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Time series analysis of irrigation returnflow in a semi-arid agricultural region,IranHadi Jafari a , Ezzat Raeisi a , Mohammad Zare a & Ali AkbarKamgar Haghighi ba Department of Earth Sciences, Shiraz University, Shiraz, IslamicRepublic of Iranb Department of Water Engineering, Shiraz University, Shiraz,Islamic Repubic of IranPublished online: 19 Jul 2011.

To cite this article: Hadi Jafari , Ezzat Raeisi , Mohammad Zare & Ali Akbar Kamgar Haghighi (2012)Time series analysis of irrigation return flow in a semi-arid agricultural region, Iran, Archives ofAgronomy and Soil Science, 58:6, 673-689, DOI: 10.1080/03650340.2010.535204

To link to this article: http://dx.doi.org/10.1080/03650340.2010.535204

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Time series analysis of irrigation return flow in a semi-arid

agricultural region, Iran

Hadi Jafaria, Ezzat Raeisia*, Mohammad Zarea and Ali Akbar Kamgar Haghighib

aDepartment of Earth Sciences, Shiraz University, Shiraz, Islamic Republic of Iran;bDepartment of Water Engineering, Shiraz University, Shiraz, Islamic Repubic of Iran

(Received 11 July 2010; final version received 16 October 2010)

The irrigation return-flow coefficient (IRFC) is based on rule of thumbestimations in most aquifers in Iran. The errors may be significant, and thusmisleading for water resources management. We used lysimeters to moreaccurately predict IRFC. Five wheat and barley farms of different soil textures,which were irrigated using a border system, plus one with a sprinkler system, wereselected for the installation of lysimeters. The practices at each farm were appliedto the lysimeters. Irrigation return flows (IRF) were measured every other dayover two growing seasons. The IRF time series displayed sharp peaks at the initialstages of the growing season and decreasing towards the end. IRFCs wereclassified into early and late stages. The average IRFC during the early stage was29.9%, decreasing to 6.5% in the late stage. High IRFC values are due to thelimitations of border irrigation to provide a small uniform amount of water, andover-irrigation due to low water demand during the early stage of growth.Variations in annual IRFCs of 0.4 to 38.7% are functions of total applied water,border length, management and soil texture. The early stage IRFC for thesprinkler system was small. Therefore, high early stage IRFCs can be reduced bychanging from border irrigation to a sprinkler system.

Keywords: irrigation return flow (IRF); free drainage lysimeter; wheat; semi-arid,Iran

Introduction

‘Irrigation return flow (IRF) is defined as the excess of irrigation water that is notevapotranspirated or evacuated by direct surface drainage, and which returns to anaquifer’ (Dewandel et al. 2007). The quantity depends on many factors such as soiltype, soil moisture characteristic curve, meteorological parameters, crop type,irrigation method and depth to water table. The IRF can be a significant componentof the groundwater balance, particularly in intensively irrigated areas. ‘To avoid anyinaccurate aquifer budgeting and/or modeling, and consequently any erroneouswater resource management, the IRF needs to be accurately assessed at an adaptedtime-step’ (Dewandel et al. 2007).

The IRF is measured either using a lysimeter or by water balance, chloride massbalance, change in depth to water table or Darcy’s law methods (Humphreys et al.2003). The lysimeter is the only method of directly measuring drainage (IRF) from

*Corresponding author. Email: e_raeisi@yahoo.com

Archives of Agronomy and Soil Science

Vol. 58, No. 6, June 2012, 673–689

ISSN 0365-0340 print/ISSN 1476-3567 online

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the plant root zone, but it is labor-intensive and costly to install. Lysimeters can beclassified into weighing and non-weighing types (Aboukhaled et al. 1982). They canalso be categorized into tension and zero-tension (free-drainage) types. In tensionlysimeters, a suction device is installed at the bottom of the lysimeter, which allowswater to be sucked at different tensions. Zero-tension lysimeters collect soil wateronly under the force of gravity. Lysimeters are classified as monolithic and filled-intypes based on principles of construction (Aboukhaled et al. 1982). A monolithiclysimeter consists of an undisturbed soil block, whereas with a filled-in lysimeter, soilis disturbed during the excavation and backfilling.

