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Master Gardener Pilot Training

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Title: Master Gardener Pilot Training


1
Master Gardener Pilot Training
  • Residential Irrigation and Water Conservation
  • Fort Worth, TX
  • June 24-26, 2009

2
Landscape Irrigation and Water Issues
3
Landscape Irrigation In Texas
  • 3.5 million acres of maintained turfgrass in
    Texas
  • 1.9 million acres of highway roadsides
  • Single family households account for 58 (or 2.03
    million acres) of maintained turfgrass

4
Landscape Irrigation
  • 89 of single family households practice
    irrigation
  • Average household is 50,000 - 60,000 gallons of
    water per year
  • 2.55 billion spent on turfgrass maintenance

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Texas Water Supply, 1990
17
Projected Texas Water Supply By source
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State Laws, Regulations and Licensing Programs
related to Landscape Irrigation
26
Texas Landscape Irrigation License Program
  • Administered by the Texas Commission On
    Environmental Quality
  • Requires a Basic Course, a comprehensive exam,
    and annual CEUs
  • Licensed Irrigators must follow design standards
    as defined in Chapter 344 - Texas Water Code
  • Program is required under State Statute
  • HB 4, HB 1656 SB 3

27
Texas Landscape Irrigation License Program
  • Licensed Irrigators
  • Can design, install, maintain, repair and service
    an irrigation system, including the connection of
    a system in or to a private or public, raw or
    potable water supply system.
  • Must have knowledge of the hydraulic limitations
    of an irrigation system.
  • Must design the system to promote water
    conservation through zoning and scheduling.

28
Texas Landscape Irrigation License Program
  • Licensed Irrigation Technician (Formerly Licensed
    Installer)
  • Works under the DIRECT supervision of the
    Licensed Irrigator to install, maintain, alter,
    repair, service or supervise the installation of
    an irrigation system.
  • Cannot Design or Alter a Design
  • Requires a basic course, comprehensive exam and
    CEUs for license renewal.

29
Local Ordinances Programs
  • In 2007 Legislative Session, Texas Legislature
    adopted House Bill 1656
  • This required populations of over 20,000 to adopt
    ordinances to regulate the installation of
    irrigation systems within the cities
    jurisdiction.
  • Violation of the Ordinance is considered a Class
    C Misdemeanor with fines not to exceed 2,000.00

30
Irrigation Inspectors
  • Effective January 1, 2009
  • Requires municipalities with a population of
    20,000 or more (about 117 cities) to adopt and
    enforce a landscape irrigation program.
  • Water Districts may also choose to employ an
    inspector.

31
Irrigation Inspectors
  • Duties Responsibilities
  • Verify the Irrigator, Installer or Technician is
    licensed
  • Verify all appropriate permits have been obtained
  • Inspect the Irrigation System
  • Determine if the irrigation system complies with
    the requirements of Chapter 344
  • Determine if the appropriate backflow prevention
    device was installed, tested, and test results
    were provided to the city

32
Irrigation Inspectors
  • Maintain a log of all inspections
  • Investigates complaints related to irrigation
    system installation, maintenance, alteration,
    repairs, or service of an irrigation system and
    advertisement of irrigation systems
  • Enforce all ordinances of the city

33
Irrigation System Design
  • A licensed irrigator is required to prepare an
    irrigation plan (design) for each site where a
    new irrigation system is installed.
  • This plan is to be on site during the
    installation of the irrigation system.
  • Upon completion, an as installed drawling is to
    be given to the irrigation system owner.
  • Irrigator must keep a copy of the as installed
    plan for a period of 3 years.

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Irrigation System Design
  • The irrigators seal, signature and date of
    signing
  • The major physical features and the boundaries
    of the areas to be watered
  • A North arrow
  • A legend
  • The zone flow measurement for each zone
  • Location and type of each
  • -Controller
  • -Sensor (rain, moisture, wind, flow, freeze,
    etc.)
  • Location, type, and size of each
  • -Water source
  • -Backflow prevention device
  • -Water emission device (spray heads, rotary
    heads, bubblers, drip, microsprays,
  • etc.)
  • -Valve (including all zone valves, master
    valves and isolation valves
  • -Pressure regulating component
  • -Mainline and Lateral Piping
  • Scale Used
  • Design Pressure.

