M.U.A. Tennakoon PhD, DSc
Global climate change and biodiversity enrichment with proper protection have become hot topics of concern among those in the scientific communities and development functionaries of governments around the world. A beginning has been made in this regard in Sri Lanka too, particularly in respect of the dry zone which is in an imperceptible peril of further drying due to the pervasively on-going climate change in it. The 2,500 year old tank-based hydraulic civilization has to be resuscitated with necessary modifications to avert this peril and many professionals concerned with it are attempting to understand the present status of the on-going climatic change in the dry zone with reference to the roots of our tank-based hydraulic civilization. It appears that in their efforts, they have difficulties in fully understanding the past tank terminology. That calls for an explanation of those terms with commentaries where necessary’.
For easy exposition, these terms and commentaries are presented in four parts. Part I deals with terminological explanation difficulties. Ellangawa is discussed in Part II because most of the terms are mainly associated with ellangawa. It is in Part III that wew or tanks and their associates are explained in detail. Last, but not the least the most important land use terms in the dry zone are explained in Part IV.
Terminology Explanation Difficulties
Admittedly, for the terms in one language, sometimes there are no equivalent terms at all, in another language. Hence, it is an accepted practice to write those original terms in a particular language yet in another language, using the letters of the alphabet of the adopted language. Take the case of the Sinhala term asweddumization. In Sinhala, it means the whole process of clearing primary or secondary vegetation in a land, uprooting tree stumps, leveling land, constructing field ridges separating different field plots (if it is for irrigated paddy farming), making necessary irrigation ditches with water inlets to different field plots, opening drainage canals, leveling of field plots where necessary and making it finally ready for cultivation/plantation.
The British Land and Irrigation officials who understood the gravity of this process but not finding a single word in English to denote clearly what in Sinhala meant by the term asweddumization, have decided to use the same Sinhala term in English writings which has even gone in to the English Dictionaries. Yet, will an English reader, not knowing the Sinhala language, have a wholesome understanding of that entire process meant by that strange term asweddumization without a supportive commentary?
In association with that 2,500- years old tank-based irrigated agriculture in Sri Lanka, there evolved a rich terminology pertaining to tank components, land use and associated irrigation systems ,agricultural practices and rituals associated with them, weights and measures etc. many of which are wrongly or inadequately understood and sometimes misused. Therefore, it is deemed necessary to provide a clear commentary of some of those terms for both local and foreign readers to understand them and use correctly. Note that in commenting on each term, what it means in Sinhala and the nearest possible English term usable for it and its physical location or the movement/s or the function/s, separately or in combination are amplified where appropriate.
An ellangava is a very low-gradient sluggishly moving water path from a head-end summit (mudunna) of a micro- or meso-valley to its down-end at a large reservoir or a secondary stream (oya), filling a chain of tanks one after another in its way down, gently spilling over the tanks’ excess water in to long flat plains in between the tanks and in that whole process the tanks accumulating, preserving, releasing and guiding water to downstream fields for irrigation.
As could be seen above, the Sinhala term ellangava like asweddumization referred to above, encompasses a whole hydro-process for which there is no equivalent word in the English language. The process that is meant by this Sinhala term ellangava is so complex and vast that it would be prudent to absorb it in to the English vocabulary as it is, like the term asweddumization , and try to understand confidently the whole hydro-process meant by it rather than trying to use a vague English term or a phrase in its place, losing its true sense and substance.
Ellangava – Numbers, Distribution and Types
There are 457 ellangavas in 50 sub-water basins in the 9 river basins in the Rajarata (panabokke, 1999). The size and shape of an ellangava depends on a topography determined by geology and subsequent geomorphic changes in that topography. In the flat plains closer to the coast, the ellangava density is low and in the prominently undulating central region of the Rajarata the density is very high. There are four types of ellangavas identified – linear, crescent shaped, dendritict and fan-like (Fig. 1)
Fig. 1. Types of Ellangava
Wew or Tanks in General and their Associates
The English equivalent of the Sinhala term wewa in the common usage in Sri Lanka is tank. To an Englishman the term tank can mean a water container made out of clay or a metal to store a large amount of water which is totally different from a reservoir of water in Sri Lanka constructed on a land surface as an inseparable part of it arresting and retaining water. Incidentally, the term tank in use in Sri Lanka has derived from the Portuguese tem tonque which the English administrators in Sri Lanka called “tank”. There are many types of tanks/wew in Sri Lanka that we need to consider one by one. They are: maha wew or gam vew; olagam wew; kulu wew; and pin wew .
