by the sun that is converted to a gas (water vapor) and returned to the atmosphere
Infiltration
Water that moves from the above-ground to the subsurface
Storage
Water held in contained areas for a given amount of time (e.g. in soil as soil moisture, in snow and ice caps)
Runoff
Water that moves away from a terrestrial location via surface/subsurface flow processes
River discharge
Flow of water within a river channel
Interception
Water that is prevented from reaching the ground by plant leaves and brances
Transpiration
Liquid water from plant leaves and stems that is converted to water vapor and returned to the atmosphere
Evapotranspiration
Combination of evaporation and transpiration
Percolation
Water that moves vertically through the soil toward the water table
Recharge
Water that is added to the water table
Groundwater flow
Water that is flowing below the water table
Water table
Subsurface boundary below which the ground is completely saturated with water
Water cycle: Fluxes in (4)
- rainfall
- snowmelt
- ground water inflow
- irrigation
Water cycle: Fluxes out (3)
- evapotranspiration
- runoff
- groundwater outflow
Water cycle: Typical storages (5)
- surface water
- soil moisture
- groundwater storage
- glaciers
- biomass
Residence time (def + eq)
Average time spent by a water molecule in one of the reservoirs of the hydrological cycle
Tr=Vol/ Q where Q is the rate at which water exits the reservoir
Water budget equation (broad aka no details)
Input - Output = Change in storage
Steady state assumption
Input - Output = 0
such that change in storage = 0
Transient state
Change in storage doesn’t equal 0
Detailed water budget equation
Δ(M,G,S) = P - (Q+E+I)
- M = soil water storage
- G = groundwater storage
- S = channel and surface water storage
- P = precipitation
- Q = river discharge
- E = evapotranspiration
- I = interception
Evaporation in arid, semi-arid and humid climates. Place in order of most evap to least evap
Arid > Semi-arid > Humid
COMPARING INTERCEPTION
Flatwoods (forest) vs Urban vs Agricultural land
(most to least)
Flatwoods > Urban = Agr
COMPARING TRANSPIRATION
Flatwoods (forest) vs Urban vs Agricultural land
(most to least)
Flatwoods > Agr > Urban
COMPARING INFILTRATION
Flatwoods (forest) vs Urban vs Agricultural land
(most to least)
Flatwoods > Agr > Urban
(but flatwoods can be variable such that sometimes agr could beat)
COMPARING SURFACE RUNOFF & SUBSURFACE RUNOFF
Flatwoods (forest) vs Urban vs Agricultural land
(most to least)
SURF: Urban > Agr > Flatwoods
SUBSURF: Flatwoods > Agr > Urban
- Flatwoods: surf < subsurf
- Urban: surf > subsurf
- Agricultre: surf = subsurf
Green water
Soil and plant water: Unsaturated water storage (soil moisture) and evapotranspiration fluxes
Blue water
Liquid water: saturated storage, and groundwater flow, and surface water fluxes
