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Water management in rural South India and Sri Lanka

 | 
Patrice Cohen
, 
S. Janakarajan

Part I. History and traditional irrigation

2. History of Hydraulic Civilization and Irrigation Systems Development in Sri Lanka

K.D.N. Weerasinghe et C.M.K. Navarathne

Texte intégral

Introduction

1Sri Lanka is a tropical island situated in the Indian Ocean at a latitude of 5°55’ and 9°51’ N and a longitude of 79°41 and 81°54 E. The total land area of the country is 65 000 km2. It has a maximum length and width of 432 km and 224 km. (Fig. 2.1)

Figure. 2.1: Major Climatic Zones in Sri Lanka

source: National Atlas of Sri Lanka

2The climate of Sri Lanka is tropical monsoonal. It has an annual rainfall of 2,500 mm received from two monsoons, north-east monsoon, from December to February and the south-west monsoon, from May to September.

3Both monsoon periods are separated by conventional rainfall during March-May and October-November. There are two distinctly marked cropping seasons, Yala (short season), during April- August, and Maha (long season), during October-February.

4In respect of the rainfall distribution, the country has been divided into three climatological zones, the dry, wet and intermediate zones (Table 2.1).

Table 2.1: Climatological zones in Sri Lanka

Table 2.1: Climatological zones in Sri Lanka

5These three zones are further subdivided into twenty-three agro-ecological zones based on rainfall, topography and soils.

6Rice is the staple food of the country and accounts for about 5,80,000 ha. More than 50 % of the paddy lands are concentrated in the dry zone, 20 % in the intermediate zone and the 30 % in the wet zone. The total land of rice under irrigation in the dry zone accounts for 2,75,000 ha.

7The identification of the dry and wet regions of the country is based on the magnitude of rainfall availability in the Yala season.

8However, in the dry zone two major hydrological regions have been identified. These are regions with a distinct monomodal distribution and regions with a distinct bimodal distribution of rainfall

9National customs and traditions of Sri Lanka are closely associated with irrigation, agriculture and Buddhism. The months of the Sinhalese calendar in the major season (Maha) are named to reflect agricultural practices (Table 2.2). This is an indication of the inculcation of agricultural practices in the national culture, in which they are given priority.

History of water resource development

10Water resource management for irrigation has ben practised in Sri Lanka on a priority basis since 500 BC, and it was treated as one of the main responsibilities of the rulers. According to the history of Sri Lanka, when the Aryans landed on Sri Lanka in 500 BC, they came with the knowledge of irrigation and water management as their main diet was rice (Seneviratne 1989). In this era, land and water were the most important resources. The people living at that time selected places to settle where the rainfall was not very heavy, but were water was readily available: this was a good condition for cultivation. All villages in which they had chosen to live were near rivers and natural canals (Ova) and the terrain was generally flat, allowing for rice cultivation.

Table 2.2: Association of agricultural practices in the Sinhalese calendar

Table 2.2: Association of agricultural practices in the Sinhalese calendar

11The first man-made water resources were the small-scale reservoirs built in every village which stored water for irrigation from the heavy rains during the monsoons. It was a collective effort undertaken by the entire community of the particular village and was done on the basis of village planning. During the same periods the smaller tanks were built by individuals or groups. In group efforts, the group evolved its own rules and regulations for water management. These tanks were well established the dry zone of Sri Lanka during the first century BC.

12Under village tank irrigation a three-fold system of land exploitation was practiced, namely, paddy field chena cultivation (slash-and-burn system) and home-garden agroforestry (Fig. 2.2).

Figure 2.2: Typical tank, village and forest system in the dry zone of Sri Lanka

source: Ulluwishewa, 1992

13During the period between the first and fifth centuries, irrigation systems were developed having large and central tanks serviced by distributory canals throughout the dry zone. Especially in the third century reservoirs were built with greater storage capacity and the irrigation systems were developed so that the farmers were able to cultivate rice three times a year.

