The Hindu : `Efficiency of irrigation projects only 40 p.c.'

Online edition of India's National Newspaper
Friday, Feb 07, 2003

Southern States

Southern States - Kerala

`Efficiency of irrigation projects only 40 p.c.'

By G. Prabhakaran

PALAKKAD FEB. 6. A recent study conducted by the Kerala Agricultural University(KAU), assisted by the Indian Council of Agriculture Research (ICAR), on the "irrigation and allied aspects in Palakkad district'' found that all the eight irrigation projects were functioning at half the designed efficiency.

While the designed efficiency of irrigation conveyance systems is 87.5 per cent the actual efficiency ranges from 40 to 60 per cent only. The poor maintenance of irrigation canals increases the conveyance losses and the silting of the dams brought down the carrying capacity affecting the efficiency of the whole project, the study found.

Of the 15 completed irrigation projects of Kerala, eight are in Palakkad. "The present efficiency of these projects vary from 40 to 63 per cent only.'' Hence, though the designed transmission loss is 12.5 per cent and the efficiency 87.5 per cent, the efficiency of the projects is currently as low as 40 per cent,'' the study by a KAU Sub Centre team at Vadakkenchery headed by I. Johnkutty, Associate Professor (Agronomy), said in their report last month.

The Malampuzha dam, which is caught currently in a controversy over use of its water for industrial purposes, constructed across a tributary of the Bharathapuzha, and a network of canals system to irrigate 21,349 hectares, was designed to have a transmission loss of only 12.5 per cent. But it has been found that the present transmission loss is of 40 per cent. Thus, the efficiency of the project is only 60 per cent as against the designed 87.5 per cent.

As per the original scheme the project had been intended for both `virippu' and `mundakan'. However, the present pattern is to let out water for irrigation from October 20 to January 30. From the data on the average release for the past 10 years, it is clear that the quantity of water available for irrigation during `mundakan' season comes to 138.94 mm. Considering the irrigation efficiency as 60 per cent, the gross irrigation requirements for the ayacut of 22515 ha., at 5 cm depth comes to 18.76 mm. That is, it would be possible to provide seven irrigations during the season. If the `virippu' is dry-sown fully and the `mundakan' completed by February middle, it would be possible to utilise 153 mm of water, by which eight irrigations could be provided. That is, on an average two irrigations per month. The cropping pattern must be planned to get more water during mundakan and to utilise it more efficiently, the study said.

A study on the Mangalam project consisting of a dam across the Cherukunnu river, a tributary of the Mangalam river, which joins the Gayathri and then the Bharathapuzha, found that the transmission loss was 40 per cent as against the designed 12.5 per cent.

The Pothundy project constructed on the Ayalur river, a sub-tributary of Gayathripuzha of the Bharathapuzha, the designed transmission loss was 16.25 per cent but the present loss was more than double as it stood at 37 per cent.

The study on the Chitturpuzha project which works on the inter-State Parambikulam Aliyar Project Water (PAP) found that the "seepage losses are around 47 per cent. Hence, the average conveyance efficiency is 53 per cent only. The overall efficiency of the distribution system is only 40 per cent."

The study also found that "the water released to Kerala is often less than that of the assured quantity.''

The major problem in irrigation management found by the study are that large quantity of water is lost during transmission mainly due to poor maintenance of the canal systems. Transmission of water from source to the field and water application methods within the fields is the two major components which decides the water use efficiency in irrigation agriculture. As such, an efficient conveyance system and minimising the losses of water applied to field will improve irrigation efficiency.

The study said that, "A comparison of irrigation facilities in Palakkad district with that of the State show that the district is enjoying about one-fifth of the irrigation facilities of Kerala. Of the total net area cultivated (all crops) in the district, 35.62 per cent is irrigated. This is almost equal to the national average (38.61 per cent), and more than double that of the State average (15.73 per cent). A major share of irrigation goes to rice as indicated by the fact that, of the total net irrigated area of all crops, 67.24 per cent is accounted by rice, while this is only 32.01 per cent at state average."

The study recommended that the major approach for improvement of irrigation facilities must include efficient management to improve the irrigation efficiency of canal systems and revamping and consolidation of tanks and wells, whether owned by individual farmers or public system.

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`Efficiency of irrigation projects only 40 p.c.'