Ecosystem based indigenous water management
1.Background of the report
The main objective of this report is to give a basic introduction
about our indigenous water management. Actually it can be
described as ecosystem management. In this regard physical
structures, practices as well as cultural aspects (concepts,
attitudes economic development model etc) related to this
ecosystem management will be briefly out lined.
Indigenous water-ecosystem management cannot be simplified
to its physical structures and practices. Presently, the
physical structures and practices are taken isolated from
the cultural aspects and then the governing economic development
model has little meaning. Therefore the intention of this
report is to introduce both of these aspects of indigenous
water ecosystem management in a holistic manner, and to come
up with some guidelines drawn from the "indigenous water
ecosystem management" which could be included in a current
water policy or in a related matter to solve some of the
problems related to water (ecosystem) in today's context.
2.Introduction
Sri Lankan history is deeply connected with its hydraulic
civilization. Today this hydraulic system is erroneously
named as an irrigation system. Nevertheless according to
most of the renowned authorities (Eng. D L O Mendis, Dr.
Ray Wejewardene) in this field this was a sustainable water
- soil - flora fauna - human ecosystem, which was mainly
based on small tanks (Wewa) in Rajarata and Ruhuna, and basically
on anicuts in Mayarata (i.e. mainly the wet zone). The history
of this ecosystem leads back to the 4th century B.C. or before.
Basawakkulama sometimes known as "Abhayawewa" was
identified as the most ancient Wewa, which was done by king
Pandukabhaya.
Ancient kings had built major tanks and village tanks simultaneously.
For an example king Parakramabahu the great had constructed
165 dams, 3910 canals, 163 major tanks and 2376 village tanks
during the last lap of Rajarata [13].
The backbone of this ecosystem was its ability to store
the rainfall water within the system for the benefit of the
whole system. Unlike in modern irrigation systems, which
are focused on supplying the crop water requirement for the
root-zone (zone in soil where the roots of trees and plants
are spread, water is absorbed to roots in this region), the
ancient "hydraulic system" was focused on the water
requirement of the entire ecosystem. To fulfil this requirement,
various types of structures such as major tanks, small tanks,
Vetiyas, Amuna, Vila (lake), Wala (Pond) etc. (Figure 1)
and inter connecting canals were constructed very much closer
to the nature.
In some areas water from major rivers was conveyed to the
major tanks and from there to the small tanks and then to
the fields, for an example Elahera-Parakkramasagaraya. In
some other areas this was happened totally the other way
round, i.e. spilling out water from small-tanks was stored
in major tanks. For examples Kuluwewas ( Small surface storage
consisting of earth bunds used as a silt trap, flow controller
for flood mitigation raising the water table in vicinity.),
which are incorporated in most of the ancient systems. In
almost all these cases small tanks were constructed in cascade
system, which facilitated efficient reuse of water. In this
manner these structures were used to store water in the ecosystem
(i.e. in the soil) in drought periods and was used in flood
mitigation in rainy periods. It should be mentioned here
that irrigation was only a part of this hydraulic system.
As mentioned earlier the heart of this ecosystem was the
wewa, which gave the lifeblood for the ecosystem. These systems
have been sustained for thousands of years. The sustainability
of these ecosystems is not only due to there physical structures
mentioned earlier. The culture prevailed in these settlements
also provided necessary conditions for this sustainability.
This culture can assume to be driven not by the self-interest
motivated by greed, but by the other motivation like sharing
resources equally (even among animals, birds etc.) and the
equity of ownership. The statement of Arahat Mahinda states
that the king is only the guardian of nature and not the
owner. Keeping a Kurulupaluwa (portion of paddy field reserved
for birds) would have been a direct outcome of this concept.
This culture with that concept proves that, we are just guardians
of the nature of the physical structures like wewa to served
this ecosystem to function for thousands of years. Actually,
in this culture-ecosystem had the in built development model
which is suitable for us i.e. our environment & culture.
Now we are almost totally apart from this tradition. Today
we do not have an idea about our development model and therefore
we cannot rehabilitate these ecosystems in a sustainable
manner. Anyhow it should be mentioned here that though we
cannot go back to the same system today, the guiding principles
provide important guidelines for a modern day sustainable
water management policy.
