Southwest Florida

District

Agricultural WaterUse Version

Ron Cohenr

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

AGRICULTURAL WATER USE MODEL

VERSION 2.0

October 15, 1992Ron Cohen, P.E.

Agricultural and IrrigationEngineer

This two part paper discusses the procedures and rational fordetermining agricultural water use requirements in the SouthwestFlorida Water Management District% permitting process.Part I explains equations and assumptions used in permittingagricultural water use. Part II is a detailed description of theDistrict's agricultural use model Additionalpermitting information is in the District's Water Use PermittingInformation A copy can be obtained from your localDistrict office.

No,

PART I

Agricultural Water UseIntroduction

: : : : : : : : : : : : : : : : :Effective Rainfall . . . . . . . . . . . .Supplemental . . . . . . . . . . . . Gross Irrigation . . . . . . . . . . . . . . .Irrigation Methods' .Land Preparation and Crop . . . . . .Other Water Use . . . . . . .Crop Water Requirements . . . .

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PART II

Agricultural Water Use Model IntroductionAdvantages

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Getting-Started .

Step One . . . .

Model . . . . . .

Last Words . . .

References . . . . .

Index . . . . . . .

APPENDIX

Crops Root Depth . .

Crop Planting Dates

Soils . . . . . . .

Data . . . . . . . .

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PART I

AGRICULTURAL WATER USES

The distribution and amounts of Florida's rainfall are not alwaysadequate to meet crop water use demands. Usually supplementalirrigation is required to meet those demands and to producefavorable yields. Also, growers irrigate for field preparation,crop establishment, crop andprotection,

field (frost-freeze, erosion)salt leaching, chemigation, and system maintenance.

This part of the paper explains irrigation water use calculationsin the District's permitting process.

Under ideal conditions, water required for favorable cropproduction is to the water lost or used during plant growth.This water goes to soil evaporation and plant transpiration.Typically both processes are combined and called evapotranspiration

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A crop's ET varies throughout: a growing season.evaporation is larger than transpiration.

After planting,

transpiration will too,As foliage increases,

evaporation.and eventually becomes larger than

Usually a crop's ET peaks during fruit production.

There are many methods and for estimating ET. Thesemethods are either physical or empirical based. Most methods usesome climatic data as an index for estimating potential ET. Thispotential is multiplied by a crop's water use coefficient to findET. The net irrigation requirement is the difference between ETand effective rainfall.

The Blaney-Criddle equation is an empirical method developed fromwork in New Mexico, Utah and California. It was developed toestimate seasonal crop water use in arid regions of the westernUnited States. The original equation estimated'evapotranspirationby correlating average monthly temperatures and percentage ofdaylight, to a ET.

U KF

where: U potential ET (inches)empirical seasonal crop water use coefficient

F ET Factor

average temperature P percentage of daylight hours.

The Blaney-Criddle method is used around the world. It is apopular method because it predicts ET, using only long term

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daylight and temperature While other ET methods require moreclimatic data, that is not always available.

The original Blaney-Criddle method has gone through many changes.J. T. Phelan noticed that although the temperatures, where thesame, the computed water use coefficients (K) were different in thespring and fall. In 1954, he developed a relationship between theK value and temperature by separating the crop and climatic factorsof ET. Phelan developed crop growth stage coefficients (Kc) byrelating a ET, to a reference ET. Then he developed alinear relationship for the crop's water use coefficient (K),growth stage coefficient (Kc), and temperature.

K =

where: K empirical seasonal crop water use coefficientKc crop growth stage coefficient

(crop ET/reference ET)Kt climate factor 0.314t = mean temperature

The Blaney-Criddle model, and its crop coefficients, need to beverified and calibrated for regions other than the arid westernUnited States. In some regions Blaney-Criddle over and underestimates requirements during the year. For example, in humidareas such as Florida, the modified Blaney-Criddle seems to overestimate crop ET in the summer months.

The Soil Conservation Service (SCS) uses Blaney-Criddle (TR-21) toestimate consumptive use. TR-21 shows different arid and humidclimate annual crop coefficients. S-CONUSE, (April 1987) the computerized version of TR-21, reduces the calculated humid area ETby twenty percent. This reduction comes from non-research fieldexperience.

Dr. Shih (1981) from the University of Florida conducted researchto determine the method's accuracy in Florida. Hiswork showed that by replacing percentage daylight with percentageincoming solar radiation, and by reducing crop coefficients, theBlaney-Criddle method gave accurate results for Florida. Theincoming solar radiation adjusts the ET distribution, so, the peakmoved to the correct month for Florida's humid climate.the crop coefficients adjusts the magnitude of ET.

Reducing

Crop coefficients for method need to be locally establishedbecause climatic factors that are not explicitly included in themodel are "lumped into these coefficients. In his work Dr. Shihaccounted for humidity and cover by reducing the originalcrop coefficients by about 85%. Doorenbos and Pruitt (1977)recommend, and gave instructions, on adjusting the original cropcoefficients for prevailing wind and humidity.

t(m)

where: U(m) crop's potential ETKc = adjusted crop growth stage coefficient

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t(m) mean month temperature # FR(m) monthly of annual incoming solar

radiation.

Both solar radiation modification and Doorenbos and crop coefficient changes used in developing the District'sprocedures for estimating supplemental irrigation requirements.Estimated ET values where computed and factors where adjusted tofield and published data.

Comparing estimated irrigation requirements to field andother data sources, shows reasonable consistency between them. Forexample the difference between estimated citrus ET in Polk andHighlands County to adjusted pan evaporation (Kp was lessthan an inch for each county,

Comparing projected water to field data showed that in mostcases projections where somewhat higher than real use. Thecomparisons showed that the monthly trends where the same. Thereare several reasons why the was higher. The model uses longterm drought conditions, specific efficiencies, and assumes optimumyields. Whereas field is very site specific, with manyunknown production

Rainfall is a main source of water for crop development. However,the crop does not use all the rainfall directly. Some water islost to evaporation, runoff, or deep percolation.

In Florida, most of the rainfall occurs during June throughSeptember. These rains are typically short-term high intensitythunderstorms, with significant amounts of water either running offor replenishing depleted aquifers and lakes.

Effective rainfall is the part of rain that is available to theplant. The amount depends on the quantity and distribution ofrainfall, soil infiltration rate and water holding capacity, rootdepth, water use demand, farming practices, and other factors. TheSCS developed an empirical for one dimensional irrigation,to predict effective rainfall. That equation considers monthlyrainfall, crop water demand, and the crop rooting zone's soil waterholding capacity. This capacity is the amount of water thatremains in the soil between field capacity (gravitational waterremoved) and wilting point. It is the water that can easily beused by the crop.

re (0.70917 * 0.11556) * U (f)

where: f = (0.531747 + + re effective depth in inchesrt monthly U crop ET by the Blaney-Criddle methodD available capacity in the root zone,

in inches.