14In the twelth century during the reign of King Parakramabahu the Great, irrigation structures were constructed with expert knowledge and skills. In this era, systematic and effective systems were worked out with a strong, and competent bureau for the maintenance of public works, particularly irrigation, agriculture and city building. Water management, which was regarded as a common resource belonging to the king, became the hub of the whole social organization in this period. The achievements in water management and irrigation during this period were at the zenith of their development.

15After the twelfth century, there was a decline and most of the massive irrigation works, which were active earlier, were ignored and as a result, most of them fell to ruin. The reasons for this neglect of the water management systems are given as climatic changes, epidemic diseases, infertility of the soil, foreign invasions and famine (Manchanayaka and Madduma Bandara 1999). The reason for the ruin of the efficient water management systems in the part was the complete disorganization or weakering of the irrigation experts of that time. Manchanayake and Madduma Bandara (1999) indicated it as a push-pull mechanism in which the wet zone began to pull the population from the dry zone where many factors conspired to push them.

16Sri Lanka was under colonial rule since 1505 by the Portugaise Dutch and British. In the Portuguese period (1505 – 1640), no attempts were made to reconstruct the irrigation works, however, during the Dutch period (1640 – 1795), a few irrigation works in maritime areas were restored. Some of these Dutch canals are still in use. Thereafter, in the early years under British rule (1815 – 1855), the maintenance of the irrigation network was totally neglected and some of them were destroyed. Later, the British rulers of Sri Lanka who governed during the period of 1855 – 1877 gave considerable attention to irrigation improvement. During that period, irrigation and water resource management were under the Public Works Department and in 1900, the Irrigation Department was established to handle the task. After the establishment of the Irrigation Department, all ancient reservoirs and other irrigation networks were repaired and maintained.

17In 1930, after the establishment of the ‘Donoughmore Constitution’ under the leadership of the Hon. D. S. Senanayake, irrigation became the most important element of agriculture. The main objectives of this policy were to increase paddy production in the island and move more people to the lands in the dry zone from the wet zone. After restoring ancient irrigation tanks, the Hon. D. S. Senanayake started a number of colonization schemes and the large reservoir ‘Senanayake Samudra’ was constructed with a capacity of 950 mln m3. A large number of reservoirs were developed after 1950 under the same policy, such as Udawalawe, Kirindioya, Galoya, etc. (Fig. 2.3). For the purpose of water management development, the country was categorized in four major regions in 1960, namely: Mahaweli project region, south-east dry-zone region, western wet-zone region and north-west dry-zone region (Fig. 2.4).

18Under the United Nations Development Programme (UNDP), the Food and Agriculture Organization (FAO) prepared a master plan to develop the water resources of the Mahaweli Ganga Basin and adjacent areas during the period of 1965 – 1968. Under this project, it was planned to irrigate an area of about 3 64 000 ha in the dry zone. Further, it aimed to restore water to nearby tanks or reservoirs that did not have nough water to irrigate the surrounding areas in either the Yala or the Maha season. The implementation period of the plan was estimated as around 30 years. The main objectives of this project were irrigation, hydro power generation and flood control. The government of Sri Lanka accelerated the Mahaweli Development Programme with the aid of foreign countries in 1978. Under this programme six large reservoirs and three canals were constructed mainly for hydro power generation and irrigation.

19In the south-east dry zone region the reservoirs Chandrika, Navakiri Ara, Unnichchai, Rugam reservoirs were built for irrigation purposes after the 1960s, and the existing reservoirs in the area such as Uda Walawe, Lunugamvehera, Muruthawela, and Senanayake Samudra were restored. The Samanala Wewa reservoir, which was built by constructing a dam across the Walawe Ganga in the upper reach, failed as there was leakage at the dam site.

20The present distribution and concentration of irrigation tanks in different parts of the country is given in Figure 2.5.

21Accordingly, the number of tanks concentrated in northern dry areas of the country exceed 80 tanks per square miles while the number of tanks in the entire dry zone is 40-80 tanks per square mile.

