Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate Change The Water Resource Sector - PowerPoint PPT Presentation

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

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Title: Decision Tools to Evaluate Vulnerabilities and Adaptation Strategies to Climate Change The Water Resource Sector


1
Decision Tools to Evaluate Vulnerabilities and
Adaptation Strategies to Climate Change The
Water Resource Sector
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 VA Assessments
  • Defining VA assessment
  • Often VA 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 VA 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

5
Effective VA 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
Water Resources A Critical VA Sector
  • Often critical to 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
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/mydroplants/delivery systems
  • Raising dam wall height
  • Increasing canal size
  • Removing sediment from reservoirs for more
    storage
  • Interbasin water transfers

8
Examples of Adaptation Water Supply (continued)
  • Adaptive management of existing water supply
    systems
  • Change operating rules
  • Use conjunctive surface/groundwater supply
  • Physically integrate reservoir operation system
  • Coordinate supply/demand

9
Examples of Adaptation Water Supply (continued)
  • Policy, conservation, efficiency, and technology
  • Domestic
  • Municipal and in-home re-use
  • Leak repair
  • Rainwater collection for nonpotable uses
  • Low flow appliances
  • Dual supply systems (potable and nonpotable)
  • 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

10
Examples of Adaptation Water Supply (continued)
  • Policy, conservation, efficiency, and technology
    (continued)
  • Industrial
  • 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

11
Tools in Water Resource VA 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

12
Tools in Water Resource VA Studies (continued)
  • Economic models
  • Macroeconomic
  • 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

13
Hydrologic Implications of Climate Change
  • Precipitation amount
  • Global average increase
  • Marked regional differences
  • 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

14
Hydrologic Implications of Climate Change
(continued)
  • Changes in runoff
  • Despite global precipitation increases, areas of
    substantial runoff decrease
  • 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

15
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16
Africa Example ECHAM4/OPYC
17
Africa Example GFDLR30
18
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

19
The Water Resource SectorWaters Trade-Off
Landscape
20
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

21
Freshwater Ecosystem Services
Extractable Direct Use Indirect Use
22
Tools to Use for the Assessment Referenced Water
Models
  • Planning
  • WEAP21 (also hydrology)
  • Aquarius
  • SWAT
  • IRAS (Interactive River and Aquifer Simulation)
  • RIBASIM
  • MIKE 21 and BASIN

23
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
  • MIKE11
  • Delft3d

24
Current Focus Planning and Hydrologic
Implications of Climate Change
  • Select models of interest
  • Deployed on PC extensive documentation ease of
    use
  • WEAP21
  • SWAT
  • HEC suite
  • Aquarius

25
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

26
Physical Hydrology and Water Management Models
(continued)
  • SWAT management decisions on water, sediment,
    nutrient and pesticide yields with reasonable
    accuracy on ungauged river basins. Complex water
    quality constituents.
  • Rainfall-runoff, river routing on a daily
    timestep

27
Physical Hydrology and Water Management Models
(continued)
  • WEAP21 advantage seamlessly integrating
    watershed hydrologic processes with water
    resources management
  • Can be climatically driven

28
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

29
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

30
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?

31
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 Simple System with WEAP21
33
An Infrastructure Constraint
34
A Regulatory Constraint
35
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

36
Different Preferences
30
10
  • For example, a center pivot operator may prefer
    to take water from a tributary because of lower
    pumping costs

0
90
37
Example
  • How much water will the site with 70 units of
    demand receive?

38
Example (continued)
  • How much water will be flowing in the reach
    between the Priority 2 diversion and the Priority
    1 return flow?

39
Example (continued)
  • What could we do to ensure that this reach does
    not go dry?

40
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 hydologic context

41
What Do We Do Now?
42
Add Hydrology
43
And this is the Climate Interface
44
Integrated Hydrology/Water Management Analytical
Framework in WEAP21
45
The WEAP 2-Bucket Hydrology Module
Surface Runoff f(Pe,z1,1/LAI)
Sw
Dw
46
One 2-Bucket Model per Land Class
47
Some Comments
  • The number of parameters in the model is fairly
    limited and is 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

48
This Last Point Leads to a Stylized Groundwater
Representation
49
Some Comments
  • The geometry of the aquifers in question is
    representative, not absolute
  • The stream stage is assumed to be invariant in
    this module
  • Although the water table can fluctuate, it
    ignores all local fluctuations

50
The WEAP21 Graphical User Interface
Languages Interface Only English French Chinese S
panish
51
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52
WEAPs Temporal and Spatial Scale
  • Time step daily, weekly, monthly, etc.
  • No routing, because 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 time steps
    (e.g., one month)
  • Smaller watersheds can apply shorter time steps
    (e.g., 1-day, 5-day, 10-day)

53
Some Ideas onCatchment Size
  • Small lt 100 km2
  • Medium 100 to 1,000 km2
  • Large 1,000 to 10,000 km2
  • Very large 10,000 to 100,000 km2

54
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

55
Data Requirements (continued)
  • Water demand data
  • Municipal and industrial demand
  • Aggregated by sector (manufacturing, tourism,
    etc.)
  • Disaggregated by population (e.g., use/capita,
    use/socioeconomic group)
  • Agricultural demands
  • Aggregated by area ( hectares, annual
    water-use/hectare)
  • Disaggregated by crop water requirements
  • Ecosystem demands (in-stream flow requirements)

56
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.org (resources)

57
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

58
Modeling Streamflow
59
Reservoir Storage
60
Looking at Results
61
WEAP21 Developing Climate Change and Other
Scenarios
  • The scenario editor readily accommodates scenario
    analysis, e.g.,
  • Climate change scenarios and assumptions
  • Future demand assumptions
  • Future watershed development assumptions

62
Licensing WEAP
  • Go to www.weap21.org 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
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