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In the equation is the net depth of irrigation. It is afunction of soil, root zone, and water table depth. The value

equal to root depth multiplied by the waterholding capacity, times allowable depletion. Typical zoneand soil SCS and publications.growers will irrigate between depletion.

Site specific conditions the value. An example is thedrained versus undrained situation. A water table may vary betweenzero and one foot the surface. Drainage lowers the watertable and increases unsaturated root zones. So, changes andmore rainfall is effective,

Field condition(s) and growing practices affect effective rainfall.For tomatoes grown with plastic mulched beds high water table,the impervious plastic, and the low soil storage capacity increasesrunoff. Plastic mulched drip irrigation sites have differentamounts of effective rain, compared to flat non-mulched sites.The root zone is in the raised bed. receives waterafter the rain first penetrates and then moves up into the rootzone by capillary rise. For most sites in the District, the watertable is so low that the is negligible.

Moat of Florida's rainfall in the summer months. Whereas, cropwater are usually during the spring growing seasonwhen rainfall is lacking. So, although the District averages overfifty Of rain, crops need supplemental irrigation to achievean economic yield,

Crop yields and economic losses occur when there enoughmoisture to meet crop water requirements. If an alternativewater supply source is available, increased yields can offset thecost of meeting the crop% water use requirements. Supplementalirrigation is the most used Alternative source of water for cropproduction.

The amount of supplemental irrigation depends on a economicvalue, water availability, irrigation system efficiency, crop wateruse and the amount of effective rainfall. Each growertakes all factors into account when using irrigation.

Knowledge of rainfall and crop water use needs is used todetermine supplemental irrigation requirements. Rainfallinformation from data. limited parameters are available, the method is used tocalculate water requirements

Effective rainfall (re) is important in deciding supplementalirrigation requirements. These requirements, are equal to the cropwater use requirements minus the effective rainfall. The netsupplemental irrigation requirements, does not consider irrigationsystem efficiencies.

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SUP u

where: SUP supplemental irrigation requirementU crop water demand found by the

Blaney-Criddle method total effective rainfall.

In the permitting process supplemental irrigation requirements arebased on an eighty percent rainfall return frequency. This return

the maximum amount of expected rainfall, 80 percent ofthe time. The irrigation amount corresponds to a 20 percentdrought return frequency. The required supplemental irrigation isthe minimum amount of water needed, assuming optimum growingconditions, and 100 percent irrigation system efficiency. isthe permitting standard for evaluating all irrigation systems.

Gross irrigation consists of the supplemental irrigationrequirements plus any water lost during delivery. These lossesinclude water supply, conveyance system, and application losses.In this part of the report we considered only application losses.Typically in the District other losses are insignificant whencompared to application Application losses involve plantinterception, systemuniformity, and other problems associated withmechanically delivering water to the root zone. All these lossesare included in system efficiency.

The gross irrigation requirement (GIR) is determined from thefollowing formula:

GIR

where: GIR gross irrigation requirementsSUP net irrigation requirements

EF irrigation system application efficiency.

Irrigation methods can be divided into four general categories:

1. Micro-Irrigation2. Sprinkler Irrigation3. Surface Irrigation4. Sub-Irrigation.

The use of a particular or combination of methods depends onmany factors: including crop type, crop production management, soilcharacteristics, chemical treatment, and economics, to name a few.All methods are not interchangeable. For example, Sub-Irrigation

is not practical in an area with a deep water table.certain systems are more adaptable. for frost and freeze

than others.

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includes drip,trickle, and bubblers.

low volume (jets and spinners),These irrigation methods include

all systems that have devices to apply water close to an individualor group of plants. Micro-Irrigation is usually efficient andmanageable. The potential high efficiency is due to reduced lossesfrom wind and evaporation during delivery.

Micro-Irrigation is relatively expensive and operation is costly.This irrigation method requires more upkeep and care than any ofthe others. It is sensitive to clogging and pressure changes. Alot of experience is needed to adapt these systems to specificsites.

Sprinkler irrigation includes all irrigation that uses theatmosphere to transport water a relative large distance. Thismethod includes overhead and undertree sprinklers, volume guns, andcenter pivots. Sprinkler irrigation is less efficient than irrigation because more water is apt to be lost to wind,evaporation, and plant interception.

Sprinkler systems are easy operate and are usually lessexpensive than micro-irrigation systems. One sprinkler provideswater to a large area. The upkeep is not difficult and mostproblems are easily detectable.

SURFACE

There are several types of surface irrigation; basin, border,flood, and furrow are the most common. Some of these systems(flood) may not be permitable within the District. While othersystems (furrow) may not be practical with Districts soils.

Surface irrigation supplies water directly to a plant by using thesoil as a conveyance median. These methods are inexpensive andeasy to operate. They potentially the least efficientirrigation method because of water losses to deep percolation andrunoff. Also, the area of exposed water makes it vulnerable toevaporative losses.

A common misnomer is that the semi-closed and open ditch irrigationpracticed in the are forms of surface irrigation methods.In reality, these methods manage the water table and are sub-irrigation. Sub-irrigation, sometimes called seepage, is anirrigation method that artificially maintains a site's water table.A sub-irrigated crop receives moisture from the water table throughcapillary rise.

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being relatively inexpensive growers use sub-irrigation fordifferent crop production reasons. Sub-irrigation keeps a plant'sroots at a manageable depth. Sod producers often sub-irrigate sothat easy to harvest.

There are three basic techniques for providing water for sub-irrigation. Open or semi-closed ditch are the most predominantones used in the District. These methods are similar, except oneconveys water to the field in an open ditch while the other uses aclosed pipe. Both methods are not efficient because of surface runoff and deep percolation. In addition, the saturated soilincreases rain runoff and evaporation losses.

Open ditch irrigation has large conveyance losses. In some areasas much as 708 of the diverted water does not reach its target.'Except for pasture irrigation very few growers in the District useopen ditch irrigation.

Although limited by the District's surface water rules subsurfacedrains have sometimes been used to supply sub-irrigation water.Water is conveyed to the subsurface by reversing flow into a drain.The drainage system functions like an exfiltration system. Watermoves from the drain tile to the surrounding soil. This method is

efficient in providing water. However, because thecharacteristics of a drain, the water is not always uniformlydistributed throughout the field.

Fully Enclosed Subsurface method is a new method of sub-irrigation. It has been tried on vegetables in Manatee andHillsborough Counties. Buried drip tubes supply water to the watertable. FES is efficient because there is no runoff or surfaceevaporation. Although less uniform than regular drip irrigation,it is more uniform than surface and sub-irrigation.