37
Irrigation Auditing
  • Is not regulated by the State of Texas, therefore
    not required to be a Licensed Irrigator to Audit
    an existing irrigation system.
  • Voluntary Certification Programs are available
    for Auditing
  • Texas AgriLIFE Extension Service (Texas AM
    School of Irrigation)
  • Irrigation Association (IA)

38
Local Water Conservation Ordinances Programs
  • Ordinances May Include
  • Limiting Time of Day to Water
  • Ex. No watering from 10am to 6pm (City of
    Grapevine)
  • No Spray on Impervious Surfaces
  • Requiring a Rain or Freeze Sensor

39
Local Water Conservation Ordinances Programs
  • San Antonio Water System
  • Seasonal Irrigation Program (SIP)
  • Utility informs customers about how much to water
  • City of Frisco
  • Water Wise Program
  • All new installs must include a smart controller
  • Contact Your Cities Water Conservation Educator
    for information on your cities ordinances and
    programs.

40
Homeowners
  • Can Install their own irrigation system
  • System must meet the standards set by TCEQ and/or
    local area
  • Must also obtain all necessary permits
  • If you pay someone to help install, the system
    becomes a business transaction and a licensed
    irrigator is required

41
What is an Irrigation System?
42
Irrigation System
  • A grouping of valves and water emission devices
    that provide an artificial application of water
    to a landscape in the absence of rainfall
  • Made up of many different components

43
Components of an Irrigation System
  • Meter
  • Controller
  • Backflow Prevention Device
  • Valves
  • Emission Devices
  • Pipe
  • Pressure Flow Regulation Devices

44
Meters
  • Measures the amount of flow to the irrigation
    system
  • Usually use the home water meter
  • Some systems will have a separate meter for the
    irrigation system
  • Watch Units, (gallons, cubic feet)

45
Controller
  • An automatic timing device that sends an electric
    signal for automatic valves to open or close
    according to a set irrigation schedule

46
Backflow Prevention Assembly Devices
  • Safety device which prevents the flow of water
    from the irrigation system back to the water
    source,
  • 4 Main Types of Backflow Devices
  • Atmospheric Vacuum Breaker AVB
  • Double Check Assembly DC
  • Pressure Vacuum Breaker PVB
  • Reduced Pressure Principle Assembly - RPZ

47
Backflow Devices
  • AVB
  • DC
  • PVB
  • RPZ

48
Valves
  • Zone Valves Solenoid
  • Isolation Valves
  • Used to Control Flow to an individual zone
  • Used to Control Flow to the Irrigation System

49
Emission Devices
  • Spray Heads
  • Rotary Heads
  • Single Stream
  • Multi Stream
  • Impacts
  • Bubblers
  • Microsprays
  • Drip

50
Spray Heads
51
Spray Heads
  • Preset spray patterns
  • such as 45, 90, 180, 270, 360 degrees
  • Can be set to produce multiple streams
  • Have a high precipitation rate
  • Work best in smaller areas and areas with tight,
    curving edges

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Rotary Heads
  • Can rotate from 0 to 360 Degrees
  • Have a lower precipitation rate than sprays
  • Easily adjusted for different flows
  • Good for irrigating larger areas
  • Golf Courses, Sports Fields Parks

55
Rotors Single Stream
56
Rotors Multi Stream
57
Impacts
  • Sprinkler which rotates using a weighted or
    spring loaded arm which is propelled by the water
    stream and hits the sprinkler body, causing
    movement
  • Usually arc pattern is 40-360 degrees
  • Cover Larger Areas
  • 20 150 feet
  • Vary in Precipitation Rate
  • 0.1 1.5 inches per hour

58
Impacts Common Heads
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60
Bubblers
  • Water emission device that tends to bubble water
    directly to the ground or that throw water a
    short distance
  • Less than a foot

61
Micro Sprays
  • Water is applied to the soil surface as drops or
    small streams through emitters
  • Operate under low pressure
  • Distribute low volume

62
Pipes
  • Trenching is usually done to install new
    irrigation systems.
  • PVC pipe is used to deliver water to the emission
    devices

63
PVC Pipe
  • Besides Size, Pipe comes in different ratings
  • 2 common ratings
  • Schedule
  • Larger Schedule Thicker pipe (Schedule 80 gt
    Schedule 40)
  • Class
  • Is Equal to the pressure rating (Class 200 200
    Psi Max)
  • These refer to the thickness of the pipe

64
Drip Irrigation Systems
  • Method in which irrigation water is applied as
    drops through emitters either above or below the
    soil surface
  • Precipitation rates vary with length, pressure
    and flow.