3.Indigenous water management
In the of ancient cultural context water management was
not taken as an isolated issue. Hear, the main objective
of water management is to optimize the conditions of the
proper function of the ecosystem. Water was mainly stored,
in the soil and conveyed through the soil and the soil facilitated
mainly the water purification process. Water was taken from
the soil (from water table) then the used water is again
put to the soil, which purify the water and feed the water
table for reuse. Water was conserved in the soil (i.e. maintaining
the water table). To facilitate this conservation physical
structures like cascade wewa system; (in Rajarata) Vetiya
(in southern area) Amuna were built according to the geophysical
nature of the region. In this manner water receive from the
two monsoons was reused several times before it ultimately
drained to the sea. Even the inter monsoon rains (Akvehi)
would have facilitated this reuse process (i.e. cyclicity).
The water evaporated from the wewas help to create convection
rains (Akvehi)( Farmers in villagers such as Puleliya, say
this by looking at the directional movements of the clouds.
When the clouds are almost stationary, they identify the
rains as Akvehi) i.e. evaporation from wewas is not a real
loss! Also these structures facilitated flood mitigation
process in the lower parts of the ecosystem in heavy rainy
periods. In this context ecosystem is defined even including
the man and the objects and the accessories required by him
for his life.
4.Concepts, attitudes related to the sustainable-development
model (for ecosystems)
Buddhism was significantly influenced the Sri Lankan life
style (e.g. attitudes, concepts). Some of such prominent
Buddhist concepts are listed below.
- Greed (Thanha) is the cause for sorrow Dukha. Therefore
it should be decreased( Buddhist Sutrapitake - Lord Buddha).
- Happiness is the most impotent wealth. ("Santhutti paramang Dhanang")
( Buddhist Sutrapitake - Lord Buddha)
- Equity of ownership
- Attitude towards nature - nature does not belong to
anybody. We are only a part of it and we can use it in
a sustainable manner for our survival without much disturbing
much to the other partners. Statement of Arahant Mahinda.
- Less selfish, holistic community based approach to
optimise the ecosystem.
- Holistic approach towards nature [9].
5.Structural features and practices of this ecosystem
5.1Rain water trapping structures
In the ancient water management, amount of rainfall (nowadays
measured in "mm") and the intensity of rainfall
(nowadays measured in "mm/day") were deliberated.
Small structures like Vetiya captures the water from very
low intensity rainfall. Small tanks capture the water from
much higher rainfalls and major tanks capture water from
even higher rainfalls [5].
 |
5.1.1Wewa
There are about 12,000 small tanks and anicuts found in
Sri Lanka and these tanks and anicuts irrigate an extent
of about 185,000ha. This is 35% of total irrigable area in
the country. Small irrigation schemes produce 191,000mt annually
accounting for 20% of the national irrigated rice production
(Agricultural implementation programme 1994 - 95). Following
are the essential components of a village tank (figure 3).
Gasgommana - It is the upstream of the land strip located
above the tank bed and water is accumulated in Gasgommana
only when the tanks spill out. Naturally grown large trees
such as Kumbuk, Nabada, Maila, Damba etc. and climbers such
as Kaila, Elipaththa, Kakukeliya, kalawel, bokalawel etc.
are subsisted in this area. The gasgommana acts as a wind
barrier and at the same time it helps to reduce evaporation
from the tank and to lower the water temperature. It gets
closer to the bund from either side where roots of large
trees make water cages creating breeding and living places
for some fish species. This strip of trees demarcates the
territory between human and wild animals.
Perahana - It is the meadow developed under gasgommana
and filters the sediment flow coming from the upstream chena
lands.
Iswetiya or potawetiya - It is the constructed soil ridge
in the upstream of the tank at either side of the tank bund
to prevent entering the eroded soil from upper land slopes.
Godawala - A manmade water hole to trap sediment and it
provides water to wild animals. This might be a strategy
used to evade man-animal conflict.
Kuluwewa - A small tank constructed above the relatively
large reservoirs only to trap sediment and not for irrigation
purposes. It provides the water necessary for cattle and
wild animals.
Tisbambe - It is a fertile land strip found around the
settlement area (gangoda) and does not belong to any body.
Tree species such as mee, mango, coconut etc. are grown in
scattered manner. Mostly this area was used for the sanitary
purposes it acts as the resting place of buffaloes. Buffaloes
were used as a protection mechanism from wild animals and
malaria.
Kiul ela - This is the old natural stream utilized as the
common drainage. Tree species such as karanda, mee, mat grass,
ikiri, vetakeya etc. and few rare small fish species are
also found in water holes along the kiul ela. Most importantly
it removes salts and iron in polluted water and improves
condition of the drainage water from the paddy tract.