For some crops, growers need two irrigation systems. Strawberries,irrigated with drip irrigation, need overhead irrigation for cropestablishment and cold protection. Vegetables with drip irrigationuse seepage for crop establishment. In most cases the secondsystem is used because the primary system can not provide enoughwater.

The use of plastic mulch with the irrigation system is primarilyeconomic. Growers use plastic to stabilize beds, fumigate, and toensure that the fertilizer remains in the root zone. A l s o ,it might be used to reduce water use by decreasing evaporativelosses and eliminating weeds.

Crops grown under plastic mulch cannot directly receive effectiverainfall. The mulch is an impervious surface that covers abouthalf the field. Only a amount of rain infiltrates between

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This moisturecapillary rise to the

moves to the water table and then throughcrops.

Efficient irrigation is a that everyone should strive for. Itis not solely system dependent. The human element has a largebearing on irrigation system efficiency. System management andscheduling are the key to irrigation efficiency. Proper schedulingconserves water and saves production costs.

Some farmers irrigate for land preparation, salt leaching and cropestablishment. They irrigate before tilling and bedding toconstruct compact moist beds, so capillary rise will move water upto the root zone. Also, moisture helps the plowed cover cropsdecay faster. In addition, during bedding applied irrigation waterreduces dust and erosion.

In some regions of the United States growers use irrigation forsalt leaching. Areas with high salinity buildup use water toremove damaging salts from a crop's root zone. Due to naturalflushing, most sites in Florida have negligible leachingrequirements.

Growers use water to establish bare root transplants, soil rootedplants, and to germinate seeds. Increased moisture provides a goodenvironment for root establishment. In addition, this moisturecools the air to eliminate additional stresses on a stressed plant.

CROP PRO-ION

Growers use water to protect their crops from the climate and thesoil from eroding. During the winter, growers irrigate to protectcrops from convective and radiation freeze damage. When waterchanges from a liquid to a solid it releases energy as heat. Waterchanging from a liquid at 32F to a solid at releases 144British Thermal Units (BTU) of heat, per pound of water. So, everygallon of water provides over 1200 of heat. This helps keepthe plant's temperature from going below 32F and damaging the crop.

Some irrigation methods are more capable to provide frost andfreeze protection than others. Micro-jets and spinners are usedextensively for citrus freeze protection. Undertree sprinklershave been successfully used for citrus freeze protection.

Overhead sprinklers have limited use for citrus freeze protection.Water on limbs and leaves turns to ice, that accumulates and breakslimbs. Sprinklers have been used successfully for nursery andstrawberry cold protection. The water from sprinklers creates athermal layer of ice that and protects the plants.

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Drip irrigation does not provide enough water to be effective forfrost and protection. However, growers have itwith success. Portable and traveling guns could be used towet a field before the cold event. However,problems am overhead irrigation.

they have the same

vegetable growers have used seepage irrigation for cold protection.Typically they wet the field before a cold event and the latentheat of the water vaporizing release energy to warm the plants.Since most vegetables in the District are planted in warmer weather

does not add seepage cold protection quantities.

Growers irrigate to decrease damaging wind erosion. Wind bornesoil particles can damage fruit and leafs. Also, some cities haveordinances against the dust created by these particles. Irrigationis used to keep the surface wet so the particles will not beblown away. Soil protection quantities are provided with Water

There are several other uses typical for irrigation systemswithin the SWFWMD.maintenance.

The two main ones are chemigation and systemSome growers chemigate and then maintain (flush)

their system during regular irrigation while others will do thisduring non irrigation periods. The District permits these andother non typical uses as a fixed percent of the net irrigation.

A crop's water requirement consists of three main elements:

GIR + CE + FP + OT

where: CWR crop water requirements (production)GIR supplemental irrigationCE crop establishment (pre-plant planting)FP frost and freeze protection.

other water uses

These elements are functions of location (topography, climate,soil), crop type and irrigation system.

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PART II

AGRICULTURAL WATER USE

The District uses methods to allocate agricultural wateruse. The Agricultural Water Use Model (AGMOD) is its main tool tofind irrigation water requirements. The intent of this part of thepaper is to describe how to run AGMOD and to explain assumptionsused to develop the model. The instructions in this paper followthe same order as they appear on the computer screen duringexecution of the model.

AGMOD comes from a Blaney-Criddle model and incorporates waterrequirements for crop establishment, cold protection, and otherwater uses. The model uses procedures described in the U.S.Department of Agriculture and Soil Conservation Services TechnicalRelease and United Nations Food and Agricultural OrganizationPaper 24. In addition, it includes Dr. solar radiationchanges. AGMOD helps the District permit irrigation amounts forspecific crops, soils, irrigation system, and climatic conditions.

The District uses AGMOD as a tool to assist in the permittingprocesses. It was used in the District's 30 year Needs and Sourcesstudy, Water Resources Assessment Project (WRAP) and as analternative method for estimating annual water use. In addition,AGMOD has been used in several other District projects.

AGMOD is made available to the public without technical support.To ensure that disk holders receive updates, only specific entitieswill distribute disks. If your disk is not registered, and youwant to have the latest version contact the District.

The Southwest Florida Water Management District (SWFWMD) covers 16counties. Soil types, climate,vary throughout the District.

crop and agricultural practicesIn addition, certain areas have

special permitting criteria. AGMOD provides staff with aconsistent approach to evaluate site specific agricultural waterneeds. It is a mechanism to treat Water Use Permit (WUP)applicants on an individual basis.

AGMOD comes from the original Blaney-Criddle equation.were made to adjust the procedure to the District.

ChangesIn addition,

AGMOD includes irrigation for crop establishment, frost freeze andother water uses. With continued use of the program and increasedfield data, permitted (crop establishment, supplementalirrigation, cold protection, other water uses) need to beevaluated. AGMOD should be reviewed and updated when crop curvesfor Florida are developed.

Projected water use comes mathematically analyzing historicalweather data. Long term climatic data is statistically analyzed to

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get average conditions and the 80 percent rainfallprobability. it is difficult to determine rainfalldistributions, assumes a reasonable distribution. Inactuality the distribution may be different.

Comparing to available field data shows the estimates arereasonable. and field data do not match up evenly becausethe values come from normalized long term historicalconditions. Whereas, field data are a snap shot in time, withspecific seasonal conditions.

The model's user is the key to success. Computers do notthink or rationalize. The human element of reasonability andjudgement must always supersede any computed results. Printouts,tables, and results must be compared to known information forconsistence with existing practices and procedures.

is written and compiled with MICROSOFT's Quick Basic 4.5.The screen routines come from a registered version of Tony Martin's

program. The documentation is created with program. To save disk space Public

Domain compression program and Public Domain DIETwere used.

Before starting any computer program, always copy the original diskand work with the copy. Keep the original disk in a safe place incase something happens to the working disk.

EP ONE

There are several ways to run the program. For hard disk drivesystems, copy all the files on the distribution disk to your harddrive. The model's name may be changed. However, all other filesmust have the same name and be in the model's path directory.

START and WHATSNEW are small information files. isa batch file for first time users. It displays the informationfiles, ntation and then runs the program. START hasinformation about permits, AGMOD, and how to read the on linedocumentation.

WHATSNEW is an to date history of AGMOD. It includes programupdates and change information. This file includes informationthat may not be in the documentation.

To run the model for the first time, type:

<RETURN> <RETURN>

If you want to view the latest changes and updates, type:

RETURN>

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TO view documentation, type:

To run type:

<RETURN>

first displays the title and program version. Also,it displays a disclaimer about the District and staff liabilities.This program is a permitting tool, provided as is, without support,and without any warranties claims.

SCREEN1Title Screen

SOUTRWEST WATER MANAGEMENT DISTRICT

DISCLAIMER OF WARRANTYThis program was developed assist the District in itspermitting effort. The is being provided on an basis without technical support. The District specificallydisclaims any warranty, expressed or implied, includingbut not limited to the warranties of merchantabilityand fitness for a particular use. The entire risk as toquality and performance is with the user. In no event willthe District or its staff liable for any direct, indirect,incidental, special, or other damages, includingloss of profit, arising out of the use of this program even ifthe District has been advised of the possibility of suchdamage.

Press return to continue. After you finish typing a name or valueprees enter unless other wise specified.yes/no questions default to no.

All of the program'sSo for

return to continue.answers just press

The input screen has fifteen variable fields. The withdrawal point(W.P.), date and time are automatically displayed and updated eachtime the screen appears. The model is designed to work with up to55 withdrawals for each water use permit (WUP).

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Input Screen

SOUTHWEST WATER MANAGEMENTAgricultural Water Use Model

Reviewers Name:

County:

Main

Aux. Irr.:

Soil:

Number: Date:01-01-91

w. Time:

Discharge (gpm): Dia (in):

Discharge (gpm): (in):

Area (ac) :

name, press return and the cursor moves to the next inputThen type the WUP number,

digit'extension.including the period and two

AGMOD uses the extension to see if the WUP is newor existing. Quantities for new permits in water use caution areas(WUCA), are based on higher efficiency then existing permits. Thisis because newer systems should be designed to be more efficientthan existing systems.

A window with the 16 counties appears. The 6 counties are listed separately. Select the number corresponding tothe location of the WUP. Any number larger than 22 will relist thecounties.

BY selecting a county, uses the corresponding meantemperature, rainfall, solar radiation and 2-in-10 rainfallcoefficient for the site's location. To keep track where theclimatic data came from the weather station's location appears onthe printout, in page one's foot notes. In addition, the years ofrecorded rainfall are in the same foot notes.

The next line is for the main irrigation system. This system isprimarily for supplemental irrigation. A window with the list ofthe major irrigation types appears.to the site's system.

Enter the number correspondingThe computer uses the main irrigation system

default efficiency and effective rainfall to calculate the site'sgross irrigation requirements.

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irrigation efficiency is a comprehensive value. Itcovers both the mechanical (system) and human (irrigationmanagement) element of irrigation. By definition the efficiencyis ratio of the volume of water beneficially used to thevolume delivered from the irrigation system".

uses the irrigation system to determine effective rainfallamounts. For mulched sites with seepage, drip, or overheadirrigation the model uses zero effective rainfall. Seepage siteswith plastic mulch have high water tables with little soil storage.So most of the rain runs off. Drip and overhead irrigated siteshave shallow rooted plants with deep water tables. Therefore, mostof the rain infiltrates below the root zone and is too deep for anysignificant upfluxing.

The main irrigation menu allows user to define the systemefficiency and effective rainfall. Select this option to defineyour own system values, or when you have new uses for expired WUCApermits. Otherwise AGMOD will treat this new use as an existingpermit.

After selecting the user defined option a window with two questionsappears. The first question asks for the percent efficiency. Thesecond question is a yes or no question, to see if there iseffective rainfall. Whenever default values are not used theprintout will show that the user defined the option.

The next field is the system's discharge capacity in gallons perminute. uses this value to see if the system can supply thepermitted quantities. If the system's capacity is limiting, a noteappears on the output saying that quantities are limited by thesystem. After typing the discharge, the computer continues to thenext line.

If the irrigation system capacity is unknown use zero (0). Thecomputer moves to the next field and asks for the system's mainlinepipe diameter expressed in inches. The computer will calculate thesystem's capacity from the continuity equation (flow (velocity)*(area)]. uses the pipe's diameter to calculate area, and afive foot per second (fps) velocity. velocity is consistentwith manufacturer, SCS, and Florida Irrigation Societyrecommendations for most irrigation pipes. After typing thedischarge, the computer continues to the next line.

The next line is for the auxiliary irrigation system. This systemis used for frost and freeze protection or crop establishment. Inmost cases this is the same as the main irrigation system.However, vegetables with drip or FES systems and some citrus sitesmay have auxiliary systems.

There are seven auxiliary system options. Including specificsystem type, the same as the main irrigation system, none, and userdefined. The specific system and the same as main irrigation

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options use default values. The auxiliary systemoption permits no cold protection or crop establishment quantities.

The auxiliary system option uses the main systems capacityto check cold protection and crop establishment quantities. Thisoption cannot be used if drip is the main irrigation system.Typically drip emitters do not provide enough water or wet enoughground for cold protection or crop establishment. Reviewers canrecommend quantities for drip cold or crop establishsentif the applicant demonstrates the successful use of drip irrigationfor these practices.

The Defined" auxiliary system option bypasses the model'sdefault values. After selecting this option a window appearsasking for inches of crop establishment, and cold protection. Thisoption is ideal for double or triple cropping where growers don'tneed to establish existing beds. After the auxiliary system, themodel advances to the discharge capacity field and continues insame manor as with the main irrigation options.

The model allocates frost and freeze protection for citrus,strawberry and nursery production. Citrus protection with irrigation (excluding drip is based on District funded

research. A three year research project at Lake Alfred foundthat micro-irrigated citrus needs between 2000-3000 gallons perhour (gph) per acre for frost freeze protection. AGMOD uses thehigher value of 3000 gph per acre (2.6 inches) for 24 hours.

In some parts of the District, freeze durations less than 24 hoursmay be reasonable. To assist the permit reviewer AGMOD prints a 14hour quantity for micro-irrigation systems. If applicants hours different than the 24 or 14, frost and freeze quantities,then use the user defined system option.

Citrus overhead or undertree sprinkler protection, is basedon typical system capacities, Most impact sprinkler systems usebetweenvalue of

to inches per hour (iph). uses the higher iph with 24 hours for undertree sprinklers, and 5

hours for overhead sprinklers. inches per day respectively.

This yields 2.8 inches per day andUndertree systems are given more

hours because they operate during a cold event. Whereas, overheadsprinklers are used only before an event to wet the ground.

Strawberry, blueberry and nursery cold protection amounts come from publications, and meeting with industry representatives.

Quantities are based on inch of water per hour, for 24 hourevents. The three crops get six inches.

All frost and freeze quantities are compared to system capacitiesand the lower of the two is used.the annual permitted amounts.

These quantities are not part of

calculations.However, they are used in peak daily

District.Permittees need to report this usage to the

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Soil type the next input field. database has over 650Florid8 soil types with profile depth8 and corresponding waterholding capacities. The model checks the roils name to see if itsin the If the soil is not found the model prompts for

A soil type can be found in S.C.S. county soil surveys.Some site8 will have more than one soil type. There are severalapproaches for sites with soils. You can use thepredominant or the most restrictive soil. Or, the site maybe divided in subsections, with adjusted areas and systemcapacities. Sometime8 soil groups have similar characteristics andcan be grouped together.

AGXOD uses soil information to effective rainfall andcrop establishment. Effective rainfall is the amount of rainavailable for plant use. It depends on the available soil moistureand the root zone. The model uses the average water holdingcapacity and adjusts soil moisture through root zone depth. Themodel for moisture by using minimum root zonedepths.

Crop establishment is a quantity that is site and system specific.For most crops (except strawberries) AGMOD uses the soil's topthree feet moisture content, to find crop establishment waterrequirements. The soil's moisture content comes from the highrange of the water holding capacity.

For crops that fumigate the first month's ET is added to the waterholding capacity. This accounts for soil evaporation while thewater table is being maintained. Then an efficiency is used tofind the gross crop establishment water requirements.

Crop establishment quantities differ for spring and fall planting.Spring planting comes in the middle of the dry season. Whereasfall planting comes after the rainy season when the soil moistureis high. Therefore, for crop establishment AGMOD uses halfthe soil profile of the spring planting establishment.

Strawberry producers use water to prepare beds and to relieve bareroot transplant stress.crop

AGMOD uses fourteen inches for strawberryThis quantity comes from research at the

Dover station. Comparing AGMOD strawberry crop establishmentquantitie8 to available field information shows AGMOD is a littlehigher.

Crop type is the next input field. At least three letters needs tobe typed or the computer will not continue. The model has data on35 different crops. By selecting a crop the computer loads thecrop curve8 and root depth. the crop is not in the model, or if

misspelled, a window with the model's crops appears.

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The original crop curves come from the arid western U.S. AGMOD usesthese crop curves with modifications for our humid climate. Forpasture and nurseries the model does not use crop curves. Pasturequantities are based on grass ET values developed from an research project in South Florida.

Nursery quantities are calculated using the full potential ET. Thefull potential is used because there are so many different plantvarieties, that are potted during different times, in various sizedcontainers with different types of potting soils. A l s o , seasonlengths and planting dates are unknown. Taking all these factorsinto account AGXOD calculates nursery quantities using fullpotential ET.

The default value for nursery production assumes a potted shallowroot zone. You can use potting soil, or any other type of soilwith this root zone as the growing media. For field grown ornurseries that don't meet the default conditions the soil and rootzones need to be adjusted accordingly. The adjustment can be donein the soil's change window after the area is entered.

Acres irrigated is the next input field.irrigated area.

AGMOD uses the grossThis may over estimate water requirements for

systems (drip, low volume) that irrigate only part of the surface. On the other hand, the dry middle's oasis effect maycause the irrigated area to need more water. Therefore, the totalwater required is probably about the same as if the gross acreagewas irrigated.

AGMOD uses acres irrigated to keep track of the withdrawals. If awithdrawal irrigates more than one crop, assume a dummy withdrawaladjusting the irrigated acres and other irrigation factors. So, iftwo crops are grown in one season from withdrawal 001, usewithdrawal 002 for the second crop.withdrawal AGMOD assumes two pumps.

When using the dummyTherefore, the for

each crop may need to be reduced.

After the acres are entered, the user can change any of the fifteeninput values. If you answer yes to changes a menu appears. Forthe first withdrawal you can change any input value by selectingthe corresponding menu number. After the first withdrawal youcannot change the reviewers name, permit number, or county. Pressthe escape key to exit the change option.

If the crop is course" or a perennial plant, a new windowappears. For golf courses, the user is prompted for tees andgreens acreage. The model allocates 50 inches per year for teesand greens irrigation. The rest of the area is treated like ashallow rooted grass. The tees and greens quantity is distributedproportional to the regular irrigation.

17

For perennial crops the user needs to provide planting andharvesting dates. These dates need to be typed in the same five

character as the screen's example. These dates areused to calculate daily water requirements and rainfall. Inaddition, theme values are used to distribute crop establishment.

uses the quadratic spline method descried in University ofCalifornia, Cooperative Extension, Leaflet 21426, to distributemonthly values into daily. The method creates a cumulative curveand finds a specific use by taking the difference in cumulative usebetween two point. The advantage of this approach is that it doesnot over estimate use for crops that are planted or harvested inmid month.

Next the soil's information window appears. The first windowappears only if the soils name was misspelled or is not in thedatabase. The computer lists all the soils with the same firstthree letters of the soil type entered. After the soil's name iscorrected a window with the soil, root zone, and thecalculated net depth of application appears. You need to accept orchange these values. If you change the values, the new 'calculatedcrop establishment quantity appears. Press return to accept thisvalue or type a different

SCREEN3Output Menu

SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICTAgricultural Water Use Model AGMOD

OUTPUT OPTIONS

1 Print Report2 Screen Report3 Save Report4 Next Withdrawal5 New Permit6 Shell To DOS7 Documentation8 End Program

Output can be sent to the printer, screen, or stored on disk. Youcan select one of these options with your cursor or typing thenumber. After each output option is completed, the program returnsto the output menu.

18

If the print report option selected the computer asks you toturn the on and type P to print. For save option youare prompted to insert a formatted (non-write protected) data diskinto Drive A. Then press S to save or to return to the menu.The computer the output in a text file using the permit'sfirst five numbers a8 the file name. The saved printout can beviewed with any word processor of text editor.

The screen report option displays a summary of a withdrawal point'sinformation. After the screen option is selected, you are askedfor the withdrawal point. The screen report is divided into threeframes. The first frame shows the number, and thebasic information. The second frame shows the permitted quantitiesin inches and gallons. The last frame shows average annual

When you are finished reviewing the information youcan view another withdrawal by typing number or return to theoutput menu.