65
Components of Drip Systems
  • Manual or Remote Valve
  • Drip Products
  • Pressure Regulators
  • Screens Filters
  • Flushing Valves

66
Drip Products Drip Tape
  • Thin Wall Flat Drip Tape
  • Contains embedded emitters
  • Operates Under Low Pressure Conditions

67
Drip Products Drip Tubing With Embedded Emitters
  • Durable Thick Wall Tubing
  • Usually contain pressure compensating embedded
    emitters
  • Can operate under higher pressures

68
Drip Products Drip Tubing with Inserted Emitters
  • Uses hard hose PE tubing
  • Allows for precision application of water
  • Flexible Precipitation Rates, based on emitter
  • Used for Shrubs and Trees

69
Pressure Regulators
  • Some systems require pressure regulators to
    achieve manufacturers recommended pressure
    requirement
  • Some devices have pressure regulators built in

70
Screens Filters
  • Used to catch plastic and sediment in the
    irrigation water
  • Prevent clogging of emitters and valves.

71
Flushing Valves
  • When sediment becomes trapped in the drip
    product, a flushing valve is used to remove it
  • Flushing valves can be automatic or manual.

72
Water Conservation Features
  • Rain shut-off sensors
  • Soil moisture sensors
  • Anti-drain (check) valves
  • Low trajectory nozzles
  • Pressure gages
  • Flow meters
  • Multi-program controllers

73
How is an Irrigation System Designed?
74
Irrigation System Design
  • Based on
  • Zoning
  • Pressure

75
Zoning Principals
WHY SHOULD WE ZONE?
  • to ensure high water use efficiency and proper
    plant growth conditions.

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Things to consider ...
  • Hydraulics
  • Plant water requirements
  • Soil characteristics
  • Sprinkler performance

79
Hydraulic Considerations
  • Available water supply (GPM)
  • Available water pressure (psi)
  • Pipe diameter (inches)
  • Elevation changes (feet)
  • Friction Losses (psi)
  • Sprinkler output (GPM)

80
Friction Loss
  • Flow rate
  • Orifice diameter
  • Material roughness
  • pipe
  • valves
  • meters
  • fittings
  • backflow prevention devices

81
Frictions Loss Pressure Loss
  • As the water travels through the irrigation
    system, the friction that is caused by the water
    rubbing the devices and PVC walls causes the
    pressure to drop.
  • This drop in pressure limits the number of
    emission devices that can be placed in each zone.
  • A minimum pressure threshold must be maintained
    for the devices in the system to operate.

82
Maximum Flow Rates Based on Pipes Size and Type
83
Plant Water Requirement
Separate plants into water use categories
  • Turf grass
  • Frequent watering
  • 0ccasional watering
  • Natural rainfall

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Frequent Watering
  • once a week or more irrigations will be
    required (i.e., turfgrass and annual flowers).

86
Occasional Watering
  • in the absence of rain, irrigation will be
    required every two to four weeks (i.e., perrenial
    flowers and tender shrubs).

87
Natural Rainfall
  • when normal rainfall does not occur, irrigation
    may be required (i.e., woody shrubs, vines and
    trees).

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Performance Indicators
  • Measurable Indicators
  • Precipitation rate
  • Pressure
  • Sprinkler spacing
  • Visual Indicators
  • Sprinkler head alignment
  • Color

90
Pressure (psi)
  • Pressure readings higher or lower than
    manufacturers recommendations will often result
    in poor irrigation efficiency.

91
Low Pressure
  • characterized by large water droplets and a
    short radius of throw.

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Low Pressure
94
High Pressure
  • characterized by misting of water. Results in
    high evaporation loss and wind drift.

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FOR TRAINED AUDITORS, BE CONSISTENT WHEN
MEASURING PRESSURE
97
FOR TRAINED AUDITORS, BE CONSISTENT WHEN
MEASURING PRESSURE
98
Performance Indicators
  • Measurable Indicators
  • Precipitation rate
  • Pressure
  • Sprinkler spacing
  • Visual Indicators
  • Sprinkler head alignment
  • Color

99
Sprinkler Spacing
  • should be designed for head-to-head coverage to
    ensure proper overlap of spray.
  • Stretched spacing will result in poor
    distribution uniformity.

100
Sprinkler Spacing
101
SPACING CAN EASLILY BE CHECKED BY MEASURE
HEAD SPACING AND ROW SPACING
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Head to Head Coverage
104
Head to Head Coverage
105
Head To Head Coverage
106
Performance Indicators
  • Measurable Indicators
  • Precipitation rate
  • Pressure
  • Sprinkler spacing
  • Visual Indicators
  • Sprinkler head alignment
  • Color

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Performance Indicators
  • Measurable Indicators
  • Precipitation rate
  • Pressure
  • Sprinkler spacing
  • Visual Indicators
  • Sprinkler head alignment
  • Color

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Basic Irrigation System Troubleshooting
  • As Related to Water Conservation