Kattakaduwa - This is a reserved land below the tank bund.
It consists of three micro-climatic environments: water hole;
wetland; and dry upland, therefore, diverse vegetation is
developed. This land phase prevents entering salts and ferric
ions into the paddy field. The water hole referred to as
'Yathuruwala' minimizes bund seepage by raising the groundwater
table. Villagers plant vetakeya along the toe of the bund
to strengthen stability of the bund. It appears to be the
village garden, where people utilize various parts of the
vegetation for purposes such as fuel wood, medicine, timber,
fencing materials, household and farm implements, food, fruits,
vegetables etc. [2]. Specifically they harvest row materials
from this vegetation for cottage industries.
Figure 3: Essential components of a village tank [2] |
5.1.2 Cascade system
A connected series of tanks are organized within the micro
catchments of the dry zone land escape, for storing conveying
and utilising water from an ephemeral rivulet (Madduma bandara
1985).
Figure 4: Functional diagram of a cascade system [2] |
It is now clearly recognized that the large number (more
than 15,000) of small tanks that are distributed across the
undulating landscape of the dry zone are not randomly located
and distributed as commonly perceived; rather they are found
to occur in the form of distinct cascades that are positioned
within well defined small watersheds or meso-catchment basins.
A cascade of tanks is made up of 4 to 10 individual small
tanks, with each tank having its own micro-catchment, but
where all of the tanks are situated within a single meso-catchment
basin. These meso-catchment basins could be varied in extent
from 6 to 10 sq.miles, with a model value of 8 sq. miles
in the North Central Province region.
A schematic representation of a typical small tank
cascade system with a scale of 1:50,000 is shown in Figure
5 [5]. The main elements to make up a cascade is namely;
(a) the water shed boundary of the meso-catchment,
(b) the individual micro-catchment boundaries of the
small tanks, (c) the main central valley, (d) side valleys,
(e) axis of the main valley, and (f) the component small
tanks as well as the irrigated rice lands are shown in
the same diagram. These small tanks from a series of
successive water bodies along small water courses and
are called a "cascading
system''. The advantage of such a system is that excess
water from a reservoir along with the water used in
its command area is captured by the next downstream reservoir,
and is thus put to use again in the command area of
the second reservoir. This water is thus continuously
recycled. This system helps to surmount irregularly distributed
rainfall, non-availability of large catchment areas and
the difficulty of constructing large reservoirs [5].
Figure 5: Schematic representation of small tank cascade
[5] |
The outcomes of the ecosystems (paddy, other crops,
water etc.), which are needed for the human lives,
are sheared among the people in the ecosystem. Ecosystem
does not belong or owns to any body. In other words,
ecosystem is virtually not divided among people instead
outcomes are sheared. Dividing the system for individual
ownership beyond a limit will disturb the system. "Bethma" and "Thattumaru" methods
of cultivations are adopted to avoid this.
5.3 Bethma method of cultivation
In water scare situations, villagers get to gather and,
an area, which could be cultivated with the limited water
is cultivated and the harvest (paddy) is divided among them.
5.4 Thattumaru method
This is adopted by villages, when the fragmentation of
lands makes it difficult to cultivate in small unit. When
a villager has a small unit, he opts to forego the cultivation
of his unit giving the opportunity another to cultivate a
larger unit including his. This makes operational unit more
viable. Each farmer gets his turn but not every season.
5.5 Water distribution
A holistic approach - This was done according to community
or group interest.
5.5.1 Bisokotuwa
Biskotuwa is a device used by ancient engineers to control
the outflow of water from wewa with considerable heights
(10-15m). As shown in figure 6, the Bisokotuwa consists of
a rectangular tank connected to the sluice; in almost all
the cases the longer side of the rectangle is kept parallel
to the bund. Though any evidence regarding the gates of the
Bisokotuwa has not been found up to now, speculation about
gates, which would have been made out wood and controlled,
by a system of levers, shown in figure 2, are mostly accepted
in the present among scholars. With these speculated gates
the function of the Bisokotuwa could be explained as follows.
