Transcript Document

AWRA Annual Meeting: 2011
Albuquerque, NM
Session: New Water Resources of NM and Obstacles to
their Development
1:30 – 3:00
Monday, Nov 7
”Economic Costs of Sustaining Water Supplies:
Findings From the Rio Grande Basin”
Frank A. Ward
NM State University
College of Agricultural, Consumer, and Environmental Sciences
NM Water Resources Research Institute
Ongoing Challenges in RG Basin
• Adaptation to droughts, floods, climate change
• Search for resilient water institutions where there
are complex watershed processes and constraints
– Agronomic
– Hydrologic
– Meteorologic
– Economic
– Political
• Search for Just, Flexible, Open Water Policies
• Understandable Science-informed policy
Road Map
• Describe Potential Benefits of Comprehensive Basin
Analysis (CBA)
• Brief history of Rio Grande Compact
• Describe principles how CBA can inform sustainable
water policies.
• Show how CBA can inform water sharing debates
• Illustrate the use of CBA for policy analysis:
sustaining RG Basin’s aquifers/reservoirs
• Conclusions
Uses of Comprehensive Basin Scale
Analysis (CBA)
• CBA can provide data to inform debates on:
– Adaptation to floods, drought, climate change
– Ways to share transboundary waters
– Irrigation water conservation subsidies
– New knowledge or method (e.g., evaporation, ET)
– Socially just, economically efficient, politically
acceptable water infrastructure
– Effective development planning
– Cost effective Payment for Environmental Services
Simple Graphics to inform complex
watershed policy debates:
Sankey Chart
• Watersheds are scientifically complex
• Policy debates add complexity
• Few simple graphics can show the choices
Water Balance: Rio Grande
• Rio Grande from Colorado (USA) to US-Mexico
border with supplies, gauged flows and depletions
by location
• Impacts of wet, normal, dry inflows
• Must abide by existing water institutions
– Rio Grande Compact
– US Endangered Species Act
– US Mexico Treaty of 1906
– New Mexico – Texas water sharing agreement (2008)
Limits of Graphics, Need for Models
• Economic and policy goals: sustainability,
sustainable diversion reductions, resilient
institutions, minimum econ losses from drought,
flood, climate change
• So we use mathematical models of hydrology,
agronomy, economics, and institutions for RG Basin
Water sharing arrangement
hammered out for Rio Grande
• 9 years debate, experiment, negotiation (29-38)
• Signed in 1938
• Based on a creative combination of:
– Observing historical use patterns
– Mathematical formula for predicting historical use
– Formula explained how historical use varied in wet v.
dry years.
– Formula was applied to share water for the future in
wet and dry conditions.
Rio Grande Compact
(Approximate) Water Sharing Formula
• CO agreed deliveries to NM (1000 af/yr)
Lobatos > - 10 + 0.27* Conejos + 0.11* Del Norte
+ .00005* Conejos2 + 0.0003* Del Norte2
• NM agreed deliveries to TX (1000 af/yr)
Elephant Butte > + 0.56*Otowi + .00001*Otowi 2
Role of CBA to Inform Water Policy
Proposals
• Historical outcomes by state, use, location, and period
under actual water policies
– Inflows: headwater supplies
– Hydrologic: streamflows, reservoir levels
– Agricultural: Irrigated land, farm income, yields, prodn,
food self sufficiency
– Urban: population, per capita use, price, supply reliability
– Environmental: key ecological assets
– Economic: Total economic benefits
Role of CBA to Inform Water Policy
Proposals
• Historical outcomes by country, use, location, and period
under potential water policy A
– Inflows: headwater supplies
– Hydrologic: streamflows, reservoir levels
– Agricultural: Irrigated land, farm income, yields, prodn,
food self sufficiency
– Urban: population, per capita use, price, supply reliability
– Environmental: key ecological assets
– Economic: Total economic benefits
Role of CBA to Inform Water Policy
Proposals
• Future outcomes by country, use, location, and period
under actual water policies
– Inflows: headwater supplies
– Hydrologic: streamflows, reservoir levels
– Agricultural: Irrigated land, farm income, yields, prodn,
food self sufficiency
– Urban: population, per capita use, price, supply reliability
– Environmental: key ecological assets
– Economic: Total economic benefits
Role of CBA to Inform Water Policy
Proposals
• Future outcomes by country, use, location, and period
under potential water policy A
– Inflows: headwater supplies
– Hydrologic: streamflows, reservoir levels
– Agricultural: Irrigated land, farm income, yields, prodn,
food self sufficiency
– Urban: population, per capita use, price, supply reliability
– Environmental: key ecological assets
– Economic: Total economic benefits
Use of a CBA
• Impacts of alternative policy, supplies, or
population by country, use, location, period.
– Inflow differences:
historic v potential
– Hydrologic differences:
historic v. potential
– Agricultural differences:
historic v. potential
– Urban differences:
historic v. potential
– Environmental differences:
historic v. potential
– Economic differences: Benefits of new policy compared to
historic policy. How these changes in benefits vary by
alternative future supplies or future populations
Policy
Flows
Conditions
Effects
Base
Base
Base
Base
Economic Value
Base
without
river inflows
reservoir storage
crop yields, prices
farm income
sustainability
crop water use (ET)
cropland
crop costs
urban benefits
reservoir evap
reservoir capacity
crop production
hydro benefits
gauged river flows
cropland capacity
crop mix
NPV farm income
Modified
water diversions
NPV urban benefits
river outflows
NPV power benefits
NPV total benefits
Modified
Modified
Modified
Modified
with
river inflows
reservoir storage
crop yields, prices
farm income
sustainability
crop water use (ET)
cropland
crop costs
urban benefits
reservoir evap
reservoir capacity
crop production
hydro benefits
gauged river flows
cropland capacity
crop mix
NPV farm income
water diversions
NPV urban benefits
river outflows
NPV power benefits
NPV total benefits
Impact of Reqd Sustainability on Selected Outcomes, RG Basin
Example Structure of CBA:
Rio Grande Basin: CO, NM, TX
Objective
NBuut
Max NPV  

