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Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate Change - The Water Resource Sector - UNFCC Climate Change Impacts and.

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Presentation on theme: "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 Vulnerability and Adaptation with respect to water resources
Hydrologic implications of climate change for water resources Topics covered in a water resources assessment Viewing water resources from a services perspective Tools/Models 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 Managed Systems External Pressure Natural Systems External Pressure State of System Little Control of processes 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 We are going to look at water resources, there are also economic based models that complement these. Economic Models Macro Economic Multiple sectors of the economy General Equilibrium - all markets are in equilibrium Sectoral level Single market or closely related markets (e.g. Agriculture) Firm level farm-level model (linear programming approach) microsimulation

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 These next couple slides look at the vulnerability of hydrology to climate change. A change that appears most likely is that global average precipitation will increase as global temperatures rise. Evaporation will increase with warming because a warmer atmosphere can hold more moisture. This capacity is governed by the exponential Clausius-Claperyon equation, which states that for an increase in air temperature by one degree Celsius the water-holding capacity of the atmosphere is increased by about seven percent. For example, Trenberth et al. (2003) hypothesized that, on average, precipitation will tend to be less frequent, but more intense when it does occur, implying greater incidence of extreme floods and droughts, with resulting consequences for water storage. Their arguments are based on the premise that local and regional rainfall rates greatly exceed evaporation rates and thus depend on the convergence of regional to continental scale moisture sources. They surmise that rainfall intensity should increase at about the same rate as the increase in atmospheric moisture, namely 7% K−1 with warming. This means that the changes in rain rates, when it rains, are at odds with the 1%–2% K−1 for total rainfall amounts as discussed previously. The implication is that there must be a decrease in light and moderate rains, and/or a decrease in the frequency of rain events, as found by Hennessey et al (1997). Thus, the prospect may be for fewer but more intense rainfall—or snowfall—events.

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 This slide looks at how the vulnerability of hydrology to climate change affects water resources.

13 Source: Nigel Arnell Different climate change models paint different pictures of annual runoff – different responses.

14 Africa Focus – ECHAM4/OPYC
Source: Nigel Arnell This is looking at changes in annual runoff in 2050 as % change compared to More relative runoff in the north with less relative runoff in the south. The ECHAM4 shows a relative decrease in runoff along the western coast in southern Africa.

15 Africa Focus – GFDLR30 Source: Nigel Arnell
This is looking at changes in annual runoff in 2050 as % change compared to The GFDLR30 shows again more relative runoff in the north but not the same relative decreases in runoff in the south.

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 Here we are looking at the assessment of water resources.

17 Water Resource Planning Water’s “Trade-Off” Landscape
When we look at water resources planning we are looking at how to balance demand from ag, industry, domestic, nature and recreation. Not only are we talking about quantity, but also quality, timing of the flow and regulations involved.

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 We want to emphasize it’s not just about runoff – want to look at how much water comes from a watershed – what does that water do – how does it provide services for the different uses including municipal, industry, biodiversity, etc. How is the system managed and regulated?

19 Freshwater Ecosystem Services
Extractable; Direct Use; Indirect Use Here is an example showing what services a watershed provides. You have upper rivers, lower rivers, a delta, and a bay. An example would be an upper river can provide water for power generation among other services. It can also help to mitigate floods and droughts and provide erosion control while a bay cannot provide those 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 WEAP21 Aquarius SWAT IRAS RIBASIM (river basin model) 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 HEC 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 These are the models we will talk more about. The focus for this workshop is planning and hydrology not hydraulics. These models are free, have good documentation, and are fairly easy to use. We will be providing you with the WEAP model. The other models you can get via the web.

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 Aquarius is an optimization model that uses perfect foresight. The graphic represents a frontier curve for optimization. The model is driven by an economic efficiency operational criterion requiring the reallocation of stream flows until the net marginal return in all water uses is equal. This occurs by systematically examining, using a nonlinear optimization technique, the feasibility of reallocating unused or marginally valuable water storage and releases in favor of alternative uses. Because water-system components can be interpreted as objects of a flow network, the model considers each component as an equivalent node or structure in the programming environment as well.

