Transcript Climate Change Impacts on water 15062016___FINALx

PRESENTATION TITLE
Presented by:
The Impacts
of Climate Change on Water
Name Surname
Directorate
Date
Presented by:
Dr S Mgquba
Director: Climate Change Research and Advice
Department of Water and Sanitation
15 June 2016
Presentation outline
• Facts: Water and climate change
• Water resources and use per economic
sector
• Water and climate change
• Hydro-climatic zones and responses
(based on GCMs)
• Drought 2014/15 (El Nino)_just sharing
• Conclusions
Key things to note about climate change
• Climate change is NOT climate variability…these must
always be differentiated
• Models are highly uncertain about future climate scenarios,
however…………..
• various climate change models agree that there will be
significant temperature increases across South Africa in
the medium to longer term,
• when it comes to changes in rainfall, the models provide
different results in certain climate change zones…..highly
uncertain
• much as there are general trends.... It is important to note
models differ (some wet scenario and dry scenarios).
• Understanding uncertainty in climate science is
fundamental.
Facts to note about water and climate change
Climate change influences key hydrological drivers…either way good
or bad, the water sector will be impacted upon :
– Temperatures
– Rainfall
– Evaporation
– Run-off
– Groundwater
Key things to note about water:
– Water transcends boundaries (trans-boundary), and
– What happens upstream has impacts downstream
– Water can be in various states (liquid, solid, gas)
– Water is not stationery
Water is a scarce resource in South Africa
(average annual rainfall & water resource situation)
 Rainfall is relatively higher in the northern
and eastern parts of Southern Africa (viz. DRC,
Zambia and Mozambique)
 The drier parts of the region include Namibia,
Botswana and South Africa
 Hence, water availability is spatially skewed
(in terms of areal distribution)
 Evaporation rates exceed precipitation mainly
due to high temperature
 Southern Africa only has 12.25% of the total
water in Africa (i.e. highly arid region)
 Dissolved salts from host rocks in some areas
(e.g. Namaqualand in the N Cape) may also
impact on the quality of water
Key message: RSA is relatively water scarce under natural conditions even
before factoring human induced impacts into the equation
Current water resources mix
Water use at 98% assurance level
Desalination
<1%
Return flows,
14%
Ground
water, 9%
Surfarce
resources, 77%
To ensure water security, this water mix needs to be altered in future by
increased use of currently under-utilized water resources such as
 groundwater, water re-use, desalination, rainwater & fog harvesting,
Water Security _Chris M
Proportion of water uses per economic
sector
61%
3%
27%
2%
3%
2%
2%
7
Water and Climate Change
Terrestrial
Ecosystems
(water dependent)
Reduced
Water
Supply
Aquatic
Ecosystems
Water
Quality
(water dependent)
(e.g. algal
blooms))
Rainfed
Agriculture
Biodiversity
(water dependent)
(reduced
producttion)
Irrigated
Agriculture
Health
(water borne
diseases)
(reduced flow)
Infrastructure
Design
(storage options)
Disaster
Risk
Management
Sea level
rise (saline
water intrusion.)
(extreme events)
Adapted from Schulze, 2013
Apart from the climate zones and hydrological boundaries as the potential units of
analysis, a combination of these two delineations including the proposed
Hydro-climatic zones
Z on e 1
Z on
e4
Zo
ne
2
Z on e 3
6
5
ne
ne
Zo
Zo
Zone
Observed Rainfall (1960 – 2010)
1: Limpopo,
Olifants &
Inkomati
2: Pongola
Umzimkhulu
Significant reduction in rainfall & number of rainy days high in autumn
(MAM)
Overall decrease in rain days in DJF and MAM and in the annual mean.
Increase trend in precipitations for southern part of the region (along
Drakensberg Mountains) in SON.
Increased rainfall in the west and decreased rainfall in the east in DJF.
Decreased precipitation in MAM. Decrease in rain days in MAM and in
annual mean of about 6 and 13 days, respectively, are observed over the 50
year period
Trends indicate some increase in precipitation and rain days along the parts
of EC, reduction in precipitation and rain days in FS and NC
3: Vaal
4: Orange
5:
Mzimvuvhu –
Tsitsikamma
Significant increase in precipitation & rain days especially around the
Drakensberg and the Southern coastal areas in all season.
