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5.2 Traditional Methods of Soil and Water Conservation
- Coconut Pick-ups, India
"Coconut pick-ups" is the term popularly used to
describe diversion weirs constructed exclusively to benefit coconut
gardens. The "pick-ups" are small structures built across
seasonal or perennial streams to slow the flow of water at appropriate
locations. This results in surface water storage, groundwater recharge,
reduction of soil loss due to erosion, and provision of water for other
activities. The technical concept is simple; i.e., to slow the flow of
water at strategic places in order to collect water using bunds
constructed of locally available materials, like stones, boulders or clay
(mud). Mud bunds are turfed with a specific variety of locally available
grass, Maane hullu. The bunds are usually built within an incised stream
bed almost to the height of ground level, depending upon the width and
steepness of the stream. During periods of peak stream flows, the berm
creates an hydraulic obstruction which backs up the water, flooding the
coconut plantations located on either side of the stream. The water
impounded in this manner generally recedes within 3 to 4 days. In addition
to supplying the plantations with water, the flood leaves a few
millimetres of silt, and associated major and micro nutrients and organic
matter derived from manure, leaves and the mineral carried downstream,
particularly during the early monsoonal flows. Excess water subsequently
flows into a storage tank. Sometimes there will be several coconut
pick-ups and tanks within a catchment, and excess flows may be conveyed
from one tank to another.
This case study illustrates the utility of this technology
by reference to a pick-up located in the Tumkur District of Karnataka.
Tumkur District receives an average annual rainfall of 688.4 mm. The net
irrigated farming area accounts for 13.8% of the net farming area, and
extends over 77 673 ha., 361.7 ha of which are irrigated with water
supplied from tanks. Tumkur District stands third in terms of the number
of pick-ups in active use, after the Mandya and Chikmagalur Districts.
The Coconut Development Board has provided $150 000 to
state governments for pick-up construction under the million wells scheme.
The amount spent on each pick-up will vary depending on the command area
served by the pick-ups. Normally petitions are submitted by the villagers
through their local government bodies (such as gram or mandal panchayats)
to the zilla parishad or public works department. A survey of the site
proposed by the villagers is conducted by the public works engineer, and
an estimate of the construction cost is sent for approval to the district
level engineer. After the technical evaluation, a financial sanction is
obtained, and a contract is awarded to the registered contractors.
Construction work is undertaken usually during the summer season.
The construction site is selected in an area with exposed
bedrock to ensure a strong foundation. The stream is also narrow at such
sites, and the sites typically form convenient sites for road crossings.
Upstream of these constrictions, there is generally an area available for
spreading the water more widely (the floodplain of the stream), and the
back water created by the pick-ups can extend up to nearly one-half of a
kilometre in length.
During the construction phase, a cofferdam created by about
200 polyethylene sandbags are used to make a temporary bund. Within this
bund, boulders are placed upon the bedrock in a slanting manner to form a
permanent bund. Each stone weighs between 100 kg and 1 000 kg, and are
generally transported to the site in a power tiller trailer over a
distance of between 0.5 km and 5 km. Wooden planks are used to load and
position heavy stones. Behind this rock wall, a supporting vertical wall
with a width of 10 cm is built, and both walls are raised simultaneously.
Between the walls, an impervious core is created by a layer of "crude
jelly" (bitumen) encased within a layer of clay. The clay is wetted
to produce a slurry which is compacted by repeated passes of the power
tiller to ensure a good seal, and further clay is added until the entire
structure is encased in earth. Construction usually takes place over a
period of several years.
During the first year, the total height of the bund is only
about 5 cm above the stream bed, although the side embankments or wing
walls are constructed on either side to a height of 10 cm to prevent the
failure of the banks during periods of high flow, when the structure is
overtopped. On either side of the bund, stone pillars are erected to
enable people to locate the bund during peak flow periods, and to assist
them in crossing the stream when the pick-up overflows. During the second
year, after observing the water flow of the previous year to determine the
effects of any seepage, overflows (possible flanking of the wing walls)
and impoundment (to determine the ability of the structure to withstand
the water load), further construction occurs and the height is increased
by another 4 cm. The length of the pick-up increases as the height
increases. During the second year also, work is completed prior to the
monsoon. During the third year, after observing the water flow, the height
is further increased by another 4.5 cm until it almost reaches the ground
level. On completion, the surface of the pick-up is covered with stone
slabs to prevent erosion of the clay surface. At this juncture, the entire
structure is encased within a mud embankment, built to a height of 0.75 m
(2-1/2 feet) above the stream bed, and turfed with Maane hullu grass to
prevent erosion and stabilize the stream banks.
The Tumkur pick-up, constructed in the above manner, is
almost impervious and has withstood even the heavy stream flows in the
last five years (since 1991).
Extent of Use
The Tumkur pick-up is a typical coconut pick-up, and is one
of five such structures situated on this water course. The Tumkur pick-up
was selected for this study as information was available for th entire
period of the construction project and for the 7 year operational period.
It is the third pick-up in the catchment. The watershed of the Huvinahalla
Stream which feeds the pick-up originates in the Handanahalli Hills.
Stream flow is seasonal, with the stream flow dependent upon the annual
rainfall. Nearly 90% of the stream reach passes through coconut
plantations or gardens.
