Water Catchment Issues (fact Sheets 1-2)

Question 1

Hydrology

Definition

Answer 1

The science of the distribution and movement of water.

Question 2

Greatest natural hazard to people is…

Answer 2

flooding

Question 3

Water controls the movement of…

Answer 3

nitrates, lake eutrophication
acid rain, river acidification
landfill leachates, pollution of ground water
movement of sediment to rivers, soil erosion

Question 4

Water resource

Answer 4

Total amount of water available in the environment

Question 5

Water supply

Answer 5

Quantity of water abstracted from the environment

Question 6

Eutrophication

Answer 6

Nitrogen or phosphorus enrichment of rivers and lakes that results in algal blooms that deplete oxygen levels and hence affect fish and macro-invertebrate populations

Question 7

Leachates

Answer 7

Mostly dissolved substances moving within subsurface (ie, below ground surface) water flow

Question 8

Catchment

Answer 8

The area of land that delivers all of its directly received precipitation (minus evaporation) to a point on a river

Question 9

Point on a river that measure catchment

Answer 9

gaging station

Question 10

Watershed

Answer 10

Edge/boundary of catchment

Question 11

Catchment water budget/ water balance

Answer 11

States that the water lost by the catchment (as riverflow or evapotranspiration), plus any change in subsurface water storage is equal to the incoming precipitation.

Question 12

Catchment water budget equation

Answer 12

P = E + Q (±∆S)

Question 13

What does P stand for in the catchment water-budget equation

and units

Answer 13

P= precipitation
units = mm hr-1

Question 14

What does E stand for in the catchment water-budget equation

and units

Answer 14

E= Evapotranspiration
units = mm hr-1

Question 15

What does Q stand for in the catchment water-budget equation

and units

Answer 15

Q= river discharge
units= M3 S-1 (cumecs)

Question 16

What does ∆S stand for in the catchment water-budget equation

Answer 16

∆S= change in subsurface water storage

Question 17

Discharge per unit catchment area

Answer 17

Q/A (catchment area)
m3 S-1/m2,
=q ms-1

Question 18

When can ∆S be omitted from the equation?

Answer 18

over the period of a year (or more) the ∆S averages to 0 so can be omitted from the equation

Question 19

What normally defines river catchments?

Answer 19

surface topography,
the assumption that water entering the subsurface hydrological systems eventually emerges within the same river catchment

Question 20

When the catchment can be wrong

3

Answer 20

1. different rock-head topography of surface of impermeable to ground surface
2. dipping impermeable strata
3. karstic systems (caves)

Question 21

Where catchments ‘leak’ water …

Answer 21

this exchange of subsurface waters is called ‘deep seepage’

Question 22

When leakage of water is below the river outlet gauge…

Answer 22

gauge underflow

Question 23

Typical size of experimental catchments

Answer 23

1-10km2 in area

Question 24

Precipitation

Answer 24

Water reaching a catchment as rainfall, snow, hail, dew or occult (i.e. mist/fog) forms

Question 25

Headwaters

Answer 25

Tributary streams close to the source (i.e. head) of a large river

Question 26

Hydrological cycle

Answer 26

The concept that evaporation gives water for precipitation, which becomes subsurface water, then river-water, then sea-water and evaporation once more.

Question 27

Evapotranspiration

Answer 27

The water lost to the atmosphere by open-water evaporation, water intercepted by the vegetation and directly re-evaporated, plus biological transpiration from plants.

Question 28

Subsurface water

Answer 28

All water below the ground surface, including ‘soil water’ (i.e. the subsurface systems close to the ground surface or water in the unsaturated zone) and groundwater (water below a regional water-table)