Presentation on theme: "1 Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate Change - The Water Resource Sector - UNFCC Climate Change Impacts and."— Presentation transcript:
1 Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate Change - The Water Resource Sector - UNFCC Climate Change Impacts and Adaptations Maputo 18 April 2005 Alyssa McCluskey, University of Colorado and David Yates, National Center for Atmospheric Research
2 Outline 1. Vulnerability and Adaptation with respect to water resources 2. Hydrologic implications of climate change for water resources 3. Topics covered in a water resources assessment 4. Viewing water resources from a services perspective 5. Tools/Models 6. WEAP Model Presentation
3 Effective Vulnerability and Adaptation Assessments Defining Vulnerability and Adaptation (V&A) Assessment Often V&A is Analysis not Assessment Why?? Because the focus is on biophysical impacts e.g. hydrologic response, crop yields, forests, etc. However, Assessment is an integrating process Requiring the Interface of physical and social science and Public Policy
4 Effective Vulnerability and Adaptation Assessments 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 The assessment process requires 1. Value 2. Credibility 3. Legitimacy 4. Consistent Participation
5 Effective Vulnerability and Adaptation Assessments V&A Assessments - 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 Water Resources – A Critical V&A Sector Often Critical to both Managed and Natural Systems Human Activity Influences Both Systems Natural Systems External Pressure State of System Little Control of processes Managed Systems External Pressure Product, good or service Process Control Example: Agriculture Example: Wetlands
7 Examples of Adaptation – Water Supply Construction/Modification of physical infrastructure Canal linings Closed conduits instead of open channels Integrating separate reservoirs into a single system Reservoirs/Hydroplants/Delivery systems Raising dam wall height Increasing canal size Removing sediment from reservoirs for more storage Inter-basin water transfers Adaptive management of existing water supply systems Change operating rules Use conjunctive surface/groundwater supply Physically integrate reservoir operation system Co-ordinate supply/demand
8 Examples of Adaptation – Water Demand Policy, Conservation, Efficiency, and Technology Domestic Municipal and in-home re-use Leak repair Rainwater collection for non-potable uses low flow appliances Dual supply systems (potable and non-potable) Agricultural Irrigation timing and efficiency Lining of canals, Closed Conduits 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
9 Examples of Adaptation – Water Demand (continued) Policy, Conservation, Efficiency, and Technology Industrial Water Re-use and Recycling Closed cycle and/or air cooling More efficient hydropower turbines Cooling ponds, wet tower and dry towers Energy (hydro-power) Reservoir re-operation Co-generation (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
10 Tools in Water Resource V&A Studies Hydrologic Models (physical processes) Simulate river basin hydrologic processes Examples - Water Balance, Rainfall-Runoff, lake simulation, stream water quality models Water Resource Models (physical and management) Simulate current and future supply/demand of system Operating rules and policies Environmental impacts Hydroelectric production Decision Support Systems (DSS) for policy interaction
11 Hydrologic Implications of CC for Water Resources Precipitation amount Global average increase Marked regional differences Precipitation frequency and intensity Less frequent, more intense (Trenberth et al., 2002) Evaporation and transpiration Increase total evaporation Regional complexities due to plant/atmosphere interactions
12 Hydrologic Implications of CC for Water Resources (continued) Changes in runoff Despite global precipitation increases, areas of substantial runoff decreases Coastal zones Saltwater intrusion into coastal aquifers Severe storm-surge flooding Water quality Lower flows, could lead to higher contaminant concentrations Higher flows could lead to greater leaching and sediment transport
16 What Problems are We Trying to Address?? Water Planning (daily, weekly, monthly, annual) Local and regional Municipal and industrial Ecosystems Reservoir storage Competing demand Operation of infrastructure and hydraulics (daily and sub-daily) Dam and reservoir operation Canal control Hydropower optimization Flood and floodplain inundation
17 Water Resource Planning Water’s “Trade-Off” Landscape
18 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 provide by freshwater systems
19 Extractable; Direct Use; Indirect Use Freshwater Ecosystem Services
20 Tools to use for the Assessment: Referenced Water Models Planning WEAP21 (also hydrology) Aquarius SWAT IRAS (Interactive River and Aquifer Simulation) RIBASIM MIKE BASIN
21 Referenced Water Models (continued) 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
22 Current Focus – Planning and Hydrologic Implications of CC Select models of interest and available at workshop Why??? Free; deployed on PC; extensive documentation; ease-of-use WEAP21 SWAT HEC suite Aquarius
23 Physical Hydrology and Water Management Models AQUARIS advantage: Economic efficiency criterion requiring the reallocation of stream flows until the net marginal return in all water uses is equal Cannot be climatically driven
24 Physical Hydrology and Water Management Models (continued) SWAT management decisions on water, sediment, nutrient and pesticide yields with reasonable accuracy on ungaged river basins. Complex water quality constituents. Rainfall-runoff, river routing on a daily timestep
25 Physical Hydrology and Water Management Models (continued) WEAP21 advantage: Seamlessly integrating watershed hydrologic processes with water resources management Can be climatically driven
26 Physical Hydraulic Water Management Model HEC-HMS watershed scale, event based hydrologic simulation, of rainfall-runoff processes Sub-daily rainfall- runoff processes of small catchments
27 Overview WEAP21 1. Hydrology and Planning 2. Planning (water distribution) examples and exercises 3. Adding hydrology to the model 4. User interface 5. Scale 6. Data Requirements and Resources 7. Calibration and Validation 8. Results 9. Scenarios 10. Licensing and Registration
28 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?