t
u
t (1  ru )
NBeet

t
e
t (1  re )
NBAuckt
NPV Ag  
t
u
c
k
t (1  ru )
NBAuckt [ Pct Yielduckt  Cost uckt ] Luckt
NBut (e.g, urban), NBet (e.g., wetlands)
19
Constraints
•
•
•
•
•
•
Irrigable land, Headwater supplies
Sustain key ecological assets
Hydrologic balance
Reservoir starting levels (sw, gw)
Reservoir sustainability constraints (sw, gw)
Institutional
– Endangered Species Act
– Rio Grande Compact (CO-NM; NM-TX)
– US Mexico Treaty of 1906
– Rio Grande Project water sharing history (NM/TX)
20
Ag water use
X ut 
 B
uck
c
Luckt
k
u  irrigated region
c  crop
k  irrigation tech ( flood , drip, pivot ,...)
21
Institutions: e.g. Rio Grande
Compact
X vt
Lobatos
X vt
SA
 Colorado runoff
 X vt
Lobatos
 NM runoff
22
Example Results: Rio Grande Basin
• Policy 1 -- Sustain natural water capital over a
20 year period: aquifers to starting levels, no
requirement for reservoirs
• Policy 2 -- Increase natural water capital over
a 20 year period: aquifers to starting levels,
reservoirs to 90% of capacity
Table 1 : Change from Base Policy in Hydrologic, Agronomic, and Economic
Outcomes: Sustaining and Renewing Natural Capital, Upper RG, 2010-29
Total, Three Basin States
Units
From Sustaining
From Renewing
Natural Capital
Natural Capital
Hydrologic Outcome
1000 ac-ft/yr
-198.1
-16%
-218.7
-19%
1000 ac
-87.3
-27%
-94.8
-31%
-34,384
-6%
-62,048
-11%
-33,710
-6%
-64,868
-12%
-674
-4%
2,820
14%
Water Consumed (ET)
Agronomic Outcome
Cropland in Prodn
Economic Outcome
Total Net Benefits
From Water Use
From Water
Environment
$US 1000/yr
Conclusions: Overcoming Obstacles to
Sustaining NM’s Water Supplies
• Information Needs
– Economic value of water
• Agriculture
• Urban
• Environment
– Cost of Water Conservation
• Irrigated agriculture – subsidies
• Urban Use -- subsidies
• Water pricing: farms, cities, environment
Conclusions: Overcoming Obstacles to
Sustaining NM’s Water Supplies
• Needs for Policies/Institutions
– Complete NM’s Stream Adjudications, Especially
Middle and Lower Rio Grande
– Build and use resilient institutions for adapting to
drought, climate change