115
What is Troubleshooting?
  • Troubleshooting is being able to diagnose the
    obvious problems that effect the efficiency of
    the irrigation system
  • Obvious Problems Include
  • Misaligned Heads
  • Heads Not Vertical
  • Sunken Heads
  • Broken Heads
  • High Grass

116
Diagnosing Irrigation Systems
117
TYPICAL WATER LOSSES FROM COMMON IRRIGATION
SYSTEM PROBLEMS
Source Alliance for Water Efficiency, 2009
118
Water Waste From Inefficient Systems
Source Alliance for Water Efficiency, 2009
119
Misaligned Head
120
Head Not Vertical
121
Head Not Vertical
122
Sunken Head
123
Sunken Head
124
High Grass
125
High Grass
126
Broken Heads
127
Broken Heads
128
Overview of Application Devices
129
Sprinkler Performance Features
  • Flow rate (gallons per minute)
  • Precipitation rate (inches per hour)
  • Operating pressure (psi)

130
Selecting Appropriate Irrigation Equipment
  • Define water needs of each hydro-zone
  • application rate
  • runoff potential
  • Research product literature and specifications
  • Invest in value-added conservation features

131
Simple System Adjustments that Can Improve
Efficiency
  • Adjust the spray pattern
  • Adjust the arc of spray

132
Adjusting Spray Heads
  • To increase the distance of spray, turn screw
    counter clockwise
  • To decrease the distance of spray, turn screw
    clockwise
  • Arc is preset based on the nozzle

133
Adjusting Spray Heads
  • To change arc, switch nozzles
  • Pull nozzle out of housing
  • Unscrew to remove
  • Screw on new nozzle

134
Adjusting Rotor Heads
  • Insert Key into Rotor, turn 90 degrees and pull
    up while holding the base down

135
Adjusting Rotor Heads
  • Insert Adjusting Key into hole above nozzle
  • Turn Clockwise to deflect/reduce stream distance
  • Turn counterclockwise to open/increase stream
    distance
  • Be Sure to leave set screw in at least 1/8

136
Adjusting Rotor Heads
  • To adjust the spray arc, turn head till it stops
    turning
  • Insert key into the /- slot on top of the head
  • increases the arc
  • - decreases the arc
  • Minimum arc 40 degrees

137
Nozzles
  • Spray body Nozzles
  • Spray MulitStream
  • Rotor Nozzle

138
Determining Precipitation Rates
139
Typical Precipitation Rates
140
How do I determine precipitation rate?
  • Manufacturers performance tables
  • Equations relating pressure and nozzle diameter
  • Area/flow method
  • Catch can tests

141
Manufacturers Performance Tables
  • gives average precipitation rates for specific
    nozzle sizes operating at certain pressures and
    sprinkler spacing.

142
Flow and Nozzle Diameter Equation
  • calculates theoretical precipitation rate for
    individual sprinkler heads.

143
Area/Flow Method
  • calculates average precipitation rate.
    Requires measurement of sprinkler coverage area
    (in square feet) and flow rate in gallons per
    minute.

144
Example 1 - Area/Flow Method
80 feet
HC 2 GPM QC 1 GPM
145
Example 1 - (continued)
Total Flow (gallons per minute)
(2HC x 2GPM) (4QC x 1 GPM)
8 gallons per minute
146
Example 1 - (continued)
Total Area (square feet)
40 feet x 80 feet
3200 square feet
147
Example 1 - (continued)
Precipitation Rate (inches per hour)
96.25 x 8 GPM
3200 square feet
0.24 inches per hour
148
Catch Can Method
  • Select Catch Device
  • Determine Throat Area (At)
  • Identify Stations and Location of Heads
  • Lay Out Catch Devices
  • Run Each Station
  • Record Catch Volumes (V) and testing time
  • Calculate Precipitation Rate (PR)

149
Throat Area (At)
  • At p x d2
  • 4
  • At - Throat Area (square inches)
  • p PI (3.14)
  • d diameter (inches)

150
Precipitation Rate
  • PR ?V x 3.6612
  • n x At x RT
  • PR Precipitation Rate, in/hr
  • ?V Summation of a catch can volumes, ml
  • 3.6612 Conversion Factor
  • N Number of catch devices
  • At Throat Area of catch device, in2
  • RT Test Runtime, minutes

151
Area Flow Method
  • Determine the Flow Rate of Each Station
  • Reference Manufacturers Specifications
  • Determine Coverage Area
  • Square Feet
  • Calculate Precipitation Rate