The Withdrawal" option brings you back to the first inputscreen. The withdrawal number is increased and the reviewer'sname, permit number and appear. You start entering the nextwithdrawals information. The model keeps the withdrawals@information until the program is exited, or the new WP option isselected.

The option the model back to the first screen.The program starts from the beginning with withdrawal one. All thenew permit's information is requested. Past information is clearedfrom memory.

Shell to DOS allows the user to temporarily leave the programwithout losing any data. This option is helpful if you want to usea text editor to view part of the printout or to do something elsewith the computer. To return from DOS type at the prompt.

Option seven calls the on disk documentation. Thedocumentation can be printed out by typing ALT-P. You can looksomething up by pressing and the word/subject you want. Thefirst line on the screen will be the next time the word appears inthe document. This is helpful if you want some specificinformation. Escape will return the program to the output menu.

The last option is to end the program and exit to DOS. This optionclears the models memory and removes all data. The screen clearsand the computer's DOS appears.

ED

The printed report provides the users with documentation of theirwork. It also provides a piece of paper to follow the modelscalculation and to examine if the model worked correctly. The

heading lists the WP number, reviewer, date, and county.

Each withdrawal number has own specific information. Thisinformation includes crop, irrigated area, irrigation system

19

types, capacities, and irrigation efficiency. For perennial cropthe heading shows planting and harvesting dates. If the userbypassed any of the model's default values, the heading will showthe user defined the value.

The next nine lines deal with monthly permitted quantities. Thefirst line, wan rainfall, comes from the data file. The secondline shows calculated evapotranspiration (ET). This value comesfrom a Blaney-Criddle equation using mean temperature, solarradiation and crop curve.

The third line shows the calculated peak month. This quantity inmost cases is based on zero rainfall and is the most irrigationthat can be used in a given thirty day period. The peak monthvalue is the highest of either the ET divided by irrigationefficiency or the crop establishment quantity. For crops witheffective rainfall assumes zero rainfall from October to thefirst of June.

Average effective rainfall average irrigation respectively arethe next two lines. rainfall comes from the SCS equationand average rainfall probability. Average irrigation is thedifference between the average effective rainfall and ET, dividedby the system efficiency.

Lines six and seven show the a-in-10 effective rainfall and 2-in-10irrigation. This rainfall comes from the averageeffective rain times the percent chance of occurrence. Theirrigation is the difference between ET and this effective raindivided by an efficiency. For most crops this irrigation is thepermitted irrigation quantity,.

Pasture plants are typically more tolerate to drought stress thenother plants. So uses the 6-in-10 effective rain for pastureirrigation. The irrigation is calculated the same asdescribed above.

Other water uses is the next line. This quantity is based on thetype of irrigation system. Micro irrigation is given 10% of thepermitted irrigation, other systems are given 5%. The microsystems are given more water because these systems use more waterfor fertigation, and

The last line is the sum of permitted water use including cropestablishment. Where strawberry crop establishment is added to themonth of planting and for other crops, it is distributed betweenthe last 31 days before planting.

Next there will be a space and a summary of the withdrawal'svalues. In the event that the system's capacity limited thepermitted quantity, it will be noted before the summary. Monthlyvalues would be adjusted to meet system capacities.

The summary has six lines and four columns. The columns list thevalues in inches, gallons, gallons per day. It is important to

20

note that table relate8 'only to the specific withdrawal. Thecomposite value8 be than individual withdrawals.

prints two withdrawal8 and the summary per page. composite includes an accumulation of the total month

water unit8 are listed in the heading.according to the highest

They change

Below the water use table is a list of notes. They helpexplain the print out and give information about the calculations.For example note five tells which version of was used andwhen it last modified. The last note gives the date and timethe program was executed.

The second page consists of a monthly breakdown of total water use.These value8 include crop establishment, supplemental irrigation,and Strawberries crop establishment is in thesame month a8 planting, while other crop establishment is dividedbetween the 31 days before planting. This table has a set of notesto explain its contents.

The summary box also called the Weber Box has five values. Threeare in gallons par day and one in inches. The average annualpermitted values is the total water use divided by 365 days. Thisuse includes crop establishment, supplemental irrigation, and theother water use category described in design aid four. The peakmonth quantity is the value listed in the composite breakdowndivided by thirty. This includes the same water uses listedabove. The month in inches appears next to the gallon value.

Frost freeze is listed for crops that have this permitted quantity.That quantity is the maximum for a 24 hour period. Formicro-irrigated systems a frost freeze quantity for 14 hours isadded to the box.

The output's calculated irrigation requirements are compared to theirrigation system capacities. This capacity is for operating thesystem 90 percent per day (21.4 hr.) times 365 days. Monthlycapacity is calculated by dividing the annual capacity by 30 days.If the capacities are less than the required amounts, permittedvalues are limited to the system capacities.

Computers don't think, people do. Before and after using acomputer the input and output information must be reviewedfor errors and reasonability the results.

November 3, 1992

21

ASAE. in Proceedings of theNational Conference on Advances in Evapotranspiration,December 1985.

Use of Water and Irrigation Requirements,"September 1973.

Albregts, Howard, Overhead Sprinkler Irrigation toEstablish Strawberry Plants in the Fruiting Field," ResearchReport, Project 1978.

Albregts, Howard, "Water Use in Strawberry TransplantEstablishment," Research Report, DOV-1985-2.

Clark, et al. Requirements and Crop Coefficients ForStrawberry Production In S.W. Florida Final ProjectReport, March 1992

Doorenbos and Pruitt. "Guidelines for Predicting Crop WaterRequirements, FAO Irrigation Drainage paper 24 revised1977.

Fry, A.W. "Frost Protection By Sprinkler," Rainbird.

Geurink, Jeffrey. "Agricultural Water Use Permitting SWFWMD.

Marlowe, G.A., Overman, A.J., Feinberg, S.G. "Results of andIrrigation Survey for Tomatoes and Strawberries inHillsborough and Manatee Counties, ProcedureFlorida State Horticultural Society

Marlowe, G.A., overman, A.J., Rationale for Determination ofIrrigation Needs for Vegetable Crops Grown With SeepIrrigation," Research Report

Parsons et al. Volume Micro Sprinkler Undertree Irrigationfor Frost Protection of Young Citrus Trees," ProcedureFlorida State Horticultural Society

Rogers, J.S., Harrison, D.S., "Irrigation Water Requirements ForAgronomic Crops in Florida," Water Resources CouncilWRC-5

SJRWMD. "Technical Memorandum 30 Year Mean Blaney-CriddleSupplemental Irrigation

SFWMD. "Agricultural Water Model," computer disk.

