Transcript Water resources

Decision Tools to Evaluate
Vulnerabilities and Adaptation
Strategies to Climate Change
The Water Resource Sector
Outline
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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
Effective V&A Assessments
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Defining V&A assessment
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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
Effective V&A Assessments
(continued)
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General questions
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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
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Participants bring differing objectives/
expertise
These differences often lead to dissention/
differing opinions
Effective V&A Assessments
(continued)
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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
Water Resources –
A Critical V&A Sector
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External
Pressure
Often critical to both managed and natural
systems
Human activity influences both systems
Managed
Systems
Product, good
or service
Process Control
Example: Agriculture
External
Pressure
Natural
Systems
State of System
services
Little Control
of processes
Example: Wetlands
Examples of Adaptation –
Water Supply
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Construction/modification of physical infrastructure
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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
Examples of Adaptation –
Water Supply
(continued)
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Adaptive management of existing water
supply systems
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Change operating rules
Use conjunctive surface/groundwater supply
Physically integrate reservoir operation
system
Coordinate supply/demand
Examples of Adaptation –
Water Supply
(continued)
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Policy, conservation, efficiency, and technology
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Domestic
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Municipal and in-home re-use
Leak repair
Rainwater collection for nonpotable uses
Low flow appliances
Dual supply systems (potable and nonpotable)
Agricultural
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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
Examples of Adaptation –
Water Supply (continued)
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Policy, conservation, efficiency, and technology
(continued)
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Industrial
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Water re-use and recycling
Closed cycle and/or air cooling
More efficient hydropower turbines
Cooling ponds, wet towers and dry towers
Energy (hydropower)
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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
Tools in Water Resource
V&A Studies
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Hydrologic models (physical processes)
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Simulate river basin hydrologic processes
Examples – water balance, rainfall-runoff, lake
simulation, stream water quality models
Water resource models (physical and
management)
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Simulate current and future supply/demand of
system
Operating rules and policies
Environmental impacts
Hydroelectric production
Decision support systems (DSS)
for policy interaction
Tools in Water Resource
V&A Studies (continued)
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Economic models
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Macroeconomic
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Sectoral level
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Multiple sectors of the economy
General equilibrium – all markets are in
equilibrium
Single market or closely related markets
(e.g., agriculture)
Firm level
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Farm-level model (linear programming
approach)
Microsimulation
Hydrologic Implications of
Climate Change
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Precipitation amount
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Precipitation frequency and intensity
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Global average increase
Marked regional differences
Less frequent, more intense (Trenberth et al., 2003)
Evaporation and transpiration
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Increase total evaporation
Regional complexities due to plant/atmosphere
interactions
Hydrologic Implications of
Climate Change (continued)
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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
Africa Example –
ECHAM4/OPYC
Africa Example –
GFDLR30
What Problems Are
We Trying to Address?
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Water planning (daily, weekly, monthly, annual)
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Local and regional
Municipal and industrial
Ecosystems
Reservoir storage
Competing demand
Operation of infrastructure and hydraulics
(daily and sub-daily)
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Dam and reservoir operation
Canal control
Hydropower optimization
Flood and floodplain inundation
The Water Resource Sector
Water’s “Trade-Off” Landscape
Water for nature
Water for agriculture
Water quantity
Water quality
Seasonality of flow
Regulation
Water for recreation
Domestic water
Water for industry
Water Resources from
a Services Perspective
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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
Freshwater Ecosystem
Services
Extractable; Direct Use; Indirect Use
Nutr.
cycling
Flood/
drought
mitig.
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Trans
-port
Harvest.
biota
Water
for ag.,
urban,
indust.
Recreation,
aesth.
beauty
Upper
Rivers
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Lower
Rivers
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Delta
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Bay
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Power
gener.
Regen.
of soil
fertility
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Erosion
control
Habitat
/
biodiversity
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Water
purification
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Tools to Use for the Assessment:
Referenced Water Models
Planning
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WEAP21 (also
hydrology)
Aquarius
SWAT
IRAS (Interactive
River and Aquifer
Simulation)
RIBASIM
MIKE 21 and
BASIN
Referenced Water Models
Operational and hydraulic
HEC
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HEC-HMS – event-based
rainfall-runoff (provides
input to HEC-RAS for doing
1-d flood inundation
“mapping”)
HEC-RAS – onedimensional steady and
unsteady flow
HEC-ResSim – reservoir
operation modeling
WaterWare
RiverWare
MIKE11
Delft3d
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(continued)
Current Focus – Planning and
Hydrologic Implications of Climate Change
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Select models of interest
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Deployed on PC; extensive documentation;
ease of use
WEAP21
SWAT
HEC suite
Aquarius
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
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Cannot be
climatically driven
Physical Hydrology and
Water Management Models
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SWAT management
decisions on water,
sediment, nutrient and
pesticide yields with
reasonable accuracy on
ungauged river basins.
Complex water quality
constituents.
