GOVERNMENT ENGINNERING COLLAGE,VALSAD

11

IRRIGATION ENGINEERING(170602)

GUIDED BY:-Prof. Kuldip Patel

PREPARED BY

NAME ENROLLMENT NO.

PATEL NIRALI A. 100190106003KHOLIYA ASHISH B. 110193106011

Irrigation engineering Necessity of irrigation Scope of irrigation engineering Benefits of irrigation engineering Ill-effect of irrigation Irrigation development in india Types of irrigation system Soil-water plant relationship Classification of soil water Soil-moisture content Depth of soil water available to plants

INTRODUCTION

IRRIGATION:-Irrigation is defined as the process of artificially supplying water to soil for raising crops.

IRRIGATION ENGINEERING:- It is the science dealing with planning, designing, construction, operation and maintenance of various irrigation works

IRRIGATION ENGINEERING

Inadequate rainfall Non-uniform rainfall Growing number of crops during year Growing perennial crops Growing superior crops Increasing the yield of crops Insurance against crops

NECESSITY OF IRRIGATION

Engineering aspect

Agriculture aspect

Management aspect

SCOPE OF IRRIGATION ENGINEERING

It involves the development of source of water for irrigation and arrangement for the conveyance of water from the source right up to agricultural fields.

a) Storage ,diversion or lifting of water.b) Conveyance of water to the agricultural fields.c) Application of water to agricultural fields.d) Drainage and reliving water – logging.e) Development of hydropower.

ENGINEERING ASPECT

It involves the timely and systematic application of irrigation water to the agricultural fields. It deals with following points:

1) Proper leveling and shaping of the agricultural fields.

2) Soil investigation and classification of the agriculural land.

3) Provision of field channel.

4) Distribution of water uniformly and periodically.

5) Capacities of different soil.

6) Conservation of soil against erosion.

7) Choosing proper crop pattern.

8) Reclamation of waste and alkaline ands.

AGRICUTURAL ASPECT

It deals with the successful implementation and efficient management of both the engineering as well as the agricultural aspects of the project.

Following points are considered in this aspect:-

1) The farmers should be trained and educated.2) The cultivation should be carried out in a scientific manner with due

control on all the inputs so as to obtain the maximum yield.3) The distribution of water to the farmers should be managed properly.4) The agricultural land holding of the small farmers should be

consolidated to increase the efficiency of irrigation.5) Suitable measures are to be adopted to eliminate the ill effect of

irrigation.

MANAGEMENT ASPECT

1) Increase in crop yield2) Protection from famine3) Cultivation of crash crops4) Elimination of mixed cropping5) Increase in the wealth of country 6) Increase in prosperity of people7) Generation of hydro-electric power8) Domestic and industrial water suplly9) Inland navigation10) Communication facility11) Canal plantation12) Increase in ground water storage13) Overall development of the country14) Aid in civilization

BENEFITS OF IRRIGASTION

It is due to the excess irrigation and unscientific use of irrigation water may give rise to the ill-effects. some of the common ill-effect of irrigation are:

1) Water logging2) Mosquitoes nuisance3) Damp climate4) Pollution of ground water

ILL-EFFECT OF IRRIGATION

Classification based on availability of water

TYPES OF IRRIGATION SYSTEM

Irrigation system

Flow irrigation

Lift irrigation

Perennial irrigation

As per source

Inundation irrigation

Well irrigation

Lift canal irrigation

Direct irrigation

Storage irrigation

Combined irrigation

The flow irrigation system can be further classified based on duration into two classes:

1) Perennial irrigation system2) Inundation irrigation system

PERENNIAL IRRIGATION SYSTEM:- In this system water is supplied as per the crop

requirements at regular intervals, through the crop period. INUNDATION IRRIGATION SYSTEM:- In this system large quantity of water flowing in a river

during flood is allowed to flood or inundated the land to be cultivated.

FLOW IRRIGATION

DIRECT IRRIGATION SYSTEM

STORAGE IRRIGATION

COMBINED IRRIGATION SYSTEM

LIFT IRRIGATION

CLASSIFICATION BASED ON CULTURABLE COMMAND AREA

Major project(CCA >10,000)

Medium project10,000<CCA>2000

The water added to a soil mass during irrigation ,is held in the pores of the soil mass, which is termed as soil water. It is classified as following:-

1) Gravitational water2) Capillary water3) Hygroscopic water

CLASSIFICATION OF SOIL - WATER

SOIL MOISTURE CONTENTT:-The amount of water present in soil is termed as soil moisture content.