The Tumkur pick-up was designed and built by an individual
farmer, and constructed using locally available materials. The design was
approved by, and construction inspected by, the public works department
prior to the implementation of the project. The formal inspection process
and granting of operating permission by the public works department is
intended to avoid litigation by downstream farmers. The project was
completed over a span of three summers, with the height of the pick-up
being raised each year until the crest of the weir was almost at ground
level. The crest of the weir is stabilized and is used as a cross-over
road to reach the other stream bank during high flow periods.
Details of the number of pick-ups, and their command areas
and beneficiaries in the Tumkur District for the period 1991-92 to
1994-95, are given in Table 22. Table 23 shows typical construction
dimensions of these structures.
Operation and Maintenance
The pick-ups are constructed by individual farmers, who are
responsible for both the operation and maintenance of the structures. The
primary maintenance requirement is that the structure remain impervious to
minimize the possibility of dam failure.
Level of Involvement
The pick-ups are managed by the individual farmers who
build, operate and maintain the structure. Government may be involved in
the funding and/or initial sanctioning of the project site, and in the
inspection of the dam. Mainly, governmental actions will be carried out by
the local self-governing bodies involved.
TABLE 22. Pick-ups in the Tumkur District Constructed
Under the Million Wells Scheme.
aNA=Data Not Available
TABLE 23. Typical Dimensions of a Coconut Pick-up.
|Rock weir bund
|Max.Height (from the basin)
|Total length of the pick-up
|Side embarkment length
|Mud guide bunds
|Back water : Depth (max)
The rights of the farmer who has constructed the
pick up are as follows: the farmer may make use of the silt accumulated
behind the bund; the farmer may construct a storage tank and provide such
tanks with a sump from which to pump water that has been conveyed to the
tank from the pick-up (however, neither the farmer nor any other
individual can directly pump water from the pickup); and, the farmer can
raise bamboo, teak and other suitable species of tree on their katha bund
(wingwalls) and along their periphery.
The costs incurred in the implementation of this technology
are summarized in Tables 24 and 25.
TABLE 24. Capital Cost of Project Implementation.
Effectiveness of the Technology
This technology augments available water resources by
storing surface water and recharging groundwater. As shown in the data
provided in Table 26, there was an observed recharge in six open wells as
a result of infiltration from the coconut pick-ups from the second year
This traditional technology is ideally suited for the local
conditions prevailing in this region of India. In terms of costs, the
pick-up is valued at about$7 000, based upon the nominal rates used by the
government ($353/ha). However, by using locally available materials and
using existing farm labour, the farmer actually spent $1 825 in
constructing the Tumkur pick-up. It is therefore important to create
awareness of this technology amongst the farmers, and encourage local
initiatives in its construction.
TABLE 25. Details of Expenditures Incurred.
|Crude jelly ( $2.15/load )
| Stones and boulders ($4.25/load)
| Clay ($1/load)
| Labour ($0.50/day )
|Empty cement bags ($)
|| $ 5.75
|Stone pillars ($1.15 each)
|Power tiller ($4.25/day )
* Imputed costs
The principle benefits which may be derived from using this
- The availability of impounded water, the depth and extent of which
depends upon the terrain, width and depth of the stream, and the
duration of which depends upon the soil type, usage and frequency of
- Enhanced groundwater recharge due to both vertical percolation and
horizontal interflow, revitalizing percolation tanks, open tanks and
tube wells; the recharging of open wells is almost immediate within a
radius of up to one-half of a kilometre depending on soil structure and
The ponds created by the pick-ups serve as drinking water
sources for livestock from 8 to 10 villages in the communities surrounding
the pick-up. These ponds also serve as a common place for washing clothes
and conducting religious ceremonies (Ganga Pooja); for seasoning
wood and wooden poles by submerging them in water, which is a common
practice; for retting coconut husks and agave leaves; and for other,
similar activities. The waterbodies attract birds and serves as habitat
for aquatic creatures, and can provide water for pisciculture.
Agroforestry practices can be implemented along the periphery of the
waterbody, which creates a microclimate that is more congenial for the
growth of plants, including coconut and arecanut plants.
The pick-ups reduce the impacts of soil erosion and
downstream siltation, while retaining silt that can be collected in the
pick-ups and carted off to the coconut plantations during summer months to
improve soil structure and fertility, and, in turn, increase their
productivity. The pick-up structures can also serve as a vital link
between villages, especially during the rainy season when travel may be
restricted by flooding rivers.
In certain areas, seepage into percolation wells as a
result of groundwater recharge from the pick-ups is used to irrigate
coconut and arecanut gardens, other field crops like ragi and maize, and
even paddy crops.
TABLE 26. Benefits Derived from the Use of Pick-ups.
a Direct Benefits include the
plantations benefited by flooding as well as groundwater irrigation;
Indirect Benefits comprise the plantations benefited by groundwater
b An additional benefit is the
reduction of siltation downstream.
Possible disadvantages include increased nuisance due to
mosquitoes breeding in stagnant water that may collect upstream of the
Further Development of the Technology
Based on the aforementioned observations, methods of
involving the local people in planning and executing such projects is very
important to achieving long lasting benefits from such ventures.
Gracy C.P., B.L. Chinanda, C.K. Jalajakshi, and K.H. Vedini
1995. Traditional Methods of Soil and Water Conservation - A Case of
Coconut Pickups. In: Proceedings of the National
Workshop on Traditional Water Management for Tanks and Ponds. Centre
of Water Resources and Ocean Management, Anna University, Madras.