Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate Change Water Resources Sector

1. Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate ChangeWater Resources Sector Sebastián VicuñaUniversity of California, Berkeley/SEICGE Hands-on Training Workshop on V&A Assessments for the Latin America and the Caribbean RegionAsunción, Paraguay, 14-18 August 2006

2. Outline • Vulnerability and adaptation with respect to water resources • Hydrologic implications of climate change for water resources • Tools/models • WEAP model presentation • Role for Multi-Criteria Analysis (MCA)

3. Effective V&A Assessments • Defining V&A assessment • Often V&A in the water sector focuses on analysis over assessment • Why? Because the focus is on biophysical impacts, e.g., hydrologic response, crop yields, land use, etc. • Assessment is an integrating process requiring the interface of physical and social science and public policy

4. Effective V&A Assessments (continued) • General questions • What is the assessment trying to influence? • How can the science/policy interface be most effective? • How can the participants be most effective in the process? • General problems • Participants bring differing objectives/ expertise • These differences often lead to dissention/ differing opinions – this is where MCA can help in prioritization

5. Effective V&A Assessments (continued) • To be valuable, the assessment process requires • Relevancy • Credibility • Legitimacy • Consistent participation • An interdisciplinary process • The assessment process often requires a tool • The tool is usually a model or suite of models • These models serve as the interface • This interface is a bridge for dialogue between scientists and policy makers

6. The Water Resource SectorWater’s “Trade-Off” Landscape

7. Water Resources from a Services Perspective • Not just an evaluation of rainfall-runoff or streamflow • But an evaluation of the potential impacts of global warming on the goods and services provided by freshwater systems

8. Natural Systems External Pressure State of System Little Control of processes Water Resources – A Critical V&A Sector • Must consider both managed and natural systems • Human activity influences both systems Managed Systems External Pressure Product, good or service Process Control services Example: Agriculture Example: Wetlands

9. Hydrologic ‘External Pressures’ related to Climate Change • Precipitation amount • Global average increase • Marked regional differences • Temperature increase • Change in timing of streamflows • Glacier retreat • Precipitation frequency and intensity • Less frequent, more intense (Trenberth et al., 2003) • Evaporation and transpiration • Increase total evaporation • Regional complexities due to plant/atmosphere interactions

10. Specific Pressures: Annual Runoff Change in annual runoff (A2 scenario) Arnell., 2003

11. Specific Pressures: Annual Runoff Change in annual runoff (A2 scenario) Arnell., 2003

12. Specific Pressures: Annual Runoff Change in annual runoff (A2 scenario)

13. Specific Pressures: Runoff timing, analogy to North American West Stewart et al., 2004

14. Analogy with Western North America http://plasma.nationalgeographic.com/mapmachine/index.html

15. Analogy with Western North America http://plasma.nationalgeographic.com/mapmachine/index.html

16. Refill lost Inflow spilled Specific Pressures: Runoff timing, analogy to North American West

17. Specific Pressures: Retreating glaciers Evolución del glaciar Chacaltaya (Bolivia) Retroceso del glaciar Broggi Glaciar en 1979 y 1997 Fluctuación del frente de 4 glaciares en Perú Comunicación Nacional del Perú a la UNFCCC Francou et al., 2000

18. Specific Pressures: Retreating glaciers • Meltwaters are depended upon during dry season to sustain low flow periods • Probable diminished volume and earlier timing of flows • Has implications for hydropower production, agricultural demands, and river and riparian quality and ecosystem needs

19. Specific Pressures: Extreme weather • Climate variability (El Nino/Nina Southern Oscillation) impact water availability and all economic sectors en several countries in the region (e.g. Peru, Ecuador, Central America) (IPCC 2001). • Some climate models indicate more El Nino-like climate with increased greenhouse gases concentrations (Meehl and Washington 1996; Trenberth and Hoar, 1997)

20. Specific Pressures: Extreme weather Change in extremes by the 2050s, under HadCM3 Arnell., 2003

21. Specific Pressures: Extreme weather Change in extremes by the 2050s, under HadCM3 Arnell., 1999

22. Examples of Adaptation in Water Resources • Construction/modification of physical infrastructure • Canal linings • Closed conduits instead of open channels • Integrating separate reservoirs into a single system • Reservoirs/hydro-plants/delivery systems • Raising dam wall height • Increasing canal size • Removing sediment from reservoirs for more storage • Inter-basin water transfers

23. Examples of Adaptation in Water Resources(continued) • Adaptive management of existing water supply systems • Change operating rules for reservoirs • Use conjunctive surface/groundwater supply • Physically integrate reservoir operation system • Coordinate supply/demand • Indigenous options

24. Examples of Adaptation in Water Resources (continued) • Policy, conservation, efficiency, and technology • Domestic • Municipal and in-home re-use of water • Leak repair • Rainwater collection for non-potable uses • Low-flow appliances • Dual-supply systems (potable and nonpotable) • Agriculture • Irrigation timing and efficiency • Drainage re-use, use of wastewater effluent • High value/low water use crops • Drip, micro-spray, low-energy, precision application irrigation systems • Salt-tolerant crops that can use drain water

25. Examples of Adaptation – Water Supply (continued) • Policy, conservation, efficiency, and technology (continued) • Industry • Water re-use and recycling • Closed cycle and/or air cooling • More efficient hydropower turbines • Cooling ponds, wet towers and dry towers • Energy (hydropower) • Reservoir re-operation • Cogeneration (beneficial use of waste heat) • Additional reservoirs and hydropower stations • Low head run of the river hydropower • Market/price-driven transfers to other activities • Using water price to shift water use between sectors

26. Tools in Water Resource V&A Studies • What tools are available to understand both water resource vulnerabilities and evaluate possible adaptation strategies? • How can stakeholders be engaged in these processes?

