1. WATER RESOURCES THE IMPORTANCE OF IRRIGATION MEANS OF IRRIGATION – WELLS/ CANALS/ TANKS/ TUBEWELLS/ DAMS / MULTIPURPOSE PROJECTS NEED FOR CONSERVATION OF WATER RAIN WATER HARVESTING AND ITS IMPORTANCE

2. NEED & IMPORTANCE OF IRRIGATION VARIABILITY 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

3. 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

4. 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.

5. TYPES OF WELLS UNLINED 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 TUBEWELLS DEEPER 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.

6. 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.

7. 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

8. 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.

9. CANAL IRRIGATION IMPORTANT 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 INDIA REASONS 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

10. 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.

11. 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.

12. WAYS TO IMPROVE CANAL IRRIGATION CONSTRUCTION BY PRIVATE – PUBLIC CONTRACTS GRID SYSTEM SHOULD BE ENCOURAGED SUBSIDY SHOULD BE GIVEN TO SMALL FARMERS

13. TANK IRRIGATION COMMON 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.

14. 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.

15. 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.

16. DRIP IRRIGATION IT 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 LOSS LOCALISED APPLICATION AND REDUCED LEACHING. HIGH EFFICIENCY IN WATER APPLICATION. LEVELLING OF THE FIELD NOT REQUIRED.