Agriculture, irrigation and ecosystem development

22According to Brohier (1934), the evolution and the development of ancient irrigation systems in Sri lanka has four stages:

  1. Rainwater tanks from which water was baleout
  2. Small village tanks
  3. Large reservoirs each submerging a number of small tanks
  4. Augmentation of a large reservoir by diversion from a river.

Figure 2.3: Distribution of major irrigation systems

Source: IIMI Major Research Site

Figure 2.4: Water Resource Development in Sri Lanka

Source: Natural Resource of Sri Lanka, 1991

Figure 2.5 : Concentration of Irrigation tanks in Sri Lanka

Source: Natural Resource of Sri Lanka, 1991

23The first tanks were the numerous small tanks in the foothills near fields or terraces to catch the runoff water which ws baled out as needed. Then a number of small dams and, bunds, were built, often in a series on the upper reaches of tributaries of the greater rives, thus retaining annual or inundator flow and discharging it as desired by small canals along the valley side. As time went on, larger dams were built submerging or rendering unnecessary smaller ones (Fig. 2.6).

Figure 2.6: Evolution and development of water and soil conservation Ecosystems

Source: Mendis 2001

24As mentioned by Brohier (1934), in pre-Christian times Ceylon attained the idea of controlling the waters of streams formed by nature to satisfy the many needs of the unfertile regions He illustrated the development of irrigation in Rajarata (Royal Country), where an old diversion channel to Nuwara Wewa was built before the Nachchaduwa tank, which had submerged its head work (Fig. 2.7).

Figure 2.7 : Ancient Irrigation System of Rajarata

Source: Natural Resource of Sri Lanka, 1991

25The next step was revolutionary, a weir (anicut, Tamil tekkam) was built much higher up the main river to form the headwork for a long lateral waterway to join the annual monsoon supplies in the great reservoir. This method, ambitious as well as scientific, had numerous advantages: it harnessed a greater volume of water than any local catchment area could yield; it put both monsoon and other rainfall to full use, and secured a resource in dry the period as well as an even supply in normal years. This method also lessened the problem of silt accumulation because the feeder canal could be cleared periodically and much more easily than the tanks.

26According to D. L. O. Mendis (2001), the ancient irrigation system in Sri Lanka is a man-made water and soil conservation ecosystem that had evolved and developed in seven stages by a process akin to natural selection:

  1. Rainfed agriculture
  2. Seasonal or temporary river diversion and inundation irrigation
  3. Permanent river diversion and channel irrigation
  4. Development of weirs and spillways on irrigation channels
  5. Invention of the sluice (Sorow wa) with its access tower (Bisokotuwa)
  6. Construction of storage reservoirs equipped with sluices
  7. Damming a perennial river.

27Remains of sluices were not found and it is logical to think that man had practised pastoral after the early hunter-gatherer stage, had known rainfed agriculture and discovered the possibility of settled agriculture in river valleys, before he learned to construct storage reservoirs. Natural ponds and dug wells may have been used for domestic water supply, and even for some irrigation. The construction of storage reservoirs, according to Mendis, depended on the invention of the sluice. P. A. G. Paranamanna (cited by Mendis 2001), studied the minor irrigation network in southern Sri Lanka (Mau Ara Project) and found that dams of the abandoned small tanks had their ends curved in the downstream direction and that they were built in echelons at corresponding elevations on tributary streams of the Mau Ara (Fig. 2.8).

Figure 2.8 : Bunds Constructed for Ground Water Recharge

Source: Mendis 2001

28Since the Sinhalese farmer had experience with rice cultivation in which the maintenance of the water level was practised in a series of checks and bunds constructed to follow the contours in valleys, that experience may have evolved to the construction of bunds of larger sizes to retain water in small ponds and tanks. Thus the evolution of the paddy bund to vetiya and the sequence of minor tanks and the paddy fields in the catena is, in our view a distinct illustration of the evolution of water conservation technology from the paddy check to the vetiya system as part of paddy cultivation (Figure 2.9).

