Introduction Flashcards
1
Q
Definition of Hydrology
A
The study of the distribution, movement, quantity, and quality of water throughout the Earth
2
Q
What does they study of hydrology include?
A
- Hydrologic cycle
- Water phases
- Watersheds
- Water resources/management
- Water quality
3
Q
What are some of the possible disciplines of hydrology?
A
Hydrometeorology, Surface Hydrology, Glaciology, Snow Hydrology, Hydrogeology, Water Chemistry, Water Resource Engineering and managing.
4
Q
Driving forces and ingredients for hydrology
A
Driving forces: Solar Radiation, Gravity, Friction
Ingredients: Water, Soil, Rock, Air, Vegetation
5
Q
Spatial Scales of interest in Hydrology
A
- Local (channel development, urban drainage, kettle lakes)
- Regional (Rainshadow, watershed, rivers)
- (Sub) Continental (El nino events, Great Lakes, Deserts/Arid Regions, Large-scale Dams)
- Global (Thermohaline circulation, humidity)
6
Q
Temporal Scales of interest in Hydrology
A
- Seconds to Hours (Thunderstorms)
- Days
- Seasons
- Years (Hydrographs)
- Decades (Drought, dust bowl ‘30’s)
- Centuries (subsurface ground water movement, salt water intrusion)
- Millennia (sometimes GW recharge of ancient aquifers) (river channel erosion - Grand Canyon)
7
Q
Ice Cores
A
Proxy for paleoclimate and atmospheric conditions
8
Q
Where is the world’s water distributed?
A
Saline 97% Fresh 3% - Ground Water 30.1% - Ice & Glaciers 68.7% - Other (Permafrost) 0.9% - Surface Water 0.3% ---Rivers 2% ---Swamps 11% ---Lakes 87%
9
Q
6 important facts about water
A
- Abundant and covers 71% of Earth’s surface
- Found in all 3 phases at Earth’s surface
- High melting & boiling points
- Universal solvent
- Density decreases on freezing (Ice floats)
- High specific heat & thermal conductivity (Climate regulation, takes lots of energy to bring heat up)
- Internal cohesion & surface tension
10
Q
What phase are clouds?
A
Clouds are all 3 phases
- Water vapour condenses to liquid or solid around a nucleus.
- Higher altitude = higher likelihood of solid/ice
- Particles take different shapes at varying altitudes and topographies (ocean clouds can be pure liquid particles)
11
Q
Why does ice float?
A
- Density (mass/volume) changes with temperature
- Expands by 9% volume when frozen
- Hexagonal lattice structure of ice crystals pack together in a way that maximizes hydrogen bonds polarities (positive & negative poles attract and detract)
12
Q
Why is it important that ice floats?
A
- Allows freezing from top to bottom in fresh water (less dense ice floats on surface)
- Thermal density effects cause circulation in lakes and oceans (denser water sinks, less dense rises)
- Max density at +4 degrees C.
13
Q
Generic Hydrological Cycle (Trenberth et al. 2007)
A
- Generic numbers = uncertainty
- Most of the water evaporated from the ocean reprecipitates into the ocean
- Not much of the evaporated water from the ocean transfers to land to recharge surface & Groundwater
14
Q
Reservoir
A
Place where water resides
15
Q
Flux
A
Movement of water between reservoirs
16
Q
Types of Water movement
A
- Evaporation (liquid-gas)
- Transpiration (evap from plants)
- Convection (upward circulation)
- Advection (horizontal circulation)
- Precipitation (liquid/solid water that comes from atmosphere & reaches the ground)
- Percolation & Diffusion
- Runoff (natural & urban overland flow of water)
17
Q
Verga
A
Precipitation that doesn’t reach the ground (returns directly to atmosphere before reaching the ground)
18
Q
Energy sources & Forces:
Evaporation & Transpiration
A
Surface energy budget (Need energy to drive the process)
- Mostly solar radiation & Sensible Heat
19
Q
Energy sources & Forces:
Convection
A
Mostly solar radiation
- Warm, moist, air rises: Buoyancy forces
20
Q
Energy sources & Forces:
Advection
A
Winds carry the moisture
- Driven by pressure gradient force
21
Q
Energy sources & Forces:
Precipitation
A
Cloud processes - condensation, nucleation, Bergeron (pressure gradient force), collision-coalescence
- Gravity
22
Q
Energy sources & Forces:
Percolation & Diffusion
A
Soil, sediment, rock processes
- Flow in porous media, fractures etc.
- Gravity, capillary pressures, pressure gradient forces
23
Q
Energy sources & Forces:
Runoff
A
River, soil, snowpack, processes
- Gravity
- Friction
24
Q
What does movement of water carry with it?