SATURATION CAPACITY:-It is the amount of water required to fill all the pore spaces between soil particles by replacing all air held in pore spaces.

FIELD CAPACITY:-The field capacity is the moisture content of the soil after free drainage has removed most of the gravity water.

PERMANENT WILTING POINT:-Permanent wilting point or the wilting coefficient is that water content at which plants can no longer extract sufficient water from the soil for its growth.

SOIL – MOISTURE CONTENTS

TEMPORARY WILTING:- Temporary Wilting of plants usually occurs on a hot day, but the plants recover - from wilting in the cooler portion of the day or during the night without any addition of water to the soil. Thus, temporary wilting of plants may occur even without much reduction in the soil moisture content.

ULTIMATE WILTING:-Ultimate wilting of plants Occurs when they become completely wilted and dead after ultimate wilting has occurred, the plants do not recover from wilting even after the addition of water to the soil.

The water content at which ultimate wilting occurs is termed as ultimate wilting point.

MOISTURE EUIVALENT:- Moisture equivalent is Defined as the percentage of moisture retained in an initially saturated sample of soil 10 mm thick after being subjected to a centrifugal force of 1000 times gravity for a period of 30 minutes.

AVAILABLE MOISTURE:- The difference in Moisture content of soil between the field capacity and the permanent wilting point is called the available moisture.

READILY AVAILABLE MOISTURE :-It is that portion of the Available moisture that is most easily extracted by plants. It is approximately 75% of the available moisture.

SOIL MOISTURE TENSION:-The force per unit area that Must be exerted in order to extract water from the soil is known as soil moisture tension.

EXTRACTION OF SOIL MOISTURE IN ROOT ZONE

CROP WATER AND NET IRRIGATION REQUIREMENTS

In irrigation, it is essential to know the amount of water needed by crops.

This determines the quantity of water to be added by irrigation and rainfall and helps in day to day management of irrigation systems.

DUTY:- Duty represents the irrigating capacity of a unit water. It relation

between the area of a crop irrigated and the quantity of irrigation water required during crop growth.

For example:If 5 cumec of water is required for a crop sown in an area of 5000 hectares, The duty will be 5000/5=1000 hectares/cumec.

DELTA:- It is total depth of water required for a crop during the entire

period the crop is in the field and is denoted by Δ. The unit of delta is days.

RELATION BETWEEN DUTY AND DELTA

There are four types of duty:1) GROSS DUTY:-It is the duty of water measured at The head of main

canal.

2) NOMINAL DUTY:-It is the duty sanctioned as per Schedule of an irrigation department.

3) ECONOMIC WATER DUTY:-It is the duty of water Which results in the maximum crop yield.

4) DESIGNATED DUTY:- It is the duty of water assumed in an irrigation project for designing capacities of the channel.

TYPES OF DUTY

RELATION BETWEEN DUTY AND DELTA

Let,

D=duty in hectares

∆ = total depth of water supplied in meters

B = base period in days

1) If we take a field of area D hectares, water supplied to the field corresponding to the water depth ∆ meters will be,

= D x ∆ hectares – meters

=D x ∆ x 104 cubic meters

2) For the same field of area D hectares , water is supplied at the rate of 1 cumec for the entire base period of B days , then the total quantity of water supplied to the field,

=1 x b x 24 x 60 x 60 cubic meter

=8.64 x 104 B cubic meter

D = 8.64 B/ D meters

CROP PERIOD:-It is the time in days, that a crop takes from The instant of its sowing to that of its harvesting.

BASE PERIOD:- The base period is the relation between he First watering and the last watering supplied to the land.

PALEO:- It is defined as the first watering before sowing the Crop.

GROSS COMMAND AREA(G.C.A):-It is defined as the total Area lying between drainage boundaries which can be commanded or irrigated by a canal.

DEFINATIONS RELATED TO IRRIGATION

CUTURABLE COMMAND AREA(C.C.A):- It is that portion of G.C.A which is cultivable or cultivable.

CROP RATIO:- It is defined as the ratio of the land irrigated During the two main crop season rabi and kharif.

TIME FACTOR:- It is the ratio of number of days the canal has actually run to the number of days of irrigation Period.

CAPACITY FACTOR:- It is the ratio of mean supply to the Full supply of a canal.