6: BreedGouritz and
Berg Olifants
The annual mean rain days has decreased significantly by 11 days over 50
year period. Increase in rain days in the Western coastal region.
Zone
Projected Rainfall (2040 -2060)
1: Limpopo,
Olifants &
Inkomati
Under business as usual (i.e. RCP 8.5 – without mitigation) scenario there
are no clear pattern of drying
2: Pongola
Umzimkhulu
Rainfall anomalies projected exhibit a clear pattern of drying under business
as usual scenario
3: Vaal
Rainfall anomalies projected exhibit a clear pattern of drying under business
as usual scenario
4: Orange
Rainfall projections under business as usual scenario remain within the
realm of the present day climate
5:
Mzimvubu –
Tsitsikamma
Clear trends of drying under worst case scenario
6: BreedGouritz and
Berg
Olifants
Clear trends of drying under worst case scenario
Zone
1: Limpopo,
Olifants &
Inkomati)
2: Pongola
Umzimkhulu
3: Vaal
4: Orange
5: Mzimvuvhu
– Tsitsikamma
6: BreedGouritz and
Berg Olifants
Observed Temperature (1960 – 2010)
Significant increase in maximum temperature occur in JJA (0.022 0C/year)
and in annual mean (0.018 0C/year).
The average maximum temperatures highest for MAM (0.02 0C/year and
0.012 0C/year for the annual mean).
There is a strong warming trends in maximum temperatures of almost 2 0C
(0.034 0C/year) in MAM and almost 1.5 0C (0.029 0C/year) in JJA.
Significant increase in maximum temp of between 0.025 0C/year and 0.039
0C/year in all seasons
Significant increase in maximum temp at a rate of 0.017 0C/year to 0.03
0C/year in all season except for summer
Significant increase in maximum temp from 0.015 0C/year to 0.027 0C/year
in all season. Significant warming has worsened over the past 10 – 12 years
with persistent above average temperatures
Zone
1: Limpopo,
Olifants &
Inkomati
2: Pongola
Umzimkhulu
3: Vaal
4: Orange
5:
Mzimvuvhu –
Tsitsikamma
6: BreedGouritz and
Berg Olifants
Projected Temperature (2040 -2060)
Annual temp: 2015 – 2035, increase of up to 20C. From2040 - 2060,
increase of between 1 and 3 0C. From 2080 to 2100 drastic increase of
between 3 and 6 0C. This is based on worst case scenario.
Annual Temp: 2015 -2035 to reach 1 and 2 0C. Between 2040 - 2060
average annual temp will increase by up to 4 0C. From 2080 - 2100 annual
averages temperature will increase by 3 to 6.5 0C.
Annual temp to reach values of 1 and 2.5 0C between 2015 - 2035.
Between 2040 - 2060 average annual temp will increase by between 1 and
5 0C. From 2080 - 2100 annual averages temperature will increase by 3 to
8 0C.
Annual temp to reach values of 2,5 0C between 2015 - 2035. Between
2040 - 2060 average annual temp will increase by between 1 and 3 0C.
From 2080 - 2100 annual averages temperature will increase by 3 to 5.5
0C
Annual temp to reach values of 2 0C between 2015 - 2035. Between 2040 2060 average annual temp will increase by between 1 and 2 0C. From
2080 - 2100 annual averages temperature will increase by 2 to 5 0C
Annual temp to reach values of 1,5 0C between 2015 - 2035. Between
2040 - 2060 average annual temp will increase by between 1 and 2 0C.
From 2080 - 2100 annual averages temperature will increase by 2 to 4 0C.
Example 1: Projected Temperature change
Example 2: Projected rainfall
1. Water Management Areas
Apart from the climate zones and hydrological boundaries as the potential units of
analysis, a combination of these two delineations including the proposed
Zone 1
Z on
e4
Zo
ne
2
Z on e 3
5
e6
ne
Zo
Z on
Example 3: Projected Water Quality
Impacts
The 2014 /15 drought:
What is El Nino, La Nina, ENSO?
