Scenario Based Approach for Adaptation in the Water Sector Case of Santiago de Chile

Transcription

1 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

2 Structure 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

3 1. Climate change impacts Less precipitation and higher temperatures reduced water availability for irrigation Increased heavy rainfall events Flooding of transport system and water infrastructure Heat island higher water demand for irrigation of green areas Higher temperatures and less precipitation Change in the run-off and variation in seasonality and magnitude Source: ICLEI 2011

4 2. Geographical situation - The Maipo-watershed The Metropolitan region of Santiago de Chile and the Maipo-watershed (Source: SIIT 2013, Cartography: KIEMLE)

5 Precipitaton in mm precipitation in mm 3. Current Situation - Water availability Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan. Feb. Mrz High inter and intra-annual variation of rainfall (ENSO-phenomenon) Average rainfall: ~ 360 mm Most rainfall in winter months Station Quinta Normal, MRS (DMC) 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

6 3. Current Situation - Water availability Average Max (wet) years Min (dry) years Annual renewable fresh water (km³/a) Available fresh water resource for inhabitants (m³/cap.*a) Total amount of annual renewable fresh water varies between 3 km³ - 10 km³ with an average of 6 km³

7 3. Current situation water demand Agricultural demand: Irrigation surface: 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 % 18% 8% Urban Industry Agriculture

8 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 Development of MRS 1975/2008 (UNEP 2010)

9 4. Scenario - Methodology Climate Scenarios Universidad de Chile, Chile Socio-economic scenarios Kit/ITAS, Germany For future scenarios A2 and B1 according to IPCC, a standard downscaling methodology was applied for years Development of two scenarios A2 ( worst case ) B1/B2 ( best case ) Socio-economic, technical, legal and institutional scenarios for the MRS 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

10 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)

11 4.2 Socio-economic scenarios Business as Usual (BAU) 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. Collective Responsibility (CR) 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

12 4.2 Socio-economic scenarios Future annual water demand in km³ in 2050 BAU 8.5 mio population ha irrigated area 60% irrigation efficiency 180 l/cap *d urban water demand 40% water losses CR 7.9 mio. population ha irrigated area 75% irrigation efficiency 150 l/cap*d water demand 10% water losses Agricultural Urban Industry Total Agricultural Urban Industry Total

13 4.3 Future water balance Supply 2011 A 2050 B 2050 min max average Demand 2011 BAU CR total Relationship between future renewable water resources (according to climate scenarios) and demand (according to socio-economic scenarios in km³ 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 %)!

14 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 Reuse of (improved) treated waste water for agricultural irrigation Reduction of water losses in the network Reduction of water demand for irrigation by changing the cropping calendar, crop mix, irrigation method, & area planted Strengthening of public interests by improvement of public institutional capacities 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

15 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

16 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

17 Discussion Thank you for your attention! Questions? More information: