Contents preface (VII) introduction 1—37

6.4.8. Night Irrigation
Another important issue in the operation of the main system is related to night irrigation. In most of the canal irrigation projects, the canal water continues to flow at nights as well and is either badly used or wasted. Darkness, cold, fear, normal working hours and desire for sleep discourage the irrigation staff, farmers, and labourers to work at night. In India, about 47 per cent of the 24 hours day is the time of darkness (between sunset to sunrise with an allowance of 20 minute twilight period each after the sunset and before the sunrise). According to Chambers’ approximate estimate, about 40 per cent of the canal irrigation water on medium and major systems (i.e., with commands over 2000 ha) is either applied in night irrigation or sent into drains at night (1). He further estimates that, except in north-west India where warabandi is practised at night, 25 per cent of the canal irrigation water is wasted at night and much of the 15 per cent which is applied at night is used inefficiently. In view of the magnitude of these losses, night irrigation is too important to remain neglected any more. Farmers usually dislike night irrigation for the following reasons (1):
(i) Loss of sleep and disruption in the normal sleeping duration,
(ii) Discomfort due to cold night and difficulty in moving around in sticky soils and mud,

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(iii) Danger and fear of snakes, scorpions, accidents, violence including murder, and other problems related to law and order,

(iv) Inefficient application of water due to darkness, and
(v) Higher costs due to higher night wages, non-availability of family labour, especially women, old people and those very young to work at night, and need of firewood, beverages and lighting.
In addition, field conditions, type of crop, and its stage of growth may add to the difficulties of irrigating at night. Sloping lands with difficult soils and standing crops are difficult to be irrigated at night. Paddy, trees, and crops which are low and wide apart or are in early stages of growth can be irrigated with relative ease. High and dense crops, and crops in the later stages of growth are relatively difficult to be irrigated at night. The difficulties in night irrigation may influence a farmer’s choice of crop if he has to rely on only water received at night.
However, sometimes night irrigation is preferred by farmers due to the following reasons
(1):
(i) In warmer regions, farmers find it more comfortable to irrigate at night.
(ii) Part-time farmers having other work during the day would prefer night irrigation. (iii) Tail-end farmers may get relatively more adequate and reliable supply during night.

In addition to the above characteristics of night irrigation, the following features must also be noted (1):

(i) It is during the night that illicit appropriation of water (breaching of bunds, remov-ing checks, blocking streams, opening pipes, pumping out of channels etc. to secure water for an individual or a group) takes place.
(ii) During nights, evaporation losses are much less. This saving is, however, more than offset by wastage.
(iii) Most physical damages such as erosion in steep minors, watercourses and field chan-nels due to relatively larger flows on account of lesser withdrawals upstream, and aggravation of waterlogging and associated soil salinity and alkalinity problems seem to occur at night.
It is, therefore, obvious that night irrigation presents many problems. This situation can be improved either by reducing irrigation at night or improving it. Reduction in night irrigation can be either with or without saving water for subsequent use. Measures to reduce night irrigation with water saving involve storage of water which can be achieved in five different ways – in main reservoirs, in canals, in intermediate storage reservoirs, on-farm storage, and in ground water storage. On the other hand, three obvious measures to reduce night irrigation without saving water are: (i) stopping river diversion flows, (ii) redistributing day water so that even tail-enders get adequate supplies, and (iii) passing water to escapes and drains. For obvious reasons, measures with water saving are more desirable but much needs to be done to make them practicable. Night irrigation can be improved in the following ways (1):
(i) Making flows predictable and manageable. For this purpose, the warabandi system has obvious advantages. Each farmer knows the time of his turn and does not need to recruit labour to capture and guard his supply.
(ii) Improving convenience and efficiency by measures such as (a) good lighting, (b) or-ganisation of groups of farmers for night irrigation for mutual benefits of shared labour and common protection from water raiders, etc., (c) installing and maintain-

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ing structures, channels, fields and water application methods requiring minimum observation and adjustment, (d) shaping fields for easier water application, and (e) providing ways and means for easy movement from residences to the fields and within the fields.
(iii) Choosing easy crops such as paddy and trees and crops which are low and wide apart.
(iv) Zoning for night flows which means using day flows for more difficult crops and soils and night flows for relatively easier crops and soils.
(v) Phasing night irrigation for shorter, warmer, and moon-lit nights would, obviously, be more convenient for farmers.
It should, however, be noted that night irrigation had not received any attention till recently. Only a beginning has been made and lot more needs to be done to mitigate the problems related to night irrigation.