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 SWAT addresses simple management issues, with more focus on the supply side. It lightly touches on the demand side of water management modeling. Model Objective Predict the effect of management decisions on water, sediment, nutrient and pesticide yields with reasonable accuracy on large, ungaged river basins. Model Components Weather, surface runoff, return flow, percolation, ET, transmission losses, pond and reservoir storage, crop growth and irrigation, groundwater flow, reach routing, nutrient and pesticide loading, water transfer.

25 Physical Hydrology and Water Management Models (continued)
WEAP21 advantage: Seamlessly integrating watershed hydrologic processes with water resources management Can be climatically driven WEAP21 has many advantages. While it’s main purpose is a river basin model that looks at supply, demand, and infrastructure, it also has a hydrologic model that can determine runoff along with irrigation “cropwat” type modeling capabilities. This will be our model of focus.

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 HEC models are looking more at hydraulics, modeling sub-daily These models are used to get runoff – used for for flood studies, urban flooding, etc. The Hydrologic Modeling System is designed to simulate the precipitation-runoff processes of watershed systems.

27 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 Now going to be moving on to the WEAP model

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? Now breaking down the two main components of a water resources river basin model such as WEAP which includes hydrology and planning…. Given a set of parameters specific to a catchment, these are questions the hydrology model answers.

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? We now put human factors into the model that will affect the way the catchment utilizes water. These are some questions that can be analyzed/answered using WEAP.

30 A Simple System with WEAP21
60 40 How the planning model works – some supply with a demand. The next few slides show how water is distributed and tracked in the WEAP21 model. Legend: Red Circle = Demand Site Blue Line = River (arrow points downstream- value at the top in blue represents the headflow of the river) Green Line = Transmission Link (brings water from supply to demand) Black Line = Represents where the water is flowing and how much This slide – 100 units of water coming in via headflow of the river, 40 units are pulled from the river to meet the demand, leaving 60 units to continue downstream

31 An Infrastructure Constraint
70 30 10 Unmet Here there is an infrastructure constraint on the transmission link (maximum allowed is 30 units) 100 units of water supplied via the headflow of the river While the demand site is asking for 40 units, it will only receive 30 units because of the constraint on the transmission link. This leaves 70 units to continue downstream

32 A Regulatory Constraint
70 30 10 Unmet IFR Met Here there is a minimum flow requirement downstream of 70 units of water. There is no constraint on the transmission link, but the flow requirement has a higher priority than the demand site. 100 units supplied as headflow, 1 priority is downstream flow requirement of 70 units, which leaves only 30 units for the demand site. The demand site is unmet by 10 units.

33 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 40 60 10 unmet This example shows the priority system in WEAP21. Each demand site is given a priority (represented in the schematic by the black number in the red circle). Higher priorities receive water before lower priorities. The water will be distributed equally among demand sites of the same priority. In the schematic the small holder demand has the higher priority. Since there is only 100 units of water supplied, the large farmer’s demand is unmet by 10 units. If the large farmer had a higher priority then the small holder would only receive 30 units (a 10 unit deficit).

34 Different Preferences
30 10 For example, a center pivot operator may prefer to take water from a tributary because of lower pumping costs 90 This example shows the supply preference in WEAP21 We just saw how a demand will have a priority in the overall system. If a demand site is connected to more than one supply source, it can have a preference on which supply source it prefers more. For example, the demand site in the schematic is connected to two different supply sources (two rivers). It prefers to receive as much water as possible from river 1 (30 units of headflow). Since River 1 can only supply 30 units, the demand site will receive its remaining 10 units from river 2 (100 units of headflow). Preferences can vary due to water quality issues, cost issues, political issues, etc.

35 Example How much water will the site with 70 units of demand receive?
The orange line represents a 20 unit return flow from the 40 unit demand site. Here we have flow requirements on each river that have the highest priority. The 40 unit demand has a higher priority than the 70 unit demand. The 40 unit demand prefers water from river 1 (30 unit headflow) over water from river 2 (100 unit headflow). The 40 unit demand site receives 10 units from river 1 (20 units on river 1 goes to the flow requirement). The 40 unit demand site also receives 30 units from river 2. River 2’s flow requirement will be met by the 20 unit return flow. Therefore, the 70 unit demand site will receive all 70 units from river 2. Not just a rainfall runoff model -

36 Example (continued) How much water will be flowing in the reach between the Priority 2 diversion and the Priority 1 return flow? The 40 unit demand site took 30 units from river 2, the 70 unit demand site took 70 units from river 2. There will be no flow between priority 2’s demand site and priority 1’s return flow.

