Surface Irrigation
In this method water flows and spreads over the surface of the land. Varied quantities of water are allowed on the fields at different times. Hence, flow of water under surface irrigation comes under unsteady flow. As a result it is very difficult to understand the hydraulics of surface irrigation. However, suitable and efficient surface irrigation method can be adopted after taking into consideration various factors which are involved in the hydraulics of surface irrigation.
Overhead or Sprinkler Irrigation
In this method an attempt is made to simulate natural rainfall. Irrigation water is applied to the land in the form of a spray. This method is also known as sprinkler irrigation, Sprinklers can be used on all soil types of any topography. According to the equipment and procedure used the sprinkler method may fall in fixed type or portable type.
Drip or Trickle Irrigation
It is a latest advancement over other methods. The name of the method itself implies water saving. In this method irrigation water is conveyed on the surface in 12 to 16 mm diameter tubing’s fed from large feeder pipes. The water is allowed to drip or trickle slowly through the nozzle or orifices at practically zero pressure. In this way the soil in the root-zone of crops is constantly kept wet.
By using this method crops can be grown successfully over the saline lands also. This method has been found to be of great value in reclaiming and developing desert and arid areas. The main drawback of this method is its high cost. But with growing realisation of the value of water this method has been introduced in other countries of the world particularly in desert areas. The method is still in initial stages of development in our country.