The irrigation return-flow coefficient (IRFC) is defined as the ratio of IRF toapplied water. The IRF and IRFC have been measured under different soil types,depth of irrigation, crop types, etc. These studies show that IRFCs vary from 2 to450% for different crops under various management practices (Steiner et al. 1985;Meyer et al. 1987; Meyer and Mateos 1990; Willis et al. 1997; Moss et al. 1999;Bethune et al. 2001; Jalota and Arora 2002; Causape et al. 2004; Dewandel et al.2007; Jimenez-Martınez et al. 2009). Humphreys et al. (2003) reviewed fieldinvestigations into water balance components for several crops in Australia. Theyconcluded that IRFs and IRFCs are highly variable across and within soils and landuse, and can be influenced by soil and crop types, range of management practicesand saline water. Humphreys et al. (2003) confirmed the conclusions of Lyle (2002)and Bethune (2001) that there is a need for a systematic and comprehensiveapproach to understand the variations in IRF for a range of soil types, land uses andmanagement practices.

In Iran, lysimeters have been used extensively in research fields to measureactual evapotranspiration, but no reports are available on IRFC measurements.Therefore, IRFCs were estimated to be 15–25%, based on engineering judgmentsin most water-balance projects (e.g. Haseb Fars 2003; Parab Fars 2008). Inengineering judgments, IRFC is not calculated, rather rule of thumb estimationsare made based on parameters such as soil type, irrigation system, farm levelingand amount of water applied. However, IRFC is a significant component of thegroundwater balance in most aquifers in Iran. Errors in engineering judgmentsmay be so large that they can be misleading for water resources management. Asa first step to solve these problems, it is important to measure IRFCs under theactual traditional management practices used in order to determine the reasonsfor the high IRFC values. The objective of this research was to measure IRFsand IRFCs for wheat and barley using non-weighing drainage lysimeters underdifferent conditions of soil type, irrigation system and traditional agronomicpractice. In addition, IRF was measured every other day to determine theparameters controlling the IRFC time series.

Study area

The study area of Harat is located in Yazd province, in the central region of Iran(Figure 1). The climate is semi-arid with average annual precipitation andtemperature of 110 mm and 188C, respectively. The Harat study area consists ofHarat and the Khansar plains, with a total cultivated area of 131 and 15 km2,respectively (Figure 1). The main crops are wheat and barley (58 km2), pistachio andalmond (52 km2), corn (10 km2), alfalfa (7 km2) and apricot (4 km2) (Haseb Fars2003).

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Sources of water in the Harat plain are 137 wells, 3 springs and 38 qanats (aqanat is an underground gallery dug out inside the alluvium, transferring water fromthe aquifer to the ground surface), with annual discharge of 44, 12 and 21 6 103 m3,respectively. Ninety-five percent of the groundwater is used for irrigation. The depthto the water table in this aquifer is *100 m in the west, decreasing to 5 m in thenorth-east. Aquifer transmissivity values vary widely from 27.5 to 1600 m2 day71

and show a decreasing trend from west to east. Overexploitation of groundwater haslowered the water table level at an average rate of 39 cm year71 since the late 1980s(Haseb Fars 2003). Haseb Fars consulting engineers (2003) studied the water budgetof the Harat aquifer assuming an IRFC of 15% (11.3 6 103 m3) based onengineering judgments.

Sources of irrigation water in the Khansar plain are 13 wells and 26 springs, withannual discharges of 4.1 and 0.4 6 103 m3, respectively. No further hydrogeologicaldata are available in the Khansar plain.

Materials and methods

Site selection

The agricultural farms of the Harat study area have different types of soil texture.Forty-four soil samples were taken up to a depth of 2 m from these farms.

Figure 1. Map of the study area showing the locations of the lysimeters and the soil texturesof the irrigated farms. C1, gravelly loamy sand; C2, gravelly sand; C3 coarse gravelly sand; F,silty clay loam to clay. W, wheat; B, barley.