"Permit Information Volume

Shih et al. wide Requirements Estimation in SouthernFlorida, American Society of Agricultural Engineers

22

Transactions, 1983.

Shih et al. of of EvapotranspirationEstimation American Society of Agricultural Engineerspaper No.

Shih et al. Estimation for Data-ShortEnvironment," Journal of Irrigation and DrainageEngineering, February 1991.

Smajstrla et al. of PotentialEvapotranspiration in Florida," American Society ofAgricultural Engineers paper #FCS-84-003.

Smajstrla et al. of Florida AgriculturalIrrigation Systems," 88-l.

Snyder, et al. "Determining Daily Reference Rvapotranspiration Cooperative Extension University of California

Division of and Natural Resources," Leaflet21426, April 1987.

USDA-SCS. "Irrigation Water Requirement Technical Release No.

USDA-SCS, Consumptive Use Computer Program," 1987.

Wyllie, Mike. "Final Report Evapotranspiration Study forSouthwest Florida Water Management District," The FloridaResources and Environmental Analysis Center.

23

A -----Acre 17, Advantage 1, 12, 20AGMOD 4, 10, 12-23Annual 3-4, 12, 18, 21, 24Applicants 12, 17Application 6, Arid 2-3, 19Atmosphere 7Auxiliary 17

BBasin 7, 26Beds 5 , 9 , 17, 19Blaney Criddle l-3, 5-6, 12,

22, 25Blueberry 18Border Irrigation 7Bubblers 7

----- C -----Capacity 4-5, 16-18, 22-24Capillary 5, 8-9Category 7, 24Center Pivots 7Chemical 7Chemigation 2, 10Citrus 4, 17, 25Climate 3, 6, 15, 19Coefficient 2-4, 15, 25Composite 23-24Comprehensive 16Conservation 3, 9, 12Consumptive 3, Containers 19

3, 26Convective Counties 8, 12, 15, 25Cover 3, 9Covers 9, 12, 16Crop 1-12, 15, 17-20, 22-25Crop Establishment l-2, 9,

11-12, 17-20, 22-25Cumulative 20Curve 12, 19, 20, 22

Daylight 2-3Diameter 16DIET 13Discharge 15-17Disclaimer 14Distribution 2-4, 13

Ditch Irrigation 8DOCS 14Documentation 13-14, 21-22Doorenbos 3-4, 25DOS Shell 21-22Drip Irrigation 5, 7-10,

16-17, 19Drought 4, 6, 23Dry 18-19Dual Sytems 9

E -----Efficiency 4-7, 9, 15-16, 18,

22-23, 26Efficient 7-9, 15Emitters 17ET 2-5, 18-19, 22-23, 25-26Evaporation 2, 4, 7-9, 18Evapotranspiration 2, 22,

25-26

FFactor 2-5, 7, 19-20Fertilizer 9, 23FES 8, 17Flood Irrigation 7-8Flushing 23Foliage 2Follow 12, 22Frost and Freeze 2, 7, 10-12,

17-18, 24-25Fully Enclosed Irrigation 8Furrow Irrigation 7-8

----- GGolf Course 20Grass 19-20

H -----Harvest 8Harvested 20Harvesting 20, 22Heat 10Humid 3, 19Humidity 3

I -----Irrigate 2, 5, 8-10, 16-17

19-20, 22, 24Irrigation l-2, 4-12,

20, 22-26

J -----Jets and Spinners 7, 10

LLake Alfred 17Latent Heat 10Leaching 2, 9Limitations 1, 12Limited 6, 8, 10, 14, 16,

23-24LZEXE 13

M -----Mainline 16Maintained 18Maintenance 2, 10Matsumoto 13Micro Irrigation 7, 10, 17,

23-25Model 1, 3-4, 12-22, 24-25Monthly 2, 4-5, 13, 20, 22-24Morgansoft 13Mulch 5, 9, 16

----- N -----Nursery 10, 17-19

----- 0 -----Oasis 19Options 17, 21Output 16, 21-22, 24Overhead Irrigation 7,

16-17, 25

P -----Pan 4Pasture 8, 19, 23Peak 2-3, 18, 22, 24Perennial 20, 22Planted 10, 20Planting 1-2, 11, 18-20,

22-24

Plastic 5, 9, 16Portable Gun 10Potted 19Print 17, 21, 22-23Printout 13, 15-16, 21-22Protection l-2, 7, 9-12,

17-18, 25Pumps 20 24

QBSCR Quadratic Spline 20Quantity 4, 10, 12, 15-20,

21-24

RRain l-2, 4-6, 8-9, 13,

15-16, 18, 20, 22-23 13-14

Registered 12-13Requirements l-6, 9,

11-12, 16, 18-20, 24-26Reviewed 12, 24Reviewer 15, 17, 20-22Root 1, 4-6, 8-9, 16, 18-20Rooted 9, 16, 20

----- S -----Salts 2, 9Save 13, 21Saves 9, 21Scheduling 9Seasonal 2-3, 13Seepage Irrigation 7-10, 16Semi Closed Irrigation 8Sod 8Soil l-5, 7-12, 15-16, 18-20,

22Solar Radiation 3-4, 10, 12,

15, 22Sprinkler Irrigation 7, 10,

17, 25Starting 13Strawberry 9-10, 17-19, 23,

25Sub-Irrigation 7-8Subsurface Irrigation 8Supplemental Irrigation

4-6, 11-12, 16, 23-25

T -v-m-Tables 13, 16Tees and Greens 20Temperatures 2-3Tomatoes 5, 25Transpiration 2Transplant 9, 19, 25Traveling Guns 10Trees 25Trickle IrrigationTubes 8

Undertree Irrigation 7, 10,17, 25

Uniformly 6, 8User 13-14, 16-17, 20, 22

Vaporizing 10Variable 4, 14Vegetables 8-10, 17 25Volume Gun 7, 10

WWarmer 10Warranty 14Weather 10, 13, 15Weber Box 24Weeds 9WHATSNEW 13-14Winter 10Withdrawal 14-15, 20-23WUCA 15-16

12, 15

APPENDIX A

OD CROP WITH ROOT

PERENNIALALFALFA 24AVOCADO 48BLUEBERRY 48CITRUS 48DECIDUOUS 40GOLF COURSE 06GRAPES 48GRASS 12

02PASTURE 18SOD 06SUGARCANE 36

ANNUALSBEANS/DRY 18BEANS/GREEN 18BROCCOLI 18CABBAGE 18CARROTS 18

1818

CORN/GRAIN 3636

CORN/SWEET 3018

EGGPLANT 18GRAIN/SMALL 24

24ONION 18PEANUTS 24PEAS 18PEPPERSPOTATO 18SOYBEANS 30SQUASH 18STRAWBERRY 09TOMATOES 24SMALL 18

B I T

H a r v e s t i n g S e a s o n s0 - f S e I F o r i d a V e g e t a b I e C r o p s

