Automation of Irrigation Methods – Next Frontier for Irrigation Management in India
India now has about 45 million ha area under irrigation. About 39%% of this area is irrigated by surface water and rest by ground water. The irrigation method adopted is invariably surface irrigation with only 3% area irrigated area under pressurized irrigation Surface systems are simple, have low energy consumption and require comparatively low initial capital. However, they are often associated with a high labour requirement and low water use efficiency The labour cost increases exorbitantly for night irrigation especially for winter crop. Night irrigation becomes necessary in surface water based sources as we can not waste water during night as well as with warabandi night irrigation is necessity. In tubewell irrigation, availability of electricity during night makes it a compulsion to do night irrigation. Rising labour costs in rural areas is making night irrigation less monitored which further reduces already low irrigation efficiency. Over irrigation also leads to nitrogen leaching and poor productivity. Continuous reduction in per capita water availability and competition for scarce water resources have generated have further complicated situation. The per capita water availability of India is now just 1471 m3 ( as per new population estimates) which makes it a water stressed nation. It has been projected that population and income growth will boost the water demand in future to meet food production, domestic and industrial requirements. The projected total water demand of 1447 BCM in 2050 will outstrip the present level of utilizable water resources (1123 BCM) out of which 1074 BCM will be for agriculture alone. Since the total projected demand will be 324 BCM more than the present level of utilizable water resources, the challenge will be to produce more from less water by efficient use of utilizable water resources in irrigated areas. This means enhancing irrigation efficiency of our irrigation methods.
Automation is one means of ameliorating the problems of high labour requirement and low water use efficiency of surface systems. It refers to the operation of the system with no or just a minimum of manual intervention beside the surveillance. However, the spatial and temporal variability of the soil infiltration characteristics means that each irrigation behaves differently and are therefore difficult to standardize and automate. A lot of work has been and is being done in developed countries. In Australia they are trying integration of on-farm and channel control technologies which may become a real possibility in the near future. Typical bay and basin systems have head ditches at one edge of the field which are fed from open channels. Initial attempts to automate these systems appear to have focused on controlling the inlets or gates that supply water to the field. In California, automation of surface irrigation systems makes decisions on when to turn the water off based on a number of variables (flow rate, advance rate,
crop height, etc). This decision is based on accurate and real‐time data (flow rate, advance rate, automated gates, ETc , and other variables). The system is optimized by considering process of all flood irrigation variables to improve on-farm irrigation efficiency. It adjust irrigation time to allow for changing crop roughness (height and density of the crop) by adjusting border/set length to allow for variable soil type across the field adjusting flow rate to an irrigation set (one or more border/land) to improve efficiency. To achieve this computer simulation models are needed for accurate measurements during irrigation events (flow rate and advance rate).
Unfortunately very little work has been done under Indian conditions. The systems developed in European countries or USA or Australia cannot be used in Indian conditions as there is no commonality in field size. However the principle used will have to remain same. We will have to innovate to develop systems which are rugged, not much expensive, can run on batteries etc. To start with it can be used for dry season crops. The irrigation methods which can be automated are furrow (potato, sugarcane, vegetables etc) and border irrigation (wheat, cotton). However automation can be done only on well laid furrows or borders (Plate 1 & 3). Very small furrows as shown in plate 2 cannot be automated. Actually it was discussion with these farmers who had very good irrigation systems laid in their fields to think further to increase efficiency and reduce labour woes.
Now question is how to proceed to design automation system for surface irrigation methods for our Indian conditions. Presently four types of systems are being used for automation. (i) Time based systems; (ii) Volume based systems; (iii) Open loop system; (iv) Close loop system. Based on my experience, I think Time Based Systems will be best suitable for our conditions. We can design programmable solenoid valves to open and close after a specified time. The time period will be a function of size of stream, length of furrow, number of furrows to be served by that feeder channel, soil infiltration rate and crop stage in case of borders. Thus an electronic device can be designed which can program a chip based card which can be fitted in solenoid valve. The pattern can be same as they program the swipe card keys used in hotels. It will also have to contain a clock to fix up both time and duration.
The second challenge will be to design a system which can be fitted in an open channel and pipeline. For open channel, it will two way: one to open towards feeder channel connecting to different furrows/border and another blocking flow forward in main channel. It can be a steel right angle system containing mechanism for opening and closing the valve. Although we think that pipeline cannot be used for conveyance in canal commands, but for slight undulating topography, a large diameter pipeline can be used for conveyance. During my work on designing canal based hybrid irrigation system, I designed a 140 mm diameter pipeline which had open channel flow on a slope of 0.9%, and it functioned very effectively for conveyance of water for rice irrigation during kharif season (plate 4).
A question may arise about the cost and affordability by the farmers, but the benefits will outweigh the cost. Automation will lead to saving in labour cost (about 65%) and water use by 5-10%. With rising labour cost, cost of pumping and focus on increasing irrigation efficiency, automation is new frontier of irrigation management in India.
Plate 1 Well laid furrows for potato (farmer’s field of Faizabad U.P.)
Plate 2: Well laid small length furrows in a small farmer’s field (Faizabad, U.P.)
Plate 3: Well laid borders for wheat in farmer’s field (Faizabad, U.P.)
Plate 4: Irrigation by pipe in Khaif rice in a canal command of Odisha (Overland slope 0.9%).