Butajira Irrigation Project Summary
Project Overview
The Butajira Irrigation Project (Project ETH/02/004) is a water resources development initiative in Ethiopia aimed at drought relief through irrigation. The project area is located approximately 25 km west of Ziway, with potential to irrigate over 6,000 hectares.
Key Features:
- Dam site on the Moja River with potential reservoir capacity of 200 million cubic meters
- Three-phase development plan (gravity-fed, pumped, and full development)
- Furrow irrigation system proposed for row crops
- Annual water requirement of approximately 1,500 mm per hectare
Project Components
1. Background
Initiated after the 1985 drought, the project aims to conserve water and provide irrigation for drought relief. Previous studies by FAO and ITALCONSULT informed the project design.
2. Topographical Surveys
Surveys completed between 1984-1987 established benchmarks and mapped the dam site, reservoir area, and command areas.
3. Farming Practices
Current dryland agriculture focuses on maize, sorghum, wheat, tef and red peppers with low yields due to traditional methods:
| Crop | % Farm Area | Average Yield (t/ha) |
|---|---|---|
| Maize/Sorghum | 47 | 7.2 |
| Peas and Beans | 22 | 3.8 |
| Pepper | 16 | 2.8 |
| Tef | 6 | 5.2 |
4. Land Resources
Soil surveys identified deep, fertile volcanic ash soils with some drainage concerns. About 8,000 ha of land was found suitable for irrigation.
5. Water Resources
The Moja River dam site was selected with:
- Mean annual rainfall: 1,150 mm
- 80% probability rainfall: 840 mm
- Effective rainfall: 638.5 mm
- Evapotranspiration: 1,478.7 mm annually
6. Irrigation System
Furrow irrigation proposed with:
- Field application efficiency: 60%
- Field canal efficiency: 75%
- Conveyance efficiency: 85%
- Overall project efficiency: 40%
7. Phased Development
| Phase | Area | Method | Elevation |
|---|---|---|---|
| I | 100 ha | Gravity | Below 1,812m |
| II | 900 ha | Pumped (self-generated) | Below 1,820m |
| III | 3,000 ha | Pumped (grid power) | Below 1,825m |
8. Infrastructure
Includes canals, pipelines, drainage systems, roads, and housing. The water supply system features:
- Low level main canal with 12.5mm gradient
- Pump station and pipeline for Phase II
- Main, secondary and field canals
Appendices
- Soil Report: Identified volcanic ash soils with good fertility but potential drainage issues
- Geological Report: Found volcanic rocks (ash and tuff) at dam site, highly fractured
- Reservoir Simulation: Water balance calculations for different development phases
- Water Quality: Analysis showed suitable water quality for irrigation
- Soil Tests: Physical properties and sieve analysis results
Recommendations
- Additional dam site investigations including core drilling
- Completion of topographical surveys for full project area
- Ongoing hydrological data collection
- Assessment of dam impact on existing swamp areas
The Butajira Irrigation Project represents a comprehensive approach to water resource development in Ethiopia, combining drought relief with agricultural development through phased implementation of irrigation infrastructure.