A
- Energy (latent heat)
- Solutes (salt, chlorides)
- Solids (suspended sediment particles)
25
How is water able to exchange Energy?
Via latent heat and kinetic motion
26
How is water able to exchange Matter?
Via changes in state between the hydrosphere and atmosphere
27
How is water able to exchange Force?
Via direct mechanical action or pressure caused by water flows or thermal expansion
28
Residence time
Time required for water to move through a component of the hydrological cycle
29
Residence time in the atmosphere
Days
| - Sometimes longer
30
Residence time of River discharge
Hours to Days
| - sometimes longer
31
Residence time of deep ocean, glaciers, groundwater
3000 to 10000 years
| - Sooner if closer to the coast
32
Why do some larger components have a longer residence time?
Glacial ice takes a long time to build, flow, melt, and re-enter ocean reservoirs
33
Why are shorter residence time cycles important?
Shorter cycles are important for supply management, flooding (especially small scale)
34
Why are longer residence time cycles important?
Longer cycles are important for long-term change and sustainability management
35
Fundamental Laws:
| Conservation of Mass
Mass cannot be created or destroyed
36
Fundamental Laws:
| Newton's First
A body maintains its state of rest or uniform motion unless acted upon by an external unbalanced force
37
Fundamental Laws:
| Newton's Second
F = ma
| The net force on an object is equal to the mass of the object multiplied by its acceleration
38
Fundamental Laws:
| Second Law of Thermodynamics
Energy is neither created nor destroyed
39
Fundamental Laws:
| Fick's Law of Diffusion
The flux of a material goes from regions of high concentration to regions of low concentration
- Applies to heat (thermal conduction), water or air (Pressure Gradient Forces), other chemicals (salt)
40
Basic water balance equation
Flux in = Flux out + Storage
| Qin = Qout + change in Storage
41
Local Water budget equation
P = Qr + E + Change in Storage
- P=Precipitation
- E=Evaporation
- Qr=River runoff
42
How can the water balance be a useful tool for estimating the effects of Climate Change (i.e. increase winter temperatures)
Less storage, more flooding, less albedo, increase in energy
43
How can the water balance be a useful tool for estimating the effects of water management?
Dams prevent floods & change downstream environment (nutrients etc), but increase storage for when water is needed.
44
Drainage Basins
- Water flows down hill....most of the time
- Beneath the surface it is pressure that controls water flow
- Water movement is intimately linked to the terrain, climate, and location
45
Determining a Drainage Basin
A divide separates different river basins
| - It is located along the highest elevations and no stream can cross it
46
What is the world's largest river?
Amazon River
- discharges 180000 meters cubed per second
- Large freshwater input into the atlantic
47
Drainage Basin Shape
- Define the aspect ratio Rb=L/W
- Commonly Rb=3 - 5
- Rb = 17 is a long narrow shape where water reaches the main river faster but final discharge much later because of aspect ratio
- The lower Rb, the more evenly (spherically) distributed the shape is
48
Global river drainage to the oceans
- Atlantic receives most discharge at 47% largely due to the Amazon River Basin
- Arctic 11%
- Pacific 13%
- Indian 13%
49
Stemflow
Water lands on a building, tree or vegetation, and flows down to the ground to become part of the groundwater, surface flow, or evaporates
50
Interception Loss
Doesn't contribute to stem flow or to a plant, it ends up evaporating into the atmosphere
- evaporates before it reaches the ground after being intercepted by vegetation
51
Throughfall
Precipitation that doesn't touch a plant or structure and goes directly to the land surface.
Some can infiltrate or contribute to overland flow (urban throughfall often flows overland where concrete inhibits infiltration)
52
Quantity
a measurable value or amount of something (size, shape, number, weight), useful to know numerical value but also need information on units & physical dimensions.
53
Dimensions
expressed in term of mass, length, time, and temperature
54
Units
a quantifiable convention of measurement
- dimensions do not equal units, units are specific to a system of measurements (metric, etc)
- speed can be expressed in m/s, km/hr/ knots, but always has dimensions of length/time
55
Assumption that past is guide/key to future
Past is no longer a sufficient guide to the future because expected viability could be outside the range of observed variability (anthropogenic influences on climate & hydrological cycle)
56
Recent changes in the Hydrological Cycle
- Increase in cloud cover since 1990's
- Precipitation increase and more variability since 1900's
- 8% decline in snow cover in NA since 1970's
- Sea level rise of 2.4 mm/yr due to human intervention & glacial ice sheet melt
- Increase in fall-spring stream flow (more flooding?)
- 77% flow affected by diversions & reservoirs
- Dams have increased 700% storage volume & tripled residence time
- Sediment transport doubled (16% in reservoirs)
57
Big water issues
- availability
- ecosystem health
- important to understand water movement & behaviour for management