i .Maha wewa (plural = wew )=(Large Tank/s)
It is rather a loosely used term to mean any large tank in an ellangava. There is no clear cut definition of a maha vewa. In the irrigation parlance, all tanks irrigating more than 200 acres are called medium tanks and the very large ones are called ‘reservoirs’. In traditional or purana (old) villages, a tank besides which there is a settlement was always referred to as Maha wewa or game maha wewa
ii.Olagam Wewa (plural = wew) =(supplementary tank/s)
While a maha wewa tank is constructed in the keel of an ellangava, there are small tanks constructed across the side slope highly ephemeral small water paths, which when spill, joins the main tanks in the keel of a – valley( Fig. 2). These are the olagam or feeder tanks. Ola means secondary or less important tanks fed by a main tank which in turn provide some water to the fields under the main tank in case of an irrigation water shortage in them . The fields downstream of them are owned and cultivated by the people living beside a closest maha wewa. As the olagam tanks are edging the village forest, they are the water holes for the wild animals. Until recently the people did not live permanently beside olagam tanks. However, with the increase of rural population during the latter half of the 20th century new permanent settlements appeared in association with them.
Fig. 2. Kapiriggama Tank and its Olagam, Kuluweu and Pinwewa
Kulla means a winnower weaved using peeled thin bamboo stripes or hard dried palmyra leaves. It is a wide-mouthed, shallow, egg-shaped on one side and linear on the opposite side, used by the house wives to separate chaffs and other impurities from grain (Fig 3).
Fig. 3. Photpgraphs of a Winnower Showing Front and Side Appearances
The same process is used by a kulu wewa retaining behind eroded soil particles before releasing sediment-free, somewhat clean water to a tank downstream. Most of the medium and large size tanks have, small kulu wew constructed across the water flows in their upstream catchments. Unlike in village tanks, these kulu wew do not have spills constructed in their bunds. Once the soil particles flow in to them in solution and suspension in water or simply dragging by flowing water and settled down in the bed of a kulu wewa, the somewhat sediment-free water escape at one or both tank bund-end/s to reach a large downstream tank ( Fig. 4).
Fig. 4 . Schematic Diagram of a Tank Environment
i .Pin wewa (plural =pin vew)=(Temple tank/s)
Through generosity, the lay Buddhists, in the past, have constructed small tanks usually in the side slope valleys of ellangavas closer to the temples to meet the water needs of the permanent temple dwellers and the lay devotees who regularly visit the temples to purify themselves by bathing or washing before attending to the religious functions in temples. These tanks were not used for irrigation purposes earlier, though in recent times, irrigable paddy lands have been asweddumized downstream of them.
This is not to be confused with diyabeduma used to mean a point at which the water coming in a canal is divided in to two or more other canals. The nearest English equivalent terms of Diyabethma is “catchment” ( in English) and “watershed” (in American English). An ellangava being a total tank-field-tank water flow in a micro- or meso-valley has its main tanks in its keel (bottom) . Each tank has its own catchment (Fig. 5).
Fig. 5. Schematic Diagram of an Ellangava Based Tank Catchments and that of the Entire Ellangava
The top end 1st tank has only a clearly distinguishable catchment of its own (Fig.%). But the successive 2nd, 3rd, 4th . etc to the last tank successively in the ellangava ,while having their side catchments separately supplying rainwater to them, have the benefit of getting water from their upstream tank/s as well. For instance, the 2nd tank in addition to getting water from its own two side slope catchments also receives water from the 1st uppermost tank in the ellangava, immediately upstream of it. Similarly, the 3rd tank while getting water from its two side slope catchment, also gets water from the 1st and 2nd tanks upstream of it. Thus, the process continues until the last downstream tank in an ellangava successively adding water coming from all its upstream tanks and from its own side slope catchments Fig. 5). This re-cycling of water from tank to tank in addition to the water that they get from their own side slope catchments, which should not be ignored because of its profound influence on enhanced irrigation in terms of double cropping or in area-wise cultivation expansion in a single season.
