Aleltu Hydroelectric Project: Reconnaissance and Prefeasibility Studies
Project Overview
The document presents the reconnaissance and prefeasibility studies for the Aleltu Hydroelectric Project in Ethiopia, conducted by Acres International Limited in June 1984. The study was supported by the Canadian International Development Agency (CIDA) and the Ethiopian Electric Light and Power Authority (EELPA).
The project involves a complex configuration of interconnected reservoirs with pressure tunnels and/or open channels, designed to optimize energy production against the cost of major project structures.
Document Structure
The report is organized into three volumes:
- Volume 1: Executive Summary
- Volume 2: Main Report
This document represents Volume 3 - Appendixes, which contains detailed technical information supporting the main report.
Key Appendices
Appendix A: Layout Optimization Model
Describes the mathematical model developed to analyze the complex reservoir system and optimize project configuration.
Key components:
- Reservoir operation rules
- Sizing and costing of structural components
- Energy and capacity calculations
- Optimization procedures
Appendix B: Hydrological Studies
Presents the hydrological analysis conducted for the project area, including:
- Streamflow and rainfall data analysis
- Preliminary and final streamflow sequence analysis
- Evaporation analyses
- Reservoir regulation analysis
- Flood flow studies
Other Appendices
- Appendix C: Geology, Geotechnical Investigations and Seismicity
- Appendix D: Socioeconomic and Environmental Assessment
- Appendix E: Cost Estimate
- Appendix F: Terms of Reference
Key Technical Details
Layout Optimization Model
The model was designed to determine reservoir elevation and corresponding dam height based on:
- Least cost of major project structures for a given degree of regulation
- Optimization of energy production against cost based on marginal cost of long-term grid energy supply
Model Components
| Component | Description |
|---|---|
| Dams | Cost function related to dam volume and reservoir elevation |
| Interconnection Tunnels | Designed based on regulated and unregulated discharges |
| Power Tunnel | Optimized based on construction cost and value of head loss |
| Penstock | Optimized similarly to power tunnel |
| Powerhouse | Cost based on equipment and structural costs, including switchyard |
Hydrological Findings
The hydrological studies revealed:
- No streamflow data available at project sites - data from surrounding stations used
- No strong correlations between Chacha and Muger stations or with outside stations
- Rainfall stations not located within project subbasins
- Rainfall records mostly incomplete and intermittent
- No reliable correlations between streamflow and rainfall records
- Synthetic streamflow sequences were derived for subbasins
The results were considered acceptable for prefeasibility level analysis but would require review once actual streamflow observations become available.
Key Tables and Plates
Selected Tables
| Table | Description |
|---|---|
| B.1 | Streamflow Records |
| B.2 | Rainfall Records |
| B.3 | Discharge Record Correlations |
| A.1 | Results of Initial Layout Model Runs |
| A.2 | Results of Final Layout Model Runs |
Selected Plates
| Plate | Description |
|---|---|
| A-1 | Schematic of Project Components |
| A-2 | Computer Model Flow Chart |
| B-1 | Hydrologic Data Base |
| B-2 | Hydrometric Recording Station |
Conclusion
The Aleltu Hydroelectric Project prefeasibility study presents a comprehensive analysis of a complex multireservoir hydroelectric system. The document provides detailed technical information through its appendices, particularly focusing on the layout optimization model and hydrological studies. The project was designed to optimize energy production while considering cost factors, with the understanding that further refinement would be needed as more site-specific data becomes available.