Modern Irrigation Networks Modern Irrigation Networks of Iran:of Iran:

Problems & ChallengesProblems & Challenges

Hassan Hassan RahimiRahimi

Agricultural DevelopmentAgricultural Development

-- Due to increasing population and growing cities Due to increasing population and growing cities and increasing demand for food, planning, design and increasing demand for food, planning, design and construction of the modern irrigation and construction of the modern irrigation networks in Iran started in 1950networks in Iran started in 1950’’s.s.

-- The first modern irrigation network, The first modern irrigation network, DezDez, was , was constructed in early 1960.constructed in early 1960.

-- So far more than 100 modern irrigation networks So far more than 100 modern irrigation networks have been constructed covering an area of 1.6 have been constructed covering an area of 1.6 mhamha..

An overview on IranAn overview on IranLand & Water ResourcesLand & Water Resources

Total Area

Total Arable Land

Total Land Annually Under

Cultivation

Forest Area

Irrigated Agriculture

Rain fed Agriculture

Area under Modern

Irrigation Networks

165 165 mhamha

5151mhamha

18.5 18.5 mhamha

12.412.4mhamha

8.5 8.5 mhamha

1010mhamha

1.6 1.6 mhamha

Total Annual Precipitation

Annual Renewable

Water

Surface Runoff Agricultural Water

430 430 bcmbcm

130130bcmbcm

9595bcmbcm

85 85 bcmbcm

a. Landa. Land

b. Waterb. Water

Based on the report published by Ministry of Energy, modern irrigation

structures have been suffering different rates of damages:

-- High to moderate 30%High to moderate 30%-- Medium to low 36%Medium to low 36%-- Low to zero 34% Low to zero 34%

The nature of the problems in The nature of the problems in irrigation networks:irrigation networks:

-- Geographical and topographical conditionsGeographical and topographical conditions-- Harsh topography, more than 2/3 of the country is Harsh topography, more than 2/3 of the country is

covered by mountains , hilly areas and deserts.covered by mountains , hilly areas and deserts.-- Geological conditionsGeological conditions

-- Locating in a highly seismic active zone, presence of 100Locating in a highly seismic active zone, presence of 100’’s s active faults which face the structures with seismic active faults which face the structures with seismic hazards.hazards.

-- Presence of weak sedimentary formation, such as gypsum, Presence of weak sedimentary formation, such as gypsum, marl, shale and saline soil. marl, shale and saline soil.

-- Climatic conditionsClimatic conditions-- Very high and very low temperatures, long freezing Very high and very low temperatures, long freezing

periods, long hot summer periods. 1/3 of country has less periods, long hot summer periods. 1/3 of country has less than 50mm annual precipitation (deserts).than 50mm annual precipitation (deserts).

-- Political, social and cultural issuesPolitical, social and cultural issues

Main causes of damages to the Main causes of damages to the irrigation structuresirrigation structures

--Technical and design related problemsTechnical and design related problems

--Poor construction practices Poor construction practices

--Poor operation Poor operation

--Poor maintenancePoor maintenance

--Cultural and social issuesCultural and social issues

Design Related ProblemsDesign Related Problems

- Insufficient discharge capacity of Insufficient discharge capacity of canalscanals

-- Insufficient freeboardInsufficient freeboard

-- Improper friction coefficientImproper friction coefficient

-- Improper flow velocityImproper flow velocity -- SedimentationSedimentation

-- ErosionErosion

-- Lack of safety structuresLack of safety structures

Problems Related to Presence of Problems Related to Presence of Problematic or Difficult Soils:Problematic or Difficult Soils:

Soils which cause damage to the upper Soils which cause damage to the upper structure when in contact with waterstructure when in contact with water

-- Swelling SoilsSwelling Soils-- Dispersive SoilsDispersive Soils-- Soluble SoilsSoluble Soils-- Collapsible SoilsCollapsible Soils-- Liquefiable Soils Liquefiable Soils –– Fine Sandy soilsFine Sandy soils-- Weak Organic Soils Weak Organic Soils –– Saturated ClaysSaturated Clays

Problems Related to Expansive Problems Related to Expansive SoilsSoils

(The soils which suffer high volume change due to (The soils which suffer high volume change due to change in water content)change in water content)

Deformed Mesh

Normal Strain

Problems Related to Dispersive Problems Related to Dispersive SoilsSoils

(The soils which are easily eroded in contact with water)(The soils which are easily eroded in contact with water)

Problems Related to Soluble Problems Related to Soluble SoilsSoils

(The soils which are easily leached in contact with running wate(The soils which are easily leached in contact with running water, r, including including gypsiferousgypsiferous and saline soils)and saline soils)

Problems Due to Liquefiable Problems Due to Liquefiable Soils Soils

(The soils which lose their shearing strength when subjected (The soils which lose their shearing strength when subjected to dynamic forces in loose, submerged conditions )to dynamic forces in loose, submerged conditions )

Problems Related to Problems Related to Collapsible SoilsCollapsible Soils

(The soils which their structure will collapse when in (The soils which their structure will collapse when in contact with water)contact with water)