1) Method of irrigation

2) System of irrigation

3) Method of cultivation

4) Type of crop

5) Base period of crop

6) Climatic condition

7) Quality of water

8) Canal condition

9) Type of soil and sub soil

10) Time of irrigation

FACTOR AFFECTING DUTY OF WATER

EVAPOTRANSPIRATION

Composed of two sub processes:-◦ Evaporation occurs on surfaces of open water or from vegetation and

ground surfaces.◦ Transpiration is the removal of water from the soil by plant roots,

transported through the plant into the leaves and evaporated from the leaf’s stomata.

Typically combined in mass balance equations because the components are difficult to partition.

Evapotranspiration

EvaporationTranspiration

Open Water Soil Vegetation

Surfaces

Plants

POTENTIAL VS. ACTUAL ET

Potential ET (PET) is the amount of evaporation that will occur if an unlimited amount of water is available.

Actual ET (AET) is the actual amount of evaporation that occurs when water is limited. For large areas can use a mass balance approach to calculate (Eq. 4.5).

Transpiration is the loss of water in the form of vapor from plants

Factors that affect transpiration ratesType of plantWindPlant Available Water: the portion of

water in a soil that can readily be absorbed by plant roots. Amount of water released between field capacity (amount of water remaining in the soil after gravitation flow has stopped) and wilting point (amount of water in the soil at 15 bars of suction).

TRANSPIRATION

EVAPORATION

Phase change of water from a liquid to a gas

o Rate of evaporation is driven by the vapor pressure deficit. Function of:1. The ability of air to hold water based on air temperature and relative

humidity.

2. The energy in the water largely based on temperature.

o Net evaporation ceases when the air has reached the saturation vapor pressure.

There are two method for the measurement : DIRECT MEASUREMENT METHOD

1. Tank and lysimeter method

2. Field experiment method

3. Soil moisture study

4. Integration method

5. Inflow and outflow studies

USE OF EMPIRICAL FORMULA

1. Penman method

2. Jensen –Haise method

3. Blanley Criddle method

4. Hargreaves method

5. Thornthwait method

MEASUREMENT OF CONSUMPTIVE USE OF WATER

PENMAN-MONTIETH METHOD

ET R GK

BP

e e

rnz z

a0

101

622

( )[(

*)( ) (

*)(. )

( )]

•More reliable for any length period daily, monthly, or seasonal.•If adequate data available.

AET0 = The evapotranspiration for grass reference crop = heat of vaporization Rn = net radiation G = soil heat flux = slope of the vapor pressure curve = psychrometric constant = density of air BP = mean barometric pressure e0

z = average saturated vapor pressure ez = actual vapor pressure * = (1+rc/ra) rc = surface resistance to vapor transport ra = aerodynamic resistance to sensible heat and vapor transport K1 = the dimension coefficient

TANK AND LYSIMETERE METHOD

IRRIGATION EFFICIENCIS

These irrigation efficiencies are brought about by the desire not to waste irrigation water, no matter how cheap or abundant it is.

The objective of irrigation efficiency concept is to determine whether improvements can be made in both the irrigation system and the management of the operation programmes, which will lead to an efficient irrigation water use.

APPLICATION EFFICIENCY

EWater in root zone after irrigation

Total volume of water applieda

Total vol of water applied Vol of Tailwater Vol of deep percolation

Total water applied

. ( . . )

Ea is inadequate in describing the overall quantity of water since it does not

indicate the actual uniformity of irrigation, the amount of deep percolation or the magnitude of under-irrigation. See diagrams in text.

Water Conveyance Efficiency

EWater delivered to the Farm W

Water of water diverted from a stream reservoir or well Wcd

s

( )

, ( )

Farm

Water lost by evapAnd seepage

Wd

Ws

WATER STORAGE EFFICIENCY (ES)

EVolume of water in the root zone after irrigation

Volume of water needed in root zone to avoid total water moisture depletions

=WS/WN X 100

Irrigation projects are planned, executed, owned, and operated by state governments. Irrigation projects are financed by state governments out of their own resources, market borrowing and loans and grants made available by the central governments. the beneficiaries in commanded areas derive considerable benefits from the project. It is , therefore, imperative that the beneficiaries pay for it. The fixation of such charges is known as assessment of irrigation water.

ASSESMENT OF IRRIGATION WATER

1) Assessment on area basis or crop rate basis2) Volumetric assessment3) Assessment on seasonal basis 4) Composite rate basis5) Permanent assessment

METHODS OF ASSESMENT