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Percentages of gravel, sand, silt and clay were measured using sieve analysis andhydrometery methods. Soil texture was determined using the USDA classificationsystem. The soil texture map was prepared based on soil analysis and field surveying(Figure 1). The textures found consisted of gravelly loamy sand (C1), gravelly sand(C2), coarse gravelly sand (C3) and silty clay loam to clay (F). Six farms wereselected for lysimeter installation based on the following criteria:

(1) The lysimeters must be installed in agricultural farms. The farms belong toseveral local farmers, owning only a few hectares each; therefore thecooperation of farmers was one of the essential criteria.

(2) The soil texture has a significant effect on the IRFC; therefore, the selectedsites must cover all of the main soil textures.

(3) Most of the farms are irrigated using the border method and a few of thefarms by the sprinkler method. In border irrigation, the farm is divided intograded strips by constructing parallel dikes. The water is applied at the upperend and flows as a sheet down the strips. Five farms irrigated by border andone irrigated by sprinkler (hand-moved wheel-line sprinkler) were selected forlysimeter installation.

The selected lysimeters were named C1W, C2W, C3W, FW, C1B and FB inwhich C1, C2, C3 and F represent the texture, and W and B represent wheat andbarley, respectively (Figure 1). The area, border length, crop type, irrigation interval,source of irrigation and soil texture of the farms equipped with the lysimeters aregiven in Table 1.

Lysimeter design, installation and operation

Free drainage lysimeters were made of galvanized iron plates with a circular cross-sectional area of 2 m2 and a depth of 2 m (Figure 2). Irrigation return flow wascollected using a drainpipe, leading water into the sampling container placed in themeasuring pit. Concrete rings were installed inside the measuring pit to increase pitwall stability. When excavating, the soil from each 30 cm layer was stored separatelyat the ground surface. A 15-cm gravel filter was placed at the bottom of the lysimeterto uniformly drain seepage water. The excavated soils were replaced in the lysimeterin the correct order and compacted to give the original conditions.

Lysimeters were installed at the center of the selected farms (Figure 3). The bufferarea (or fetch of the same vegetation) was 4800 m2 in each case. The minimumbuffer area is 400 times the lysimeter area (Aboukhaled et al. 1982). Wheat andbarley were planted in December. The practices of each farm around the lysimeter,such as irrigation depth and interval, fertilization, planting and harvesting, were usedfor the related lysimeters.

The amount of water applied to each farm surrounding the lysimeters wasdetermined in each irrigation event using the following equation:

I ¼ QT

Að1Þ

Where I is the amount of applied water, Q is the average flow rate, T is the time ofirrigation and A is the farm area. A weir was installed in each farm to measure the

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Table

1.

Characteristics

ofthefarm

susedforlysimeter

installation.

Soilproperties

Irrigation

Irrigation

interval

Sourceof

irrigation

Particle

size

distribution

(%oftotalsoilmass)

Site

Area(m

2)

Border

length

(m)

Croptype

system

(day)

water

Gravel

Sand

Silt

Clay

Texture

Zone

C3W

39800

196

Wheat

Border

8Well

54.7

40.0

2.2

3.1

GS

C3

C2W

6800

78

Wheat

Border

7Well

56.2

39.2

2.5

2.1

GS

C2

C1W

40157

92

Wheat

Border

7Well

45.6

46.3

7.4

0.7

GLS

C1

FW

18765

130

Wheat

Border

14

Spring

028.7

29.8

41.5

CF

FB

2349

56

Barley

Border

12

Qanat

019.8

41.16

39.04

SiCL

FC1B

263525

–Barley

Sprinkler

8Well

36.6

53.9

8.5

1.1

GLS

C1

Note:GS,gravelly

sand;C,clay;GLS,gravelly

loamysand;SiCL,siltyclayloam.

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flow rate accurately. The lysimeter edge was *15 cm above the soil surface toprevent irrigation overflow into the lysimeter. The calculated depth of total appliedwater to each farm (I) was added to the related lysimeter. Lysimeter C1B, with thesprinkler system, was buried 10 cm below the surface. This lysimeter was irrigatedsimultaneously with its surrounding farm. The depth of total applied water wasmeasured in two small catch cans around the lysimeter.