Figure 2.9 : Sequence of Paddy Fields and tanks distribution in a valley

Source: Natural Resource of Sri lanka, 1991

29The traditional terraced paddy field carved into the hill tops of the country also provides a profound technological background for river diversion and canal construction (Fig. 2.10). Here, the perennial rivers flowing down hill slopes were conveyed along contour canals constructed at a suitable elevation. This system goes back to 131-167 B. C.

Figure 2.10 : Canal Development in terraced Fields

Source: Kapila Gunasekara, Gamage 1992

30A new ecological unit, the cascade system, formed in this manner with a harmony of village tanks and paddy fields, is a distinct example of water conservation and an erosion control measure adopted by the Sri Lankan farmer. The revolution of this system may have occurred with the invention of the Sorowwa (valve pit) and the Bisokotuwa, as mentioned by D. L. O. Mendis (Fig. 2.11 & 2.12).

Government strategies for the development of the irrigation and water management sector

31Water has traditionally played a central role in Sri Lankan cultural and religious activities. Historians studying Sri Lanka’s ancient hydraulic civilization have marvelled at its engineering technology and water resources management systems. The temple, the village and the tank were the cornerstones of the early hydraulic civilization. However, at present, water demand is growing and major water conflicts are developing between different users. One of the main causes for water conflicts and inefficient water allocation is the lack of coordination between the large number of government agencies, NGOs and farmers organizations.

Figure : 2.11 & 2.12: View of the Sorowwa (Valve Pit)

Source: Seneviratne, 1989

32The major issues confronting the water-related problems as given in the national environmental action plan (1998-2000) are:

  1. Diminishing water supplies
  2. Lack of a rational system for water allocation
  3. Lack of management of ground-water resources
  4. Declining water quality.

33In order to alleviate the above conflict situation, the government recommendation is to formulate a set of national principles for water allocation and apply them in allocating water from any of the major river basins. It has also been suggested that a single body be created to guide and coordinate the activities of the different institutions involved in the supply, use and management of water.

Bibliographie

References

Anuruddha S., 1989. The Springs of Sinhala Cultivation RB 7 Inderpuri, New Delhi.

Brohier, R. L., 1934. Ancient Irrigation Works in Ceylon, Part one, Government Press, Ceylon.

Brohier, R. L., 1934. Ancient Irrigation Works in Ceylon, Part two, Government Press, Ceylon.

De Alwis Dharmasiri, 2000. “Planning of modern irrigation systems integrated with Human Settlement for enhanced reuse of water”, in: Challenges Facing Irrigation and Drainage in the new millennium 2000 USCID international conference proceedings, June 20-24 2000, Fort Collins, Colorado, 127-154.

Gamage, H., 1996. “Status of Art and Status of Watershed Management in Sri Lanka” in The Status of Watershed Management in Asia: Kathmandu, Nepal, 46-54.

Gunesekara, K. and Gamage, H., 1999. Some Indigenous Technology knowledge and Practices for water shed Management in Sri Lanka Kathmandu Nepal.

Manchanayake P. and Madduma Bandara, C. M., 1999. Water Resources of Sri Lanka, National Science Foundation, Colombo, Sri Lanka

Mendis, D. L. O., 2001. Evolution and development of water and soil Conservation Ecosystem A Sri Lanka Pugwash Group Publication

Natural Resources of Sri Lanka, 1991. The natural resources Energy and Science Authority of Sri Lanka.

Paranavithana, S., and Nicholas, C. W., 1960. A concise History of Ceylon – Colombo.

Paranawithana, S., 1980. Sinhalayo Lake House Investment Ltd, Colombo Sri Lanka.

Ulluwishewa, R., 1992. “Modernization and Sustainability – Disintergrating village agro-eco complexes in the dry zone of Sri Lanka”. The island News paper 14-071992. Colombo, Sri Lanka.

