Groundwater Resources in Tanzania
1. Introduction and Definition
Groundwater is the subsurface water found in the pores and fractures of soil and rocks
beneath the Earth's surface. It forms a critical component of the hydrological cycle and
sustains both surface water systems and human consumption. In Tanzania, groundwater is
a vital natural resource, especially in arid and semi-arid regions where surface water is
scarce or unavailable. It supports various socio-economic activities, including domestic use,
agriculture, industry, and ecosystem maintenance.
More than half of Tanzania's rural population relies exclusively on groundwater for
drinking and household purposes. With increasing population pressures and the
unpredictability of rainfall due to climate change, the dependence on groundwater is rising.
As such, it is imperative to understand and manage this resource effectively.
2. Types of Groundwater Aquifers in Tanzania
Groundwater in Tanzania is stored in several types of aquifers, influenced by the country’s
diverse geological structure:
- Unconfined Aquifers: These aquifers have a permeable upper layer and are directly
recharged by rainfall and surface water. They are generally shallow and easy to extract
water from but are vulnerable to contamination.
- Confined Aquifers: Enclosed between impermeable layers, these aquifers are under
pressure and often provide cleaner water. However, they are deeper and costlier to access.
- Fractured Basement Aquifers: Found mainly in central and southern Tanzania, these are
composed of Precambrian crystalline rocks. Water exists in the weathered and fractured
zones.
- Volcanic Aquifers: Located in the north (e.g., Arusha and Kilimanjaro), these aquifers are
formed from porous volcanic rocks and can yield high volumes of water.
- Alluvial Aquifers: These occur along river valleys and coastal plains, consisting of
unconsolidated sediments. They offer good water yields but are prone to pollution.
3. Characteristics of Groundwater in Tanzania
Groundwater attributes vary across regions, influenced by geology and climate:
- Yield: Yields range from less than 1 m³/hour in hard rock areas to over 50 m³/hour in
volcanic and sedimentary formations.
- Depth: Water tables can be as shallow as 10 meters or deeper than 300 meters.
- Quality: Generally acceptable for domestic use, though issues such as high salinity,
fluoride, and iron levels are reported in specific areas.
- Stability: Less prone to seasonal fluctuations compared to surface water.
- Recharge: Varies with rainfall intensity, soil type, and vegetation cover. Recharge is higher
in volcanic and sedimentary zones.
4. Uses of Groundwater in Tanzania
Groundwater supports numerous applications across the country:
- Domestic Use: It is the principal source of drinking water, especially in rural communities.
- Irrigation: Groundwater irrigates crops in semi-arid regions, boosting food security.
- Livestock Watering: Vital for pastoralists in drylands.
- Industrial Use: Used in mining, breweries, and manufacturing plants.
- Urban Water Supply: Supplements municipal systems, especially in rapidly growing cities.
5. Groundwater Recharge and Regional Distribution
Recharge occurs mainly through rainfall infiltration. Several factors influence recharge
efficiency:
- Climate: High rainfall areas (e.g., Southern Highlands) exhibit better recharge.
- Topography: Flat terrains with porous soils allow better infiltration.
- Land Use: Vegetated areas enhance recharge; deforestation and urban sprawl hinder it.
Regional Overview:
- Northern Highlands: Good recharge; high-yield volcanic aquifers.
- Central Plateau: Deep aquifers with low recharge.
- Coastal Belt: Moderate recharge but at risk from saltwater intrusion.
- Western and Southern Zones: Significant sedimentary aquifers with moderate to high
recharge.
6. Challenges in Groundwater Management
Tanzania faces several issues in groundwater governance and sustainability:
- Over-Abstraction: Unsustainable withdrawals in urban and agricultural zones.
- Contamination: Pollution from sanitation systems, pesticides, and industrial discharge.
- Salinity: Over-pumping near coastlines can cause seawater intrusion.
- Fluoride and Iron: Natural geological contamination in regions like Arusha affects
potability.
- Data Gaps: Inadequate monitoring networks and groundwater databases.
- Weak Regulation: Limited capacity for enforcement of existing policies.
7. Applications in Various Fields
Groundwater plays a role across multiple sectors:
- Public Health: Reduces incidence of waterborne diseases when clean.
- Agriculture: Enables year-round food production.
- Construction and Engineering: Groundwater considerations are vital for infrastructure
design.
- Hydrogeology: Crucial for water resource mapping and planning.
- Climate Adaptation: Offers resilience during droughts.
- Energy: Supports geothermal initiatives in the north.
8. Legal and Institutional Framework
Tanzania’s water governance includes:
- National Water Policy (2002): Advocates integrated water resources management
(IWRM).
- Water Resources Management Act (2009): Establishes permit systems and basin-level
governance.
- Ministry of Water: Coordinates national strategy and regulation.
- Basin Water Offices: Manage allocation and monitoring at river basin level.
- RUWASA: Implements rural water projects.
Challenges include limited human and financial resources to implement policies effectively.
9. Technological Developments and Innovations
Emerging technologies are enhancing groundwater management:
- Geophysical Tools: Help identify aquifer locations and depth.
- GIS and Remote Sensing: Used for monitoring groundwater trends and land use.
- Solar Pumps: Provide sustainable energy for rural boreholes.
- Artificial Recharge: Includes sand dams, recharge trenches, and retention basins.
These innovations improve water access and sustainability, especially in remote regions.
10. Case Studies and Best Practices
- Makutopora Wellfield (Dodoma): Key source for Dodoma’s water supply, showcasing
large-scale extraction potential.
- Kilimanjaro Region: Effective use of high-yield volcanic aquifers supports agriculture and
tourism.
- Handeni (Tanga Region): Deep boreholes provide water for communities and industry.
These examples demonstrate the potential and benefits of well-managed groundwater
projects.
11. Recommendations and Conclusion
Key Recommendations:
- Enhance data collection and monitoring systems.
- Encourage participatory groundwater governance.
- Enforce regulations and permit systems effectively.
- Promote affordable technologies for rural communities.
- Integrate groundwater into national planning frameworks.
Conclusion:
Groundwater is an essential natural resource for Tanzania’s sustainable development. It
underpins public health, agriculture, industry, and climate resilience. Protecting and
managing this resource requires collaboration among communities, policymakers,
scientists, and development partners. With appropriate investment and policy support,
groundwater can continue to serve current and future generations.
