Topic 5 - EQ 1 Flashcards

Question

What is a watershed?

Answer 1

The highlands which divides and separates waters flowing to different rivers.

Answer 2

0.007%, which is the main source of surface water for humans,

Answer 3

Solar energy and gravitational potential energy (GPE). More evaporation occurs as the global climate warms, which then increases moisture levels in the atmosphere. This leads to increased condensation as the air cools, and greater precipitation. GPE keeps water moving through the system in a sequence of inputs, outputs stores and flows.

Answer 4

This is a closed system which is driven by solar energy and gravitational potential energy. It is a closed system as there’s a fixed amount of water in the earth (roughly 1385million km^3). As a closed system has no external inputs or outputs, this total volume of water is constant and finite.

Answer 5

In the last ice age, more water was held in the cryosphere in solid forms as ice or snow, and less was held in oceans. Sea levels were 140m lower than today. However recent climate warming is reversing this with major ice losses in Greenland and Antarctica.

Answer 6

It is stored in rivers, streams, lakes and groundwater in liquid form. It’s often known as bluewater, the visible part of the hydrological cycle. Water can, however, also be stored in vegetation of beneath the surface in the soil. This is known as green water and is the invisible part of the hydrological cycle.

Answer 7

Ancient groundwater is found deep below the Saharan Desert and they formed as a result of former pluvial (wetter) periods. Major ice sheets (such as Antarctica and Greenland) also store ice for very long periods of time. The residence time of some Antarctic ice is over 800,000 years.

Answer 8

The area of land drained by a river and its tributaries. Drainage basins can be of any size, from that of a small stream possibly without tributaries up to a major international river flowing across boarders of several countries.

Answer 9

-Interception storage -Surface storage -Soil water storage -Groundwater store -Channel store -Vegetation store

Answer 10

Precipitation

Answer 11

-River discharge -Evaporation -Evotranspiration -Transpiration

Answer 12

-surface run-off -throughflow -soil throughflow -Infiltration -Percolation -Groundwater flow -River Channel flow

Answer 13

The storage of water when it lands on vegetation (or structures like buildings) before it reaches the soil. It is a temporary store before evaporation or stemflow

Answer 14

The storage of water on the surface including puddles, ponds and lakes

Answer 15

The storage of water in soil. Water is held in the small gaps between soil particles

Answer 16

The storage of water in the ground rocks of permeable rock. The water is held in cracks (limestone) bedding planes (sedimentary rock) or pores (chalk). Rocks with lots of water storage are called aquifers

Answer 17

The storage of water in the river channel. As water is being transported to the sea it is a store of water

Answer 18

The storage of water in the vegetation. Plants and trees take up water through their roots and water is stored here.

Answer 19

The horizontal flow of water over the surface of the land either in little channels or over the whole surface – this is usually a quick flow.

Answer 20

The input into a drainage basin system. It includes all forms of moisture entering: hail, snow, dew, frost, sleet and rain.

Answer 21

The downwards flow of water moving downwards from interception storage to the surface

Answer 22

The horizontal flow of water moving through soil (between the particles) towards the river

Answer 23

The downwards movement of water from the surface into the soil.

Answer 24

The downwards movement of water from the soil to the permeable ground rock

Answer 25

The horizontal movement of moving through the rocks (cracks/bedding planes/pores) slowly towards the river. This is the movement of water below the water table sideways to the river.

Answer 26

The movement of water in the river channel moving towards the sea.

Answer 27

The output of water when water is heated and turned from a liquid into a gas

Answer 28

The output of water where moisture is taken into plants through their roots, moved to the leaves by capillary action and then evaporates from the leaves into a gas.

Answer 29

The combined output of water from evaporation and transpiration

Answer 30

The output of water from a river channel out to sea.

Answer 31

The change from a gas to liquid, such as when water vapour changed into water droplets.

Answer 32

The temperature at which dew forms (temp which water droplets begin to condense). It is a measure of atmospheric moisture.

Answer 33

-Air cooled to saturation point with relative humidity of 100% - Condensation nuclei, such as dust particles, to facilitate the growth of droplets in clouds. -Temp below dew point.