The experiments were performed in all of the lysimeters in the 2007–2008 growingseason and additionally in 2008–2009 in lysimeters C1W, C2W, FW and FB. Thefarms enclosing the lysimeters were fallow due to crop rotation in the 2008–2009

Figure 2. Layout of the installed lysimeters.

Figure 3. Lysimeter C2W in the middle of the 2007–2008 growing season.

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growing season, therefore the previous year’s farm management practices, especiallyirrigation interval and depth, were applied to these lysimeters. No experiments wereperformed in lysimeter C1B in the second study year, because the sprinkler was notin operation due to crop rotation. Problems associated with local famers preventedfurther research on lysimeter C3W in the second study year.

In this study, the total applied water is calculated as the sum of irrigation andprecipitation. Precipitation data from the Harat meteorological station were usedfor all lysimeters. The annual precipitation of the hydrological years (startingSeptember 20) of 2007–2008 and 2008–2009 were 18.7 and 74.9 mm, respectively.These precipitations occurred mainly during late fall, winter and early spring.Interception is negligible because of sparse crop cover at these times. Therefore, theprecipitation was considered effective. The total depth of total applied water (TW)in lysimeters C3W and C1B in the first study year was 1055 and 652 mm,respectively. TW values were 898 and 880 mm in C2W, 846 and 819 mm in C1W,1030 and 1004 mm in FW, 775 and 764 mm in FB at the first and second studyyears, respectively. Variations in TW are related to soil texture, border length, wateravailability, source of water, irrigation system and farm management practices.

The IRF volume was measured every other day in all the lysimeters, exceptlysimeter C3W, in which measurements were carried out once before each irrigationevent. The main reason for the low frequency of IRF measurements in lysimeterC3W was the distance of this lysimeter from the others. IRFC was calculated foreach irrigation event. Actual evapotranspiration from wheat and barley crops(ETCa) and deep percolation (DP) were computed using the method proposed by theFood and Agriculture Organization (FAO) (Allen et al. 1998). DP is the drainage ofwater beneath the root zone and although the depth of root zone varies during thegrowing season, part of it reaches the groundwater.

Results and discussion

Irrigation and IRF time series

The time series of the total applied water and the IRF for four border and onesprinkler lysimeters (Figure 4) show the following variations:

(1) A decreasing trend in the depth of applied water is observed in most of thelysimeters. This is related to lower water demand during fall and winter, anda shortage of water during spring and summer. The water shortage is due tothe high water demand of tree and summer crops.

(2) Irregular variations in the amount of total applied water are mainly due tothe farmer management practices, changes in irrigation intervals and a lackof scientific calculations of the water requirements.

IRF lag time is defined as the difference between the time of the first irrigation eventand the time of the first drainage into the measuring container. The lag time inborder lysimeters varies from 2 to 82 days, representing the coarse to fine textures,respectively, except in lysimeter FW (Table 2). The main factors controlling the lagtime are the preferential paths and soil texture. The flow of water through the largemacropores in coarse soils decreases the lag time. Despite having a clay texture inlysimeter FW, the lag time is equal to that in coarse soils. This may be due to

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cracking in the clay soils and the lysimeter wall effect. Bronswijk et al. (1995) andWeaver et al. (2005) reported that preferential flow through the cracks of clay soilsinduces rapid transport of the irrigation water. IRF electrical conductivities and

Table 2. Irrigation return flow (IRF) lag time (day) during the two study years.

Lysimeter Soil texture Water year 2007–2008 Water year 2008–2009

C2W GS 2 2C1W GLS 16 11FW C 2 2FB SiCL 82 66C1B GLS 93 –

Note: GS, gravelly sand; C, clay; GLS, gravelly loamy sand; SiCL, silty clay loam.

Figure 4. Time series of total applied water and irrigation return flow (IRF) for lysimetersC2W, C1W, FW, FB and C1B. C1, gravelly loamy sand; C2, gravelly sand; C3 coarse gravellysand; F, silty clay loam to clay. W, wheat; B, barley.

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nitrate concentrations reduced significantly two days after each irrigation event inthis lysimeter, confirming the preferential flow (Jafari 2010).

