1.1 The drainage basin system

Question 1

Define the hydrological cycle

Answer 1

• Describes how the water move through the biosphere, atmosphere and lithosphere
• The cycle is a closed system because water cannot be created, destroyed, it gets recycled all the time

Question 2

Define drainage basin

Answer 2

• An area the river water takes in from precipitation - It is part of the water cycle
• A drainage basin is an open system meaning it has inputs and outputs

Question 3

Define watershed

Answer 3

an area or ridge of land that separates waters flowing to different rivers, basins, or seas

Question 4

Define drainage density

Answer 4

• Total length of all the streams and rivers in a drainage basin divided by the total area of the drainage basin.
• It is a measure of how well a watershed is drained by stream channels.

Question 5

How can the drainage basin system be divided?

Answer 5

• Inputs
• Outputs
• Stores
• Flows

Question 6

Inputs of a drainage basin system

Answer 6

• Precipitation
• Solar energy for evaporation

Question 7

Define evapotranspiration

Answer 7

The process by which water vapour escapes from the leaves and enters the atmosphere

Question 8

Define potential evapotranspiration

Answer 8

The amount of evaporation that would occur if a sufficient water source were available.

Question 9

Stores of a drainage basin system

Answer 9

• Vegetation
• Surface (ponds, puddles)
• Soil
• Ground water
• Water channels

Question 10

Flows of a drainage basin system

Answer 10

The different ways that water can move from point A to B in a drainage basin

Question 11

Define interception and what type of interception are there?

Answer 11

• Interception: refers to water that is caught or stored by vegetation
• Interception loss - water that is retained by plant surfaces and which is later evaporated away or absorbed by plant
• Throughfall - water that either falls through gaps in the vegetation or drops from leaves, twigs or stems
• Stemflow - water that trickles along twigs and branches and down to the main trunk

Question 12

Define inflitration and inflitration capacity

Answer 12

• The process by which water soaks into or is absorbed by the soil
• Infiltration capacity - maximum rate at which rain can be absorbed by a soil

Question 13

Define percolation

Answer 13

The movement of water moving downwards from soil into the bedrocks

Question 14

Define overland flow (surface runoff)

Answer 14

Water that flows over the land’s surface because the bankful discharge has been exceeded

Question 15

Define groundwater

Answer 15

• Refers to subsurface water
• Depends on the porosity of the rock, water can move fast/slow

Question 16

Define baseflow

Answer 16

Refers to part of a river’s discharge that is provided by groundwater seeping into the bed of the river

Question 17

Define recharge

Answer 17

Refers to the filling of water in pores where the water has dried up or extracted by human

Question 18

Define water tables

Answer 18

The layer that separates unsaturated and saturated soil

Question 19

Define springs

Answer 19

A spring is any natural situation where water flows from an aquifer (rocks that contain water) to the earth’s surface

Question 20

Define coniferous and deciduous

Answer 20

• coniferous: trees that have needle-like leaves
• deciduous: broad flat leaves

Question 21

Define throughflow

Answer 21

Refers to the water flowing through the soil in natural pipes and percolines. Usually horizontal

Question 22

Define river regime

Answer 22

• annual variation in the flow of a river
• influenced by:
  
  • the amount of precipitation
  • the rocks - porosity and permeability
  • morphology of drainage basin

Question 23

Define recurrence interval

Answer 23

The regularity of a flood of a given of a given size

Small floods may be expected to occur regularly. Larger floods occur less often

Question 24

Define porosity

Answer 24

a measure of how much of a rocks volume is open space (pores).

Question 25

Define permeability

Answer 25

a measure of the ease with which water can move through a porous rock