Irrigation engineering

Irrigation engineering : in agriculture, artificial watering of the land. Although used chiefly in regions with annual rainfall of less than 20 in. (51 cm), it is also used in wetter areas to grow certain crops, e.g., rice. Estimates of total irrigated land in the world range from 543 to 618 million acres (220 to 250 million hectares), almost half of them in India, Pakistan, and China. The United States had almost 60 million acres (23.8 million hectares) of irrigated farmland in 1991.

In Irrigation engineering Methods of applying water include free-flooding of entire areas from canals and ditches; check-flooding, in which water flows over strips or checks of land between levees, or ridges; the furrow method, in which water runs between crop or tree rows, penetrating laterally to the roots; the surface-pipe method, in which water flows in movable slip-joint pipes; sprinklers, including large-scale center-pivot and other self-propelled systems; and a variety of water-conserving drip and trickle systems. In many cases irrigation is correlated with drainage

 to avoid soil salinity, leaching, and waterlogging. Irrigation may also involve preliminary clearing, smoothing, and grading of land. Especially in areas of high evaporation rates, intensive irrigation can result in excessive quantities of salts accumulating in the upper layers of the soil as water evaporates from the surface, rendering the soil unfit for crop production.

Since prehistoric times water has been diverted from waterways to fields by ditching. Early improvements for raising water included counterbalanced poles with attached water vessels, and adaptations of the wheel and of a pump called the Archimedes’ screw. The use of canals, dams, weirs, and reservoirs for the distribution, control, and storage of water was probably initiated in ancient Egypt. A system of gently sloping underground tunnels (qanats) to deliver water from a subterranean source to distant areas where it is accessed through shafts was developed in ancient Persia and has been widely used elsewhere. In modern times pumps have facilitated the use of underground as well as surface water, but overuse of water in aquifers can exhaust their usable water. Large-scale 20th-century irrigation projects commonly also include water supply, hydroelectric power, and flood control.

 

Factors affecting the run-off
FACTORS AFFECTING THE RUN-OFF

Factors affecting the run-off

FACTORS AFFECTING THE RUN-OFF The characteristics of the rainfall play an important part in determining the amount of consequent run-off’. The various factors that affect the run-off can be summarise under two heads. Characteristics of precipitation, Characteristics of drainage basin. 1. Characteristics of Precipitation (a) Type of precipitation. Precipitation may be in the form of rain or drizzle. Run-off pattern or the hydrograph of run off is considerably governed by this factor. If precipitation occurs in the form of heavy rain,it will immediately produce bulk of run off (Peak flow of short duration). If precipitation is in the form of a drizzle it will produce run off at a slow and steady rate. (b) Rain intensity. Rain intensity has a lot of effect on the run off. If the intensity of rain increases, the run off increases rapidly. For example, if the intensity is increase four times, the run off…

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MEASUREMENT OF RAINFALL
MEASUREMENT OF RAINFALL

MEASUREMENT OF RAINFALL

MEASUREMENT OF RAINFALL Rainfall is the principal source of all waters. It is expresse as the depth of water in centimetres which falls on a pucca, impermeable levelled surface. The rainfall is measured with help of rain-gauges. Rain-gauges may be automatic or nonautomatic. Govt of India has approved use of non-automatic rain gauges at all the rain-gauge stations. Following are different types of rain-gauges. Simon’s rain-gauge. Weighing bucket rain-gauge. Float type rain-gauge. Tipping bucket rain-gauge. 1. Simon’s Rain-gauge. A typical Simon’s rain gauge is shown in Fig.  It is also known as non-recording type of rain-gauge, as it does not record the rate of rainfall at any moment but only collects rain water. It consists of a funnel fixed at the top of a receiving bottle. The receiving bottle is about 8 to 10 cm in diameter and is encased in the metal casing. This bottle is fixed in the…

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Computation of run-off
Computation of run-off

Computation of run-off

COMPUTATION OF RUN-OFF The Run-off available from a basin can be compute daily, weekly, monthly, or yearly. The following are the methods which can be used for finding out the run-off Using empirical formulae and tables Infiltration characteristics method A rational method, and Unit hydrograph method. All these methods have been explaine separately.  