The IRF time series have sharp peaks at the beginning of the growing season,gradually leveling off towards the end of the growing season. The reason for thedecline is the enhancement of crop cover and root zone, increasing evapotranspira-tion and reducing the IRF. This is discussed further later.

Temporal variation of the IRFC in the border lysimeters

The IRFC is classified into early and late stages based on the variations in the IRFand IRFC time series over the growing seasons (Figures 4 and 5). The early stagestarts from the date of planting to the time of a significant reduction in IRFC (aboutthe second half of March) and the late stage lasts to the end of the growing season(June). The IRFC is significantly higher during the early stage than the late stage inmost of the lysimeters (Figure 5). The average early stage IRFCs in lysimeters C1W,C2W and FW are 29, 44.8 and 37.5%, respectively. These values decreased to 0.7, 11and 0.6%, respectively, during the late stage (Table 3). The average early-stage IRFCof lysimeter FB was 1.1%, significantly lower than for the other lysimeters. Theirrigation interval was significantly increased in the farm enclosing lysimeter FBduring the late stages due a shortage of water, such that the two-year average of late-stage applied water for this lysimeter (259 mm) was significantly lower than for theother lysimeters. Water stress in lysimeter FB reduced the soil moisture significantlyat the end of late stages; therefore, an extensive amount of the applied water must bestored in the 2 m soil column of lysimeter FB during the early stage, consequently,reducing IRF in the early stage.

The total applied water, IRF, ETCa and DP for each irrigation event arepresented in Figure 6. DP and consequently IRF are higher in the early stage thanthe late stage in lysimeters C1W, C2W, C3W and FW. The reason for the high DPand IRF in these lysimeters is the large amount of applied water during the earlystage based on the followings:

(1) The water requirement is low for small plants during the early stage. Owingto the characteristics of border irrigation, it is not possible to provide the lowwater requirement without an excess of applied water.

(2) Water demand is low during the early stage because tree crops are irrigatedonly once or twice and there is no need to irrigate other summer crops likealfalfa. Therefore, farmers overirrigate wheat and barley fields based on theirtraditional belief, ‘more water, more yield’.

Temporal variations in IRFC are also reported in some regions of India, whereIRFCs vary from 0% during dry conditions (intercrop seasons) to 100% duringoverwatering periods that mainly occur during the monsoon seasons (Dewandelet al. 2007).

Controlling parameters of annual IRFC

Annual IRFs and IRFCs varied from 2.7 to 408.4 mm and 0.4 to 39% in the borderlysimeters, respectively (Table 4). The IRFC is expected to be a function ofseveral parameters including total applied water (TW), border length, water

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management and soil texture. The effect of each parameter on the IRF and IRFC isas follows:

(1) The correlation coefficients (r) for IRF and IRFC with TW are 0.84 and 0.77,significant at 0.01 and 0.05 levels, respectively (Figure 7). Excess appliedwater is defined as the difference between TW and ETCa. The relationshipbetween the excess applied water with IRF and IRFC is shown in Figure 8.The correlation coefficients are 0.99 and 0.98, respectively, significant at the0.01 level.

(2) The amount of water applied to each lysimeter and its surrounding farm areequal. The depths of the applied water are generally higher in farms with

Figure 5. Irrigation return-flow coefficient (IRFC) time series of lysimeters C2W, C1W, FW,C3W, FB and C1B during the two study years. C1, gravelly loamy sand; C2, gravelly sand; C3coarse gravelly sand; F, silty clay loam to clay. W, wheat; B, barley.

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Table

3.

Totalapplied

water,irrigationreturn

flow

(IRF),andirrigationreturn-flow

coeffi

cient(IRFC)duringtheearlystage(D

ecem

ber–March)and

late

stage(M

arch–June).

