Essential Components of Traditional Village Tank Systems

sixcageyMechanics

Feb 22, 2014 (3 years and 1 month ago)

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Essential Components of Traditional Village Tank Systems

P.B.
Dharmasena

Paper presented at the Seminar on Cascade Irrigation Systems for Rural Sustainability

held on 9
th

December 2010 at SLFI, Colombo, organized by Plan Sri Lanka.

Interceptor

Interceptor
(
Kattakaduwa
)


Three land phases (water hole, marshy land
and dry upland)


Reduce
tank seepage


Prevent entering Na, Mg, Fe into the paddy
land


Safeguard the tank bund


A common village garden and agro
-
forestry
system


medicine, fuel wood, timber, fencing
materials, farm and household materials, food,
fruit, vegetable, fodder


Raw
materials for cottage industry


Plant diversity (77
species


13 species
specific to
kattakaduwa

Thal
,
puwak
,
milla
, teak

Pan,
kohila
,
wadakaha
,
kankun

Gotukola
,
mukunuwenna
,
kiriala
,
Vewel

Patabeli
,
kumbuk
,
kohomba
,
divul
,
mee
,
amba

Three land phases of
Kattakaduwa

Wetakeya

Tree species

Home garden 148

Forest 76

Interceptor 77

70

21

13

34

9

23

10

Plant species in the interceptor

Function/use

No. of
species

Medicine

Fuel wood

Timber

Fencing materials

Farm and domestic tools

Food

Fruits

Vegetables

Fodder

52

52

40

31

15

12

11

9

5

Four phases of the traditional tank

Madakaluwa

(dead storage)

Jalagilma

(deep phase)

Waangilma

(High flood phase)

Wev

thaula

(shallow phase)

Four phases of the traditional tank

Waangilma

(High flood phase)

Wev

thaula

(shallow phase)

Jalagilma

(deep phase)

Madakaluwa

(dead storage)

Four phases of the traditional tank

Waangilma

(High flood phase)

Wev

thaula

(shallow phase)

Jalagilma

(deep phase)

Madakaluwa

(dead storage)

0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Rainfall (m)

Cropping
Intensity
and
Rainfall

Anuradhapura District
(1970
-
2003)

Cropping
Intensity

Geometry of water body affects the loss
y = 59.471x
-1.3351
R
2
= 0.786
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
0.7
0.9
1.1
1.3
1.5
Capacity/area (m)
Percent water loss
PARTIAL DESILTING CONCEPT


Reduces water losses


Makes upstream area free of water


Reduces salinity in the upstream area


Allows to re
-
establish
gasgommana

and
perana


Avails water during dry period


Increases cropping intensity

Area (ha)

Elevation (m)

Proposed

FSL

FSL

Sill level

PARTIAL DESILTING CONCEPT

Old tank bed

New tank bed

Tank bund

Interceptor

Removed sediment

Natural streams

Catchment area

PARTIAL DESILTING CONCEPT


Thisbambe




Buffer zone of
hamlet, resting
place of buffalo,
protection from
malaria and wild
animals, sanitary
activities, nutrient
source to paddy
field



Kiul
-
ela




Common
drainage of paddy
tract, disposal of
saline water from
kattakaduwa
, bio
-
diversity, habitats for
predators



Iswetiya





Soil erosion
control, p
revent
sedimentation, acts
as a temporary water
pond


Godawala




Sediment trap,
drinking
water for
cattle and wild
animals

Gasgommana

and
Peraana


Wind
barrier


reduces
evaporation


Reduces
temperature


Habitat of some species


Fish
breeding points


Territory between man and
wild animals


Reduce sedimentation