MOTHER THERESA INST OF ENGG&TECH IRRIGATION OF WATER (DUTY&DELTA) PRESENTED BY K.S.CHITTIBABU III-B.TECH(CIVIL) MTIET,PALAMANER

Definition: The artificial method to supplying the water to soil IRRIGATION Definition: The artificial method to supplying the water to soil

DUTY: DELTA: DUTY OF WATER AND DELTA 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. DELTA: 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( )

RELATION BETWEEN DUTY AND DELTA

FACTORS AFFECTING DUTY OF WATER Type of crop. Climatic condition of the area. System of irrigation. Method of irrigation Quality of irrigation water. Method of cultivation. Time of irrigation and frequency of cultivation. Type of soil and sub-soil of the irrigated field. Type of soil and sub-soil of the area through which canal passes. Canal conditions. Methods of assessment of irrigation water rate.

12. Skill of the cultivator. 13. Topography of land. 14 12. Skill of the cultivator. 13. Topography of land. 14. Base period of crop.

1.TYPE OF CROP Different crop require varying quantities of water and therefore duty of water varies from crop to crop. The crops which require large quantity of water have lower duty water than for the crops which requires less quantity of water.

2.CLIMATIC CONDITION OF THE AREA The water requirement of a crop varies with the climatic condition of the area and hence it also affects the duty of water. The climatic conditions which affects the duty of water are temperature, wind velocity, Humidity, Rainfall.

TEMPARATURE : IF the temperature is high, the loss of water due to evapotranspiration will be more and hence the duty of water will be less. WIND VELOCITY : Higher wind velocity will result in greater loss of water due to evapotranspiration and hence lower duty of water. HUMIDITY : The other hand higher is the humidity higher will be the duty of water since the loss of water due to evapotranspiration will be less. RAINFALL : If during the base period of a crop there is rainfall then since less quantity of irrigation water will be required to be supplied the duty of water will increase.

3.SYSTEM OF IRRIGATION In the perennial irrigation system the soil of the irrigated area remains continuously wet hence less quantity of water is required for initial saturation of the soil.

4.METHODS OF IRRIGATION The method of irrigation or the mode of applying water to the fields affects the duty of water because the water application efficiency varies with the method of irrigation.

5.QUALITY OF IRRIGATION WATER If the irrigation water contains an appreciable amount of harmful salts and alkalis dissolved in it then it is required to be applied in large quantity so that the salts are leached off.

6.METHODS OF CULTIVATION If the land is properly ploughed upto the required depth and made quite loose before irrigating. This will reduce the number of waterings and hence result in a higher duty of water.

7.TIME OF IRRIGATION AND FREQUENCY OF CULTIVATION In the initial stages the land to be cultivated may not be properly levelled and hence more than the required quantity of water may be applied, which will result in a lower duty of water.

8.TYPE OF SOIL AND SUB-SOIL OF THE IRRIGATED FIELD If the soil and sub-soil of the field to be irrigated is coarse grained then due to high percolation loss the duty of water will be low.

9.TYPE OF SOIL AND SUB-SOIL OF THE AREA THROUGH WHICH CANAL PASSES If the canal is unlined and it passes through coarse grained soil then since there will be greater percolation loss the duty of water will be low.

10.CANAL CONDITIONS In an earthen canal, the percolation loss will be high which will result in a low duty of water. The canals with good maintenance will have a higher duty of water than those having poor maintenance.

11.METHODS OF ASSESSMENT OF IRRIGATION WATER The assessment of irrigation water on volumetric basis prevents wastage of water and irrigation by the farmers, thus leading to economy of water and a higher duty of water.

12.SKILL OF CULTIVATOR The judicious use of water by the cultivators can save large quantity of water, which can be used to irrigate more area of the land thus resulting in a higher duty of water.

13.TOPOGRAPHY OF LAND If the land to irrigated is properly levelled then uniform application of water will be possible which will result in economical use of water and hence a higher duty of water.

14.BASE PERIOD OF CROP In general when the base period of a crop is long, more water may be required thus resulting in a lower duty of water.

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