Earlystage

Late

stage

Lysimeter

Wateryear

Totalapplied

water(m

m)

IRF

(mm)

IRFC

(%)

Totalapplied

water(m

m)

IRF(m

m)

IRFC

(%)

C3W

2007–2008

568.2

251.0

44.2

487.0

157.5

32.3

C2W

2007–2008

480.7

242.7

50.5

417.5

8.2

2.0

2008–2009

466.0

181.9

39.0

413.9

83.2

20.1

C1W

2007–2008

417.7

123.0

29.4

428.0

3.2

0.8

2008–2009

413.0

118.3

28.6

406.4

2.8

0.7

FW

2007–2008

560.7

248.6

44.3

469.5

5.0

1.1

2008–2009

578.0

177.2

30.7

425.9

0.3

0.1

FB

2007–2008

505.2

1.9

0.4

270.0

0.8

0.3

2008–2009

515.5

8.7

1.7

248.4

3.1

1.2

C1B

2007–2008

337.1

11.8

3.5

315.2

46.3

14.7

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longer border lengths. Therefore, it is acceptable to correlate border lengthwith depth of water applied to the lysimeters. The border lengths and TWsare correlated (r¼ 0.9) at a significance level of 0.05 (Figure 9). Enhancementof the border length increases the advance time (the time required for waterto cover the border), resulting in the application of excess water at the upperend of the border. This increases the total applied water to the farm, andconsequently, the IRFC.

(3) Mismanagement is another parameter increasing the IRFC in the study area.Farmers with access to large amounts of water typically apply excess to theirfields. The farm surrounding lysimeter FW was the only one irrigated by aspring, having an annual average discharge rate of 283 l s71. The farm

Figure 6. Total applied water, crop evapotranspiration (ETCa), deep percolation (DP) andirrigation return flow (IRF) for each irrigation event during the 2007–2008 growing season.

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Table

4.

Annualtotalapplied

water,irrigationreturn

flow

(IRF),andirrigationreturn-flow

coeffi

cient(IRFC)ofthelysimetersduringthetw

ostudy

years.

Lysimeter

Wateryear

Number

ofirrigations

Ave.

amount

ofirrigation

(mm)

Totalamount

ofirrigation

(mm)

Precipitation

(mm)

Totalapplied

water(m

m)

IRF

(mm)

IRFC

(%)

C3W

2007–2008

14

74

1036.5

18.7

1055.2

408.4

38.7

C2W

2007–2008

15

59

879.5

18.7

898.2

251

27.9

2008–2009

15

54

810.5

69.4

879.7

265

30.1

C1W

2007–2008

16

51.7

18.7

18.7

845.7

126.2

14.9

2008–2009

16

46.9

750

69.4

819.4

121.1

14.8

FW

2007–2008

10

101.2

1011.5

18.7

1030.2

253.6

24.6

2008–2009

10

93.6

936

67.9

1003.9

177.4

17.7

FB

2007–2008

984.1

756.5

18.7

775.2

2.7

0.4

2008–2009

977.2

694.5

69.4

763.9

11.8

1.5

C1B

2007–2008

12

52.8

633.6

18.7

652.3

58

8.9

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enclosing lysimeter FW was irrigated using the abundantly available, freespring water. The total applied water was 1030 mm higher than for most ofthe other lysimeters. As a consequence, the IRFC was high despite the finesoil texture.

Figure 7. Applied water versus (a) irrigation return flow (IRF) and (b) irrigation return-flowcoefficient (IRFC) for the two study years.

Figure 8. Excess of applied water versus (a) irrigation return flow (IRF) and (b) irrigationreturn-flow coefficient (IRFC) for the 2007–2008 growing season.

Figure 9. The relationship between total applied water and border length.

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(4) The average IRFC in the coarse soil lysimeters (C1W, C2W and C3W) andfine soil lysimeters (FB and FW) were 25.3 and 11%, respectively (Table 4).IRFC values for the coarse texture lysimeters are higher than for the finetexture lysimeters, with the exception of FW. The high IRFC value inlysimeter FW is due to the excess applied water, as discussed above. The highIRFC values in coarse soil are due to low evaporation and low field capacity.Evaporation is higher in fine- and medium-textured soils than in coarse-textured soils (Jalota and Arora 2002; Gee et al. 2005). The reduction inevaporation in coarse textured soil results in an increased availability of soilwater, thus increasing the IRF. In addition, field capacity decreases in coarsesoils, consequently increasing DP and IRF (Gee et al. 2005).

Despite interactions between the controlling parameters and the fact that theresearch was carried out under field conditions, it can still be concluded that IRF andIRFC are functions of excess applied water, border length, soil texture and watermanagement.