Table des illustrations

Légende Figure. 2.1: Major Climatic Zones in Sri Lanka
Crédits source: National Atlas of Sri Lanka
URL http://books.openedition.org/ifp/docannexe/image/10060/img-1.jpg
Fichier image/jpeg, 89k
Titre Table 2.1: Climatological zones in Sri Lanka
URL http://books.openedition.org/ifp/docannexe/image/10060/img-2.jpg
Fichier image/jpeg, 9,5k
Titre Table 2.2: Association of agricultural practices in the Sinhalese calendar
URL http://books.openedition.org/ifp/docannexe/image/10060/img-3.jpg
Fichier image/jpeg, 17k
Légende Figure 2.2: Typical tank, village and forest system in the dry zone of Sri Lanka
Crédits source: Ulluwishewa, 1992
URL http://books.openedition.org/ifp/docannexe/image/10060/img-4.jpg
Fichier image/jpeg, 134k
Légende Figure 2.3: Distribution of major irrigation systems
Crédits Source: IIMI Major Research Site
URL http://books.openedition.org/ifp/docannexe/image/10060/img-5.jpg
Fichier image/jpeg, 35k
Légende Figure 2.4: Water Resource Development in Sri Lanka
Crédits Source: Natural Resource of Sri Lanka, 1991
URL http://books.openedition.org/ifp/docannexe/image/10060/img-6.jpg
Fichier image/jpeg, 90k
Légende Figure 2.5 : Concentration of Irrigation tanks in Sri Lanka
Crédits Source: Natural Resource of Sri Lanka, 1991
URL http://books.openedition.org/ifp/docannexe/image/10060/img-7.jpg
Fichier image/jpeg, 73k
Légende Figure 2.6: Evolution and development of water and soil conservation Ecosystems
Crédits Source: Mendis 2001
URL http://books.openedition.org/ifp/docannexe/image/10060/img-8.jpg
Fichier image/jpeg, 42k
Légende Figure 2.7 : Ancient Irrigation System of Rajarata
Crédits Source: Natural Resource of Sri Lanka, 1991
URL http://books.openedition.org/ifp/docannexe/image/10060/img-9.jpg
Fichier image/jpeg, 81k
Légende Figure 2.8 : Bunds Constructed for Ground Water Recharge
Crédits Source: Mendis 2001
URL http://books.openedition.org/ifp/docannexe/image/10060/img-10.jpg
Fichier image/jpeg, 90k
Légende Figure 2.9 : Sequence of Paddy Fields and tanks distribution in a valley
Crédits Source: Natural Resource of Sri lanka, 1991
URL http://books.openedition.org/ifp/docannexe/image/10060/img-11.jpg
Fichier image/jpeg, 49k
Légende Figure 2.10 : Canal Development in terraced Fields
Crédits Source: Kapila Gunasekara, Gamage 1992
URL http://books.openedition.org/ifp/docannexe/image/10060/img-12.jpg
Fichier image/jpeg, 75k
Légende Figure : 2.11 & 2.12: View of the Sorowwa (Valve Pit)
Crédits Source: Seneviratne, 1989
URL http://books.openedition.org/ifp/docannexe/image/10060/img-13.jpg
Fichier image/jpeg, 79k

Auteurs

Professor of Agricultural Engineering and Dean of the Faculty of Agriculture, University of Ruhuna. He has more than twenty-five years of experience in teaching, research and extension in the field of irrigation and natural resources management, with more than forty publications in Journals and proceedings of the International seminars in the field of Irrigation, Water management, agricultural climatology, rural technology development and problem soil reclamation. The author of a number of monographs in understanding and classification of agro-climate in Sri Lanka.
The author wishes to acknowledge the assistance offered by Ms. Hemamali Ganewatte in preparation of this article by way of providing necessary materials and editorial assistance. Special thanks are due to Ms. Indika Ariyasinghe and Mr. Chandana Gunasena for technical assistance.
The assistance provided by the French Embassy in Sri Lanka, particularly the cultural counsellor Madame Esteve, M. H., which provided the necessary financial assistance to take part in this workshop is especially acknowledged.

Lecturer in Agricultural Engineering, Dean of the Faculty of Agriculture, University of Ruhuna, Sri Lanka.

© Institut Français de Pondichéry, 2003

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