basic concepts Flashcards
what are boundaries in a water system?
may be arbitrarily defined, often hydraulic divides or catchment boundaries
what is a flux?
- input/output across system boundaries
- usually a volume per time (sometimes height per time)
what is the change in storage equation?
Input- outflow = change in store
what is a steady state system?
when change in storage over time is 0 and the input=output
what is a transient stage?
when change in storage over time is not 0 and input does not equal outflow
(in reality, this is usually the case)
what is the residence time equation?
residence time = storage/ output
what are fluxes into the system?
- rainfall
- melting of snow
- groundwater inflow (from groundwater into rivers and lakes)
what are fluxes out of the system?
- evapotranspiration
- runoff from catchment
- groundwater outflow
what are stores in hydrology?
- surface water
- soil water
- groundwater
- glaciers
- biomass
what is a catchment?
all the land surface area that drains to the same outlet point
how can we delineate catchment boundaries?
- using contours on a topographic map
- digital elevation models in a GIS
what is the water balance equation?
precipitation (rainfall and snowmelt) + groundwater inflow - evapotranspiration - discharge - groundwater outflow = change in storage
P+ Gin - ET - Q - Gout = deltaS
** groundwater is often assumed to be zero so P- ET - Q = 0 in steady state
how do we measure precipitation?
rain gauges/pluviometers
how does a rain gauge work?
measure the water column times the ratio between cross-sectional area of the water column and the opening of the gauge
