# Catchment Water Budget Flashcards

1
Q

What is the catchment of a river

A

The area of land that delivers all of its directly received precipitation to specified river

2
Q

Where did the convent or catchment arise

A

Studies of Perrault (1674) and Marriott (1684) in the headwaters of the river seine (France)

3
Q

Who created the idea of the hydrological cycle

A

Edmond Halley, 1687

4
Q

What does the catchment water budget state

A

That the water lost by the catchment plus any change in subsurface water storage is equal to incoming precipitation

5
Q

Equation of catchment water budget (water balance equation)

A

P = E + Q + ^S
Precipitation evapotranspirarion
River discharge
Change in storage

6
Q

What are precipitation and evapotranspiration usually measured in

A

Mm/hr or mm/yr

7
Q

What is discharge usually measured in

A

M3/s known as cumecs

8
Q

How would we calculate the conversion of m3/s to mm/hr

A

To calculate the discharge per unit area of the catchment

M/s x 1000 x 3600 = Qmm/hr

9
Q

Why can the change in subsurface be emitted from water balance equations

A

Over a period of a year or more it averages to zero

10
Q

What is river catchment also known as

A

Drainage basins or watersheds

11
Q

What are river catchments usually defined by

A

The surface topography, with the assumption that water entering the subsurface hydrological system eventually emerges within the same river catchment.
The ground water divide is assumed to be the same as the surface divide.

12
Q

What three conditions leads to errors in assuming the ground water is the same as the surface divide.

A

If the surface of the impermeable rock ‘rock head’ has a different shape to the ground surface.
If there are dipping impermeable strata.
If there is a karstic subsurface hydrology were the subsurface flow is restricted to large cave systems.

13
Q

Example of dipping impermeable strata

A

Wyresdale Catchment

Bowland Fells

14
Q

Example of subsurface flow restricted to large cave systems

A

Doe Catchment

Ingleton

15
Q

What is deep seepage

A

Where catchments ‘leek’ water, this subsurface exchange

16
Q

What is gauge underflow (Hewlett 1982)

A

Where deep seepage is below the river outlet gauge

17
Q

What are experimental catchments

A

Intensively studied catchments humans use to study their impact in water and related processes

18
Q

How big are experimental catchments

A

1 to 10km2 in area

19
Q

What experimental catchments are talked about in this module

A

Danum (Malaysia Borneo)
Plynlimon and Slapton (Uk)
Coweeta and Hubbard Brook (USA)

20
Q

What is precipitation

A

Water reaching a catchment as rainfall, snow, hail, dew or occult forms

21
Q

What is headwaters

A

Tributary stream close to the source of a large river

22
Q

What is the hydrological cycle

A

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

23
Q

What is evapotranspiration

A

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

24
Q

What is subsurface water

A

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

25
Q

What are the problems with water catchment

A

Different to rock head topography.
Dipping impermeable strata.
Karate systems with lots of caves.

26
Q

Why do we study catchments on smaller scales

A

It’s difficult to do but scale

27
Q

Examples of experimental catchments

A

Hubbard brook
Coweeta
Plynimon
Danum in Borneo