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Rainfall-runoff, river
routing on a daily
timestep
Physical Hydrology and
Water Management Models
(continued)
WEAP21 advantage:
seamlessly integrating
watershed hydrologic
processes with water
resources management
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Can be climatically
driven
Physical Hydraulic
Water Management Model
HEC-HMS watershed
scale, event based
hydrologic simulation,
of rainfall-runoff
processes
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Sub-daily rainfallrunoff processes of
small catchments
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
Data are organized in a tree
structure that you edit by rightclicking here.
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Use the
View bar to
switch
between
your
analysis
and its
results.
You can create multiple scenarios and use
this box to switch between them.
Enter or edit
your data by
typing it
here.
Your data
are shown
here as
either a
graph or a
table.
Hydrology Model
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Critical questions
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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?
Planning Model
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Critical questions
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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?
A Simple System
with WEAP21
40
60
An Infrastructure Constraint
10 Unmet
30
70
A Regulatory Constraint
10 Unmet
30
70
IFR Met
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
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40
60
0
10 unmet
Different Preferences
30
10
For example, a center
pivot operator may prefer
to take water from a
tributary because of lower
pumping costs
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0
90
Example
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How much water
will the site with
70 units of
demand receive?
Example (continued)
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How much water will
be flowing in the
reach between the
Priority 2 diversion
and the Priority 1
return flow?
Example
(continued)
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What could we do to
ensure that this
reach does not go
dry?
What Are We Assuming?
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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
What Do We Do Now?
Add Hydrology
And this is the Climate Interface
Integrated Hydrology/Water
Management Analytical Framework in
WEAP21
Irrigation
City
The WEAP 2-Bucket
Hydrology Module
P
Plant
Canopy
Et= f(z1,kc, , PET)
Pe = f(P, Snow Accum,
Melt rate)
u
z1
Rd
Sw
L
Surface Runoff =
f(Pe,z1,1/LAI)
Interflow =
f(z1,ks, 1-f)
Percolation =
f(z1,ks,f)
Smax
z2
Dw
Baseflow =
f(z2,drainage_rate)
One 2-Bucket Model
per Land Class
Some Comments
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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
This Last Point Leads to a Stylized
Groundwater Representation
Percolation
Pumping
lw
Sy,Ks
hd
Some Comments
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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
The WEAP21 Graphical
User Interface
Use the
View bar to
switch
between
your data
and its
results.
Use the menu to do standard
functions such as creating
new areas and saving.
You can click and drag elements of the
water system from the legend onto the
schematic directly.
Languages:
Interface Only
English
French
Chinese
GIS layers
can be
added here.
Your can
zoom your
schematic
in or out
by sliding
the bar
here.
Spanish
Data are organized in a tree
structure that you edit by rightclicking here.
Use the
View bar to
switch
between
your
analysis
and its
results.
You can create multiple scenarios and use
this box to switch between them.
Enter or edit
your data by
typing it
here.
Your data
are shown
here as
either a
graph or a
table.
WEAP’s Temporal and
Spatial Scale
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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)
Some Ideas on
Catchment Size
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Small: < 100 km2
Medium: 100 to 1,000 km2
Large: 1,000 to 10,000 km2
Very large: 10,000 to 100,000 km2
Data Requirements
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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
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Area, land cover . . .
Climate
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Precipitation, temperature, windspeed, and
relative humidity
Data Requirements
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(continued)
Water demand data
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Municipal and industrial demand
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Agricultural demands
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Aggregated by sector (manufacturing, tourism,
etc.)
Disaggregated by population (e.g., use/capita,
use/socioeconomic group)
Aggregated by area (# hectares, annual wateruse/hectare)
Disaggregated by crop water requirements
Ecosystem demands (in-stream flow
requirements)
Example Data Resources
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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)
Calibration and Validation
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Model evaluation criteria
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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
Modeling Streamflow
Jun-99
Jun-97
Jun-95
Jun-93
Jun-91
Jun-89
Jun-87
Jun-85
Jun-83
Jun-81
Jun-79
Jun-77
Jun-75
Jun-73
Jun-71
Jun-69
Jun-67
Jun-65
Jun-63
Oct-99
Oct-97
Oct-95
Oct-93
Oct-91
Oct-89
Oct-87
Oct-85
Oct-83
Oct-81
Oct-79
Oct-77
Oct-75
Oct-73
Oct-71
Oct-69
Oct-67
Oct-65
Oct-63
Oct-61
Oct-59
Oct-57
Oct-55
Reservoir Storage
FOLSOM
1.20E+06
1.00E+06
8.00E+05
6.00E+05
OBS AF
4.00E+05
MOD AF
2.00E+05
0.00E+00
SHASTA
5.E+06
4.E+06
3.E+06
OBS AF
2.E+06
MOD AF
1.E+06
0.E+00
Looking at Results
Select results to be
viewed, including
which scenario here.
Change units
and subcategories of
results, and
change the
style of the
graph here.
Select values
for the y-axis
here.
WEAP21 – Developing Climate
Change and Other Scenarios
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The scenario editor readily accommodates
scenario analysis, e.g.,
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Climate change scenarios and assumptions
Future demand assumptions
Future watershed development assumptions
Licensing WEAP
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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”