Presentation made at the Discussion Forum on Cascade Development in NCP, NP and NWP held on 26th November 2013 at the Conference Room of the Uma Oya Multipurpose Development Project, Ministry of Irrigation & Water Resources Management, No. 26, Jawatte Road, Colombo 5

1. MAIN COMPONENTS OF A CASCADE
DEVELOPMENT PLAN
P.B. Dharmasena
Chief Technical Advisor
IUCN Cascade Development Project
dharmasenapb@ymail.com
Presentation made at the Discussion Forum on Cascade Development in NCP, NP
and NWP held on 26th November 2013 at the Conference Room of the
Uma Oya Multipurpose Development Project, Ministry of Irrigation & Water
Resources Management, No. 26, Jawatte Road, Colombo 5

2. • ‘A connected series of village
irrigation tanks organized
within a micro-(or meso-)
catchment of the dry zone
landscape, storing, conveying
and utilizing water from an
ephemeral rivulet’
• Landscape requirement:
– Dendritic drainage pattern
• Occurrence:
– There can be one or few
tank cascades within one
mini-watershed
– Scale: Watershed, sub-
watershed, mini-watershed,
micro-watershed
A TANK CASCADE
Kapriggama Tank Cascade System

3. TANK CASCADE SYSTEM OF THE IUCN PROJECT
Watershed: No. 90th of 103
Malwathu Oya
Sub-watersheds: (6th of 14)
Kadahathu Oya
Mini-watershed: (4th of 9)
Kapiriggama tank
cascade system
Micro-watersheds: (3)
Cascades:
Pinagama, Konakumbukwewa
and Messalewa

4. Restoring Traditional Cascading Tank Systems for
Enhanced Rural Livelihoods and Environmental
Services in Sri Lanka

5. Project Objectives
• Overall:
Enhancement of living standards of rural communities living in
the Kapiriggama cascade through restoration and improvement
of traditional system on sustainable basis
• Specific:
Restore and improve the traditional tank-village systems on
sustainable basis through:
• Rehabilitation of 23 tanks and restoration of tank
ecosystems;
• Productivity enhancement in the paddy fields of 23 tanks;
• Tank catchment management of the entire cascade;
• Strengthening of local institutions in 11 villages;
• Establishment of the cascade knowledge base
• Learning, sharing and replicability assessment of cascade
system management

6. Project Approach
• Finding solutions to primary
cause
• Implementation mechanism
through administrative
structure
• Integrated approach for
service agencies
• Participatory and flexible
approach for planning and
implementation
• Environmental protection and
restoration is a priority area

7. Activities:
1. Rehabilitation of tanks and
restoration of tank ecosystems;
2. Enhancement of productivity in the
paddy fields;
3. Development and conservation of
Tank catchments;
4. Empowerment of village
communities;
5. Development of the knowledge base
6. Sharing experience for future

8. Consultation
• Established a National
Consultative Committee with
– IWMI, University of
Colombo, HARTI, CEA,
MASL, DOA, University of
Peradeniya, Forest
Department, Ministry of
Environment and Renewable
Energy, ID etc.
– Prof. Madduma Bandara, Dr.
C.R. Panabokke, Dr. M.U.A.
Thennakoon, Mr. Udula
Bandara, Eng. D.L.O. Mendis,
Eng. Harsha Sooriyaarachchi
etc.
• Regular participation in the
Divisional Agricultural
Committee (DAC)

9. Consultative meetings
Chief Minister
Officials:
• District Secretary,
DS/Rambewa
• District DAD, ASC/
Kallanchiya
• PDOA
• FD
• NC Provincial Council
• ID
• PRDPU
• NWS&DB
• Raja Rata University
• Independent Consultants
Community of Kapiriggama

10. Rehabilitation of tanks and restoration of tank
ecosystems
• Tank structural
repairs
• Partial removal of
sediments (partial
desilting)
• Downstream canal
system rehabilitation
• Ecosystem
restoration

11. High Flood area
Shallow phase
Deep phase
Dead storage
Partial desilting approach

12. Tank-village
Ecosystem

13. Enhanced productivity in the command area of
village tank
• Groundwater as a supplementary
source for lowland cultivation
(Community wells)
• Crop diversification
• Soil fertility enhancing activities

14. Tank catchment management
• Sustainable rain-fed
farming (conservation
farming approach
without agro-chemicals
and inorganic fertilizer)
• Productive home garden
development
• Restoration of natural
streams
• Reforestation of barren
lands with multi-
purpose trees (Fruit
forest garden concept)

15. Community mobilization and empowerment
• Small groups
• Village committees
• Cascade management committee

16. Enhanced livelihood for women empowerment
• Bio-fertilizer
production
• Livestock
integrated
farming
• processing and
value addition
• Cottage industry
development

17. Development of a Sound knowledge base
• Socio-economic
• Physical resources,
structures etc.
• Ecological database
• Local knowledge and
best practices

18. Learning, sharing and adaptive management of
tank cascade systems
• Previous cascade
restoration
experiences learnt
• Present experience on
cascade restoration
shared with others
• Replicability of the
project interventions
assessed

19. Main irrigation canal
Natural drainage
Irrigable land
Homestead
Other field crops
Village forest
Main road
Village road
Farm tract
Communal
lands
Tank
Lower Canal
Upper Canal
Fruit forest gardens
Upstream reservation
Downstream reservation
Proposed Land Use Model in Kaluganga EIA

20. 50 m
60 m
50 m
35 m
Farm road
Village road
Irrigation canal
35 m
Village forest
Fruit forest
Rainfed/ Homestead
Irrigated upland
Irrigated lowland
Proposed Land Use Model in Kaluganga EIA

21. Possible Impacts of NCP Canal on Cascade Systems
• Augmentation – increased water availability, land use changes,
increased cropping intensity, matured home gardens, ecological
changes……..
• Dilution – hardness reduced in groundwater (Ca and F dilution)
• Increased land value, illegal encroachments, threats to habitats
• Reduced forest cover, reduced bio-diversity
• Rise of groundwater table
• Soil erosion and Sedimentation of tanks
• Accumulation of Cd and P – eutrification, algal blooming, CKDu
• Drainage problems – development of salinity, health hazards
• Flood hazards
• Damage to existing irrigation structures and natural streams
• Upstream - downstream conflicts
• Dependency for water from outside