Lecture 4 climate + hydrology Flashcards
Define: climate
Statistical characterization, often averages, of weather over many years
Define: weather
Specific atmospheric conditions at a particular place and time
Define: hydrology
Science of the distribution and circulation of water on and under the surface of the earth, the mechanical and chemical properties of water, and the organization of rivers into networks
What controls the weather of BC?
Alternating sequences of west-east flowing pressure systems, both low (cyclonic) and high (anticyclonic) pressure systems
Low pressure systems often form in the aleutian islands in the north pacific
What are BC’s 5 distinct microclimate regime?
1) Coast Mountains and Islands
2) North, Northern and CEntral Plateaus and mountains
3) South, Interior plateaus
4) North, The great Plains
5) Columbia Mountains and Southern Rocky Mountains
What are Extreme Weather Events
Precipitation and wind events of sufficient intensity and duration to generate floods, slope failures and extensive surface erosion
Where is the earths water distributed?
Oceans 97.5%,
Glaciers, snow and permafrost 1.725%
Ground water 0.075%
lakes, swamps and rivers 0.025%
What is precipitation?
The input of the hydrological cycle, comes in the form of rain and snow. it has spatial and seasonal variability
What are precipitation spatial patterns?
Determines the relative importance of the other components of the hydrological cycle.
- location
- effect of elevation
- Lake effects
What are precipitation seasonal patterns?
ex. monsoon seasons, large rain events in vancouver. Coastal BC rain on snow events during late autumn-early summer
What is interception?
Part of precipitation is intercepted by plants (from the system)
- some precip witll be intercepted in the canopy and lost back to atmosphere by evaporation
- can be measured by having a gauge in open area compared to gauge in canopy area
What is evaporation?
The rate of liquid water transformation to vapour from open water, bare soil, or vegetation
- rate is controlled by energy availability at the evaporated surface and the ease by which water vapour can be diffused in the atmosphere
- Evaporation = Vaporization - condensation
Define: stream:
A long, narrow body of flowing water occupying a trench-like depression, or channel, and moving to lower levels under the influence of gravity
What is stream discharge?
The volume of water per unit time passing through a cross section of the stream at that location (cubic meters/second)
What is stream gradient?
Rate of fall in elevation of the stream surface in the downstream direction
What is in stream flow velocity?
Max velocity occurs at stream center and near the water surface.
At a vertical, velocity increases with distance above channel bed.
What is a hydrograph?
Graph which plots the discharge of a stream with time at particular stream gauge. increases in response to precip
What is base flow?
Portion of the discharge of a stream contributed by groundwater flow
What is a watershed?
Entire land area or basin above a specific point on a stream where water flows across the surface into a stream
What Climatic factors influence flow hydrograph?
- Precipitation type (snow/rain)
- Rain intensity and duration
- storm size and direction
What Geological factors influence flow hydrograph
- Rock and soil types
- vegetation types
What physical characteristics of drainage basin influence hydrograph shape?
-topography
-drainage system density
-surface gradient
Other factors:
-Land use-urbanization/ logging
-lakes
-Water diversions
Where can you find a hydrograph for BC?
BC hydrometric Network