It is the main axis stream in an ellangava running through a whole of a micro- or meso-valley( see ellangava described above). As this water path moves down in the keel of a valley, its width and volume discharged increase due to the rainwater catchment area increases from top-end to the bottom-end and diagonally across an ellhangava valley slopes as well. Volume increase in a main axis stream is also partly due to the spilling of small tanks constructed across the short-lived side slope water paths in a micro- or a meso-valley (Fig. 5)
The English equivalent in use for diyagiluma is water-spread area in a tank, also sometimes referred to as submerged area. Submerged area of a tank never remains constant; it is oscillating all the time depending on the increase and decrease of water supply to a tank. In the irrigation terminology, if an average tank spills out from its main tank a one foot thick volume of water, the upper shore line of the water spread area will be the maximum possible extent of the water spread area. When spilling of a tank stops after discharging excess of water in it, the upper shore line of water recedes reducing the water spread area or the diyagiluma. When the outside incoming water to a tank stops and tank water is released for downstream field irrigation, the upper shore line of the water spread area recedes steadfastly. If there is no recommencement of water supply to the tank from outside, this recession continues towards the tank bottom (mandakaluwa) . While this recession is on, if the tank receive rainwater from its catchment or from a tank upstream, the recession begins to reverse increasing the water spread area accordingly.
The behavior of the tank water spread area determines the extent of the open bare land or the tank’s parkland (Wew pitiya),around the water spread area. The contours of the water spread area at different times are determined by the terrain of the land on which a tank is situated. When the water spread area increases the open bare land or the tank parkland extent shrinks. Conversely, when the water spread area recedes, the open bare land expands providing a grazing space for cattle. Fig. 6).
Fig. 6. A Bare Park of Upper most tank of Alisthana
In the past, the tank bottom or the mandakaluwa always made to retain some water by fixing the lowest level sluice in a tank slightly above the tank bottom so that the little water that it contained safeguarded even a few fish varieties which can withstand muddy water until the arrival of the next rainy season. In drought seasons, this was the only source of drinking water for the village cattle. With imperceptible silt accumulation in tan bottoms over the past decades, the tanks’ mud levels have risen, reducing their water retention capacities enabling the once above-the-water- level sluices to completely drain out the water in tank ottoms. Now the completely dried tank beds are not uncommon in the dry zone (Fig.7).
Fig. 7. Alisthana – Dried tankbed with salt/ Alkali deposits in September 2014
Silt accumulation in tanks continued unabated since the 1960s. Before the Department of Agrarian Services took over the maintenance of small tanks in the mid-1960s, there was a system called kattikepeema, meaning the removal of a certain amounts of earth from the dried rim of the tank bottom (mandakaluwa), determined to be dug and removed on to the tank bund for mending the bund. Cubes of earth (10x10x1 ft each) to be removed were apportioned to the field owners downstream of the tank in accordance with the extents of land that they individually own. This system is no more in practice today.
Thavalla ( plural Thavalu)
This term is one of the most misunderstood in the tank terminology. It has no English term to be used as the term asweddumization, not even a near equivalent. To many, thavalla denotes a land cultivated somewhere in the upper shore line area of a tank during the main (maha) cultivation season (Fig.8).
fig. 8. Thavalla
Some have even erroneously termed it as ‘tank-bed cultivation’. The term thavalla has gone out of the screen today, because that mode of cultivation was prohibited long ago. Still, it is worthwhile to know where exactly the cultivation was practiced in the tank domain and how it was practiced.
The land chosen for this mode of cultivation was that strip of land marked x between the uppermost shore line of the water spread area when the main tank spill throws out a foot thick water body and that upper shore line of tank prevailing with the cessation of tank spilling. The former shore line recedes in a few days till the cessation of spilling, but the latter level of the shore line remains almost constant for a longer period.
