Irrigation (सेचनविधानानि)

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Irrigation (Samskrit: सेचनविधिः) has played a vital role in the agricultural history of India from ancient times. Water which is one of the essential requirements for the growth of crops. Atharvaveda (7.18.2) mentions in the Vrsti suktam (वृष्टिसूक्तम्) thus

आपश्चिदस्मै घृतमित्क्षरन्ति यत्र सोमः सदमित्तत्र भद्रम् ॥२॥ (Atha. Veda. 7.18.2)

Meaning: Wherever soma and other medicinal plants are worshipped, there the wintery frost and summer heat does not cause trouble (to people) and it rains appropriately leading to abundance (of crops or prosperity).

Our ancient texts have described various facilities for watering fields and plants both at micro and macro levels like watering after transplanting the plant and water supply on a larger scale with irrigational facilities.

According to Shatapatha Brahmana, water and trees depend upon each other and enrich themselves along with the mankind. It is an interesting fact waters are preserved for the bountiful growth of plants and trees, and those trees prevent water bodies from breaching their banks in the reservoirs; thus showing their interdependability.

परिचयः ॥ Introduction

Water is essential for the growth of crops. Rain water is the first and the foremost source of water supply. But, in many cases it is either insufficient or irregular or not available at the proper time. Rain water has to be supplemented by man-made devices of supplying water. Even in the case of other natural sources of water, such as rivers, streams, lakes and ponds, human effort is required to carry or direct water to the field. Thus, irrigation falls into two clear categories, natural and artificial.

Rshi Parashara starts his exposition with the discussion of Vrshti or rains because

वृष्टिमूला कृषिः सर्वा वृष्टिमूलं च जीवनम् । तस्मादादौ प्रयत्नेन वृष्टिज्ञानं समाचरेत् ॥ (१०.३) (Krsh. Para. 10.3)

On rain is dependent agriculture it is the life source of all beings. Hence the knowledge of rains has to be first obtained.

Water Resources

Yajurveda alludes to a comprehensive list of water resources namely rivers, lakes, ponds, stagnant water, wells, seas, steams, big streams, canals and so on. Yajurveda, in the Rudra sukta mantras describes the presence of Rudra in many kinds of water bodies as follows

नमः काट्याय च नीप्याय च नमः कुल्याय च सरस्याय च नमो नादेयाय च वैशन्ताय च ॥... (Shuk. Yaju. Veda. 16.37)

The list of water bodies mentioned in these mantras include water streams (शीभ्या), large water bodies like rivers which have waves (ऊर्म्या (सूर्म्या), lakes having still water (अवस्वन्या without sound), rivers (नद्याः), water surrounding land mass completely (द्वीपम् deltas or islands) small water steams (काट्य), waterfalls and their flow (नीप्य), wells (कूप्यः), water in tirthas (तीर्थम्), banks of rivers (कूल्यम्), large lakes (सरस्), canals (कुल्यम्), deep water bodies (हृदय्यम् । such as seas and oceans).

Rains in Literature

The Vedic literature testifies to the realisation of the importance of rain. The high position of Indra in the Vedic pantheon and the allegoric references to his killing Vrtra and releasing the cows glorify the phenomenon of rains. In ancient texts we have numerous references to the benefits of rains, to the eager waiting of it, and to the joy and festivities on its coming.

That Yajnas are performed for bringing rains is well known and rites like Varunayagam are performed even in the present days. Rig veda mentions the Varshakaamasukta mantras which are recited during yajnas performed for bringing rains. That yajnas bring rain are also mentioned in Bhagavadgita (3.14) and Manusmrti (3.76).

The natural phenomenon accompanying rains was carefully observed and analysed. The Puranas describe the formation of clouds and their different types with their characteristics (Vayu. Pura. 51.28-46; Br. Pu. II 22.23.50). The process of the formation of clouds and of rainfall was described in terms of an embryo and delivery. The pregnancy of clouds last six months and a half. It begins in margasira according to Brhat Samhita (21.5.6) while according to some others it begins in the first half of Kartika masa.

The Krsi-Parasara shows how astronomical knowledge was used for forecasting rainfall in the interest of cultivation. One could have a knowledge of rainfall on the basis of the planets which happen to be the lord and minister of the year (shlokas 11-22). It lays down indications for determining the nature of rainfall in various months from Pausa to Sravana on the basis of the planets and natural phenomena (shlokas 30-64). The movement of planets from one zodiac to another is also taken to indicate rainfall and drought (shlokas 71-79). The text mentions certain natural phenomena and the behaviour of human beings, birds, animals etc. as indicating immediate rainfall (shlokas 65-70).

Wells and Embankments

The Vedic literature implies a clear knowledge of wells and water being drawn from them (RV. 1. 116.9). RV. X.101.5. The Smrti literature shows that the digging of wells and tanks was included in the list of works of high religious merit designated as Istapurti.

