The water cycle and water insecurity

What is the global hydrological cycle?

The closed system of all of earths water. It consists of many different stores, by which water is moved in and out of by solar and gravitational potential energy.

What is a store in the global hydrological cycle?

A place where water is held. Eg a reservoir or the atmosphere

What is a flow in the global hydrological cycle?

The movement of water between stores. Eg a river or rain

What is a process in relation to a flow?

A process is a physical mechanism that drives a flow. Eg gravitational pull drives a river

Name the flows in the global hydrological cycle

Surface runoff, infiltration and percolation, through flow and groundwater flow.

What is the difference between infiltration and percolation?

Infiltration is rainwater soaking into the soil, whereas percolation is the movement of water within the soil itself.

What is the difference between throughflow and groundwater flow?

Through flow is the downslope movement of water through the soil, roughly parallel to the ground surface whereas

Groundwater flow is the very slow horizontal movement of water through rock

What are the two different categories of water store?

Blue water- visible water such as rivers and lakes

Green water- non visible water in stored such as trees and soil

What is residence time?

Average amount of time a water molecule stays in its store

What is a drainage basin?

The area of land drained by a a river and it tributaries.

What is a watershed?

The boundary of a drainage basin

What are the tree types of rainfall?

Orographic, frontal and conventional

What is orographic rainfall?

orographic rain is formed when air is forced to cool when it rises over relief features in the landscape such as hills or mountains. As it rises it cools, condenses and forms rain which falls on one side of the mountain, whereas the other side remains dry

What is frontal rainfall?

Frontal rainfall occurs when a warm front meets a cold front. The heavier cold air sinks to the ground and the warm air rises above it. When the warm air rises, it cools. The cooler air condenses and form clouds. The clouds bring heavy rain.

What is conventional rainfall?

When the sun heats the earths surface, the air above it warms and rises. As it rises it cools and condenses to rainfall. This type of rainfall is common in tropical areas

What are the two outputs in the hydrological cycle?

Evaporation and transpiration. (Evapotranspiration EVT)

What is potential EVT?

The water loss that would occur if there was an unlimited supply of water in soil available for plants.

Name the physical factors the effect drainage basins

- The climate (eg the amount of precipitation and seasonal patters)
- vegetation (type and amount)
-the soil
- the geology of the area (permeable or impermeable)
- the relief

Name the human factors that effect drainage basins

- Reservoir creation
- deforestation (reduces interception so surface runoff increases)
- land use change (use of tarmac, which is impermeable, can cause flooding)

What is a water budget?

It is the annual balance between precipitation, evapotranspiration and runoff

What is the water budget equation and what does each character stand for?

P= Q + E +/- S

P= Precipitation
Q= Channel discharge
E= Evaporation
S= Change in store

How can this equation show positive or negative water balance?

P>Q+E = +ive

P

What is a river regime?

The annual variation in discharge or flow of a river at a particular point or gauging station. Usually measured in cubic meters per second (cumecs)

Simple river regime

Where the river experiences seasonally high discharge followed by seasonally low discharge. Inputs typically depend on meltwater or storms.

Tends to be rivers in temperate and mountainous regions

Complex river regimes

Where larger rivers cross several different relief/climatic zones and so also experience different seasons + effects. Eg the river Ganges or the amazon

Human factory’s can also make river regimes more complex. Eg dams

Other factors that impact river regimes

- Catchment size
- geology
- land use
- evaporation rate
- vegetation type

What does a storm hydrograph show?

The variation in discharge of a river within a short period of time in response to input of precipitation

What are the two types of hydrograph?

Flat and flashy

What physical factors can effect the shape of a hydrograph?

- vol and duration of precipitation
- river size
- catchment area
- relief +geology
- vegetation cover

What human factors can effect the shape of a hydrograph?

- deforestation (Vegetation cover)
- urbanisation (surface runoff)

What are the four types of drought?

- meteorological
- hydrological
- agricultural
- famine drought

What is meteorological drought?

Drought caused by lack of precipitation

What is hydrological drought

Drought caused by changes in the input and output of bodies of water

What is agricultural drought?

When water content of soil is low, causing plant biomass to decrease

What is famine drought?

A humanitarian crisis in which agricultural failure has lead fo wide spread food shortages

What are the natural causes of drought?