Thus, a thavalla has a quickly drying strip of upper land and a water-logged lower strip of land with standing water for one or two months ideal for wet paddy cultivation. The upper land strip is set apart for dry grain cultivation and small patches of vegetable cultivation as well, while the lower strip, relatively bigger than the upper strip, is devoted for flooded paddy cultivation. As it was a combination of chena cultivation and wet paddy cultivation in the past, the thavalu cultivators did not usually cultivate chenas.
The timing of thavalu cultivation always remained crucial, where sawing of raw seeds had to be done not too early not too late. Too early sawing of seeds run the risk of non-germination of seeds, if the drought ending rains (nikinipalu vehi ) get late and a failure to saw raw paddy (kekulan vee) in time in the lower strip of a thavalla, can be denied of a paddy cultivation with unexpected early submergence of it.
In the past, tanks in the dry zone had well maintained tree girdles or the gasgommanas along the upper shore lines in them when the tanks are full of water( Fig.9).
Fig. 9. Alluthwewa, Gasgommana
From the patches of tree girdles still remaining here and there, it is to be seen that the surviving trees are indigenous varieties such as mi (Bassia longifolia), Kumbuk (Terminalia arjuna), Lunuwarana(Cretea adansonii),Timbiri( Diosoyros malabarica), etc., Some tanks have no tree girdles around them ,except for a few isolated trees. The tree girdles where available as wind shields effectively checked the dry wind causing high evaporation in traversing (Fig. 9.). Measurements taken at the Maha Iluppallama Agricultural Research Station during the dry months from June to September in 2014 have shown that the average monthly evaporation was 6”.The maintenance of these tree girdles enables the increase of tank-based biodiversity and improvement of the micro climate around them as well..
It is a reed bed maintained alongside the upper shore line of a tank when it is full. Only the palimpsests of them are to be seen in some tanks. Fig 10 ).
Fig 10. Perahana (Reed bed)
Under the torrential tropical rains, the bare lands are subjected to sheet erosion and the eroded soil particles are washed down to the tanks in moving water in solution, suspension and even by dragging. Perahana forms and effective barrier arresting those eroded soil particles letting the filtered water in to the downstream tank. The role of a reed bed in the tank biodiversity enhancement is very significant. As some of the reeds over grow and lodge in water they are found to be ideal for the wading birds to rest and nest. They also provide shelter and victuals to the shallow water loving indigenous small varieties of fish. Micro-organisms increase in association with the read beds. While different habitats increase in types and numbers their inter-dependence increases and they all act in a total symbiotic relationship.
This is the tank parkland area which expands and shrinks conversely in keeping with the shrink and expansion of a tank water spread area as could be seen under diyagiluma described earlier. It is a grazing ground of village cattle during the dry seasons (Fig. 6).
Iswetiya (plural isveti)
When a tank is constructed across a water path in a relatively narrow valley with somewhat high earth mounds on either side of it, there is the possibility of soil washing down in to the tank caused by very heavy rainfall. Like the eroded soils from the wider catchment area of that tank reduces its water storage, these side slope soil creeps too contribute to the reduction of tank storage capacity. To prevent this soil creep, the strategy used was the construction of earth bunds, like field ridges, perpendicular to the tank bund, but at the extreme ends of it. In common parlance, these ridges are called ‘isweti’ (Fig.4)
Ralapane (The rip-rap)
Rip-rap is a rubble pack placed on the inner toe of a tank bund to prevent wave attrition of the stored water in a tank eroding and weakening the inner toe of the tank bund. The larger the tank, the more violent the waves lashing the tank bund, notably during the times of storm occurrences. However, most of those small tanks do not have rip-raps, as their shallow and small water bodies are able to create only mild waves that are less harmful to the tank bunds (Fig.11)
Diyaketa pahana( water gauge)
It is the water gauge in a tank. There are two types of them. One is a stone pillar with different water levels ‘ etched’ in it and installed near a sluice, usually near the main sluice. The other is the use of a natural rock out crop within a tank that is visible to a sluice site also with etched water levels in it. These are of course rare (Fig. 12)
Fig. 12. Diyakata Pahana – Alisthana Tank
A diyaketa pahana is useful in two ways. It helps to ascertain the most critical level at which a further rise in the tank water level has to be contained by cutting wide openings at both or one end of a tank bund quickly releasing a good amount of water reducing the gravity stress of water on the tank bund and even water spilling over the tank bund, eroding it and eventually breaching it, when more than a containable amount of water reaches a tank. The other usefulness of diyaketa pahana comes during the dry season when the farmers have to judiciously ascertain the irrigable extent to be cultivated downstream of a tank, based on the water level indication in the water gauge. If the water gauge indicates that the water level has reached a critical threshold and likely to fall further, the farmers’ obvious decision will be not to attempt an irrigated cultivation with available water, but to preserve that water to meet the domestic water needs of the people during the critical dry period in the offing.