The results from filled-in lysimeters may be questioned due to variations in soilproperties during installation. Variations in soil structure and texture in lysimetersdid not have any considerable effect on the IRF measurements for the followingreasons:

(1) The lysimeters were installed six months before planting date. Therefore, thesecond-year studies were started one and half years after the lysimeters wereinstalled.

(2) The IRFC values and time series of IRF for the first and second years weresimilar. However, this research is being continued by the Yazd regional waterauthority. The extended experiments will provide a better judgments on theIRF data.

IRFC values were also calculated for the farms using the water balance method(Jafari 2010) as a scale check to apply lysimeter IRFC values to the farms. Thedifferences in IRFC values using the lysimeter and water balance methods were lessthan +4%, except for lysimeter FB, which was 78.9%. As mentioned previously,the continued research by the Yazd regional water authority will give a betterunderstanding for scaling up lysimeter results to the study area.

The average IRFC values for the sprinkler lysimeter C1B during the early and latestages were 3.5 and 14.7%, respectively (Table 3). The total depth of applied water inthis lysimeter was 337 mm during the early stage, which is *33% lower than theaverage total depth of applied water of the border lysimeters. Using the sprinklermethod, water can be delivered directly to the crop without flowing onto the surfaceand across the field; therefore, the crop can be irrigated to any desired depth. Farmersare able to apply a low amount of water, especially during the early stage when rootdepth and evapotranspiration are both low. This can reduce the IRF significantly.

The high value of IRFC in lysimeter C1B during the late stage is notcharacteristic of a sprinkler irrigation system. This result is due to mismanagementand malfunctioning of the sprinkler irrigation system. For example, in irrigationevents 6 and 7, the lysimeter area was irrigated twice instead of once, applying largeamounts of water, in excess of the crop water requirement. The IRFC valueincreased significantly after these two irrigations.

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The soil textures of lysimeters C1B and C1W were the same. Therefore, thesprinkler and border irrigation methods can be compared in these two lysimeters.The IRFC values for lysimeters C1B and C1W were 3.5 and 29.4%, respectively,during the early stage (Table 3). It can be concluded that a sprinkler irrigationsystem under scientific management is able to solve the problem of high IRFCduring the early stage in coarse soils.

Conclusions

The IRFC, an important parameter of groundwater balance, is traditionally basedon rules of thumb in Iran. Determination of the IRFC under field conditionsimproves water balance calculations. IRF was measured directly in several lysimetersinstalled in wheat and barley farms under traditional farm-management practices.

In the border lysimeters, the lag time between the first irrigation event and thefirst drainage varied from 2 days in coarse soils to 82 days for fine soils. The highavailable water capacity of fine soils is the main reason for their higher lag times. Thecracking of clay soils can decrease the lag time, despite higher available watercapacity. Water stress in a previous growing season increases soil moisture depletionat the beginning of the next season, resulting in an increase in lag time.

The IRF time series have sharp peaks at the initial stages of the growing season,disappearing towards the end of the season. The IRFC time series were divided intoearly and late stages. Low evapotranspiration and shallow root zones decrease thewater requirement during the early stage. Providing the low amount of waterrequired without an excess of applied water is impossible in border irrigation,therefore, the IRF and IRFC increase during the early stage. In addition, there is nowater demand from tree and other summer crops like alfalfa during the early stage,and farmers traditionally believe in over-irrigation at a time of overabundance of thewater supply. Severe soil moisture depletion before planting is able to decrease theIRFC during the early stage. Annual IRF and IRFC values are functions of excessapplied water, border length, mismanagement and soil texture. The high IRFCs,especially during the early stage, can be reduced significantly by changing fromborder irrigation to a sprinkler system.

References

Aboukhaled A, Alfaro A, Smith M. 1982. Lysimeter. FAO Irrigation and Drainage Paper 39.Rome (Italy): FAO.

Allen RG, Pereira LS, Smith M. 1998. Crop evapotranspiration – guidelines for computingcrop water requirements. FAO Irrigation and Drainage Paper 56. Rome (Italy): FAO.

