Transcript NRCS Farm Irrigation Rating Index FIRI

NRCS Farm Irrigation Rating
Index
History and Use
By
Clare Prestwich
Irrigation Engineer
NRCS National Water and Climate Center
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
The Need
• A uniform and objective evaluation method
for planning irrigation water conservation
• Method of documenting present water use as
well as the effects of changes made by
improving both irrigation system and
management
• Reduce the need for difficult and time
consuming complete seasonal field
evaluations
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
The Process
• Multidisciplinary team was
formed from several western
states and a national committee
• Basic data and procedures
originated as a result of a west
wide water conservation
emphasis program during the
1980’s
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
The Results
• Farm Irrigation Rating Index (FIRI)
• Assist Offices
– Plan water management improvements
– Estimate water conserved by improved
management
– Estimate the runoff and deep percolation
– Provide a tool for follow up and
document accomplishment in water
management
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
What it is not
• Replacement for on site evaluations
• A finite farm or field application
efficiency, or specific deep percolation
and runoff amounts
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
What it is
• A procedure for comparing improvements
or changes
– Year to year
– Field, Farm and project level
• Relative rating
• A season long evaluation not a single
event
• Composed of three elements
– Management
– System
– Potential efficiency
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Management
• Water management is the human element.
Decisions scientifically based, knowledge
to operate the system, and maintenance
performed.
• The management element is defined by 6
factors
–
–
–
–
–
–
Water measurement
Soil moisture monitoring and scheduling
Irrigation skill
Maintenance
Water delivery constraint
Soil Condition
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
System Element
• Factors selected according to irrigation
type
• System element is defined by nine factors
–
–
–
–
–
–
–
–
–
Water distribution control
Conveyance efficiency
Land leveling
Climatic
Sprinkler design
Wind
Tail water reuse
Emitter clogging
Trickle design
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Potential Efficiency Element
• A measure of the optimum application
efficiency for the method of irrigation
being used
• Values based on full canopy cover
and systems are well designed and
maintained.
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Default Potential Efficiencies
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Management Factors
Water Measurement Factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Irrigation Skill and Action Factor
Soil Moisture/Scheduling Factor
Water Delivery Factor
Maintenance Factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Soil Condition Factor
System Factors for all
Systems
Water Distribution Control Factor
Conveyance Efficiency Factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Sprinkler System Factors
Climate Factor
Sprinkler Design Factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Wind Factor
Surface System Factors
Land Leveling Factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Tail water reuse factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Micro System Factors
Trickle Design Factor
Emitter Clogging Factor
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Climate Factor
Wind Factor
Rating Index
FIRI  PE  SYS  MGT
SYS  Wc  Ce  L  R
 Wc  Ce  C W  Sd
Surface Systems
Sprinkler System
 Wc  Ce  C W  T  E
MGT  M d  S  I  M  D  Sc
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Micro System
Very easy to put into a
program
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Or spreadsheet
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
FIRI use
• Use extensively during the 1994
Irrigation induced erosion survey
• Project ranking and comparison for
NRCS programs (e.g. EQIP, CSP)
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Example
Pasture irrigated by uncontrolled flood
with 3000ft of earth ditch on sandy
loam soil. Water delivered on a18 day
rotation limited rate
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Present condition
• Potential Efficiency - 50
• Management
– No water measurement .9
– Schedules based on Plant indicators .94
– Irrigation Skill – Lacks full attention
– Maintenance – good .98
– Water Delivery – fix rotation limited rate
.85
– Soil Condition – conservation tillage .98
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Present Condition
• System
–
–
–
–
Control at - Farm delivery .94
Conveyance – 3000ft earth ditch .91
Unleveled fields - .82
No tail water reuse -1.0
• MGT= .9 x .94 x .96 x .98 x .85 x .98 = .663
• SYS = .94 x .91 x .82 x 1 =.701
• FIRI = 50 x 0.663 x 0.701 = 23.3
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Future
• Operator wants to change to a graded
furrow system with land leveled fields
and tail water reuse. Ditch replaced
with gated pipe
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Future Condition
• Potential Efficiency – change to
graded furrow 50 to 75
• Management changes
– Add measuring device .90 to .96
– Scheduling - no change .94
– Irrigation skill - follows plan .96 to 1
– Maintenance - no change .98
– Delivery - no change .85
– Soil tillage - no change .98
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Future Condition
• System
–
–
–
–
Control – change to each set .94 to 1
Conveyance – change to gated pipe .91 to .99
Land – change to laser level .82 to 1
Add tail water reuse – change 1 to 1.08
• MGT = .96 x .94 x 1 x .98 x .85 x .98 = .737
• SYS = 1 x .99 x 1 x 1.08 = 1.069
• FIRI = 75 x 0.737 x 1.069 = 59.1
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Compute the water
conserved
• Water conserved with seasonal net
irrigation of 2 ac-feet/ac
Present
2
 8.6 Ac-ft / ac
.233
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Future
2
 3.4 Ac-ft / ac
.591
Guide lines for deep
percolation and runoff
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Problems
• Management Section has greatest weight
– More subjective to the person doing rating
• NRCS required to report water saved or
conserved
– FIRI rating taken as actually efficiency
– More water saved than available
• Most states restrict water rights to 4 to 5
ac-ft/ac
– From our example
• 8.6-3.4= 5.2 ac-ft/ac saved
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Possible changes
• Update Potential Efficiencies
• Add systems like LESA, MESA, SDI, etc.
• Update Management factors to reflex
current Technology
– Soil moisture/scheduling Flow measurement,
etc.
• Change computation method from straight
multiplication to a statistical method.
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
• Original method
– PE x f1 x f2….x Fn
• Proposed method
– PE x (1-sqrt((1-f1)2+(1-f2)2….+(1-fn)2))
• The multiplication approach essentially assumes a
worst case scenario where each influence has full
weight regardless of the other factors
• The Statistical approach recognizes that if one
condition is poor, that the influence of another
variable is not as great as it would be if it were the
only problem.
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Comparison of the two
methods
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service
Value of FIRI
• Still an Effective tool
• Quick, uniform and provides reasonable
comparisons
• Users need to be realistic
– Better input gives better comparison
– Not meant for black box use
• Still a relative value
United States Department of Agriculture
NRCS
Natural
Resources
Conservation
Service