Assessment of the Prospects of Irrigated Agriculture Development on the Mext-Zwat Area

Author: Water Resources Development Authority

Date: October 1986

1. Introduction

The report assesses the potential for irrigated agriculture development in the Meki-Zwai area of Ethiopia's Rift Valley. It examines water resource availability, environmental impacts, and economic aspects of proposed irrigation projects.

2. Key Findings

Physical Environment

• Located in northern part of southern Rift Valley (150km south of Addis Ababa)
• Average temperature: 19.3°C, annual rainfall: 642mm (half of PET)
• Main water sources: Meki River (2300 km² catchment) and Catar River (3400 km²)
• Lake Zwai (434 km²) flows into Lake Abiyata via Bulbula River

Current Land Use

Organization	Current Irrigation (ha)	Proposed Expansion (ha)
Ministry of State Farm Dev.	600	400
Zwai Prison Farm	265	1500
Meki-Zwai Project	3000	2000

Environmental Impacts

Three scenarios were analyzed for water abstraction:

Economic Aspects

• Zwai State Farm exports flowers to Europe (80% of revenue)
• Fishery potential: 3000 tons/year (60% of Addis market)
• Tourism at Abiyata-Shalla National Park (300 bird species)
• Proposed projects: Ethio-Korea Livestock (6600ha), Soda Ash (20,000 tons/year)

3. Conclusions and Recommendations

1. Master Plan Study: Needed to coordinate competing water uses and prioritize projects
2. Meki River Diversion: Should be reassessed before implementation
3. Subsurface Drainage: Required for Ethio-Korea project due to alkaline soils

4. Key Tables

Climatic Data at Zwai

Case	Abstraction	Impact on Bulbula River Flow	Lake Area Reduction
1	3000 ha irrigation	46.5% reduction	60 km² (Abiyata)
2	6400 ha irrigation	58.4% reduction	75 km² (Abiyata)
3	6400 ha + Meki River diversion	Complete cessation	130 km² (Abiyata), Zwai becomes terminal lake

Parameter	Value
Average temperature	19.3°C
Annual rainfall	642mm
Potential evapotranspiration	1240mm

Lake Measurements

Lake	Area (km²)	Max Depth (m)
Zwai	434	4
Abiyata	205	14
Langano	230	46