When it is required to release water from the wewa, gate
A is opened gradually while B is kept open at a particular
opening (or gate B would have not existed); then the water
level in the Bisokotuwa will come to a height less than that
of the water level in the wewa. Then water will flow through
the sluice to the out side canal driven by the head of the
Bisokotuwa, hence without subjecting the sluice across bund
to high pressure as well as velocities created directly from
the head of the wewa. When stopping the water release from
the wewa, gate A is closed then water inside in the Bisokotuwa
will flow through sluice XY (Figure 6) without creating any
vacuum condition. In this manner the Bisokotuwa acts as a
'surge' tank, but this is not simply a 'surge' tank; if this
was only a surge tank such large cross-sections are already
mentioned are not needed.
When water is going out from the wewa, the water first
enters the Bisokotuwa the head of water entering it is decreased
by allowing it to expand-it is an effective expansion tank.
This may probably be reason for laying the Bisokotuwa in
such as way that its longer side is parallel to the bund
i.e perpendicular to the sluice- the direction of water flow.
In the Bisokotuwa the flow (and pressure) of water outgoing
from wewas with high heads are controlled by dissipating
energy in the water by letting it expand in the Bisokotuwa
or rather by letting the water coming to the Bisokotuwa to
collide with water inside the Bisokotuwa and thereby releasing
its energy by a marvelous non-destructive method. For this
to take place properly, the volume of water inside the Bisokotuwa
is of critical importance. The large cross section of the
Bisokotuwa stated above will fulfill this requirement. In
some wewas, for example Urusita wewa at Sooriyawewa, water
enters the Bisokotuwa by one conduit (sluice) at the bottom
center and goes out by two conduits beginning from the bottom
of the opposite wall. With this arrangement the effect of
momentum of inlet water on outlet water will be minimized,
i.e the outflow will be very calm. Also velocity of water
in the outlets will be lower than that of the inlet. Higher
velocity in the inlet will increase energy loss; low velocity
in the outlets will give a gentle flow, which will be not
harmful to the bund as well as to the outgoing canal.
The Bisokotuwa is also used to divert water flows. One
such example is seen at an outlet in Parakrama Samudra. In
this case, water enters the Bisokotuwa from one side and
leaves it from a side perpendicular to it. The forces required
to divert the flow of water is obtained from the water itself
(inside the Bisokotuwa). Therefore, no effects such as erosion
of conduits take place.
Figure 6: Schematic diagram of Bisokotuwa |
5.5.2 Karahana
This provides a more even, simple distribution method when
compared with modern methods. Once a certain amount of water
released from the wewa each and every plot will approximately
get an equal amount of water. No body is needed to regulate
water from plot to plot.
Figure 9 -Water dividing devices (Karahana) used in cannels
in Puleliya [3] |
Figure 10: Water distribution methods [4] |
5.6 "Rajakariya"
A community based maintenance methodology for the ecosystem.
In this method, about 40 days of each year villages worked
for the benefit of the whole community (ecosystem).
5.7 Trans basin canals developed within the ecosystems
Holistic approach, insitu time tested irregation and
water supply projects developed gradually. eg : Jaya
Ganga:-The Jayaganga, indeed an ingenious memorial of
ancient irrigation, which was undoubtedly designed to
serve as a combined irrigation and water supply canal,
was not entirely dependent on its feeder reservoir, Kalaweva,
for the water it carried. The length of the bund between
Kalaweva and Anuradhapura intercepted all the drainage
from the high ground to the east which otherwise would
have run to waste. Thus the Jayaganga adapted itself
to a wide field of irrigation by feeding little village
tanks in each subsidiary valley, which lay below its
bund. Not infrequently it fed a chain of village tanks
down these valleys the tank lower down receiving the
overflow from the tank higher up on each chain".
Parakrama Sagaraya:- King Vasabha (65-109) built the Elahera
anicut and canal in the first century; nearly three centuries
later King Mahasen (276-303) built the Minneriya weva at
the tail end of the canal, and probably started its extension
beyond Minneriya. Later kings, up to Aggabodhi I, (575-608)
completed the extension, and Aggabodhi II (606 - 618) built
the Gantalawa weva (Kantale tank) at the tail end. Beyond
Kantale Weva, channels led to Tambalakamam bay and the sea
at Trincomalee.
This system functioned in the next nearly six centuries,
until the reign of Parakrama Bahu (1153-1186), who restored
and greatly improved the system. This king raised the Elahera
anicut, and strengthened the first 24 miles of the canal
from Elahera to Konduruweva, thus creating the second Sea
of Parakrama, or Parakrama Sagara, described in the Culavamsa
as Koththabadhdhanijjara. This Pali word was translated
by Geiger in two different ways which have the same meaning
as it should namely "the weir furnished with a reservoir",
and "the reservoir whose flood escape was walled up".
