Drainage Basin — Flows (Water moving from one store to another)

Question 1

Define Infiltration

Answer 1

.The process of water moving from the surface into the soil

. Water flows at medium speed

Question 2

Define Overland Flow / Surface Run off

Answer 2

. Water flowing over the land on a slope. Occurs if surface stores are full of water

. It can flow as sheet flow (lots of water flowing over a large area) or in rills (small channels similar to stream. They are unlikely to carry water during period where there is no rainfall)

. Occurs as rain is falling on ground faster than the rate of infiltration. The infiltration capacity has been exceeded

. Water flows FAST due to lack of obstacles

Question 3

Define Throughflow

Answer 3

. Refers to water moving slowly downhill through the soil and into streams or rivers.

. Occurs above interflow

. Water flows at medium speed

. It is slower than overland flow

Question 4

Define Percolation

Answer 4

.Water seeping down through soil into the water table. This water can then be held in pore spaces in the rocks as ground water storage

. It is when water moves from the ground or soil into unsaturated porous rock or rock fractures

. The percolation rate is dependent on the number of rock fractures that may be present and the permeability of the rock

. Water flows slow

Question 5

Define Groundwater Flow

Answer 5

. Water flowing slowly below the water table through permeable rock

. Usually water flows VERY SLOWLY

. Water mostly flows slowly. However, rocks that are highly permeable (e.g. limestone) with lots of joints or rock fractures can have faster groundwater

. It ensures that there is water in river, even in long period of dry weather

Question 6

Define Baseflow

Answer 6

. Normal discharge of the river

• Think of Hydrograph

Question 7

Define Interflow

Answer 7

. Water downhill flowing through permeable rock ABOVE the water table

. Occurs below throughflow

. Water flows at medium speed

Question 8

Define Channel Flow

Answer 8

. Water flowing in river or stream itself.

. Water flows fast

. Also called the river’s discharge

Question 9

Name the 10 types of flows

Answer 9

. Infiltration
. Overland flow
. Throughfall
. Stemflow
. Throughflow
. Percolation
. Groundwater flow
. Baseflow
. Interflow
. Channel Flow

Question 10

Define Throughfall

Answer 10

. Precipitation that reaches the ground by dripping from leaves, twigs and stems

. This occurs when the canopy surface rainwater, exceeds its storage capacity

Question 11

Define Stem Flow

Answer 11

. intercepted water reaching the ground by flowing the trunks of trees or stems of plants

. Water flows fast

• It is NOT dripping down the tree. That is throughfall

Question 12

Name the factors that affect rate of infiltration

Answer 12

. Soil type
. Soil structure
. Antecedent Conditions
. Gravity
. Longevity and intensity of precipitation

Question 13

Explain how ‘Antecedent Conditions’ affect the rate of infiltration

Answer 13

. The saturation of soil increases after an antecedent rainfall event. As soil moisture levels increase, infiltration rates decreases. If there has been long and intense rainfall, any excess precipitation after the rainfall event would infiltrate into the soil at slower rate.

.There are three reasons for this:

.The filling of small pores on the soil surface with water reduces the ability of capillary forces to move water into the soil. This reduces the infiltration capacity

. As soil moistens, clay particles (if present) absorb water causing the clay particles to expand. The expansion of the clay reduces the size of the soil pores. This reduce the rate of infiltration and field capacity

. Raindrop impact breaks large soil clumps into smaller particles. These particles then clog soil surface pores, reducing the rate of infiltration into the soil and reduction the infiltration capacity and field capacity

• BE VERY CAREFUL when using infiltration capacity and field capacity. THEY ARE DIFFERENT and they do NOT always WORK for EVERY SCENARIO.

Question 14

Explain how ‘soil structure’ affects the rate of infiltration

Answer 14

. Pores and fissures can be made larger, which can increase the rate of infiltration

. For example, burrowing of soil through organisms such as worms and moles increase the size of macro and micro channels within the soil.

.The penetration of plants roots can also create passages for water to flow through from the surface into the soil

. This increases the infiltration capacity

Question 15

Define Fissures

Answer 15

.large cracks in the ground that are formed as a result of soil surface tension

Question 16

Explain how the ‘type of soil’ affects the rate of infiltration

Answer 16

. Coarse soil have larger pores and fissures than fine grained soils and therefore allow for more water flow. There is an larger infiltration capacity

. Fine grained soils have smaller pores and fissures so they have less infiltration of water. There is a smaller infiltration capacity

Question 17

Define Field Capacity

Answer 17

. Refers to maximum amount of water soil can hold before it becomes saturated

Question 18

Factors that affect Through Flow

Answer 18

1. ) The more vegetated the area, the faster the rate of throughflow because it is aided by root channels found in the soil
2. ) If there are cracks or animal borrows forming natural channels in the soil, through flow will be faster
3. ) Speed of throughflow is dependent on type of soil.

.Clay soil with a high field capacity and smaller pore spaces have a slower rate

. Sandy soil drain and flow quickly because they have lower field capacities and larger pores spaces.

Question 19

Why is water faster on the surface?

Answer 19

. Water flows faster on the surface as there is less obstacles

. Water underground has to pass through soil and rock.

. In a woodland, there may be channels created by roots and burrowing animals creating free movement

Question 20

CHAINS OF REASONING FOR EXAM QUESTION

ADD FULL DETAIL FROM OTHER FLASHCARDS

Answer 20

1. ) Precipitation falls
2. ) May get intercepted and interception storage
3. ) Throughfall And stem fall
4. ) Once water reaches the surface, infiltration occurs into the soil
5. ) Soil storage
6. ) Maybe vegetation storage if plants take water from soil storage
7. ) Surface storage (if infiltration capacity reached)
8. ) Overland flow (if surface stores are full)
9. ) Evaporation + Transpiration + Evapotranspiration occurs anywhere
10. ) Throughflow and interflow may be occur after infiltration
11. ) Percolation may occur following infiltration
12. ) After percolation, water stored as groundwater storage.
13. ) Groundwater flow
14. ) All water flows into river and leaves system and water stored as channel storage
15. ) Water leaves the system as river discharge or stream flow

Question 21

Define River Discharge

Answer 21

.volume of water flowing through a river channel

. Measured in cubic metres per second

Question 22

Define Saturated

Answer 22

. Refers to any water store that has reached its maximum capacity

Question 23

Define Unsaturated

Answer 23

. Refers to water that has not yet reached its maximum capacity