Amibara Project Design Report Summary
Project Overview
The Amibara Project is a major irrigation development in Ethiopia's Awash Valley, designed by Sir William Halcrow & Partners for the Imperial Ethiopian Government's Awash Valley Authority (AVA). The report, dated September 1973, outlines the design and implementation plans for irrigating approximately 10,000 hectares of land.
Key Project Components:
- River diversion structure at Melka Sadi
- Flood protection works including dykes
- Primary and secondary irrigation canals
- Drainage network
- Road system and bridges
- Settlement villages and housing
- Regional township and administration center
Project Layout and Design
Water Supply System
The project proposes a single river diversion structure at Melka Sadi rather than two structures as originally considered. This approach offers cost savings and operational advantages.
Irrigation System
The design features:
- Primary canal following the central ridge of the project area
- Secondary canals supplying settlement and concessionaire farms
- Concession sizes ranging from 210 to 660 hectares
- Measurement structures at key points
Flood Protection
The western flood dyke is designed to protect against Awash River floods up to 2000 m³/sec, with an average height of 3 meters.
Crop Water Requirements
| Project Area | Gross Irrigable Area (ha) | Design Maximum Flow (cumecs) |
|---|---|---|
| Melka Sadi | 5,100 | 5.5 |
| Amibara | 10,100 | 12.2 |
| Bolhamo (future) | 8,900 | 10.8 |
| Angelele (future) | 4,750 | 5.8 |
Implementation Plan
Contract Structure
The project is divided into multiple contracts:
- Preliminary Works (bush clearing, site investigations, link road)
- Buildings and Services (settlers housing, AVA housing)
- Main Works Contract (barrage, canals, drains, roads)
Program Timeline
- Preliminary works to begin in 1973-1974
- Main contract award targeted for 1974
- First irrigation water to Melka Sadi by June 1976
- 4,200 ha of Amibara irrigated by June 1976
- Remaining 5,800 ha irrigated within 12 months
- Full 10,000 ha of cotton to be planted in 1977
Labor Strategy
The project emphasizes labor-intensive methods where economically viable, particularly for:
- Excavation of smaller canals
- Construction of minor structures
- Bush clearing operations
Key Appendices
Appendix B: Single vs. Dual Diversion Structures
Detailed analysis showing that a single diversion structure at Melka Sadi would save approximately Eth$2 million compared to two structures, while also alleviating drainage problems and simplifying water control.
Appendix C: Future Developments
Considerations for potential future expansions to Angelele and Bolhamo areas, including increased canal capacities and access roads.
Appendix F: Contract Types
Description of various contract forms including site investigations, link road construction, bush clearing, and the main works contract.
Decisions Required from AVA
The report concludes with a list of decisions needed from the Awash Valley Authority, including:
- Approval of the proposed project layout
- Comments on preliminary designs
- Approval of implementation proposals
- Confirmation of liaison arrangements
- Approval for expedited tendering procedures