• El Nino: an extreme climatic event that occurs every 2
to 7 years, caused by the warming of the east-central
equatorial Pacific Ocean
• La Nina: caused by the cooling of the sea surface
waters of the Pacific (characterised by the wetting
conditions). La Nina is the opposite of an El Nino.
• ENSO: El Nino Southern Oscillation is a periodic
fluctuation in sea surface temperature (El Niño) and the
air pressure of the overlying atmosphere (Southern
Oscillation) across the equatorial Pacific Ocean. It is a
general term used to describe both the El Nino and the
La Nina
The Oceanic Nino Index is an indicator for
monitoring the El Nino and La Nina
Impact of El Nino
• The El Nino occurs when the sea surface temperature in the
east central equatorial Pacific exceeds 0.5ºC (for La Nina
less than -0.5ºC)
• The El Nino / La Nina events have historically occurred as a
result of natural climate variability, with increasing frequency
under a changing climate
• The 97/98 El Nino which is the El Nino of the century was
greater than the current yet the impact in terms of drought
was less that may be attributed to
– The contribution or impact of climate change to the current drought
– That El Nino was preceded by the La Nina and followed by a
moderate to strong La Nina
• The current El Nino, is still one of the strongest on record
• Only 10% of El Nino events were followed by another El
Nino. Prospects are good, about 40% that there will be a La
Nina in 2016/17, or neutral conditions (~ 50% chance)
27
As the warming decreases from late summer, the
wetting is projected to gradually increase
2015
confirmed as
the driest year
on record for
SA (since
1921)
29
Systems (i.e. hydrological) response
• High temperatures lead to high evaporation rates
that in turn reduces runoff and groundwater
recharge
– This means less water available to fill the dams and to
replenish groundwater storage
• Less water in dams, rivers, soil means
– Less water available for energy generation, food security,
poverty eradication, livelihoods or for economic growth
– Increased degradation of water quality due to increased
concentration of dissolved materials
• The Department addresses these challenges
through development of supply systems and/or
management of demands (or requirements)
In summary so far …,
• The current drought cannot only be attributed to the El Nino,
but also to climate variability and change as well as other
factors (e.g. increased water use)
• The model projections are all in agreement that the warming
(El Nino) is gradually decaying and may reach neutral state
during winter, yet temperatures are likely to remain high for
some time
• There is also a likelihood of above normal rainfall in spring
• The hydrological responses include inadequate water available
for filling dams and replenishing groundwater storage.
• Interventions include water conservation and demand
management measures, use of relevant decision support tools
including forecasts and operating rules to inform decisions
underpinned by monitoring data and information
• Diversification of water sources and resizing of storage
capacity are also important adaptation measures used by the
DWS
Water security AND climate change , challenges
& opportunities
•
Measures to enhance water security include:
– Adaptive (scenario planning & experimental) approaches
– Reviewing and updating hydrological analyses
– Improving & implementing operating rules for reservoirs,
– Monitoring & improving the early warning systems,
– Promoting water conservation and demand management
– Enhanced water storage (e.g. artificial groundwater recharge)
•
Challenges & opportunities posed by changing climate:
– Economic challenges (costs due to redesigns - to cater for change)
– Increased water demands in an already water scarce country
– Increased temperature, sediment, nutrient, pollutant loading
– Opportunities: Innovation / developing new technologies
Water Security _Chris M
What do we do so long: Sustainable water
management
•
•
Good and sustainable water management entails, amongst other
aspects:
 Development of appropriate policies, strategies, plans, regulations
etc
 Planning and implementation of options to reconcile water
requirements with water availability with a high level focus on
priority interventions such as water conservation and water
demand management
 Optimal operation and maintenance of the water infrastructure
(both surface water and groundwater) using appropriate decision
support tools
 Involvement of stakeholders including strong partnerships at all
levels
 Regular monitoring & evaluation that entails collection, storage,
analyses and interpretation of data thus leading to informed
actions (interventions)
Requisite technical and management skills to ensure that DWS is on
top of the game is crucial
THANK YOU!
34