Bethune M. 2001. Recharge review. Attachment 3 in Wood (2001). Improved irrigationpractices for forage production, module 1: flood irrigation research review. Final report.Tatura (Australia): Department of Natural Resources and Environment.

Bethune M, Austin N, Maher S. 2001. Quantifying the water budget of irrigated rice in theShepparton Irrigation Region, Australia. Irrigation Sci. 20:99–105.

Bronswijk J, Hamminga W, Oostindie K. 1995. Rapid nutrient leaching to groundwater andsurface water in clay soil areas. Eur J Agron. 4(4):431–439.

Causape J, Quilez D, Aragues R. 2004. Assessment of irrigation and environmental quality atthe hydrological basin level (I) irrigation quality. Agr Water Manage. 70:195–209.

Dewandel B, Ganolfi JM, de Condappa D, Ahmad S. 2007. An efficient methodology forestimating irrigation return flow coefficients of irrigated crops at watershed and seasonalscale. Hydrol Process. 22:1700–1712.

688 H. Jafari et al.

Dow

nloa

ded

by [

H. J

afar

i] a

t 10:

59 0

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ctob

er 2

013

Gee GW, Keller JM, Ward AL. 2005. Measurement and prediction of deep drainage frombare sediments at a semiarid sites. Vadose Zone J. 4:32–40.

Haseb Fars Consulting Engineering Company. 2003. Groundwater studies of Harat regionand modeling, part 2: geology and hydrogeology, Haseb Fars Consulting EngineeringCompany Report [in Farsi]. Yazd (Iran): Yazd Regional Water Authority.

Humphreys E, Edraki M, Bethune M. 2003. Deep drainage & crop water use for irrigatedannual crops and pastures in Australia. CSIRO Land and Water Technical Report 14/03.Griffith (Australia): CSIRO Land and Water.

Jafari H. 2010. Physiochemical characteristics of irrigation return flow in a semi-aridagricultural region, Iran [PhD thesis]. [Shiraz (Iran)]: Shiraz University.

Jalota SK, Arora VK. 2002. Model-based assessment of water balance components underdifferent cropping systems in north-west India. Agr Water Manage. 57:75–87.

Jimenez-Martınez J, Skaggs TH, van Genuchten MTh, Candela L. 2009. A root zonemodeling approach to estimating groundwater recharge from irrigated areas. J Hydrol.367:138–149.

Lyle C. 2002. Proposed research program for better catchment planning and water resourcesmanagement. Case study – the Northern Murray Darling Basin. Land and WaterAustralia Consultancy Report prepared by Clive Lyle and Associates and AquatechConsulting Pty Ltd. (Australia): Australian Cotton Cooperative Research Centre.

Meyer WS, Dunin FX, Smith RCG, Shell GSG. 1987. Characterizing water use by irrigatedwheat at Griffith, New South Wales. Aust J Soil Res. 25:499–515.

Meyer WS, Mateos L. 1990. Soil type effects on soybean crop water use in weighing lysimetersIII. Effect of lysimeter canopy height discontinuity on evaporation. Irrigation Sci. 11:233–237.

Moss J, Gordon I, Zischke R. 1999. Vertosols do ‘leak’! – water and solute movement belowirrigated cotton. Proceedings of the Murray Darling Basin Groundwater Workshop 1999;Griffith, NSW, Australia. Griffith (Australia): MDBC. p. 298–303.

Parab Fars Consulting Engineering Company. 2008. Water balance studies in Mond RiverBasin. Parab Fars Consulting Engineering Company Report [in Farsi]. Shiraz (Iran): FarsRegional Water Authority.

Steiner JL, Smith RCG, Meyer WS, Adeney JA. 1985. Water use, foliage temperature andyield of irrigated wheat in south-eastern Australia. Aust J Agr Res. 36:1–11.

Weaver TB, Hulugalle NR, Ghadiri H. 2005. Comparing deep drainage estimated withtransient and steady state assumptions in irrigated vertisols. Irrigation Sci. 23:183–191.

Willis TM, Scott Black A, Meyer WS. 1997. Estimate of deep percolation beneath cotton inthe Macquarie valley. Irrigation Sci. 14:141–150.

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