Answer 34

-The amount of precipitation -The type of precipitation e.g snow can act as a temporary store -Seasonality, seasonal rainfall has huge impacts on physical processes operating in the drainage basin. -Intensity of precipitation -Distribution of precipitation within the basin, particularly noticeable in big drainage basins such as the Nile, where tributaries start in different climatic zones.

Answer 35

-Conventional rainfall -Frontal (cyclonic) rainfall -Relief (orographic) rainfall

Answer 36

The western side of the UK. North-west UK such as Cumbria can receive over 2000mm of rainfall a year, making them prone to saturate surfaces, high water tables and antecedent moisture. This makes flooding more likely.

Answer 37

Drainage basins in East Anglia. These are much drier but in the summer months experience heavy rainfall bursts due to convection air instability. In these months the ground warms up, evaporation takes place and summer thunderstorms produce short bursts of heavy rain which can lead to flash floods.

Answer 38

The eastern side of the UK receives less rain than the west, because the western hills force moist air to rise as it approaches the Atlantic - leading to orographic rainfall in the north and west.

Answer 39

Warm moist air is forced to rise over high areas. The air cools and condenses forming clouds. Precipitation occurs. This air then descends and warms, leaving a rain shadow on the other side of the mountain peak. This is in the west of the UK as warmer, moist Atlantic air rises over the western uplands. Heavy rain falls on western and northern parts of the UK.

Answer 40

The sun first heats the land and the air above, this warm air rises, cools and condenses forming clouds. Rain the falls. Typically, this is in the east and southeast of the UK during summer. This is due to periods of high temperatures. The rain is often intense and associated with electrical storms and thunder.

Answer 41

Warm air is forced to rise over cold air. Condensation occurs which leads clouds to form. It the rains heavily along the front (where warm air hits the cold air). This brings the majority of the UK rainfall over the year. Fronts are formed as part of a low-pressure area when warmer moist air from the southwest meets colder polar air from the north or north west. Warmer air is forced to rise over the denser and colder air.

Answer 42

The rate of interception is dependent on two factors, the precipitation and vegetation. Interception is greatest when the precipitation is light and of short duration. This is because dry leaves and stems have the greatest water storage capacity. For vegetation, denser types such as coniferous forests (intercepts 25-35% annual rainfall) will intercept more than sparser deciduous forests (15-25% rainfall). This is especially true when deciduous trees shed their leaves in winter. All forests however intercept more than grasses or crops (10-15% rainfall)

Answer 43

Hugh winds are also bad for interception loss as wind displaces rain which causes evaporation to happen more quickly.

Answer 44

This is water that is retained by plant surfaces and later evaporated or absorbed by the vegetation and then transpired

Answer 45

The maximum rate and which rain can be absorbed by a soil.

Answer 46

If the soil was already moist before, the soil will reach the point of saturation more quickly and therefore the infiltration rate will be lower.

Answer 47

Infiltration capacity decreases with time through a period of rainfall until a more or less constant low value is reached.

Answer 48

Whether the soil is sand, silt, loam or clay influences soil porosity. Sandy soils have a higher infiltration capacity (3-12mm/hr) than less permeable clays (0-4mm/hr).

Answer 49

Infiltration is far more significant in land covered by forests (50mm/hr) or moorland (42mm/hr) due to less risk of flooding from heavy rain. Tree cover can prevent soil for saturation and the infiltration rate falling. Permanent pasture has infiltration rates of 13-23 mm/hr depending on grazing density and soil type.

Answer 50

The nature of the soil surface and structure is also important. Compacted surfaces inhibit infiltration (around 10 mm/hr), especially when rain splash impact occurs.

Answer 51

Slope angle can be very significant. Very steep slopes tend to encourage overland run-off. Shallowing slopes however promote infiltration.

Answer 52

This occurs when water accumulates in the soil until the water table reaches or ponds on the surface, forcing further rainwater to run off the surface. This is most common with thin soils of moderate permeability. Concavities near a stream or riverbank often have high moisture levels and may produce saturated overland flow early in a rainstorm cycle.