152
Precipitation Rate
  • PR 96.25 x GPM
  • A
  • PR Station Precipitation Rate, in/hr
  • 96.25 Constant Converts GPM to inches per hour
  • GPM Total Flow Rate through the station
  • A Area of Coverage, ft2

153
Meter Method
  • Determine Coverage Area
  • Record Initial Meter Reading
  • Run Station
  • Record Final Meter Reading
  • Calculate Precipitation Rate

154
Calculate Flow Rate in GPM
  • Final Meter Reading - Initial Meter Reading
  • Test Runtime
  • Meter Reading - Gallons
  • Test Runtime Minutes
  • 1 cubic foot 7.48 gallons

155
Precipitation Rate
  • PR 96.25 x GPM
  • A
  • PR Station Precipitation Rate, in/hr
  • 96.25 Constant Converts GPM to inches per hour
  • GPM Total Flow Rate through the station
  • A Area of Coverage, ft2

156
Conducting an Irrigation System Test
157
Landscape Irrigation Test Procedures
  • Select site
  • Inspect site
  • Formulate audit plan
  • Determine soil type and root depth
  • Measure landscape area (for flow method)
  • Perform test
  • Calculate seasonal irrigation schedule
  • Implement base schedule

158
Selection Criteria
  • Automatic irrigation systems with programmable
    controllers
  • Zoned irrigation systems (e.g., turf areas
    separated from planting beds)
  • Predominately warm season grasses

159
Automatic Irrigation Systems
  • Allow flexibility to adjust schedules for
    individual zones (e.g., trees, turf, shrubs,
    etc.)
  • Allows for independent station programming

160
Inspecting the Site
  • Briefly run each station to check for problem
    areas
  • Note the problem on the plot plan
  • Record these comments on the Test Data sheet
  • Notify the resident

161
Common Hardware Problems
  • Broken heads
  • Mis-aligned heads
  • Sunken heads
  • High pressure
  • Low pressure
  • Mixed sprinkler heads types

162
Broken Heads
163
Mis-aligned Heads
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Sunken Heads
166
Low Pressure
167
High Pressure
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169
Formulate Test Plan
  • Briefly run the system to identify individual
    stations
  • Flag each sprinkler head (I.e., red flags for
    station 1, yellow flags for station 2)
  • Record the location of each station and
    individual sprinkler head on the plot plan

170
Flag Stations
171
Flag Stations
172
Collect Other Information
  • Soil type (clay, loam, or sand)
  • Root zone depth (inches)
  • Landscape area (square feet) for meter method

173
Soil Type
  • Clay, Loam, or Sand
  • Clay soils - tend to ribbon
  • Sandy soils - gritty to the touch
  • Loam soils - mixture of sand, silt and clay

174
Root Zone Depth (inches)
  • Depth of soil containing active roots
  • Deep soils permit infrequent irrigations
  • Shallow soils require frequent irrigations
  • Potential root zone may be deeper that the actual

175
Sampling with Soil Probe
176
Sampling with Soil Probe
177
Determining Root Depth
178
Determining Root Depth
179
Determining Root Depth
180
Performing the Test
  • Layout catch devices (one station at a time)
  • Turn on station to collect water
  • Turn off station - record test run time (in
    minutes) and catch volumes (in milliliters or
    inches) on the Test Datasheet
  • Repeat test for each station in the landscape

181
Catch Device Layout
Sidewalk Sprinkler Head Catch device
182
Catch Device Placement
  • General rule of thumb - at a head, in between
    heads
  • Use a grid-like layout with all the devices
    about equally spaced
  • If in doubt, use more devices
  • Suggested separation distances
  • 2 to 3 feet from spray heads
  • 5 to 6 feet from rotors and impacts

183
Catch Device Layout
184
Catch Device Layout
185
Reading a Catch Device
186
Reading a Catch Device
187
Test Datasheet
Precipitation Test Data
188
Typical Test Run Times
  • Sprays - 5 to 10 minutes
  • Rotors - 10 to 15 minutes
  • Impacts - 10 to 20 minutes

189
Sprays
190
Rotor
191
Additional Suggestions
  • Conduct the audit under normal operating
    conditions
  • Desire similar pressure and wind conditions
  • Early morning auditing is suggested. This is
    typically when wind speeds are lowest.

