GATE Civil Engineering (CE) 2027 Test: Irrigation Techniques & Water Requirement

Initially, when supply increases plants will get adequate water depth for their growth but ager certain limit water will cause water logging thus, degrading the growth of plants.

Concept:
Duty: 

• It is the number of hectares of land irrigated for full growth of a given crop by a supply of 1 cumec of water continuously during the entire base period of that crop.
• Duty is the area that can be irrigated by the discharge of 1 cumec of water.
• At the head of the canal, there are numerous losses to occur later which requires more amount of water to irrigate a particular field. However, if considered on the field, all losses have already occurred and a lesser amount of water is required to irrigate the same considered area.
• Duty of water changes from place to place, it will be maximum at the field and minimum at the head of the canal.

Crop consumptive water use is the amount of water transpired during plant growth plus what evaporates from the soil surface and foliage in the crop area. In short, evapotranspiration needs of cropped area plus the minor quantity required in plant metabolism. 

Permanent wilting point is the point beyond which the roots of plant cannot access water. It is the hygroscopic water. 
Useful soil moisture for plant growth is capillary water.

Drip irrigation is used in areas with severe water scarcity because it delivers water directly to the plant roots. This method:

• Minimises evaporation
• Reduces runoff
• Conserves water efficiently

The efficiency of water conveyance primarily depends on factors such as the geometry of the conveyance system, the nature of the boundary of the conveyance system, and the method of application of water. These factors directly influence the flow characteristics, friction losses, and overall effectiveness of water delivery.

Climatic conditions, while they can affect evaporation rates and other environmental factors, do not directly impact the efficiency of the conveyance system itself.

Therefore, the efficiency of water conveyance does not depend upon: Climatic conditions

The soil moisture tension at the permanent wilting point is usually around 15 atmospheres or -15 bars. This is the point at which plants can no longer extract enough water to meet their needs and remain wilted until water is added to the soil. 

• Soil: Different soil types have different water holding capacities. Sandy soils require more frequent irrigation compared to clay soils.


• Crop: Different crops have different water requirements. Some crops may need frequent irrigation while others can survive with less water.


• Climate: The climate of a region plays a crucial role in determining irrigation frequency. Regions with high temperatures and low humidity may require more frequent irrigation.

• Soil type determines the water holding capacity and drainage capabilities, which directly impact irrigation frequency.


• Crop water requirements vary based on factors like growth stage, root depth, and transpiration rates, influencing the frequency of irrigation.


• Climate conditions such as temperature, humidity, and wind speed affect evapotranspiration rates, which in turn determine irrigation needs.

Considering the interplay of soil, crop, and climate factors is essential in determining the most suitable irrigation frequency for optimal crop growth and water use efficiency.