Answer 53

Infiltration-excess overland flow occurs when the rainfall intensity exceeds the infiltration capacity. This causes excess water to flow over the ground surface. Any surface runoff will quickly deliver water into the river channels, increasing the risk of flooding downstream.

Answer 54

It will continue to move slowly down into the rocks by percolation. This water fills the spaces between the rocks, creating groundwater storage and an aquifer. Thus will occur where the permeable layer lies above an impermeable layer, so that the water cannot percolate any further, creating a saturation zone. The upper level of this zone is called the water table. This water may move as groundwater flow if geological structure allows it.

Answer 55

It depends on the permeability of the rock, which is linked to its porosity or perviousness. Porosity is do to with the total volume of pore spaces. This is highest in coarse-grained rocks such as sandstone, pervious rocks like limestone have joints and bedding planes along which water can flow. This means groundwater flow and percolation increased with porosity and perviousness. Granite (an impermeable rock) will prevent percolation or water moment. Groundwater flow also depends on the angle of the rock strata, a steeper gradient allows gravity to operate more efficiently.

Answer 56

In the tropics due to the ITCZ. I’m the ITCZ, intense solar radiation fuels the convection of warm, humid air. This results in condensation and precipitation. The highest average annual rainfall is in Mawsynram, India with 11,873mm of rain per year. This is mostly in the monsoon season of June to September.

Answer 57

These are in stable areas of high atmospheric pressure. E.g Quillagua in the Atacama Desert. This is the driest place on earth, receiving less than 0.2mm of rain per year.

Answer 58

At this point, the soil is full of water and cannot hold anymore.

Answer 59

Precipitation is greater than potential evapotranspiration and the soil water store is full, so there is a surplus of soil moisture for plant use, run off into streams and recharging groundwater supplies. The soil is said to be at field capacity.

Answer 60

High temperatures can cause maximum evapotranspiration, precipitation is at a minimum and therefore plants use up the soil moisture store. River levels will fall and crops will need irrigation.

Answer 61

This occurs when potential evapotranspiration decreases so that it is lower than precipitation, and the soil store starts to fill up again.

Answer 62

Potential evapotranspiration increases and exceeds precipitation, so there is more water evaporating from the ground surface and being transpired by plants than is falling as rain. Water is also drawn up from the soil by capillary action. The water is gradually used up.

Answer 63

The soil moisture store has been used up by high rates of evapotranspiration and low precipitation. Plants can only survive if they’re adapted to periods of drought or are irrigated.

Answer 64

The water budget reflects the natural annual balance between the inputs and outputs in a given river area.

Answer 65

P = Q + E +/- store change, where P = precipitation. Q = channel discharge. E = evapotranspiration. Whatever falls as precipitation should be balanced by other components.

Answer 66

Water Budget/Balance graphs provide a direct comparison of natural water supply and demand and the impact this has on soil water availability. They help us identify where P>ET = positive balance (flood) and where P

Answer 67

This describes the annual variation in the discharge of a river at one particular point. Many physics factors affect the river regime throughout the year, however they aren’t completely natural as the regimes are affected by activities in the river drainage basin.

Answer 68

-The size of the basin and where in the basin measurements are taken. -The amount,pattern and intensity of precipitation. -Temps experienced: evaporation will be marked in summer as the temperatures are warmer. -The geology and overlying soils, especially their permeability and porosity. Groundwater store is slowly released into the river as base flow. -amount + typed of vegetation cover -Human activity e.g dam building.

Answer 69

In these areas, evapotranspiration tends to be stable (high) but summer rain causes a peak.

Answer 70

European mountain river have a high-water period when glaciers feeding them melt most rapidly.

Answer 71

Melting of snow cover either in mountainous areas during early summer or over the Great Plains of North America in spring. This causes a peak in discharge.

Answer 72

In many oceanic areas of Europe, rainfall is evenly distributed but high evapotranspiration in summer leads to low run-off.

