basic concepts

Question 1

what are boundaries in a water system?

Answer 1

may be arbitrarily defined, often hydraulic divides or catchment boundaries

Question 2

what is a flux?

Answer 2

• input/output across system boundaries
• usually a volume per time (sometimes height per time)

Question 3

what is the change in storage equation?

Answer 3

Input- outflow = change in store

Question 4

what is a steady state system?

Answer 4

when change in storage over time is 0 and the input=output

Question 5

what is a transient stage?

Answer 5

when change in storage over time is not 0 and input does not equal outflow
(in reality, this is usually the case)

Question 6

what is the residence time equation?

Answer 6

residence time = storage/ output

Question 7

what are fluxes into the system?

Answer 7

• rainfall
• melting of snow
• groundwater inflow (from groundwater into rivers and lakes)

Question 8

what are fluxes out of the system?

Answer 8

• evapotranspiration
• runoff from catchment
• groundwater outflow

Question 9

what are stores in hydrology?

Answer 9

• surface water
• soil water
• groundwater
• glaciers
• biomass

Question 10

what is a catchment?

Answer 10

all the land surface area that drains to the same outlet point

Question 11

how can we delineate catchment boundaries?

Answer 11

• using contours on a topographic map
• digital elevation models in a GIS

Question 12

what is the water balance equation?

Answer 12

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

Question 13

how do we measure precipitation?

Answer 13

rain gauges/pluviometers

Question 14

how does a rain gauge work?

Answer 14

measure the water column times the ratio between cross-sectional area of the water column and the opening of the gauge