192
Calculate Irrigation Schedule
  • With the Texas Irrigation Scheduling software,
    you can calculate the irrigation schedule
  • Computer will calculate
  • station precipitation rate
  • station distribution uniformity
  • plant water requirements
  • available soil water holding capacity
  • base irrigation schedule
  • Or, you can calculate the PR (Precipitation Rate)
    yourself (a catch device that reads in inches
    is easiest)

193
Precipitation Rate
  • Defines how fast water is applied (inches/hour)
  • Varies from station to station
  • Easy to measure with catch devices (known throat
    area, volume and test run time)
  • May exceed soil infiltration rate in heavy soils

194
Distribution Uniformity
  • Measures how uniformly water is distributed
    throughout a station
  • Ratio of dry vs wet areas
  • Primarily effected by irrigation system hardware
  • Low DUs result in longer station run times to
    apply a given depth of water

195
Distribution Uniformity
196
Distribution Uniformity
  • May require over-irrigating in some cases to
    adjust for uniformity
  • Allows water to reach a uniform depth within a
    root zone
  • If using catch can devices to calculate
    Precipitation Rate, no need to adjust for
    uniformity
  • Already adjusted using average precipitation rate

197
Distribution Uniformity
198
Plant Water Requirement
  • Potential evapotranspiration - from automated
    weather station
  • Effected by climatic variables (relative
    humidity, wind speed, solar radiation and
    temperature)
  • Plant type

199
Available Soil-Water Holding Capacity
  • Defines the amount of water that is available in
    the soil (inches water per foot of soil)
  • Clays have high AWHC, sands have low AWHC
  • Helps determine irrigation frequency

200
The Irrigation Schedule
  • Provides recommended station run times (in
    minutes) and irrigations per week for each month
    of the year
  • Based on
  • Climate
  • Plant type
  • Irrigation system performance

201
Irrigation Schedule
Site Brown Residence
202
Station Statistics
Dominant Turf Type Warm Season Overall DU
(decimal) 0.66
203
Implement Irrigation Schedule
  • Is the schedule reasonable
  • Adjust schedules for microclimates (shade, slope,
    heavy soils)
  • Input station run times and irrigation days per
    week on the controller

204
ET-based Irrigation Schedules
205
Plant Water Requirement The Scientific Approach
BASED ON
  • A standard plant and its water requirements as
    affected by the climate
  • Plant type (plant coefficient)

206
The Standard Plant
  • A cool season grass growing 4-inches tall under
    well-watered conditions
  • Varies according to climate (I.e, temperature,
    relative humidity, wind speed and solar
    radiation).
  • Calculated using weather information provided by
    weather stations
  • Used as a reference value to relate other plant
    types

207
MONITORS
  • Temperature
  • Wind Speed
  • Humidity
  • Solar Radiation
  • Rainfall

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Basic Equation
  • WR ETo x Kc
  • WR water requirements
  • ETo evapotranspiration
  • Kc plant or crop coefficient

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Irrigation Runtimes and Frequency
  • Based on the soil water holding capacity, or
  • The amount of water that can be held or stored in
    the soil

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Determining the Water Requirements of Landscapes
  • How to do scheduling calculations

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Evapotranspiration, ET
  • Measurement of the total requirements of plants
    and crops
  • The word evapotranspiration is a combination of
    the words evaporation and transpiration
  • Very difficult to measure directly
  • May be calculated using weather data

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Evapotranspiration, ET
  • Many methods have been proposed to calculate ET
    from weather data
  • Methods that use solar radiation have proven to
    be the most accurate

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Solar Radiation
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Reference Evapotranspiration, ETo
  • The standardized Penman-Monteith Equation is
    considered the most accurate
  • Requires hourly or daily data on solar radiation,
    temperature, relative humidity and wind speed
  • Calculates the water requirements of a cool
    season grass growing 4-inches tall under well
    watered conditions.

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Reference Evapotranspiration, ETo
  • Also is called the Potential ET (PET)
  • Used as a reference from which the water
    requirements of all other plants can be
    determined
  • Note ETo PET
  • ETo is the potential evapotranspiration (PET) of
    a cool season reference grass growing
    4-inches tall under well watered conditions

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Crop Coefficient (Kc)
  • Crop coefficients (Kc) are used to relate ETo to
    the water requirements of specific plants and
    crops
  • Percentage of plant water use of Eto
  • Sometimes referred to as the plant coefficient,
    turf coefficient, etc.

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Crop Coefficient (Kc)
  • Kc varies depending on the type of plant/crop and
    growth stage
  • Kc may also be adjusted for such factors as
  • Plant density
  • Desired plant quality
  • Level of stress
  • Site conditions
  • Micro-climates
  • etc.