27. Types of Water Resources Models • Hydraulic: biophysical process models describing streamflow, flooding • Hydrology: rainfall/runoff processes • Planning: water resource systems models Which model?... What questions are you trying to answer?

28. Hydraulic Model • Critical questions • How fast, deep is river flowing (flooding effects) • How do changes to flow and channel morphology impact sediment transport and services provided (fish habitats, recreation, etc).

29. Hydrology Model • Critical questions • How does rainfall on a catchment translate into flow in a river? • What pathways does water follow as it moves through a catchment? • How does movement along these pathways impact the magnitude, timing, duration, and frequency of river flows, as well as water quality?

30. Planning Model • Critical questions • How should water be allocated to various uses in time of shortage? • How can these operations be constrained to protect the services provided by the river? • How should infrastructure in the system (e.g., dams, diversion works) be operated to achieve maximum benefit (economic, social, ecological)? • How will allocation, operations, and operating constraints change if new management strategies are introduced into the system?

31. Tools to Use for the Assessment: Referenced Water Models Operational and hydraulic • HEC • HEC-HMS – event-based rainfall-runoff (provides input to HEC-RAS for doing 1-d flood inundation “mapping”) • HEC-RAS – one-dimensional steady and unsteady flow • HEC-ResSim – reservoir operation modeling • WaterWare • RiverWare • MIKE11 • Delft3d

32. Hydraulic Water Management Model • HEC-HMS watershed scale, event based hydrologic simulation, of rainfall-runoff processes • Sub-daily rainfall-runoff processes of small catchments • Free, download from web

33. Tools to Use for the Assessment: Referenced Water Models (continued) • Planning/ hydrology • WEAP21 • Aquarius • SWAT • IRAS (Interactive River and Aquifer Simulation) • RIBASIM • MIKE 21 and BASIN

34. Current Focus – Planning and Hydrologic Implications of Climate Change • Selected planning/hydrology models: can be deployed on PC, extensive documentation, ease of use, free (or free to developing nations)… • Aquarius • SWAT (Soil Water Assessment Tool) • WEAP21 (Water Evaluation and Planning)

35. Physical Hydrology and Water Management Models • AQUARIUS advantage: Has economic efficiency criterion requiring the reallocation of stream flows until the net marginal return in all water uses is equal • Cannot be climatically driven – flows prescribed by user • Economic focus

36. Physical Hydrology and Water Management Models (continued) • SWAT advantage: Can predict effect of management decisions on water, sediment, nutrient and pesticide yields on ungauged river basins. Considers complex water quality constituents. • Rainfall-runoff, river routing on a daily timestep • Focuses on supply side of water balance

37. Physical Hydrology and Water Management Models (continued) • WEAP21 advantage: Seamlessly integrates watershed hydrologic processes with water resources management • Can be climatically driven • Based on holistic approach of integrated water resources management (IWRM) – supply and demand

38. Overview WEAP21 • Hydrology and planning • Planning (water distribution) examples and exercises • Adding hydrology to the model • User interface • Scale • Data requirements and resources • Calibration and validation • Results • Scenarios • Licensing and registration

39. WEAP and Planning • Provides a common framework for transparently organizing water resource data at any scale desired – local watershed, regional or transboundary river basin • Scenarios can be easily developed to explore possible water futures • Implications of various policies can be evaluated

40. Uses of WEAP • Policy Research • Alternative Allocations • Climate Change • Land Use Change • Infrastructure Planning • Capacity Building • Negotiation • Stakeholder Engagement

41. Can do High level planning at local and regional scales Demand management Water allocation Infrastructure evaluation WEAP Capabilities Cannot do • Sub-daily operations • Optimization of supply and demand (e.g. cost minimizations or social welfare maximization)

42. 40 60 A Simple System with WEAP21

43. 10 Unmet 30 70 An Infrastructure Constraint

44. 10 Unmet 30 70 IFR Met A Regulatory Constraint

45. 40 60 0 10 unmet Different Priorities • For example, the demands of large farmers (70 units) might be Priority 1 in one scenario whereas the demands of smallholders (40 units) may be Priority 1 in another

46. Different Preferences • For example, a center pivot operator may prefer to take water from a tributary because of lower pumping costs 30 10 0 90

47. WEAP is Scenario-driven • The scenario editor readily accommodates analysis of: • Climate change scenarios and assumptions • Future demand assumptions • Future watershed development assumptions

48. Futures and Scenarios: Why? • Scenarios: a systematic way of thinking about the future • To gain a better understanding of the possible implications of decisions (or non-decisions across scales and time • To support decision-making

49. Driving Forces Technological • Computer and information technology • Biotechnology • Miniaturization Environmental/Climatic • Increasing global stress • Local degradation • Some remediation in richer countries Governance • Global institutions • Democratic government • Role for civil society in decision-making Demographic • More people • Urbanization • Older Economic • Growing integration of global economy Social • Increasing inequality • Persistent poverty Cultural • Spread of values of consumerism and individualism • Nationalist and religious reaction

50. Who are the Actors? • Government • Private sector • Civil society • Public • Rich farmers • Poor farmers • Urban users • Environmentalists • Or?