Lecture 20: Water resources i

What SDG goal is about water

Goal 6 → ensure access to water and sanitation for all

How many people in 2023 didn’t have access to clean drinking water?

1 in 4

How much safe fresh drinking water does a person need each day?

20 -50l of safe freshwater

How many people worldwide don’t have access to safe freshwater?

894 million

How many diarrhoeal deaths are due to ack of clean water?

88%

How many people live without basic sanitation?

2.6 billion

How may children live without basic sanitation?

1 billion

When does a child die from poor sanitation?

90 seconds

How many deaths are preventable through sanitation?

1.5 million per year

How many people live in area where water is scarce?

1.2 billion

in 2025, how much of the world population will be living in water stressed areas?

half of the world’s population will be living in water stressed areas

How much of fresh water is sourced from ice caps and glaciers?

68.7%

How much of fresh water is sourced from groundwater?

30.1%

How much of fresh water is sourced from surface water?

0.3%

How much water used in irrigation comes from groundwater?

43%

What will climate change do to evaporation?

increased evaporation from oceans and land

What type of air holds more water?

warm air holds more water

1C increase causes 7% increase water in atmosphere

What does more water in atmosphere mean?

causes more intense rainfall events

→ higher fractions water runoff

→ groundwater becomes less replenished

→ increase in hard surface

Recharge

water from precipitation and surface that infiltrates down to water table and adds to water storage in aquifer

evapotranspiration?

evaporation of bare surface and transpiration from plants

how much water is lost by evapotranspiration?

60-70%

how is the amount of water infiltrates into the subsurface to feed groundwater aquifers calculates?

precipitation minus evapotranspiration

Aquifer

area underground where space between gravel, sand, clay, or rock filled with water

What is a way to calculate evapotransiration?

Penman-Monteith method

water table

subdued version of surface topography

all pore space below are entirely occupied by water = phreatic zone

above has water and air = vadose zone

unconfined aquifer

high porosity and permeability

reaches ground surface

aquitard

low permeability and slows down prevent groundwater

confined aquifer

high porosity and permeability

beneath aquitard

aquicludes

almost 0 permeability and prevents water flow

bedrock aquifer

water found in cracks and pores in rock

throughout Ireland

sand and gravel aquifer

‘unconsolidated aquifer’

water found in spaces between sand and gravel

localised

What causes salt water intrusion?

over pumping of freshwater aquifer causing salty water to be pumped up and can contaminate groundwater rocks

How much drinking water is supplied by groundwater?

20-25%

which counties have a higher proportion?

Roscommon

Cork

Offaly

more than 50%

How many wells in Ireland?

170,000

What are point contamination sources for groundwater?

• Farmyard wastes 

• Septic tank effluent 

• Sinking streams  

• Leakage  

• Spillages 

• Pesticides used for non-agricultural purposes 

• Leachate from waste disposal sites

What are diffuse sources for groundwater?

• spreading fertiliser and pesticides

Paleowater

groundwater that has remained sealed in an aquifer for a long period of time

water gaps

measure the difference between renewable water availability and water consumption within a specific region

Nubian Sandstone Aquifer System

• largest aquifer system

• 2m km2 and contains 540,000km3 of water

  • 15,340km3 expolited

What is the global baseline water gap currently?

457.9km3 per year

How much will it increase by for under 1.5C warming?

26.5km3/year

+5.8%

How much will it increase by for under 3C warming

67.4km3/year

+14.7%

What countries are projected to have water gaps greater than 25km3/years?

• India

• Pakistan

• United States

• Iran

• Iraq

• China

  • Egypt

What are the Israeli Occupational Territories allocation to water?

• 56% agriculture

• 38% household

• 6% industry

Sources of water to the Israeli Occupational Territories? (per year)

Sea of Galilee - 700million m3

Mountain Aquifer - 370million m3

Coastal Aquifer, Gaza - 320milllion m3

other - 410million m3