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Turf Coefficient, Tc
  • A factor used to relate ETo to the actual water
    use by a specific type of turf
  • Reflects the percentage of ETo that a specific
    turf type requires for maximum growth

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Allowable Stress
  • A factor reflecting an acceptable turf quality
    when water supply is reduced
  • Research shows that turf water supply can be
    reduced by 40 or more and still maintain an
    acceptable appearance

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Adjustment Factor, Af
  • A modification to the crop coefficient
  • Used to reduce water application for allowable
    stress

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Equation for Calculating Water Requirements (WR)
  • WR ETo x Kc x Af
  • Example
  • ETo 1.59 inches (1st week of August 2007 in
    Dallas)
  • Kc 0.6 (warm season turf)
  • Af 0.5 (Low plant quality adjustment)
  • WR 1.59 x 0.6 x 0.5
  • WR 0.48 inches (1st week in Aug)

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Effective Rainfall (Rainf )
  • The portion of rainfall that does not runoff, but
    becomes available for plant water use
  • A simplified method to account for the complex
    relationships between infiltration and runoff
    during rain events.
  • Includes the effects of slope, soil type, surface
    roughness (i.e., depressional storage) and
    other factors
  • Does not consider how wet or dry the soil is

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Effective Rainfall(Rainf )
  • Should be estimated based on actual site
    conditions
  • When using long-term averages (monthly or yearly
    average rainfall data), can assume Rainf is
    about 2/3 (67) of normal rainfall
  • DO NOT use 2/3 for individual storm events or
    daily/weekly actual rainfall data

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Effective Rainfall(Rainf )
  • For landscape irrigation scheduling, some use a
    surface storage approach based on soil type (see
    SWAT handout to be discussed later in class)
  • Most landscape (home sites, parks, commercial
    properties) have very shallow root zone depths.

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Effective Rainfall(Rainf )
  • For individual storms or weekly totals of actual
    irrigation and in absence of site specific data
    for homes and commercial sites
  • 0 0.10 inches Rainf o
  • 0.10 1.0 inches Rainf full amount
  • 1.0 2.0 Rainf 0.67 x total
  • gt 2.0 inches Rainf 0

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Effective Rainfall(Rainf )
  • Example during the 1st week in Aug 2007, Dallas
    received 0.04 inches of rainfall
  • Since the total rainfall is less than 0.1 inches,
    we assume no rainfall fell

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Water Requirements with Rainfall
  • Problem during the 1st week in Aug 2007, Dallas
    received 0.04 inches of rainfall, what is our
    total WR (previous example)
  • Since the total rainfall is less than 0.1 inches,
    we use a RAINf 0
  • WR (ETo x Kc x Af ) RAINf
  • WR (0.48 inches) 0
  • WR 0.48 inches

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Irrigation System Efficiency
  • Sometimes water requirements (WR) is adjusted for
    irrigation system efficiency
  • Application efficiency (AE)
  • spray/evaporative losses before the water
    reaches the ground
  • Distribution efficiency (also known as the
    distribution uniformity -DU)
  • how even the water is applied over the area

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Irrigation System Efficiency
  • Spray/evaporative losses typically range from
    20-30 -(application efficiency of 70-80)
  • Distribution efficiency (or distribution
    uniformity) varies widely (40-90)
  • Texas AgriLife recommendations
  • Generally, do not adjust WR for DU

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Scheduling Concepts
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Irrigation Frequency
  • The soil and root zone depth determines the
    frequency of irrigation
  • The concept is to
  • wait to irrigate until the plants have depleted
    the water in the root zone
  • Run the irrigation system just long enough to
    fill back up the root zone
  • Usually, these calculations are done on a weekly
    basis

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Irrigation Frequency
  • The process is to
  • first calculate the Plant Available Water (PAW)
  • Then calculate the Irrigation Frequency (I) and
    station runtime (RT)

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Plant Available Water
  • PAW D x SWHC x MAD
  • PAW Plant Available Water in root zone
  • D Effective root zone depth
  • SWHC Soil Water Holding Capacity
  • MAD Managed Allowable Depletion

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Definitions
  • Plant Available Water (PAW)
  • The amount of water in the effective root zone
    available for plant uptake
  • Effective root zone (D)
  • The depth of the root zone that contains about
    80 of the total root mass
  • Soil Water Holding Capacity (SWHC)
  • The amount of water that can be held or stored in
    the soil
  • Managed Allowable depletion (MAD)
  • How dry the soil is allowed to become between
    irrigations (50 for most plants)

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Effective Root Zone
  • The depth containing about 80 of the total root
    mass
  • Excludes tap and feeder roots
  • Easily measured with a soil probe

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Plant Available Water
Soil Water Holding Capacity
  • The amount of water that can be held or stored
    per foot of soil depth
  • The amount of water in the effective root zone
    available for plant uptake

