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Transcript of irrigation
It is an waterway construction to convey water for irrigation.
In Pakistan, canal irrigation system is
related to five big rivers.
The water in the rivers flow slowly, there
fore water in the canals also flow slowly,
so it is easy to irrigate in the fieldS.
There are three types of canals in Pakistan i.e
Perennial canal 5.4.1; describe different methods of irrigation used in Pakistan
canal irrigation: karez, inundation and perenial canal
lift irrigation: persian wheel and tube well
dams: mangla, tarbela and warsak
barrages: guddu, sukkur and suleiman ki;
5.4.2; explain the importance of irrigation in the perspective of Pakistan; Irrigation;
It is the artificial supply of water to the land to encourage plant growth.
In this system water is supplied from natural water resources to those parts where the crops are grown.
There are four methods of irrigation used in Pakistan
1. Canal Irrigation
2. Lift Irrigation
4. Barrages 5.4.3; discuss the causes of water logging and salinity;
5.4.4; explain ways through which the land damaged by water logging and salinity can be restored;
5.4.5; evaluate how agricultural practice and water management can be improved to prevent water logging and salinity from happening IRRIGATION 1. Karez:
It is a horizontal underground canal in the foothills
that brings underground water to the surface.
By building this canal underground, evaporation is
This is an old system practiced only in Balochistan where
water is scarce and evaporation rate is high. 2. Inundation:
The canals which flow through rainy seasons especially during floods when water flow is high are called inundation canals.
Most of the canals flowing in Pakistan are inundation canals. 3. Perenial Canals:
The canals which are constructed after construction of dams on rivers.
These canals flow through out the year.
They are used for growth of rabi (winter) and Kharif (summer) crops.
Mostly found in Sindh, Punjab, and some areas of Khyber PakhtunKhawa.
Need dams and barrrages for storage of water. TYPES OF CANAL IRRIGATION Lift Irrigation:
It is a method of irrigation in which water isn't transported by natural flow but is lifted with pumps or other means.
There are different methods used for lift irrigation like Persian wheel and Tube well.
Earlier the water was lifted by hand in a bucket attached to a rope but later shaduf was introduced.
Shaduf consisits of a bucket suspended by a rope from one end of a rope and a weight placed on other end. TYPES OF LIFT IRRIGATION Persian Wheel:
The system is used to pull the water from wells for continouos supply of water to the lands.
This helps to irrigate a comparitively larger area operated by bull.
Mostly found in Sindh, Punjab and Khyber PakhtunKhwa. Tube well:
These have diesel or electrically operated pumps that raise water from the depth of 92 metres to irrigate farms of more than 1000 hectares.
It also help in protecting land from water logging and salinity by keeping the water level balanced. Dams:
It is barrier that impounds water or underground stream.
It is a misconception that dams deplete rivers and reduce their flow actually store and save surplus flood waters and add these to the flow of the rivers. Dams are built to overcome shortage of water, and not to increase it. DAMS IN PAKISTAN Tarbela Dam:
Tarbela Dam is a large dam on the Indus River in Pakistan, which is located about 50km North West of Islamabad.
This dam was designed to store water from the Indus River for the purpose of irrigation, flood control and for the generation of hydro-electric power.
Its height is about 143meters and 2743meters wide.
Tarbela Dam is a major source of Pakistan’s total hydro-electric capacity. Mangla Dam:
Mangla Dam is constructed about 100miles south-east of Islamabad, the capital of Pakistan.
It is the 12th largest dam of the world..
. The length of the Dam is 10,300ft (3140meters) and its height is 454ft (138meters). STUDENT LEARNING OUTCOMES (SLOs) Warsak Dam:
In Pakistan, Warsak dam is located on Kabul river approximately 2019metres north west of city Peshawar in khyber pakhtunkhwa.
It has created long lake upstream of the dam, which is the favourite picnic spot. Barrages:
Barrages in Pakistan are very long structures used for irrigation and flood control.
It's size and capacity depends on the width of the river.
Barrages can be made even in flat areas as well at mountainous region. THREE MAIN BARRAGES IN PAKISTAN Guddu Barrage:
It is on the river Indus near Kashmore in the province of Sindh.
It controls water flow for irrigation and flood control purposes. Sukkur Barrage:
It is on River Indus near Sukkur in province Sindh.
It is the largest barrage in the world.
It is 1440.18 metres long. Suleiman Kirthar Hills:
Suleiman range is located towards left of river Indus.
It rises to the average height of 1500 and it's higest peak is Takht-e-sulaiman.
Limestone and sandstone are main minerals found in this region.
Futher south it meets the Kirthar Range,which is backed by the pab river. Imporatnce Of Irrigation In Pakistan
Irrigation helps in improving yeilds.
Removes dryness of land and makes it fertile.
.We have little rainfall therefore we get the help of irrigation in preparing our crops.
The progress of our country depends upon the means of irrigation and their progress.
To regulate the water supply throughout the year the water is stored by constructing barrages,dams. Waterlogging:
The rise of water-table to the surface level is called waterlogging.
The appearance of salty patches on the surface is called salinity.
It is the sum of evaporation and transpiration.
(Evaporation is the movement of water to the air from sources such as the soil, waterbodies.
Transpiration is the movement of water within a plant and the subsequent loss of water as vapor through stomata in its leaves). How The Saline And Waterlogged Land Can Be Restored....??????
Excess of calcium in the form of powdered gypsum rock is added to the soils, which restore the soil structure, and the salts can then be leached down.
Rice husk can be used to mitigate saline soil or land.
Saline ones should never be left fallow for extended periods.
Open surface run-off drains should be constructed so that under ground water from the affected areas gets accumulate in these drains.
Saline soils may be improved by leaching the salts from the root zone. Leaching:
Leaching is the process in which extra water is added to a field and allowed to soak through the soil and drain away underground. Prevention
The system should permit a small fraction of the irrigation water to be drained and discharged out of the irrigation project.
Canal closures, lowering of canal water levels can be used for prevention.
Tube wells and drains can be installed which suck out water at a faster rate of that subsoils. Causes Of Water Logging And salinity
Due to the availablity of Perennial canal water is regularly supplied to the fields through out the year which is more than that which can be the lost of evapotranspiration which results in rising up of water table.
They are caused by natural disasters (flood, excess rainfalletc).
By poor drainage system
.Due to poor water and agricultural management.
They can also be concentrated in soils due to human activity, for example the use of potassium as fertilizer, which can form sylvite, a naturally occurring salt. Thank You Special Thanks To
Presented by group#4
Rubab Concluding Activity Food For Thought
Q, What is meant by irrigation?
Q, List down the methods of irrigation used in Pakistan and also describe them.
Q, Describe the importance of irrigation in Pakistan.
Q,Define water logging and salinity.
Q, List atleast 5 major causes of water logging and salinity.
Q,How decrease in irrigation rate and land damage occurs through water logging and salinity?
Q,Evaluate how agricultural practice and water management can be improved to prevent water logging and salinity?