Transcript background - New Mexico State University

Irrigation Efficiency
Improvements: Technical,
Economic,and Policy Issues
NM Geological Society
NM Tech University, Socorro
Frank A. Ward
NMSU ACES
April 12, 2013
History of Water Use in Rio Grande
• Why that history is important
– Identify history/culture
– Uncover long term water supply trends
– Piece together lessons for current drought/climate adaptation
• Data sources
– Stream gauges since late 1800s (in and out of NM)
– Historic tree ring analysis
– Water delivery records of cities, towns, and other water
suppliers (e.g., Santa Fe, Albuquerque, LC).
– Historic farm land in production
– Historical Documents (3 better-known)
• Great River: The Rio Grande in NA History (P. Horgan, 1984)
• Water in NM, A History of its Mgmt, Use (I. Clarke, 1987)
• Historic Management of NM’s Acequias (Ackerly, 1996) 2
Acequias
• A community-operated watercourse (canal,
ditch, ditch system,…).
• A publicly owned and operated irrigation
facility.
• In northern NM, the oldest were established
before 1600.
3
History: some high points
• 1598 – north of Rio Chama Rio Grande confluence:
Onate build an acequia to irrigate crops (I Clark, 1987)
• early 1600s – remarkably similar throughout the region
(Torquemado, 1609)
• 1700 - 1800, more than 100 acequia systems built
(Dominguez).
• 1752, Rio Grande below Albuquerque completely dry
(Humbolt, 1966).
• 1855-7, European immigrants learned hard lessons
about the limits of crop growing without regular rainfall
and streamflows (Davis, 1857).
• Licenses for land worth little without water.
4
More High Points
• 1891 (JW Powell)
– Water control systems were limited by water,
inefficient, and temporary
– about 15000 acres irrigated in Taos Valley
– Only about 1/3 of land under the ditch actually tilled
(water limits land).
– Also a problem in Afghanistan today.
5
Messages
• Water supply limits (human) water use.
• You can infer the history of water use in the Rio
Grande if you can estimate long term supplies.
• Before modern large storage dams, pumps,
interbasin transfer projects, desalination
technology, recycling and reuse, water in the
river was the limiting resource
6
What did past water use in NM’s Rio
Grande Basin look like?
7
Reconstructed Flows, Tree Rings, Rio
Grande at Otowi Gauge (1450-2002)
Source, Treeflow: Woodhouse, Lukas, and Meko
http://treeflow.info/riogr/riograndeotowinatural.html
8
Historic RG Flows into NM (k-af/yr)
USGS Stream Gauge Data – 3 hws
• Rio Grande at Del Norte (CO)
– Flows = 657.93 – 109.17 post 2000
– 1891-2010
(110 years)
• Conejos River at Mogote (CO)
– Flows = 238.59 – 49.16 post 2000
– 1899-2010
(101 years)
• Rio Chama at Chamita
(NM)
– Flows = 438.14 –99.05 post 2000
– 1970 – 2010
(41 years)
9
Background
• Climate Change: more floods/droughts, greater
conflict potential in dry places like NM
• Continued population and urban demand growth
• Shrinking key ecological assets
• Irrigated ag consumes 85-90% of water in NM
• Ongoing search for ways to conserve water in
irrigated agriculture
– technology
– policy
– Projects
(drip, sprinkler, water saving crops)
(subsidies, regulations, pricing, … )
(infrastructure, leveling, … )
10
Reducing irrigation water use
• Reduce land in production
– Cities buy or rent water or water rights from ag
– Farm prices deteriorate
• Alter crop mix, e.g.:
– More acres in cotton
– Fewer acres in alfalfa, pecan orchards
– Develop more drought tolerant crop varieties
• Reduce water application rates (deficit irrigate)
• Shift to water conserving irrigation technology
– To sprinklers
– To drip irrigation
11
Reminder
Evaporation v Transpiration
Irrigation / Ac
Weighted Ave over Crops (EBID)
Technology Apply
ET
E?
T? I. Eff
Surface
4.27
2.74
0.64
Drip
3.45
3.16
0.90
12
Separating E from T
Z. Samani, NMSU, April 3, 2013
• No simple methods for separating E and T. His satellite
ET map of EBID does not split E-T.
13
Gaps
• Little work in NM (or elsewhere) explaining what
affects irrigation water savings that integrates
– Farm economics:
profitability
– Farm hydrology:
water application
– Agronomy:
yields by crop
– Basin hydrology:
net water depletions
– Basin institutions:
protect senior water rights
14
Aims
• Data: Assemble data on crop water applications,
crop water use, yields, land in production, crop
mix, cost, and prices that characterize economics
of irrigated ag in NM’s RG Project Area
• Economic analysis: Analyze profitability,
production, land and water use in the Area.
• Policy Analysis: Forecast the same for:
– Several drip irrigation subsidies
– Selected water supply scenarios
2
6
15
Study Region: Elephant Butte
Irrigation District
• http://www.ebid-nm.org/
16
Approach
• Analyze water conservation subsidies
that reduces capital cost to convert
from surface to drip.
