WATER RESOURCESTHE IMPORTANCE OF IRRIGATIONMEANS OF IRRIGATION – WELLS/ CANALS/ TANKS/ TUBEWELLS/ DAMS / MULTIPURPOSE PROJECTSNEED FOR CONSERVATION OF WATERRAIN WATER HARVESTING AND ITS IMPORTANCE

NEED & IMPORTANCE OF IRRIGATIONVARIABILITY IN RAINFALL – VARIATION IN QUANTITY , INCIDENCE & DURATION

UNEQUAL DISTRIBUTION OF RAINFALL – eg. Windward and leeward side

MEETING CROP REQUIREMENTS AND SOIL NEEDS – eg., rice, sugarcane need more water & need irrigation even in areas of heavy rain./ sandy soil requires frequent water supply than alluvial or black soil.

TO MAXIMISE PRODUCTION – to facilitate double and triple cropping.

MANY INDIAN RIVERS ARE NOT PERENNIAL

METHODS OF IRRIGATION• PRIMITIVE METHODS

• WELLS / TANKS

• USED TO IRRIGATE SMALL AREA

• DO NOT NEED MODERN MACHINERY TO OPERATE

• MODERN METHODS

• CANALS AND TUBEWELLS

• USED TO IRRIGATE LARGE AREA

• NEED MODERN MACHINERY TO OPERATE

SUITABLE CONDITIONS FOR WELL IRRIGATION –

SUITABLE CONDITIONS FOR WELL IRRIGATION –

WATER TABLE SHOULD BE HIGH

CHEAP POWER SHOULD BE AVAILABLE FOR LIFTING WATER

AREA MUST HAVE PREFERABLY ALLUVIAL SOIL

THERE SHOULD BE SUFFICIENT AMOUNT OF GROUND WATER.

TYPES OF WELLSUNLINED WELLS

KUCCHHA WELLS / NOT LINED WITH BRICKS OR STONES

DUG NEAR FIELDS

CONSTRUCTED WHERE WATER TABLE IS HIGH [ 15 m]

EASY AND CHEAP TO DIG

LINED WELLS

PUCCA WELLS/ LINED WITH BRICKS OR STONES

TUBEWELLSDEEPER WELL

GENERALLY OVER 15 m DEEP

WATER IS LIFTED WITH THE HELP OF A PUMPING SET OPERATED BY AN ELECTRIC MOTOR OR DIESEL ENGINE.

REQUIRES SOME GEOGRAPHICAL CONDITIONS FAVOURING ITS INSTALLATION. – SUFFICIENT GROUND WATER / REGULAR SUPPLY OF CHEAP ELECTRICITY / SOIL SHOULD BE FERTILE SO AS TO RECOVER THE COST OF OPERATING THE TUBEWELL.

ADVANTAGES & DISADVANTAGES OF WELL IRRIGATION

• ADVANTAGES

• SIMPLEST SOURCE OF IRRIGATION• CHEAPEST SOURCE• CAN BE DUG AT ANY CONVENIENT PLACE• CAN BE USED WHEN NECESSITY ARISES

• DISADVANTAGES / DRAWBACKS

• MAY RUN DRY IF NOT DEEP ENOUGH• CAN IRRIGATE ONLY A

SMALL AREA• PREFERRED TO BE DUG

WHERE WATER TABLE IS HIGH• WATER UNSUITABLE FOR

IRRIGATION AS IT CONTAINS HIGH PERCENTAGE OF MINERALS.

REASONS FOR WELL IRRIGATION BEING POPULAR IN NORTH INDIA

# THE WATER TABLE IS HIGH IN THE GANGA PLAIN# SOFT ALLUVIAL SOIL MAKES IT EASY TO DIG WELLS.# ADEQUATE RAINFALL REPLENISHES THE GROUND WATER.# AVAILABILITY OF CHEAP HYDRO ELECTRICITY

ADVANTAGES & DISADVANTAGES OF TUBE WELLS

• ADVANTAGES

• CAN IRRIGATE LARGE AREAS.• RELIABLE SOURCE OF

IRRIGATION.• CAN IRRIGATE FIELDS

THROUGHOUT THE YEAR.• MAJOR ROLE PLAYED IN

GREEN REVOLUTION• CROPS CAN BE GROWN IN

AREAS WITH LOW RAINFALL WITH HELP OF TUBE WELLS. [ RICE CULTIVATION IN PUNJAB]

• DISADVANTAGES

• NEED CHEAP POWER WHICH IS NOT EASILY AVAILABLE IN MOST STATES.• GROUND WATER EXTRACTION VERY EXPENSIVE FOR FARMERS.• OVERUSE OF GROUND WATER HAS LOWERED THE WATER TABLE IN MANY STATES.

CANAL IRRIGATIONIMPORTANT FACTS –# ONE OF THE MOST IMPORTANT SOURCES OF IRRIGATION IN INDIA.# OVER 40 PERCENT OF THE TOTAL IRRIGATED AREA DEPENDS UPON CANALS.# CANAL IRRIGATION IS MORE WIDESPREAD IN NORTHERN INDIAREASONS FOR THIS –

~ LOW RELIEF AREA~ DEEP FERTILE SOIL THAT HELPS RECOVER COST OF CANAL CONSTRUCTION.~ EVEN SURFACE MAKING DIGGING EASY~ PERENNIAL FLOW OF RIVERS ORIGINATING FROM HIMALAYAS~ TWO TYPES OF CANALS – INUNDATION & PERENNIAL CANALS

PERENNIAL & INUNDATION CANALS• PERENNIAL CANALS

• FLOW THROUGHOUT THE YEAR.