29 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? How will allocation, operations, and operating constraints change if new management strategies are introduced into the system?
32 A Regulatory Constraint 70 30 10 Unmet IFR Met
33 0 40 60 10 unmet Different Priorities For example, the demands of large farmers (70 units) might be Priority 1 in one scenario while the demands of smallholders (40 units) may be Priority 1 in another
34 30 10 90 0 Different Preferences For example, a center pivot operator may prefer to take water from a tributary because of lower pumping costs
35 Example How much water will the site with 70 units of demand receive?
36 Example (continued) How much water will be flowing in the reach between the Priority 2 diversion and the Priority 1 return flow?
37 Example (continued) What could we do to ensure that this reach does not go dry?
38 What Are We Assuming? 1. That we know how much water is flowing at the top of each river 2. That no water is naturally flowing into or out of the river as it moves downstream 3. That we know what the water demands are with certainty 4. Basically, that this system has been removed from its HYDROLOGIC context
45 Some Comments The number of parameters in the model are fairly limited and are at least related to the biophysical characteristics of the catchment The irrigation routine includes an implicit notion of field level irrigation efficiency Seepage can only pass from the lower bucket to the river, not the other way
46 This Last Point Leads to a Stylized Groundwater Representation
47 Some Comments The geometry of the aquifers in question are representative, not absolute The stream stage is assumed to be invariant in this module While the “water table” can fluctuate, it ignores all local fluctuations
48 The WEAP21 Graphical User Interface Languages: Interface Only English French Chinese Spanish
50 WEAP’s Temporal and Spatial Scale Time step: Daily, weekly, monthly, etc. No routing, as all demands satisfied within the current time step Time step at least as long as the residence time of period of lowest flow Larger watersheds require longer times steps (e.g., one month) Smaller watersheds can apply shorter time steps (e.g., 1-day, 5-day, 10-day)
51 Some Ideas on Catchment Size Small <100km 2 Medium 100 to 1000km 2 Large 1000 to 10,000km 2 Very Large 10,000 to 100,000km 2
52 Data Requirements Prescribed supply (riverflow given as fixed time series) Time series data of riverflows (headflows) cfs River network (connectivity) Alternative supply via physical hydrology (watersheds generate riverflow) Watershed attributes Area, land cover... Climate Precipitation, temperature, windspeed, and relative humidity
53 Data Requirements (continued) Water demand data Municipal and industrial demand Aggregated by sector (manufacturing, tourism, etc.) Disaggregated by population (e.g., use/capita, use/socio-econ group) Agricultural demands Aggregated by area (# hectares, annual water- use/hectare) Disaggregated by crop water requirements Ecosystem demands (in-stream flow requirements)
54 Example Data Resources Climate http://www.mara.org.za/climatecd/info.htm Hydrology http://www.dwaf.gov.za/hydrology/ GIS http://www.sahims.net/gis/ General http://www.weap21.orghttp://www.weap21.org (resources)
55 Calibration and Validation Model evaluation criteria 1. Flows along mainstem and tributaries 2. Reservoir storage and release 3. Water diversions from other basins 4. Agricultural water demand and delivery 5. Municipal and industrial water demands and deliveries 6. Groundwater storage trends and levels
59 WEAP21 – Developing Climate Change and Other Scenarios The scenario editor readily accommodates scenario analysis Climate change scenarios and assumptions Future demand assumptions Future watershed development assumptions Etc.
60 Licensing WEAP User Name: UNFCCC, Mozambique WEAP Workshop Registration Code: 1031200517844 License Expires : 10/31/2005 (after which saving data will be disabled) After 6 months you will need to go to www.weap21.org and register for a new license (free for government, university, and non-profit organizations in developing countries)www.weap21.org Register WEAP under Help menu and select “Register WEAP”
61 WEAP Hands-On Training Two sets of exercises General WEAP without hydrology WEAP with hydrology/climate (LATEST AND GREATEST) We will be training on the latest version with hydrology and climate. Follow along or enter the data along with me!