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Average annual rainfall & index of damp
Average annual rainfall & index of wetness

Average annual rainfall & index of damp

AVERAGE ANNUAL RAINFALL AND INDEX OF WETNESS The amount of rain collect by a rain gauge in 24 hours is know daily rainfall and the amount collect in one year is know annual rainfall. This annual rainfall at a given station should be record over a number of years say 35 to 40 years or so. In India this rainfall cycle period is take about 35 years. When we talk of the rainfall of a given place we generally refer to the average annual rainfall of that place. Thus when we speak of rainfall figures of a particular place, it means that this figure has been averaged over a long period of about 35 years. This is know as normal rainfall. But in any given year the rain may not be equal to this amount. It may be less than this average value or may exceed it. The ratio of…

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FERTILITY OF SOIL
FERTILITY OF SOIL

FERTILITY OF SOIL

FERTILITY OF SOIL A soil is said to be fertile when it contains all the nutrients which essential for growing a healthy crop. Presence of nitrogen, organic materials, and soluble compounds in a soil are the usual fertilizing agents. Physical properties of soil, adequate amount of water and drainability of the soil are such elements which help in making fair utilisation of the nutrients. Fertility of the soil can be maintained by following measures. By spreading all the farm wastes in the field. On disintegration they supply fertilizing agents to the soil. Preparing land by scientific methods. Practicing rotation of crops, and further by introducing leguminous crop in the rotation. By applying suitable chemical fertilizer. By green manure. By adopting measures which prevent soil erosion. By allowing storm dust to be entrapped in freshly ploughed fields. By allowing silt of water deposit in fields.  By applying composite manure to the…

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Assessment of irrigation water
ASSESSMENT OF IRRIGATION WATER

Assessment of irrigation water

ASSESSMENT OF IRRIGATION WATER Irrigation water supplie to the farmers through canals, or reservoirs is at the expense of the government. Farmers are charge suitably by the government for having used this facility. The fixation of such charge is known,the assessment of irrigation water. The following are the reasons for which farmers are charge: To recover the cost of the project due to which this facility has been possible. To collect revenue so that it may augment the state resources.  collect the maintenance cost of the project. To put some restrictions on farmers against careless and uneconomical use of water.

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Internal distribution of water
INTERNAL DISTRIBUTION OF WATER

Internal distribution of water

INTERNAL DISTRIBUTION OF WATER Internal distribution of water amongst the farmers is carriedout on Wara band basis. Wara bandi is enforce by Executive Engineer of Irrigation Department. Under this system whole of the area under the charge of a particular outlet is to be supplie water once in a week. Each farmer is allott fixedhours of irrigation water in a fixed day of the week. Hours of irrigation to each farmer, are allotte in direct proportion to the irrigable area held by him. Any farmer flouting the wara bandi or forcibly taking water of any other farmer, is suitably deal court of law.

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Methods of taking unauthorised irrigation water from canal
METHODS OF TAKING UNAUTHORISED IRRIGATION WATER FROM CANAL

Methods of taking unauthorised irrigation water from canal

METHODS OF TAKING UNAUTHORISED IRRIGATION WATER FROM CANAL Following are some methods of taking unauthorised irrigation water from the canal: ..By making deliberate cuts in canals and flooding the adjoining area. This mischief is mostly those farmers whose land lies in the vicinity of the canal alignment. Tempering the outlets. Fixing wooden planks touching the free sprout of water emanating from the outlet. . By adopting to syphons. All these mischiefs should be challenged in court of law and guilty persons should be severely punished.  

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Some important terms as applied crops
Some important terms as applied to crops

Some important terms as applied crops

SOME IMPORTANT TERMS AS APPLIED TO CROPS There are some important terms as applied to crops: Dry crops. These crops grown without irrigation. Wet crops. These crops grown with irrigation water. Crop ratio. It is the ratio of the areas irrigated in Rabi and Kharif seasons. \[Crop ratio= \frac{Area irrigated during Rabi season}{Area irrigated during Kharif season}\] Water requirements of Kharif crops is much more than those of rabi crops. The crop ratio in two seasons  such that water requirements of crops e from the canal throughout the year. 4. Overlap Allowance. Sometimes, it so happens that crop of previous crop season has not yet been harvest and the crop of coming season has also been sown. Under such circumstances irrigation water will have to be providedfor some time to both the crops. The time period in days for which crop of previous season overlaps the new sown crop is…

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Hydrology & Hydrological Cycle
HYDROLOGY AND HYDROLOGICAL CYCLE

Hydrology & Hydrological Cycle

HYDROLOGY AND HYDROLOGICAL CYCLE Hydrology. It is a science which concerns with the occurrence, distribution and movement of water. It may also be define the science that deals with the depletion and replenishment of water sources. When we say movement of water, it includes movement of water in atmosphere, on the surface of the earth, and below the surface of the earth. In atmosphere, water is present in form of vapours. On surface of earth it is in form of rivers, lakes, ponds and snow etc. Below the earth surface it is present in form of moist soils. The water occurring below the surface of the earth is known as ground water. Ground water occupies the voids of the soil. Hydrological Cycle. Except for the deep ground water, the total water supply of the earth remains in constant circulation between earth and atmosphere. This water again falls over the earth…

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