3.2 Nexus and Resource Security South Africa

water security - change in rainfall patterns

* predicted due to decreased frequency in low-intenisty rain and longer dry periods
* increase likelihood of floods and droughts

water security - what is suggested by climate models

* higher precipitation in east
* shorter winter season in southwest
* less rain in far west
* as much as 20% decrease

distribution of natural water resources

they are unevenly distributed

* over 60% of surface flows are from 20% of land

what is green water

water absorbed by plants and soil

what is blue water

water absorbed by water bodies and groundwater

dryland agriculture

* most rainfall taken up as green water so it impacts dryland agriculture as this is the only water they get

blue water impacts

energy system, water infrastructure, irrigation and food processing

evapotranspiration rates

increase with

* rising temps
* changes in radiation
* humidity
* wind speed

what is evapotranspiration

all processes by which water moves from the land surface to the atmosphere via evaporation and transpiration.

affect of rising evapotranspiration rates

reduce water in reservoirs

reduce green water available to agriculture

energy systems and evapotranspiration

increase the amount of water lost in cooling processes

* coal and nuclear power plants

water scarce areas and energy

renewable energy requires less water

* consider when planning for energy sources in water scarce areas

what can impact renewable energy production

hydroeletric impact

* wind patterns
* cloud coverage
* rainfall

HEP vunerable to drier future climate

climate change increasing energy use

as a result of adaptation policies

* hotter= more air conditioning demand

what is the most direct impact of climate change on food security

why?

what will change?

crop and livestock productivity changes

* higher temp and humidity known to reduce yields; heat stress on livestock
* higher CO2 conc favour weeds over crops
* agricultural production, prices and infrastructure. limit amount and quality of food

niger cattle loss % and year

1982-84

loss 62%

1993 Namibia loss

22% cattle

41% sheep and goats

factors of climate change on resources

* average temp increase
* increased drought severity
* change in rainfall and pattern
* increased intensity of extreme events