Kalinguwa or kal-ingiya
In the Sinhala term kalingu, kal means ‘time’ or ‘period’ and ‘ingu’ or ‘ ingi ‘means a hint or a clue( of an event to occur).Hence, the wholesome meaning of the two terms when put together is ‘fore warning’ or clues ( of disasters to come). The dry zone villagers before the onset of the northeast monsoon (that is in the month of September) restlessly begin to look for the clues in the weather patterns to ascertain whether the rainfall to follow would fail leading to drought or will give excessive rainfalls leading to local floods. If they get clues of a likely rainfall failure in the northeast monsoon to come, from October to the end of December , they fear that they have to face crop losses due to drought. If the clues give them the suspicion that the expected monsoon rains are likely to cause a flood havoc even leading to a disaster of tank bund breaching they have to have strategies to prevent it well in time. This perpetual dilemma of drought or floods to come, haunts the minds of the farmers and irrigation managers from the month of September onwards.
The ancient irrigation engineers were able to come up with a solution to ease the dilemma. That is, the construction of a twin tank system as shown in Fig. 13.
Fig. 13. Kaligu dam as both flood control and drought mitigation device
Here, a large tank is divided in to two portions ( A and B) where one portion is smaller than the other portion. The larger portion is actually the heart of the twin tank system, downstream of which, is the largest extent of land to be irrigated (K ,J and L ). Under the smaller A section of the twin tank, the downstream extent cultivable is very negligible. .
The tank is divided in to two, with a small earth bund running upstream perpendicular to the main bund of the total tank complex (CD). Note, that, the uppermost shoreline H1) ’is the maximum level reached when the main spill ‘I’ throws out a one foot thick volume of water. When spilling of the tank stops totally, that maximum upper show line 1 (also marked H1), recedes to shore line 2. The bund constructed perpendicular to the main tank complex ends at ‘D.
First, the gap between shore line 1 also marked as H1, H2, and H3 and shore line 2 is very important to arrest bund breaching due to excessive water reaching the tank. In such a situation, the outer spill of the smaller part of the tank at ‘G’ is cut open to expel the excess water. The excess water in the main part of the tank passes through the gap between upper most shore line 1 and shore line 4 in to the smaller part of the tank, enabling a significant reduction of excessive load of water in the main part of the tank as well, preventing its bund breach. This is a marvelous engineering design put in place by the ancient irrigation engineers to prevent tank bund breaching.
Second, after the cessation of monsoon rains, due to the continuous release of water from the main part of the tank for irrigation of its downstream fields, its upper shore line begins to recede from 1 to 2, 2 to 3, 3 to 4 and towards the tank bottom (madakaluwa), but in the smaller part of the tank there is no such a rapid recession of its shore line as it has a very limited irrigable fields downstream of it, for a rapid release of large quantities of water to irrigate them. It then will contain a surplus of water while the main part of the tank is running in to a water deficit. Note that in the smaller tank A, after the water shore line 4 there will be no recession to the 5th and 6th shore lines and further downwards as in tank B provided that no release of water in A from a sluice. When that main part of the tank, , desperately requires additional water to meet the shortfalls of water in irrigating its downstream fields cultivated. Then, the surplus water in the smaller part of the tank is channeled to the main part of the tank by opening the sluice gate at ‘F’ in that diagonal bund replenishing the main part of the tank (that is B), enabling it to provide an additionally required irrigation water to its downstream fields. This is also an equally ingenious devise used to fight drought.