5.8 Construction of anicuts
Construction of anicuts across water flows such as
perennial rivers to direct water for canals were also
a major part in the ancient water management system.
In this case, dams were built obliquely across (or sometimes
halfway) the flow ("Redibendilla"). This would
have resulted in less silt acumination above the anicut
(proper studies has to carried out in the aspects). In
some cases there construction were temporary. Any way
us all these cases the ancient engineers were very much
concern about the ecosystem and the behaviour of the
silt. The constructions were done to reduce the accumulation
of silt and providing methods to washout the accumulated
silt. Also in these constructions the natural flows were
not interrupted totally. Proper studies have to be carried
out in order to get the ancient knowledge of the construction
of anicuts etc without disturbing the ecosystem.
6. Comparison of water management methods
Comparison of water movement-circulation in a typical indigenous
ecosystem and water distribution-drainage system in a typical
modern system is illustrated as follows (A proper study has
to be carried out for more details).
6.1 Indigenous ecosystem
- Ecosystem perspective ( A perspective, which is based on
the sustainable development of human and environment
with in the context of Sri Lankan culture.) - water received
as rain is stored in the ecosystem in a usable manner
then used and drainage is again fed to the system and
reuses several times.
- Small water cycles through soil: - Water cycle is connected
with soil in local vicinity.
- Water purification is mainly done by the soil
- Irrigated whole land together water conserved, conveyed
through the soil or unlined canals
- Evaporation (specially from wewa) is facilitated local
water cycles as they give rise to convectional rain (Akvehi)
- People live along the cascade, this facilitated reuse
of water
According to above reasons, water has been reused.
6.2 Modern system
Storage tank perspective - water gained from rain is stored
in tanks, then used and drainage. Water cycle is large connected
with sea or other reservoirs, mainly through pipeline, concrete
cannels (i.e. water supply and derange).
- Water cycle is less connected with the soil in local
vicinity
- Less water purification by the soil
(pollution is also high)
- Less water reuse
Today with urbanization connection of water with soil
is reduced. Individuals suck water from wells (from water
table) and store them in overhead tanks. These will deplete
the water table then in most areas the used water is send
to sea through drains without much contact with the soil. Therefore the
cyclicity of water through soil is disturbed this will
give rise for water shortages, in the region. Also for
towns water is pumped from rivers and other sources, no
reuse as in a wewa in village. Population is clustered
in towns unlike in cascade systems. Today in most development
projects canals are constructed for irrigation purposes
and separate pipelines are laid for domestic purposes.
In ancient systems irrigation as well as other purposes
were fulfilled by the same water system, with very much
closer to the nature and with very much less pollution
[7] ( Mahamankadavala Piyarathana Thera at Eppawala said
that about 30 years ago they drank the water from the canals,
but now with introduction of chemicals the water system
has been polluted and separate waterways are needed for
human consumption).
7. Paddy cultivation and water management
Paddy cultivation is highly connected with water management
in Sri Lanka. Almost all the recent irrigation development
projects were aimed at supply water for paddy fields. Anyway
mentioned here that actually crop water requirement of paddy
and the amount of water used for paddy cultivation in conventional
paddy cultivation systems (in paddy fields) are different. Water in conventional
paddy field systems caters for many requirements of the ecosystem. Specially
wet zone paddy fields acts somewhat as small wewas. Rainfall water, which
could have easily drained to sea, is stored in these fields. Also these
acts as sponges during heavy rains and are a buffer against
erosion. They develop the water table in the vicinity providing
water to the ecosystem. Paddy a plant, which could withstand
flood condition were grown in these "wewas".
Therefore one cannot directly say that water in paddy fields are, a requirement
of paddy, and paddy is a crop, which "waste" water. Therefore proper
studies has to be carried out on this matters based on ecosystem perspective.