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Soils
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Plant Available Water for Three Root Zone Depths
at 50 MAD
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Plant Available WaterDallas Example
  • Effective root zone depth is 5 inches
  • The soil is a loam.
  • Step One check units for root depth and SWHC
  • Convert units of rooting depth if necessary
  • SWHC 1.8 inches/ft
  • Root zone depth 5 inches 5/12 ft 0.42 ft

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Plant Available WaterDallas Example
  • PAW D x SWHC x MAD
  • D (Effective root zone depth) 0.42 ft
  • SWHC (Soil Water Holding Capacity) 1.8 in/ft
  • MAD (Managed Allowable Depletion) 0.5
  • PAW 0.42 x 1.8 x 0.5
  • PAW 0.38 inches

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Irrigation Frequency
  • I WR/PAW
  • I Number of Irrigations Per Week
  • WR Water Requirement
  • PAW Plant Available Water
  • I 0.48/0.38
  • I 1.26 times/week 2 times

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Station Runtime
  • Precipitation Rate - measurement in inches per
    hour of how fast an irrigation system applies
    water to a landscape
  • Station sprinkler group on a common valve that
    may be pat of an automated irrigation system that
    operates at the same time
  • Runtime how long a station is operated during
    an irrigation event

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Station Runtime
  • RT (WR x 60)/(I x PR)
  • RT Station Runtime (minutes)
  • WR Water Requirement (inches per week)
  • I Number of Irrigations per week
  • PR Precipitation Rate (inches per hour)

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Station RuntimeDallas Example
  • RT (WR x 60)/(I x PR)
  • WR 0.48 inches per week
  • I 2
  • PR 0.5 inches per hour
  • RT (0.48 x 60)/(2 x 0.5)
  • RT 28.8 minutes for each irrigation
  • Cant input decimals to controller so use 29
    minutes

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Tools for Producing Irrigation Schedules
  • TexasET Website http//TexasET.tamu.edu
  • Texas Irrigation Scheduler Software

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Smart Controllers
  • (lecture)

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Operating Irrigation Controllers
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Types of Irrigation Controllers
  • 2 Basic Types
  • Time Based Controllers
  • Smart Controllers

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Time Based Controllers
  • Most Common Controller found in Residential
    Settings
  • Requires 4 Inputs
  • Current Time
  • Start Time
  • Run Time
  • Watering Days

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Controller-User Interfaces
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Controller-User Interfaces
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Controller-User Interfaces
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Programming Controllers
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Programming Considerations
  • Will we need to cycle and soak?
  • Do slopes exist?
  • Types of Application Devices
  • Rotors
  • Sprays
  • Drip

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6 Steps to Programming a Controller
  • Determine the stations Precipitation Rate
  • Create An Irrigation Schedule
  • Set the Controller Clock
  • Date
  • Time
  • Set the Start Time(s)
  • Select the Days to Water
  • Set each valves runtimes

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Precipitation Rate
  • Obtained from
  • Catch Can Test
  • Meter Method
  • Manufacturers Performance Data

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Creating An Irrigation Schedule
  • Based on Historical ET
  • What are we irrigating?
  • Plant Type
  • Warm Season or Cool Season
  • Depth of Root Zone
  • Soil Type
  • Are there watering restrictions?
  • Days of the week we can water?
  • Time of the day we can irrigate?

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Setting The Controller Clock
  • Turn Dial to the Date/Time Setting
  • Use the Up/Down Arrows to adjust the Date Time

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Setting The Start Times
  • Turn Dial to Start Time Setting
  • Use the Up/Down Arrows to set the program start
    time

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Selecting the Days to Water
  • Turn Dial to Days to Water
  • Use the Arrows to Select/ Deselect Days you
    want/can Water.

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Setting the Valve Runtimes
  • Turn Dial to Run Times
  • Use the Arrows to set the runtime of each valve
  • Consider Soil Type when entering runtimes

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Conserving Water in Landscape Irrigation Systems
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Common Problems in Landscape Irrigation
  • Over-irrigation
  • Improper design and installation
  • No routine maintenance
  • Improper scheduling practices
  • Low priority in many cases
  • No budget for maintenance and upgrades

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Maximizing Irrigation Use - What Can We Do?
  • New irrigation systems
  • Existing irrigation systems

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New Irrigation Systems
  • Select a reputable Texas Licensed Irrigator
  • Review the design plan prior to installation
  • Make sure the system is zoned correctly
  • Common Plant Type
  • Common Precipitation Rate

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Existing Irrigation Systems
  • Inspect the site for problem areas that reduce
    efficiency
  • Measure the performance of each zone separately
  • Schedule irrigations that match plant water use
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