– Farm Income effect
– Hydrologic effect on water app/depletion
• Integrates farm economics and basin
hydrology
17
Farm Economics
• NMSU Farm costs and returns
• Published by NM county, year, crop, and
irrigation technology
• Web -- http://aces.nmsu.edu/cropcosts/
18
Pecans, drip irrigated
19
Pecans, surface irrigated
20
Pecans: Drip or Surface Irrigated
21
Farm Water Economics 101
• Compare drip and surface irrigation
– Drip: better applies quantity and timing of
water that the plant needs for max yields
– Drip: higher yields higher ET, lower aquifer
recharge
– Drip: reduces water applied
– Drip: conversion costs are high
22
Cost of Converting:
Surface to Drip Irrigation
• Conversion Capital Costs:
– About $2500 / ac for 10 year life
– About $365 / ac per year at 7% interest
• Conversion is a major investment, so for the
conversion to increase income:
– Yield gain must be high
– or
– $ Value of saved water must be high
23
EBID Remote
Sensing: NMSU
• Basin-wide
Evapotranspiration mapping
• Demand forecasting, water
operations support
• Depletion changes with:
– Management options
– Changing crops
– Drought cycles
• Informs sustainable water
management
24
Quantitative Analysis of NM Ag
Water Conservation
• Maximizes Farm Income by choosing
land in production, by
– crop
– irrigation technology
• Subject to Constraints
25
–
–
–
–
Hydrologic (gw, sw)
Agronomic: yields, including salinity
Economic: Pecan acreage
Institutional
Crop Water Data Used, EBID, NM (Samani)
A
Crop
Tech
ET
R
Yield
ton/ac
ac-ft/ac/yr
A
Tech
ET
R
Yield
ton/ac
ac-ft/ac/yr
Alfalfa
S
5.0
3.3
1.7
8.00
D
4.1
3.7
0.4
9.00
Cotton
S
3.0
2.3
0.7
0.42
D
2.8
2.5
0.3
0.46
Lettuce
S
2.5
1.5
1.0
11.88
D
1.9
1.7
0.2
13.83
Onions
S
4.0
2.3
0.7
16.88
D
3.0
2.7
0.3
20.08
Green Chile
S
3.0
2.0
1.0
11.00
D
2.7
2.4
0.3
13.25
Red Chile
S
3.0
2.0
1.0
1.75
D
2.5
2.2
0.3
1.95
Pecans
S
5.0
3.0
2.0
0.58
D
4.1
3.7
0.4
0.72
26
Under the Hood
27
Max Irrigation Income
Incuckt
NPV Income     
t
(1

r
)
u
c
k
t
u
u  location
c  crop
k  irrig tech ( surface v. drip )
t  year
Incuckt  [ Pct *Yielduckt  Costuckt ] Luckt
28
Constraints
• EBID land: about 90 K acres
• EBID area water price and supply
– SW = 4 – 6”
– GW = $90 per af pumped
• Salinity impacts on yields
2013
2013
• Institutional
–
–
–
–
Endangered Species Act
Rio Grande Compact
US Mexico Treaty of 1906
Rio Grande Project operation agreement (NM/TX)
• Water Rights Protection
– No increase in water depletions: NM OSE
29
Results
30
Table 1. Economic Value of Depleted Water in Irrigation by Level of
Supply and Source, Lower RG, USA, 2012 ($US/Ac-Ft Consumed)
sw_supply
1-100_pct
2-80_pct
3-60_pct
4-40_pct
5-20_pct
6-00_pct
subsidy
1-0
2-100
1-0
2-100
1-0
2-100
1-0
2-100
1-0
2-100
1-0
2-100
Depletions (k-ac-ft/yr)
sw
gw
tot
169
0
169
169
1
170
135
14
149
135
34
170
101
37
139
101
67
168
68
69
137
68
102
169
34
103
137
34
135
169
0
128
128
0
171
171
$US/a-f depleted
sw
gw
0
0
38
0
38
0
38
0
81
0
83
0
126
0
124
0
126
0
128
0
366
0
328
0 31
Lessons Learned: waterconserving technology
• Irrigators invest in water-saving technologies when faced
with lower costs for converting from surface to drip.
• Drip irrigation subsidies  farm income,  crop yields, 
value of food production, and  crop water applications.
• By raising crop yields and raising crop water ET, drip
irrigation subsidies put upward pressure on water depletions.
• Where water rights exist, authorities need to guard against
 depletions with growing subsidies that reduce water
applications.
• In RG Project Area, NM, the economic value of water is
$126 - $128 per acre foot depleted with 20% of full
surface supplies (e.g. 2013).
32
Research Questions
• What policies would sustain NM’s aquifers affordably?
• What actions would reduce ag water use likely to occur?
– Without climate change
– With climate change that affects:
• Yields
• Evaporation
• ET
• Supplies
– With high, medium, low future:
• Prices
• Yields
• Costs
33
Tentative answers
• Better water measurement
– Gauges
– Tracking use by crop (application, ET)
• Better water accounting
– Current use patterns
– Potential use patterns
• Adjudications
– Who has the senior/junior rights in the
face of future supply variability.
Important as drought/climate intensifies.
– Can promote trading water for $
34
Thank you
http://agecon.nmsu.edu/fward/water