It is worthwhile to coat the following phase from "rice paddy ecosystem" in
Bali by Steve Lansing because it would be much helpful in understanding our
ancient paddy ecosystem also. "The role of water in rice paddy ecosystem
goes for beyond providing water to the roots of paddy plants. By controlling
the flow of water into terraced fields, the farmers are able to create pulses
in several important cycles. The cycle of wet and dry phases alters soil
pH; include a cycle of aerobic and anaerobic conditions in the soil that
determines activity of micro-organisms, circulates micro-nutrients; fosters
the growth of nitrogen- fixing cyan bacteria; excludes weeds; stabilizes
soil temperatures; and over the long term governs formation of a plough pan
that prevents nutrients from being leached into the subsoil. On a larger
scale the flooding and draining of blocks and terraces also has important
effects on pest populations. If farmers on adjacent fields can synchronize
their cropping patterns over a sufficiently large area, rice pests are temporarily
developed of their habitat and pest populations can be sharply reduced."
8. Evolution and Development of Irrigation Eco-Systems
in Ancient Sri Lanka [4]
9. Conclusion/comments
Water management cannot be identified as an isolated issue.
It is highly related to the economic development model- related
activities, physical structures-practices and concepts-attitudes
in the related culture. A basic introduction about these
interrelated categories in modern and ancient contexts is
given in this report. Therefore in addressing water related
issues one should based on this threefold approach.
Figure 10: Water distribution methods [4] |
(a). Today in the process of solving the water shortage
problems one should first study the methods and ways of improving
the cyclicity of water through soil separately for each geophysical
situations. Conserving water in soil must be considered first
i.e. water table should be uplifted. In "hydraulic" water
works only rainfall data from isohyets and topography of
catchments are taken into consideration. Cyclicity of water
through soil (as well as through atmosphere) is ignored.
Evaporation from tanks (wewaa) and seepage are taken as losses!
Also instead of net rainfall, rainfall intensity (mm/day)
has to be taken in to account [8]. Rainfall intensity has
a direct bearing on the distribution of water in soil, therefore
by considering this fact proper structures such as Vetiya,
wewa has to be constructed in order to store water from rainfalls
of varies intensities, in soil in an usable manner i.e. water
should be stored at low matric potentials as much as possible
( When water is stored in soil matrix it will be in a negative
pressure relative to atmosphere. Surface water and water
in water table has zero matric pressure).
In water balancing calculations for a ecosystem (or for
the whole country) one cannot say that the total out flow
from a ecosystem (or from the whole country through rivers
etc) through underground seepage or upland rivers could be
used totally, or in other words that one can stop these flows
and use that water for other purposes. Because this might
disturb and unbalance the ecosystem. Negative out comes of
the projects of damming perennial rivers throughout the world
are well documented [6]. Principles of indigenous water management
do not allow us to treat as total waste. Water balance calculations
are done based on ecosystem perspective i.e. by considering
the whole ecosystem, its activities functions etc. related
to all of its flora & fauna. Also it should be mentioned
here that water used by a particular crop or cultivation
also should be determined according to this perspective.
In this case we may have to redefine the efficiency terms
related to these aspects. Proper ecosystem based studies
has to be carried out.
(b). As mentioned in section 7, in water management projects
related to the paddy cultivation one should based on ecosystem
perspective instead on the crop water requirement of the
paddy plant.
(c). Cultural practices such as Bethma method should be
introduced wherever possible. Also instead of considering
only on paddy, ecosystem based chena cultivation and home
garden cultivation should be promoted.
(d). The trend is that the decisions such as how the amounts
of water that should be allocated for irrigation and hydropower
generation are determined by the market price of paddy and
electricity. This however distorts, the sustainability of
the ecosystem. Therefore a proper national based valuing
system should be introduced for paddy, electricity etc in
the ecosystem perspective.
(e). Today most of the irrigation projects, which has not
shown proper results (E.g. Lunugamvehera, Udawalawe) has
been carried out on the basis of a map described as the water
recourses development map of Ceylon-1959, which does not
identify (give proper value) the ancient structures Wewa,
Vetiya etc, which facilitated water storing purification
conveying through soil. This map is 1 mile to an inch and
100-foot contours are shown. Also according to Eng. D L O
Mendis, the dams of these projects have been situated too
much closer to the sea. This will reduced the reuse of water.
The proposed Moragahakanda project is also based on this
map the projects carried out based on this map and on modern
hydraulic-civil engineering perspective do not concern about
our ecosystem base perspective which has been time tested
for thousands of years.
(f). In Lunugamvehera project about 12 small Wewas, which
were with in the storage area, and 30 Wewas in the command
area has been demolish. Prior to the project i.e. before
the construction of the massive dam all these interconnected
wewas had been functioned in a typical ecosystem with the
reusing of water [14]. Almost all the necessary food items
such as jack coconuts were produced in this system. Now water
in the Lunugamvehera tank is not sufficient to feed the estimated
command area and farmers are moving in to the direction of
cash crops, which require less water such as banana. Therefore
now the ecosystem has degraded physically and culturally.