Varahamihira makes it dear that the treatment of the subject of dakargala was for the digging of wells (Brhatsamhita 53. 77, 121- 123). He considers wells situated in the Agneya (east-south), Nairrta (south-west ) and Vayavya (west-north) directions to be inauspicious and recommends their placement in the other five directions (shlokas 97-98). Likewise, he recommends a vapi (reservoir) which is east-west long and not south-north; the latter is destroyed by the water agitated by winds. In such a reservoir the flow of water is to be enclosed by strong wood, stones or baked bricks and the embankments are to be hardened by being crushed by elephants, horses and other animals (verse 1 18). At one place there was to be an outlet gate with a well made bed, the channel lined with stones and a panel, without aperture, fixed in a frame and covered by grit heaped against it (verse 120).

The Arthasastra (11. 1.20) mentions two types of setus (embankments), the sahodaka referring to tanks, wells etc., which have a natural supply of water, and the dhdryodaka, which store water in reservoirs. Discussing the comparative benefits from the different types of irrigational works, Kautilya remarks that one which is of perennial w'ater is better than that which is fed with water drawn from other sources, and of works with perennial water that which can irrigate an extensive area is better (AS. VII. 12.4.5).

Narada (XI. 18) classifies irrigational works into two: kheya (canal) or that which is dug into the soil in order to drain off excessive water, and bandhya (embankment) or that which is constructed to prevent water from flowing away. The Brhatkalpasutra Bhasya (123a) records the regional peculiarities of irrigation devices. Certain regions (like Laata) depended solely upon rains, others (like Sindhu) used the rivers, some others (like Dravida country) relied upon reservoirs, some (like Uttarapatha) used wells, at some places (like Banasa) seeds were sown after the floods had receded, while in others (like Kananadvipa) paddy crop was cultivated on boats.

Laksmidhara lauds the merit of constructing a special type of reservoir called dvarnbandha. It was made by damming a mountain spring and thus forming a high level reservoir useful for irrigation (Krt. pp. 292. 286 and Introd. pp. 116-17).

Suyya, a minister under King Avantivarman of Kashmir, accomplished a remarkable work of engineering skill. He dammed the river Vitasta (Jhelum). He built stone embankments for seven yojanas and temporary stone dams at all threatened points and succeeded in shifting the junction of the river with the Sindhu to its existing position (Raja. V. 84-121).

The Arthashastra (II. 1.20-22, 39) requires the king to construct reservoir filled with water either perennial or drawn from some other sources. He is to provide sites, roads, timber and other necessary materials to people undertaking the cooperative construction of irrigational and other works. He is advised to maintain those constructed earlier and to provide for new ones. The construction of tanks is evidenced by archaeological excavations.

The mathematical texts show the actual relevance of the functioning of the reservoirs. They refer to the regulation of fountains {nirjharas) for filling a vapi, the lime taken to fill it when a given number of channels (pranaiis) are operated, and for water to flow out of it through a device (yantra) (Li. p.39, no.95; GSS. VII. 32-33; IV. 28-39).

The Kashyapiyakrshisukti is the only known Sanskrit text which deals with practical details about irrigational facilities for fields. It emphasises the need for the construction of a water reservoir near a village or town. It is to be constructed near a hill or on a table-land with a big lake and, in the case of a plain on a firm-land, near a perennial spring. It is to be provided with a causeway and channels and sluices for filling and emptying it. It may be fed by a mountain rivulet, a big lake, a forest brook or a big river and should be provided with a suitable contrivance for the distribution of water. It is to be provided with a very strong and big culvert and several small channels branching out of it for the easy outflow of water. The text also recommends irrigation from ponds, tanks and, more particularly, from wells. After ascertaining the presence of water by the examination of the soil by an expert of the rules of water-divining and by observing the strata of the earth from the direction of the roots of trees a well or a pond is to be dug.

Water Lifting Devices

A wheel device for drawing water from well is evidenced in the Rgveda, but its nature cannot be determined precisely.

The Arthashastra (11.24.18) refers to a number of devices for lifting water for irrigation. These are hastaprdvartimam, skandhaprdvartimam, srotoyantrapmvartimam and nadisarastatakaku--podghatam. The precise meaning of these expressions has not been determined. Kangle translates them as meaning ‘set in motion by the hand’, ‘set in motion by shoulders’, ‘set flowing in channels by a mechanism' and ‘lifted from rivers, lakes, tanks and wells.’ It may be pointed out that prdvartimam here does not qualify a mechanism or device set in motion. It refers to the diversion of water or its being brought from one’s own irrigation work (svasetu), Kangle takes hastaprdvartimam as referring to the carrying of water in pitchers.

Ghatiyantra

Ghatiyantra referred to the main part consisting of the wheel and the pitchers. The rotation of the cycle of pitchers is often referred to metaphorically in a number of texts in a philosophical context of the cycle of birth and death {Kuv. pp. 227, 277; Upa, Pr. pp.l6, 418, 723; Cham. U comm. n. 15.5; Br. Su. IL2.19). The texts mention only those parts of the device which are relevant to their context, hence the negative argument of the absence of reference cannot be earned too far. The functioning of the device is also mentioned in the Pancatantra stories (Tan, pp. 142-43; Pane. pp. 231-44), writings of Bana (Hsa. n, p 42; Kdd. pp. 85, 322), Mrcchakatika (X.59) and Gathasaptasati (V. 90).

The earliest epigraphic reference to the device is traced in the Madasore inscription of Yasodharman (A.D. 352). The Upamitibhavaprapancakatha of Siddharsi (A.D. 906) gives a detailed account of the various parts of the device and its functioning.