In summary, the construction of a tank with a bund diagonally across the main tank bund with relevant tank appurtenances served two purposes – preventing tank bund breaching with excessive floods and averting drought losses .
Mahavaana (main spill)
It is the main tank appurtenance used to expel excess water in a tank (Fig.4). It is this spill that determines the upper shore line of tank water at full storage level (see Diyagiluma ). The main spill is usually placed in the tank bund where originally the main axis stream was blocked by throwing the bund across it or at a point closer to it, enabling the spilled water to regain the main axis’s original path at a distance from the spill, minimizing possible flood damages to the downstream fields closer to the tank bund.. In very small tanks the spilled volume of water being small and it is relatively during a short period of time a spill is located at any least damaging point in the bund.
It is to be noted that the British folly of constructing spills vertically dropping down water, , has completely blocked the free movement of fish causing a significant reduction of fresh water fish populations in upstream tanks.. This serious error has to be corrected forthwith, either by fixing fish ladders or changing the concrete structures of spills in such a manner to facilitate the free upstream movement to increase fish population over a widely spread innumerable upstream tanks. The importance of fresh water fish amidst the rising cost of sea fish cannot be just ignored. It will be a source of potential nutrition and income for the rural population in the dry zone.
Pitavaana (plural pitavan) or the outer spill/s)
A medium size tank may have one or two small spills made of low and small earth bunds at the very extreme end or ends of a main tank bund ( G in Fig.4), ready to cut open to release more water than what is expelled from the main spill to reduced the over pounded water storage in the tank as observed above (Fig,12) in explaining the role of a diyaketapahana, during a heavy rainy season. Not realizing the need to cut open these earth-ridged spills in an emergency, some of them have been made of concrete structures in recent years.
Maha or meda horowwa (main sluice)
Sluices have a fascinating history. There were very advanced types of sluices in use in the tanks of ancient Sri Lanka. Parker (1909) has stated that there was evidence of using a valve system of sluices in Pandawewa near present Panduwasnuwera as early as the 5th century B.C. From about the 3rd century B.C., to the 6th century A.D., the Sri Lankan irrigation engineers have fitted the large tanks with very sophisticated sluices called bisokotuwa sluices.
Even the exact meaning of the term bisokotuwa is still not known. One explanation is that it is not biso kotuwa where the bisos (queens) had nothing to do with it, but the term has come from bissa kotuwa, meaning a grain storage which has a top-end grain inlet and a bottom-end grain outlet to fill and release grains respectively as an when necessary. Using the same principle, making the water to fall down from the water level in a tank to an inner chamber, which in its bottom has a releasing outlet (Fig.14). Because of the grain storage operation principle followed, it is said, that the term biso kotuwa has derived from the term bissa kotuwa.
Fig. 14. A diagram of an Inner Chamber of a Bisokotuwa
We have no proper records about the sluices in use during the dark age of our irrigation civilization from the mid-13th century to the time of the arrival of the British in Sri Lanka during the late 18th century. Nevertheless, there are two vital pieces of record, one kept by Robert Knox in 1681 and the other kept by R.W. Ievers in 1899. Robert Knox says that the Sinhalese (‘Chingulias’) cut open a tank bund at one end of it releasing tank water a little by little and wetted the paddy fields downstream. He has no mention made about a sluice.
Ievers has made a more authentic record on the use of sluices in the 18th and 19th centuries in Sri Lanka. Using the information collected from his subordinate officers in Anuradhapura district, he has shown that in the early 18th century the farmers used hollowed tree trunks buried deep down across under tank bunds to release tank water to the paddy fields downstream and when the fields were adequately wetted, the tank side end of the hollowed tree trunk was sealed with grassy sods of earth. Speaking more specifically on tank irrigation during the latter half of the 19th century, Ievers has mentioned that people used clay-pot sluices (hutti horow) where clay pots piled upon one another up to the water surface level and removing one by one from the top of the pile of pots to release the lowering tank water to irrigate downstream fields Fig. 15).
