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Scenario Based Approach for
Adaptation in the Water Sector –
Case of Santiago de Chile
International Conference
Climate Change and Regional Response 2013 (CCRR-2013)
May 27-29, 2013,
Dresden, Germany
L.M. Simon, Dr. Lehn, M. Oertel
ITAS – Institute for Technology Assessment and Systems Analysis
KIT – Karlsruhe Institute of Technology, Germany
1. Introduction
2. Geographical situation
3. Current water supply and water demand
4. Scenario-Methodology
5. Climate Scenarios and socio-economic scenarios
6. Proposal for climate change adaptation measures
7. Conclusions
Structure
Less precipitation and higher temperatures
reduced water availability for irrigation
Heat island
higher water demand for
irrigation of green areas
Source: ICLEI 2011
1. Climate change impacts
Increased heavy rainfall events
Flooding of transport system and water
infrastructure
Higher temperatures and less precipitation
Change in the run-off and variation in
seasonality and magnitude
2. Geographical situation - The Maipo-watershed
The Metropolitan region of Santiago de Chile and the Maipo-watershed (Source: SIIT 2013, Cartography: KIEMLE)
3. Current Situation - Water availability
High inter and intra-annual
variation
of rainfall (ENSO-phenomenon)
Average rainfall: ~ 360 mm
Most rainfall in winter months
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Pre
cip
itato
n in m
m
Maipo River: snow dominated regime = most run-off results from melt of snow and ice
of the winter-accumulated snowpack with high flow rates in summer months
This regime is important for a Mediterranean climate type, as most of the water flows
during the dry months, allowing irrigation and water supply during the hot and dry
season
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Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan. Feb. Mrz
pre
cip
itation in m
m
Station Quinta Normal, MRS (DMC)
Total amount of annual renewable fresh water varies between 3 km³ -
10 km³ with an average of 6 km³
Annual renewable fresh
water (km³/a)
Available fresh water resource
for inhabitants (m³/cap.*a)
Average 6.2 901
Max (wet) years 10.2 1483
Min (dry) years 2.8 407
3. Current Situation - Water availability
3. Current situation – water demand
Agricultural demand:
Irrigation surface: 136.000 ha (13% of total agricultural land)
Irrigation efficiency: around 36%
Urban demand:
Average per capita demand: around 220 l*inh.*d
Infrastructure losses: 32%
Industrial demand:
Scare information
Increasing demand since 1990
18%
8%
74%
Urban Industry Agriculture
Development of MRS 1975/2008
(UNEP 2010)
4. Scenario-Methodology
Scenarios are images of how the future might
look like
Interconnectedness of future water resource
with land uses, economic activities, population
growth etc.
Necessity to draft more comprehensive
scenarios, where climate scenarios were
integrated within different socio-economic and
technical futures
socio-economic parameters are e.g. population
growth, economic development, technical
changes , management strategies, legals
aspects
Climate Scenarios Socio-economic scenarios
Universidad de Chile, Chile Kit/ITAS, Germany
For future scenarios A2 and B1
according to IPCC, a standard
downscaling methodology was
applied for 2045-2065 years
Socio-economic, technical, legal and
institutional scenarios for the MRS
Development of two scenarios
A2 (‘worst case’)
B1/B2 (‘best case’)
Development of two scenarios
Business As Usual (BAU)
Collective Responsibility(CR)
The results of the A2 climate scenario were related to those of the BAU
scenario to produce a ‘worst case’ model for both supply and demand
The ‘best case’ was formulated by combining the results of B1/B2 with
the CR scenario
4. Scenario - Methodology
4.1 Climate scenarios Increasing temperatures of about 1-2 degrees, increase of days (> 30 °C)
Reduction of average total rainfall events, more heavy rainfall events
Change in the balance and availability of water
Strong reduction of Maipo’s run-off up to 40% in summer months
Comparison between historic and future annual run-off of the Maipo River and precipitation for scenario
A 2050 and B 2050 (Cortes et al. 2012)
4.2 Socio-economic scenarios
Business as Usual (BAU) Collective Responsibility (CR)
The MRS in 2050 examines the
consequences of continuing recent
trends in population, economic
growth, urbanization, technology
and human behavior. It assumes
that current market based policies
remain and environmental health
and ecological integrity are of less
interest.
The MRS in 2050 is dominated by
a strong state presence and
market regulation. Environmental
protection, social justice and
equity are major political goals.
Introduction of clean and resource
efficient technologies are key
determinants. This scenario
assumes less population growth
Future annual water demand in km³ in 2050
BAU
• 8.5 mio population
• 120.000 ha irrigated area
• 60% irrigation efficiency
• 180 l/cap *d urban water demand
• 40% water losses
CR
• 7.9 mio. population
• 135.000 ha irrigated area
• 75% irrigation efficiency
• 150 l/cap*d water demand
• 10% water losses
4.2 Socio-economic scenarios
Agricultural Agricultural
Urban Urban
Industry Industry
Total Total
4.3 Future water balance
Due to higher water efficiency in agriculture the water balance will improve
but only if the irrigated agricultural area is not increased
In the year 2050 the total water demand accounts for 60-65% of the total
availability in an average year
In dry years the water demand exceeds the availability by far (between
150 and 180 %) !
Supply 2011 A 2050 B 2050
min
2.8
1.9
2.1
max
10.2
9.3
9.5
average
6.2
5.2
5.6
Demand 2011 BAU CR
total
4.3
3.4
3.1
Relationship between future renewable water resources (according to climate
scenarios) and demand (according to socio-economic scenarios in km³
6. Proposal for adaptation measures
Supply side Demand side Legal framework
Building of new artificial water
storage capacities in the Andes
or in the “Santiago Basin”
Increase of irrigation efficiency
in agriculture
Adaptation of water codex to
changing circumstances
Raise public awareness about
the treatment and reuse of grey
water and implementation of
the system in new built up
areas
Reduction of water losses in
the network
Strengthening of public
interests by improvement of
public institutional capacities
Reuse of (improved) treated
waste water for agricultural
irrigation
Reduction of water demand for
irrigation by changing the
cropping calendar, crop mix,
irrigation method, & area
planted
Implementation of integrated
governance structures for the
watershed Maipo/Mapocho
Collection and storage of rain
water
Introduction of water - efficient
tap fittings in existing private
houses and hotels
…
6.1: Introduction of water-efficient irrigation technologies
Aim
Establishing a subsidy system for the implementation of water-efficient irrigation
Coordination with the regional planning, which avoids the extending of irrigated
agricultural area
Establishing a bonus system
Co-Benefits:
Minimizing water costs for farmers
Less explotation of groundwater resources
Increase of ecological flows
7. Conclusions
Necessity to combine climate and socio-economic scenarios
Less water availability
Less water demand
Increasing gap between water availability and water demand in dry
years
There exist great potentials in many sectors to reduce the water
demand
Adaptations measures consider demand side, supply side and the
legal framework