37 Example (continued) What could we do to ensure that this reach does not go dry? We could put a flow requirement on that reach. We could implement demand side water saving strategies.

38 What Are We Assuming? That we know how much water is flowing at the top of each river That no water is naturally flowing into or out of the river as it moves downstream That we know what the water demands are with certainty Basically, that this system has been removed from its HYDROLOGIC context

39 What Do We Do Now? What happens if we don’t know the headflow of the rivers or the exact amount demanded from the demand sites. What type of data do we know?

40 Add Hydrology We now gather data on the hydrologic components so that we can calculate the headflows in WEAP. We also gather data on what crops are being grown so that we can calculate the agricultural demands.

41 And this is the Climate Interface
What do we know now? We added hydrology. Hydrology is impacted by climate change – temperature, relative humidity, precipitation, how pasture, vegetables irrigation demands are going to change.

42 Integrated Hydrology/Water Management Analytical Framework in WEAP21
This is the background for the training portion – this is the framework of using catchments in WEAP– watershed produces runoff – water is distributed to different uses. The full catchment is divided into 4 sub-catchments.

43 The WEAP 2-Bucket Hydrology Module
Surface Runoff = f(Pe,z1,1/LAI) Sw This represents how WEAP translates precipitation into surface runoff, interflow, and baseflow. This is a stylized limited parameter hydrologic model. We are computing a watershed mass balance in a stylized way –we will be going through these parameters in the example and if you want more details you can read the supporting papers. Runoff from the upper storage occurs as direct, surface, and interflow, while baseflow originates only from the lower storage. P = Precipitation Et = Evapotranspiration Pe = Effective Precipitation Sw = Upper storage capacity (Root zone) Dw = Lower storage capacity (Deep water zone) Z1 = average, long-term relative storage in the root zone (percentage of total available capacity; % of Sw) Z2 = average, long-term relative storage in the deep water zone (percentage of total available capacity; % of Dw) Dw

44 One 2-Bucket Model per Land Class
Each separate land class is analyzed with the 2 bucket model (ie, there will be parameters associated with each land class –Sw(Root Zone Water Capacity) = 400 mm for trees, 300 mm for grass, and 350 mm for pasture.)

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 Model uses a predictor/corrector to solve continuous water balance algorithm You set the upper and lower thresholds – this implies the irrigation efficiency. The further apart the thresholds, the more irrigation is required.

46 This Last Point Leads to a Stylized Groundwater Representation
When in irrigated setting the system may take water out of groundwater then you have a stylized groundwater module in WEAP WEAP also allows for modeling the interactions of surface water and groundwater.

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 WEAP has an integrated user interface where you can drag and drop objects onto your schematic and click on each object to find the information/data associated with the object.


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 <100km2 Medium 100 to 1000km2 Large 1000 to 10,000km2 Very Large 10,000 to 100,000km2

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 Hydrology GIS General (resources)

55 Calibration and Validation
Model evaluation criteria Flows along mainstem and tributaries Reservoir storage and release Water diversions from other basins Agricultural water demand and delivery Municipal and industrial water demands and deliveries Groundwater storage trends and levels You can calibrate and validate the model by gathering this type of information.

56 Modeling Streamflow You can look at streamflow as part of your validation and calibration process.

57 Reservoir Storage Here is an example of a calibration; looking at modeled versus observed streamflow. We want to make sure that our modeled releases mimic what the observed data shows.

58 Looking at Results The results section in WEAP is very user friendly. You can slice-and-dice your data in a number of different ways. You can export it directly to Excel.

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: License Expires : 10/31/2005  (after which saving data will be disabled) After 6 months you will need to go to and register for a new license (free for government, university, and non-profit organizations in developing countries) 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!

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