Fig. 15. Hutti Horowwa
The clay pots being friable when soaked in water the breakage losses were high and to get over the problem the British irrigation engineers introduced pre-caste short cement block pipes on the same model of the hutti horow pipes and came to be known as keta horrowwa (Fig . 16).They functioned well but the nagging problem was their heaviness causing difficulties in mounting them on one another and dismantling them one by one as necessitated.
Goda horowwa (Plural Horow)
They are secondary type of sluices constructed to release tank water to the individually owned field blocks or akkara vel on either side of the Old Field ( purana vela), on higher elevations. Both hatti horow and keta horrow sluices were used in controlling and releasing water. They were usually in full operation during the Main (maha) cultivation season. With the recession of the tank water level they cease to operate.
Horow Ela (sluice canal)
This is the first part of the canal from the sluice to a point at which the water is distributed to one or two sub-canals (bedum ela/s) leading to the different field blocks downstream.
Bedun Ela (plural Bedum Elawal) or Distributory canals
At some distance from the point of dividing the sluice canal water to sub-canals these sub-canals are further divided into even smaller canal to take water in to the small field units of different elevations in the large Field blocks. It is to be noted that under very small tanks these sub-divisions are not found and the sluice canal itself run up to the point of field channel separation
Veli (Field channels)
The term veli used in the north central dry zone should not be confused with the same term used elsewhere to mean dams . A distributor canal or a distributor sub-canal is finally divided in to veli or the field channels at the head-end of a field block or at the head-end of a field unit of a field block comprised of individually owned field strips called pangu meaning shares of land. This intricate field water distribution has been diagrammatically well explained by Ievers in 1899 (Fig 17). Each field unit (issara) has a single field channel with openings ( vakkada or watura kada )to each pangu in that unit.
Fig. 17. IEVER’S SCHEMATIC DIAGRAM OF AN IDEAL PURANAWELA SYSTEM
.It is the responsibility of all the shareholders (pangukarayo) in that field unit to keep the field channel cleaned ensuring a swift flow of water in it up to its last pangu. The tail-end shareholders (pahala pangukarayo) are to get the entire water flow first and then the top-enders (ihala pangukarayo) last.
Vagal (a Field darinage channel)
This is a temporary drainage channel opened from the head-end portion of a field unit down to the tail-end field unit and beyond, across all in between shares (pangu) in a single long line across the lowest line of field plots (liyaddas) to drain water from slightly higher field plots diagonally opposite to the temporary drainage channel for leveling and sowing seeds by the shareholders (pangukarayo) during an agreed upon time as short as a day or two (Fig.18)
Fig. 18. Vagala
In this draining process a considerable amount of alkali trapped in fields is flushed away by the temporary drainage channel (vagala). Once seeds are sown and a field surface is dried for a few days, the field openings made to discharge water are mended to impound water to facilitate the paddy plant growth in standing water.
Land use terminology in a Dry Zone Rural Settlement
When one understand the different land use components in a dry zone total village settlement, it would be easy to understand the traditional terms used in respect of each land use type in villages. The accompanying schematic diagram facilitates the explanation of different land use zones – the Tank, the Old Fields, Field Blocks or akkara vel ,Parkland and Forest (Fig. 19).