Answer 73

-Size of the river -Amount/pattern/intensity of precipitation -Temperature experienced -Geology and overlying soils -amount + types of vegetation cover -Human activities

Answer 74

Many large rivers have complex regimes, which come from varied catchments. It’s therefore also important where measurements in the basin are taken.

Answer 75

The river regime often reflects rainfall seasonal maxima or when the snow fields or glaciers melt.

Answer 76

Especially with permeability and porosity, water is stored as groundwater in permeable rocks and is gradually released into the river as base flow. This tends to regulate the flow during dry periods.

Answer 77

Wetlands can hold the water and release it very slowly into the system.

Answer 78

Dam building, which can regulate the flow of a river.

Answer 79

The water loss that would occur if there was an unlimited supply of water in the soil for use of vegetation.

Answer 80

Key changes in global use (E.g deforestation) are a key influence. Deforestation reduces transpiration rates. However, artificial reservoirs (such as behind mega dams) cuts down surface storage and therefore increased evaporation.

Answer 81

Human activity can affect precipitation by cloud seeding. They use silver iodide pellets to act as condensation nuclei to attract water droplets. The aim is to increase rainfall in drought-strikes areas. It was also used in Beijing for 2008 Olympics to help clear pollution.

Answer 82

Interception is largely determined by vegetation type and density. Therefore, deforestation as well as afforestation both have significant impacts. Deforestation leads to increased surface run-off. This increases flooding potential and a decline in surface storage. Although afforestation should do the opposite, it was seen in Wales that after afforestation occurred in the Catchment area of river Severn, there was increased runoff due to soil compaction from tractors.

Answer 83

Nepal, where deforestation led to dry soil due to increased surface runoff, as well as more sediment load further down stream. The rain drop impact causes soil compaction. So less soil could infiltrate leading to increase run-off.

Answer 84

Impacts on infiltration largely result from a change of land use. Infiltration is 5x greater on land under forests in comparison to grassland. Conversion to farmland means increased soil compaction, more overland flow and less infiltration. While farming and grazing animals can cause soil compaction, ploughing increase infiltration by loosening the soil. If there’s poor drainage, water logging and salinisation can be common. Installing drainage helps to avoid this.

Answer 85

Human use of irrigation for certain types of farming has led to declining water tables, e.g in Texan aquifers. This irrigation reduces water flowing into rivers, and then as a result less water reaches oceans. Many British cities have been affected by reduction in irrigation, groundwater levels began to rise and other issues such as surface water flooding became big issues, with flooding increasing in cellars and basements as well as London Underground tunnels.

Answer 86

Twenty percent of the forest has been destroyed to make room for agricultural and cattle farming, as well as towns and roads. Not only does this affect the atmosphere, as trees act as the lungs of the earth, but there is also an enormous impact on water cycling. Usually in a forest 75% of intercepted water is returned to the atmosphere by evapotranspiration. However, this reduces to 25% with deforestation. This leads to a drier climate, which can cause droughts and even make forest fires more likely. Water run-off can also however cause flooding, and surface runoff causes soil erosion which can lead to a lack of soil nutrients.

Answer 87

This is a graph showing variation in discharge (volume) of water at a given point over a short period of time, normally an individual storm (few days).

Answer 88

This is the point where the river is as full as it can be (up to the top of river banks) before it begins to flood with any more water.

Answer 89

This represents the normal day to day discharge a river will experience and how it changed this the groundwater slow slowly entering the river.

Answer 90

-Humans -Vegetation -Geology and soil -Size of river -Temperature -Precipitation

Answer 91

Short lag time, high peak, steep rising limb.

Answer 92

Long lag time, low peak, gently sloping rising limb.

Answer 93

The normal, day-to-day discharge of the river.

Answer 94

-Intense rain, exceeding infiltration capacity or rapid snow melt - Impermeable rock e.g Granite - Low infiltration rate e,g clay soils - Steel relief - Small basins - Circular basins - Low density vegetation, little infiltration. - Wet antecedent conditions - Urbanisation.

Topic 5 - EQ 1 Flashcards

(120 cards)