Structure of Collapsible SoilStructure of Collapsible SoilFine Sand & Coarse SiltFine Sand & Coarse Silt

Structure of Collapsible SoilStructure of Collapsible SoilFine Sand & Coarse SiltFine Sand & Coarse Silt

Structure of Collapsible SoilStructure of Collapsible SoilFine Sand & Coarse SiltFine Sand & Coarse Silt

نشست موضعی سطح زمين بر اثر رمبندگی خاک

A view of the collapsed ground A view of the collapsed ground surfacesurface

Problems in Unstable Fine Sandy Problems in Unstable Fine Sandy Soils (Physical Soils (Physical DispersivityDispersivity))

(These type of soils are mostly made of uniform, fine sand, (These type of soils are mostly made of uniform, fine sand, which are easily eroded by flowing water)which are easily eroded by flowing water)

Problems Due to Problems Due to Weak , Organic Soils

(The soils which have high moisture and organic contents)(The soils which have high moisture and organic contents)

Problems Due to Low Quality Problems Due to Low Quality Construction MaterialsConstruction Materials

Low Quality Construction MaterialsLow Quality Construction Materials

--Improper mix design of concreteImproper mix design of concrete

--Chemical attacksChemical attacks

--(sulfate attack, alkali (sulfate attack, alkali -- silica reaction)silica reaction)

--Climatic attacks Climatic attacks

--(hot & cold weather, freezing, etc.)(hot & cold weather, freezing, etc.)

--Low quality ingredients Low quality ingredients

--(Portland cement, aggregate, mixing water, etc.)(Portland cement, aggregate, mixing water, etc.)

Poor Construction PracticePoor Construction Practice

-- Improper consolidation of concrete liningImproper consolidation of concrete lining

-- Improper compaction of Improper compaction of subgardesubgarde soilsoil

-- Improper finishing of concrete surfaceImproper finishing of concrete surface

-- Improper joint systemImproper joint system

--(contraction (contraction -- expansion, construction)expansion, construction)

Poor Operation and MaintenancePoor Operation and Maintenance

-- Lack of dredging operationLack of dredging operation

-- Using improper dredging equipmentsUsing improper dredging equipments

-- Uncontrolled weedsUncontrolled weeds

-- Lack of annual repairsLack of annual repairs

-- Improper service of hydroImproper service of hydro--mechanical equipmentsmechanical equipments

-- Uncontrolled traffic in service roadsUncontrolled traffic in service roads

-- Abandoning canal for long timeAbandoning canal for long time

Social and Cultural IssuesSocial and Cultural Issues

--Destruction of canals Destruction of canals by farmers toby farmers to obtain more waterobtain more water

--Destruction of canals due to differences between farmersDestruction of canals due to differences between farmers

--Filling of canals for transportation purposesFilling of canals for transportation purposes

--Damage to canals Damage to canals due to sewage discharge due to sewage discharge

--Dumping rubbish into canalsDumping rubbish into canals

--Vandalism and damage to hydroVandalism and damage to hydro--mechanical equipmentmechanical equipment

--Over due of water costsOver due of water costs

--Lack of participation in maintenance and operationLack of participation in maintenance and operation

Damages to canal lining for water removalDamages to canal lining for water removal

Damage to the Structures for Illegal Damage to the Structures for Illegal Exploiting of WaterExploiting of Water

Damages to Regulating StructuresDamages to Regulating Structures

ConclusionsConclusions-- In spite of great achievements in design and construction In spite of great achievements in design and construction

of modern irrigation networks, there are many technical of modern irrigation networks, there are many technical and managerial issues facing these projects in Iran. and managerial issues facing these projects in Iran.

-- Technical problems are mostly caused by special geological Technical problems are mostly caused by special geological features which have caused presence of several types of features which have caused presence of several types of problematic soils all over the country. Expansive, problematic soils all over the country. Expansive, dispersive and soluble soils are the most common dispersive and soluble soils are the most common problematic soils which have caused severe damages to the problematic soils which have caused severe damages to the irrigation structures. irrigation structures.

-- Lack of training and lack of farmersLack of training and lack of farmers’’ participation are participation are other main issues facing modern irrigation projects which other main issues facing modern irrigation projects which have caused unsuccessful performance in many cases. have caused unsuccessful performance in many cases. Organizing water user associations (WUA) and Organizing water user associations (WUA) and participatory irrigation management (PIM) are the best participatory irrigation management (PIM) are the best solutions in this regard. So far, minor steps have been solutions in this regard. So far, minor steps have been taken, but are not enough and should be extended in many taken, but are not enough and should be extended in many ways.ways.

-- Regional and international exchange of experiences in Regional and international exchange of experiences in design, construction and managing irrigation projects are design, construction and managing irrigation projects are vital for the success of such projects. Holding joint vital for the success of such projects. Holding joint seminars, workshops and other technical sessions and seminars, workshops and other technical sessions and publishing the results of gained experiences are good publishing the results of gained experiences are good examples for such activities.examples for such activities.