Fig. 19. Schematic Representation of Village Land use
Zone I in Fig.19. consists of the irrigation tank. The tank constructed by building an earth dam thrown across a water path plays an important part in the spatial organization of land use in a village. Particularly the size of the village settlement and the extent of land irrigated downstream of the village tank directly depend upon the amount of water that the tank holds
Purana vela (The Old Field)
Zone II in Fig. 19 , identified by the villagers as the Old Field ( purana vela or maha vela) occupies the land immediately below the tank. Once a tank is newly constructed or renovated after a very long period of abandonment, the Old Field is the first to be developed as Codrington has described thus with what he witnessed in Vavuniya district in 1938 as follows:
“They …..go to divide the field (vela). Looking in the jungle for good land and sending men to various spots in the jungle and on the bund to cry ‘hoo’. They then come to one place sit down and call upon the Gods… Then one rises with a katta ( billhook) and cries ‘ha pura’ ( let us start) and cuts a tree at once, this is ‘nakata-ta-val allanava’(taking possession of ) the jungle at a lucky time. After cutting boundaries in the jungle in three places, at right angle to the bund, they measure the Ihala bage, lengthwise with kirivel creepers in bambe or fathoms leaving the kurulupaluwa, alapatha and alapth panguwa, and dividing the rest crosswise in to pangu and gamwasama. There should be ten pangu in all but if there may be many people and several bages there may be seven pangu in each bage….Then the pahala bage is measured in the same way. Afterwards the jungle is felled and mudukiriyal rice grown. After reaping mudukiriyal is grown again, and after the tree stumps have rotted and have been burnt the field ridges (niyara) are made”1
But no person other than Ievers has diagrammatically shown the field layout with channel irrigation network with various land blocks in an Old Field so clearly(Fig.19). Generation after generation ,if sub-division of land continued, the original shares have made the later day individually held portions very small and by selling those uneconomical portions to the others have made some villagers landless in the Old Field
Akkarawel (Fiel Blocks)
With the gradual increase of village population leading to continuous sub-division of the land in the Old Field and even the emergence of landlessness in villages, the villagers have started clamouring to get Crown land suitable for irrigation in the outer periphery of the Old Field towards the end of the 19th century. As a consequence, the government authorized the grant of an acre of land to each eligible applicant which came to be known as akkara wela or ‘ Acre-Field’or Field Blocks meaning one acre in extent (Fig.19). Double cropping is seldom possible in ‘Acre Fields’ due to water shortage in tanks after the rainy season.
In the outer periphery of the akkarawel (Acre Fields) there is almost a continuous Parkland with a few isolated trees spared here and there. The Parkland performs two vital functions. First is that the Field Block owners need to have an open space around their irrigated paddy fields to protect their fields from invading nocturnal wild animals such as elephants and wild boar. The second is that when all
the fields in the Old Field and the Field Blocks (Acre Fields) are under cultivation, it is the Parkland which becomes the grazing land for the village cattle (Fig. 19).
Landa (plural-, landu)
Landa means a scrub jungle. It is in the outer periphery of the Parkland, formed of a land abandoned after two or three seasons’ chena cultivation in a cleared forest where re the growth of thorny bushes and the earlier pruned tall bushes for chena clearings takes place. A scrub jungle takes about 8 to 10 years to be fully grown as a forest suitable for chena cultivation once again.
Earlier it was the forest which separated villages from one another. During the first half of the 20th century the forest zone was the largest land use zone in a traditional dry zone rural settlement. In the 1970s, the forest extents reduced drastically as there was a rush to grow subsidiary food crops the import of which remained stringently curtailed due to the country’s foreign exchange difficulties at the time. In the process of chena cultivation the timber wheeler-dealers butchered the forest to extract timber. Ruination of forest has accelerated the blowing of dry winds drying the dry zone. Even though the chena cultivation is prohibited, a tropical forest when destroyed takes a long time to re-grow because its growth during the long dry seasons remain slowed down (Fig. 19).
The word chena is a corrupted form of the Sinhala term’ hena. There were several reasons for the farmers’ to resort to the cultivation of chenas, clearing forest patches. While irrigated paddy cultivation provided food, chenas provided mostly the cash crops. It was the source of food for the landless, it was a crop insurance in the case of a failure of the irrigated rice crop and its practice of sowing both drought resistant and more moisture tolerant seed together giving and assured crop in the season to come will get a poor rainfall or too much of rain. Today chena cultivation is a prohibited form of cultivation..
Amuna (plural =Amunu)
An amuna is a device used to reuse the irrigation water that leaked out from the upper field stretches, in fields downstream. The tendency of that leaked out water, if allowed to flow freely, is to find its way to the keel of a micro valley and flow in to a tank below. Water released in drainage channels (vagal) as shown in Fig.18, too joins with the leaked water flows from the fields becoming considerably large flows They are dammed by throwing earth bunds to raise their water levels to have additional water to the tail-end field .
Godawala (plural =godawalawal)
In Sinhala, goda means a highland and wala means a depression thus giving the wholesome meaning, a depression in a highland. These undisturbed depressions are found in the forest areas in to which rainwater gets collected and last during a longer period of the year or even throughout the year. These are the water holes for the wild animals around which lush vegetation too prevails.