CE6703-WATER RESOURCES AND IRRIGATION ENGINEERING

PRESENTED BY,

AJITH KUMAR, B.E ( CIVIL)

MOHAMED SATHAK ENGINEERING COLLEGE RAMANATHAPURAM

UNIT-3 IRRIGATION ENGINEERING

SYLLABUS

Need-Merits and Demerits-Duty, Delta and base period- irrigation efficiencies- crops and seasons- crop water requirement- Estimation of consumptive use of water.

Irrigation engineering

Irrigation may be defined as the process of artificial application of water to the land or soil to create an optional soil moiture region for maximizing crop production.

Necessity of Irrigation

Insufficient RainfallUneven or Non-Uniform Rainfall DistributionImprovement of Perennial Crops.Development of Desert Area.

Irrigation problem

Benefits of irrigation

Increase in crop yield Protection from famine Elimination of mixed cropping Economic development Hydro power generation Domestic and industrial water supply Sources of RevenueGeneral Communication

Benefits of irrigation

Aesthetic ViewDevelopment of fisheryAid to Civilization.Increase of Groundwater Level.RecreationSelf-Sufficiency in Food

Benefits of irrigation

Demerits:

Effects of Irrigation

Effects on Raising Water Table.Damp ClimateBreeding Places of MosquitoesLoss of Valuable LandReturn of Revenue

Effects of Irrigation

Base

Base is defined as the period from the first to the last watering of the crop just before its maturity.

Also known as base period.

Denoted as “B” and expressed in no of days.

Duty

Duty represents the irrigating capacity of a unit water.

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

Duty of water is defined as no of hectares that can be irrigated by constant supply of water at the rate of one cumec throughout the base period.

1 cumec-day = 1 m3/sec for one day

FACTORS AFFECTING DUTY OF WATER

1.Type of crop.

2.Climatic condition of the area.

3.System&Method of irrigation.

4.Quality of irrigation water.

5.Method of cultivation.

6.Time of irrigation and frequency of cultivation.

7.Type of soil and sub-soil of the irrigated field.

8.Canal conditions.

9.Methods of assessment of irrigation water rate.

Delta

Each crop requires certain amount of water per hectare for its maturity.

If the total of amount of water supplied to the crop is stored on the land without any loss, then there will be a thick of water standing on the land.

This depth of water layer is known as Delta for the crop.

It is total depth of water required for a crop during the entire period of the crop is in the field and is denoted by delta

Irrigation Efficiency

It is the water stored in the root zone after losses to the water pumped or supplied in the system, i.e. it is the ratio of the water output to the water input and usually expressed in percentage. Loss of water occurs in conveyance, water application, water storage and water use. Therefore, irrigation efficiency may be efficiency in conveyance, efficiency in water application, efficiency in storage and efficiency in water use.

Example

• For ex, if 1 cumec of water is pumped to the farm, but 0.75 cumec is delivered in length of 1 km from the well, the loss (1-0.75) = 0.25 cumec is due to conveyance.

• Therefore, Efficiency of water conveyance= 0 .75 x 100 = 75 %

Cropping Seasons

Water Requirement of Crops

Factors Affecting Water Requirements:Water TableClimateType of soilIntensity of IrrigationGround slopeMethod of application of water

Consumptive Use of Water (CU)

Water requirement of crop is the total quantity of water from the time the crop is sown to the time it is harvested. This water requirement may vary from crop to crop, from soil to soil and period to period. Water required to meet the demand of evapo-transpiration and metabolic activities of the crop to-geather is known as consumptive use (CU) of water

Factors Affecting Consumptive Use (CU)

Evaporation which is dependent on humidityMonthly precipitationWind velocity in the locality which affects

evaporationSoil type and its topographyCropping pattern, growth stage and type of

cropGrowing season of the cropMethod of applying irrigationIrrigation water depth

Factors Affecting Consumptive Use (CU)

THANK YOU FOR THE GREAT OPPURTUNITIE

I hope you have learnt something!