• CONSTRUCTED BY PUTTING A BARRAGE ACROSS THE RIVER.

• BARRAGE HELPS IN MAINTAINING A HIGH LEVEL OF WATER ON UPSTREAM SIDE.

• IRRIGATE LARGE AREAS AS THE CANALS DRAW WATER THROUGHOUT THE YEAR.

• INUNDATION CANALS

• DRAWN DIRECTLY FROM RIVERS WITHOUT CONSTRUCTING BARRAGES.

• PROVIDE IRRIGATION MOSTLY DURING RAINY SEASON WHEN RIVERS ARE FLOODED.

• WHEN RIVERS SUBSIDE THE WATER LEVEL FALLS BELOW THE CANAL HEADS AND THE CANALS DRY UP.

ADVANTAGES & DISADVANTAGES OF CANAL IRRIGATION

• ADVANTAGES

• CHEAPEST SOURCE FOR FARMERS AS ARE NOMINAL IN COST• WATER CAN BE TRANSPORTED FROM SURPLUS AREA TO DEFICIENT AREA THROUGH CANALS.[ INDIRA GANDHI CANAL / RAJASTHAN]

• DISADVANTAGES• CHANGING CROP PATTERN• ENVIRONMENTAL

DEGRADATION AND CREATION OF WASTELANDS DUE TO EXCESSIVE IRRIGATION & INTENSIFICATION OF AGRICULTURE.• WATER LOGGING PROBLEMS

DUE TO EXCESSIVE IRRIGATION, SEEPAGE & POOR DRAINAGE.• INCREASE IN SALINITY IN

SOME REGIONS DUE TO RISE IN WATER TABLE LEADING TO SUBMERGENCE OF LAND.

WAYS TO IMPROVE CANAL IRRIGATION

CONSTRUCTION BY PRIVATE – PUBLIC CONTRACTS

GRID SYSTEM SHOULD BE ENCOURAGED

SUBSIDY SHOULD BE GIVEN TO SMALL FARMERS

TANK IRRIGATIONCOMMON FACTS –

TANKS ARE FOR WATER STORAGE DEVELOPED BY CONSTRUCTING A SMALL BUND OF EARTH OR STONES BUILT ACROSS A STREAM.MOST TANKS ARE SMALL SIZED AND BUILT BY INDIVIDUAL FARMERS OR GROUPS OF FARMERS.TANK IRRIGATED AREA IS CONSTANTLY REDUCING DUE TO INCREASE IN CANAL AND WELL IRRIGATION.TANK IRRIGATION IS WIDELY PREVALENT IN TAMIL NADU, ANDHRA PRADESH, KARNATAKA AND ORISSA.TANK IRRIGATION MORE IMPORTANT IN THE DECCAN PLATEAU.

REASONS FOR TANK IRRIGATION POPULARITY IN DECCAN PLATEAU

UNDULATING TERRAIN OF DECCAN PLATEAU MADE OF HARD ROCKS MAKES IT DIFFICULT TO DIG CANALS & WELLS.

VERY LITTLE PERCOLATION OF RAIN WATER & HENCE GROUND WATER IS NOT AVAILABLE IN LARGE QUANTITY.

MOST OF THE REGION’S RIVERS ARE SEASONAL & DRY UP IN SUMMER. THEREFORE THEY CANNOT SUPPLY WATER TO CANALS THROUGHOUT THE YEAR.

SEVERAL STREAMS IN THIS REGION OVERFLOW WITH WATER DURING RAINY SEASON. THE ONLY WAY TO MAKE BEST USE OF THIS IS TO IMPOUND IT BY CONSTRUCTING BUNDS AND BUILDING TANKS.THE SCATTERED NATURE OF POPULATION AND AGRICULTURAL FIELDS ALSO FAVOUR TANK IRRIGATION.TANKS ARE EASIER AND CHEAPER TO BUILD.

ADVANTAGES AND DRAWBACKS OF TANK IRRIGATION

• ADVANTAGES

• EASY AND ECONOMICAL TO CONSTRUCT.

• ALLOW MONSOON WATER TO BE STORED AND USED LATER WHEN NEEDED.

• HELP IN RAISING UNDERGROUND WATER LEVEL.

• DRAWBACKS

• SILTING OF THE TANK BED IS SERIOUS PROBLEM.• ARE NON PERENNIAL SOURCE OF

IRRIGATION. DRY UP IN DRY SEASON AND FAIL TO PROVIDE IRRIGATION WHEN MOST NEEDED.

• THEY USE UP LARGE AREAS OF CULTIVABLE LAND.

• MOST OF THE WATER IS EVAPORATED FROM THE LARGE EXPAANSE OF SHALLOW WATER.

DRIP IRRIGATIONIT IS A SYSTEM OF CROP IRRIGATION INVOLVING THE CONTROLLED DELIVERY OF WATER DIRECTLY TO INDIVIDUAL PLANTS THROUGH A NETWORK OF TUBES AND PIPES.

ADVANTAGES :MINIMAL FERTILIZER & MINERAL LOSSLOCALISED APPLICATION AND REDUCED LEACHING.HIGH EFFICIENCY IN WATER APPLICATION.

LEVELLING OF THE FIELD NOT REQUIRED.