P l a n t i n g I I H a r v e s t i H a r v e s t

SEP NOV JAN MAR MAY

S n a p b e a n s

C a b b a g e

C a r r o t s

s w e e t c o r n

C u c u m b e r s

Eggp I ant

L e t t u c e

P e p p e r s

P o t a t o e s

Rad i shes

S q u a s h

i es

T o m a t o e s

I o n s

F

CORN FOR GRAIN

CORN

CORN FORAGE

COTTON

O A T S

POTATOES

SOY BEANS

S U G A R C A N E

T O B A C C O

WINTER WHEAT

GRA I N

H A Y

P lant ng and Harvest ng Seasonso f S e l e c t e d F l o r i d a F i e l d C r o p s

PLANT I BEGINNING HARVEST

% NTENS HARVEST •nIu END NG HARVEST

A J U N DEC MAR J U N

II

I

BD. VAR.

ANCLOTE

VAR.ANGIEANGIEANGIE VAR.ANKONAANKONA,DP.

ARCHER

ASTOR

BAS FL.

BAYBOROBAYBORO, PD.

BESSIE

BIBB

BRIGHTON

VAR.

VAR.CANDLER

VAR.

VAR.

DR.

VAR.

VAR.

CORNELIACOROLLA

DADEDANIADAYTONA

DOROVAN

DUETTE

EATON

EBROECONFINAEGLINELECTRA

ELECTRA VAR.ELECTRA

ESTER0

FELDA

FLEMINGTON

VAR.

VAR.FLUVAQUENTSFORT FORT MEADE VAR.

VAR.FRIPP

FUQUAY

GAINESVILLEGALVESTONGARCONGARCON , FL.GATOR

GENTRYGILEAD

GRADY

GREENVILLEGRITNN

HAGUE

HEIGHTS

HOMOSASSA

HURRICANE

IBERIA

IRVINGTONISLESISLES

IUKA

JOHNS

JUMPER

KALIGAKALIGA VAR.

SUBS.

KENDRICK

VAR.KESSON

KUREB

DP .

LEAF

LEON

LUCY

MABEL

MANATEE

MANDARIN

MARLBORO

MASCOTTE

MCKEEMEGGETTMICANOPYMICCOMILLHOPPER

MONTEOCHAMONTVERDEMOULTRI

VAR.

NARCOOSSEE

NETTLES

NORFOIX VAR.

OCOEEOCOEE VAR.OKEECHOBEEOKEEIANTA

OKTIBBEHA

OLUSTEE SUBS.

ONA,ORTS.SUBS.ORANGEBURG

ORSINOORSINO VAR.ORTEGA

OSIER,PD.

PACTOLUSPAHOKEEPAISLEY

PEDROPEDRO PEDRO

VAR.

PEPPERPERRINEPERRINE VAR.

PINEDA,DP.PINEDA,FL.

VAR.PLANTATION

POCOMOKE

VAR.POMONAPOMPANO

POMPANO VAR.PONZERPOOLER

POPLE

POTTING SOIL

VAR.

RAINS

RAINS RED BAYREDLEVE:.RESOTA

RIVERVIEWRIVIERA

ROBERTSDALE

VAR.

SAPELOSATELLITESATELLITE VAR.SAVANNAHSAWYERSCOGGINSCRANTON

SEFFNERSEFFNER,CEM.SUBS.SELLERSSHENKS

ST.AUGUSTINEST.AUGUSTINE,CLY.S

VAR.ST.LUCIESTILSONSTOCKADE

STOUGH

SUSANNASUSQUEHANNA

TARRYTOWNTAVARES

TEQUESTA VAR.

TERM CEIATERRA

CEIAVAR.

TISONIATOCOITOMOKATOOLESTORRY

TURNBULLVAR.

UDORTHENTS

UDORTHENTS VAR.

WABASSOWABASSO,DP.

WABASSO VAR.WACAHOOTA

WAHEE

WAUBERGWAUCHULA

WEEKIWACHEE

W E S C O N N E T TWESTONWICKSBURG

WILLISTON VAR.WINDER

FL.

YONGES

ZEPHYR

ZUBER

a

0

a

icn !

0

POLK CO. CITRUS ET.AGMOD AND PAN

INCH7

6

4

3

2

1

0

4,967

1 2 8 9 10 11 12

MONTH E T A G M O D

Pan based on Kp

INCH

50

10

02 5 6 7 9 10 1 1 12

MONTH

HIGHLANDS CO. CITRUS ET.AGMOD AND PAN

ET PAN

Pan based on Kp =

INCH

6

5

3

2

01 2 3 4 5 6 7 9 10 11 12

MONTH

1

HIGHLANDS CO. CITRUS ET.AGMOD AND PAN

AGMOD

Fan on

CO. STRAWBERRY AGMOD VS. PAN

25

15

5

NOV DEC JAN FE8 MAR

MONTH PAN BLANEY

Pan based on Kp = I

INCH7

6

5

4

3 . .

2

1

NOV DEC JAN MAR

MONTH

CO. STRAWBERRY ET.AGMOD VS. PAN

Pan based on Kp = 1

CRIDDLE

%

CO. STRAWBERRY ET.

25

20

15

10

5

0

AGMOD VS. PANINCH

DEC FE0

MONTH BLANEY

Pan based on Kp =

CO. STRAWBERRY ETAGMOD VS. PAN

#

7

6

5

4

3

2

1

0

NOV DEC JAN FEB MAR

MONTH BLANEY GRIDDLE

Pan based on Kp =

30

25

20

15

10

5

0

MANATEE CO. TOMATO ETAGMOD VS. PAN

INCH

MAR MAY

MONTH PAN BLANEY

Pan based on Kp = 1

10

6

4

2

MANATEE CO. TOMATO ETAGMOD VS. PAN

INCH

MAR APR MAY

MONTH

PAN BLANEY

Pan based on = 1

MANATEE CO. TOMATO ETAGMOD VS. PAN

INCH

Kp =

MONTH

W

0a Z

0I - .

a

i

i i

AGMOD vs. GOLF COURSEManatee Co.

(Cumulative)100

an

20

0

JAN FEB MAR MAY JUN JUL SEP O C T NOV

Month

USE AGMOD

DEC

Highest Year 1888

GOLF COURSE MANATEE CO.AGMOD vs. GOLF COURSE

Million Gallons100

8 0

6 0

40

2 0

0

JAN FEB MAR MAY JUN

1989 AGMOD

JUL AUG OCT NOV DEC