Short term-
- blocking anicyclones

Med term-
- ENSO (MAKE MORE NOTES ON THIS)

Long term-
-global atmospheric circulation (worldwide system of winds)

What are human causes of drought?

- over abstraction of surface water
- deforestation
- climate change
- over extraction of ground water

CASE STUDY

SAHAL AFRICA

CASE STUDY

AUSTRALIA

ENSO (El nino southern oscillation)

a variation in air circulation around the world that results in

* warmer whether to the Americas
* wet weather and flooding in Africa

happens ever 3-7 years

la nina is the opposite pattern

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is being worsened by climate change

* more frequent
* more severe

What are the ecological impacts of drought on wetlands?

- very vulnerable when dry as organisms are adapted to wet environment
- soil dries up- can lead to easier erosion and oxidation of soil (which can real ease pollutants and nutrients in dangerously conc levels)
- some species such as birds may leave the area

What are the ecological impacts of drought on forests?

- tree growth is slowed + leaves drop which can take up to 4 years to recover from
- tree death changes food chains as well as carbon cycle
- pests spread easier in dry conditions

What are the types of flooding?

ground water, surface water flooding, flash flooding

What is ground water flooding?

occurs after ground is fully saturated and can no longer take in anymore water after prolonged heavy rain fall

What is surface water flooding?

when intense rainfall doesn’t have enough time to infiltrate and so flows over land

What is a flash flood?

A flood with a very short lag time (most dangerous)

Natural causes of flooding

* wet seasons/ too much rainfall
* impermeable rock type
* low-lying area
* area at the bottom of high relief

Human causes of flooding

- land use change (urbanisation- impermeable materials, deforestation- less interception)
- building over flood plains
- hard engineering such as straightening channels and dredging (increasing depth or river channels) while these may benefit some areas, down stream it can cause issues such as moor flooding .

How is spearman’s rank calculated?

* **Rs** = spearman’s rank coefficient
* **D** = difference in rank
* **n** = number of samples

CASE STUDY

UK FLOODING 1953

CASE STUDY

Pakistan floods LIC (geofile)

What is eutrophication?

The process of farming chemicals such as fertilisers being carried into rivers by rain water.

Why is eutrophication bad?

- the nutrients carried into the river causes a huge dense growth of plants
- higher plants (eg algae) block light from reaching deeper parts of the river- causing plant death of underwater plants
- animal death occurs due to lack of photosynthesis by underwater plants leading to low O2 concentrations in water
- overall- decreasing the biodiversity of the river

water insecurity

when people do mot have enough quality water to sustain a quality life, as well as to support socio-economic development.

physical scarcity

the lack of available water sources such as surface and ground water

CASE STUDY- physical water scarcity

salt water encroachment- Kiribati?

economic scarcity

lack of ACCESS water due to lack of money or management

CASE STUDY- economic water scarcity

* Kathmandu Nepal
* Mexico city (also case study for water conflicts)
* cape town ?? (also case study for water conflicts)

CASE STUDY- human water scarcity

aral sea

water poverty index

factors in Resources Access Capacity Use and Environment

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and is a measure of TIME needed to collect a certain volume of water

factors that increase water demand

* population
* agriculture
* hot climate (climate change)
* standard of living (better life styles= need more water)

factors that determine water supply

1. climate (precipitation levels)
2. topography (shape of land/ relief)
3. rock type (permeable or not)
4. river systems
5. pollution makes more water unusable)
6. urbanisation (causes more surface runoff)

CASE STUDY- water insecurity UK

the south of england is more water insecure to the the warmer climate. and as it is a small country there are fewer water sources.

most of Englands water comes form scotland which is a very water secure country

CASE STUDY - conflicts over water

* the Nile
* mexico city
* cape town
* colorado river

CASE STUDY- who is on control of the water (gov vs TNC)

Bolivia and the private water company Bechtel Corporation

CASE STUDY- solutions to water insecurity

UNICEF

IWRM

integrated water resources management

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* a process which promotes co-ordinated development of water management between countries

things that determine the price of water

* how hard water is to access
* demand
* level of infrastructure
* who is on control of the water (gov vs TNC)

players in water distribution

* consumers
* company / gov in control / economy
* environment

CASE STUDY- managing water supply

* three gorges dam china
* water transfer schemes china
* singapore holistic management
* desalination isreal
* IWRM
* UNs Helsinki rules

→ Colorado river