In this context, it is strongly proposed to conduct a proper
study in the ecosystem perspective to determine the actual
water usability (how much of water i.e. gained by rain is
used to develop the ecosystem in a sustainable manner), in
Lunugamvehera and Udawalawe area prior and after the construction
of the dam, the results of this kind of study will provide
proper guidelines for future such projects.
(g). In addressing water problems at present most importantly
we have to change our minds, attitudes about water and related
aspects. Here we would like to quote a part from an article
appeared in Scientific American (special report 2005)- "Making
every drop count" by Peter H. Gleick. "Part of
the difficulty, however, also lies in the prevalence of old
ideas among water planners. Addressing the world's basic
water problems requires fundamental changes in how we think
about water, and such changes are coming slowly. Rather than
trying endlessly to find enough water to meet hazy projection
in future desires, it is time to find a way to meet our present
and future need with the water i.e. already available, while
preserving the ecological cycle that are so integral to human
well been. This attitude towards water and related aspect
is very much closer to the above said attitudes and concepts
prevail in Sri Lanka in its culture.
(h). Ecosystems are not owned by anybody, humans are also
a part of the ecosystem and they fulfil their requirements
arise with in the development model, which is intern, not
going against the sustainability of the system. This is cyclic
relationship. Unlike in modern situation where development
is isolated from ecosystem and development is proceeded apart
from the ecosystem and only when ecosystem inhibits the development
the concept of "sustainability of the ecosystem" comes
to the context.
(i). Water is an integral part of the ecosystem therefore
clearly it is also not owned by anybody. Every body could
use it to fulfil their requirements with in the sustainable
limits of the system. Therefore water cannot be prized and
soled in a "free" market. Instead the state could
get a tax from water uses according to their amount of water
usages. This tax is actually a contribution to the development
of the ecosystem. If a person uses water beyond his requirement
he has to contribute in a proportional manner i.e. if some
body uses water beyond his requirement he does it due to
his ability to contribute more to the system in a less selfish
manner.
(j). Water is a scarce resource. But unlike a commodity
such as fossil-full water is in a cycle and being chemically
much stable substance water could be reuse many times within
the water cycle without breaking the cycle. In ancient water
management this reusing was mainly facilitated by soil and
atmosphere. This was almost a natural "reuse".
Today the construction of massive dams in odder to block
perennial rivers will certainly interrupt the water cycle
and hence the ecosystem will have negative results. The concept
of the king Parakramabahu the great was to reuse the water
received from rain many times as possible before it drain
to the sea.
10. Reference
1. Brohier R L, The history irrigation and agricultural
colonization in Ceylon, The Tamankaduwa District and the
Elahera - Minneriya Canal. Academy of Sri Lankan Culture
1998
2. Dharmasena P. B, Towards efficient utilization of surface
and ground water resources in food production under small
tank system, Proceedings of the workshop on Food security
and small tank system in Sri Lanka, 9. Sep.2000. NSF Colombo.
3. Leech E R, "Pull Eliya" Sooriya publication
Colombo, 2003.
4. Mendis D L O, Water Heritage of Sri Lanka, Sri Lanka
pugwash Group - Colombo 2002
5. Panabokke C. R., The Nature & properties of small
tank system of the dry zone and their sustainable production
thresholds, Proceedings of the workshop on Food security
and small tank system in Sri Lanka, 9. Sep.2000. NSF Colombo
6. Patrick Mccully, Silenced Rivers the ecology and politics
of large dams, set books London and New jersey, 1996.
Resource persons
7. Mahamankadavala Piyarathana Thera, Eppawala
8. Dr. Hadawela,
9. Dr. P. B. Dharmasena, Deputy Director, Field Crops Research
Institute, Maha Illukmallama
10. Dr. Ray Wijewardena, Chancellor University of Moratuwa
11. Mr. K. M. P. S. Bandara, Department of Irrigation
12. Mr. Ranjith Rathnayake, Villager at Palleliya
13. Mr. Prabath Vitharana, Dept. of Agrarian Services
14. Mr. Punch Appuhami Villager
Source :www.janathakshan.org
Created :December 28, 2008
Updated :
December 28, 2008
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