Thika Dam | Thika

Thika Dam, often referred to as Ndakaini Dam, is located on the Thika River in Murang'a County, Kenya, around 50 km north of Nairobi. It plays a vital role in the region’s water supply, particularly for Nairobi, which is the capital city of Kenya.

History and Construction

The dam was completed in 1994 as part of the Third Nairobi Water Supply Project, which was developed to address severe water shortages in Nairobi, especially during dry seasons. The project aimed to enhance the city's water supply capacity and reduce dependence on other water sources that were less reliable.

The dam's construction was vital in ensuring Nairobi had a steady, long-term supply of water, which is now sourced primarily from this reservoir. The water is treated at the Ngethu water treatment works before it is distributed across the city.

Key Specifications

Height: 63 meters (207 feet)

Crest Length: 458 meters (1,503 feet)

Reservoir Capacity: The dam's reservoir can hold up to 70 million cubic meters of water.

Catchment Area: The catchment area is about 75 square kilometers, primarily drawing water from the Aberdare Range.

Surface Area: The water spread across the reservoir covers an area of about 280 hectares.

Spillway Capacity: The dam's spillway can discharge up to 390 cubic meters of water per second, which is crucial for flood control during periods of heavy rainfall.

Construction Cost: The construction of the dam was estimated at 20 million Kenyan shillings at the time.

Primary Function and Benefits

The primary role of Thika Dam is to supply water to Nairobi and its surrounding areas, meeting over 80% of the city’s water demand. This supply plays a crucial role in supporting the city’s growing population, industries, and agriculture. The dam ensures that during dry spells, there is still a consistent and reliable source of water, which is vital for both domestic and industrial consumption.

The dam also regulates the flow of the Thika River. This regulation helps in controlling flooding and maintaining ecological balance by releasing a controlled amount of water downstream, which benefits both agricultural and ecological activities in the area.

Environmental Challenges

Despite its crucial role, the dam faces some environmental challenges. These primarily include:

Deforestation: The deforestation of the Aberdare Range, which is the primary catchment area for the dam, leads to soil erosion. This erosion results in siltation in the dam’s reservoir, reducing its capacity to store water.

Water Quality Issues: The runoff from agricultural activities in the catchment area introduces pesticides and fertilizers into the water, which deteriorates water quality.

Sedimentation: The increasing sediment load in the dam due to soil erosion has led to concerns about the long-term sustainability of the reservoir’s capacity.

Water Supply Distribution

Once the water is collected in the reservoir, it is transported to the Ngethu Water Treatment Works, where it undergoes treatment to ensure it meets the required standards before being distributed to Nairobi. The water supply from Thika Dam supports both residential and commercial needs, ensuring that Nairobi’s urban population has access to clean and reliable water.

Future Developments

To address the challenges of growing water demand and regional water scarcity, Kenya is undertaking a major expansion project. The Thika 3A Dam Project is set to be constructed at a cost of 21 billion Kenyan shillings. This new dam will help boost the water supply to Thika and Githunguri townships in Kiambu County, as well as supplement the water supply to Nairobi.

The Thika 3A Dam will have a larger capacity and will play a crucial role in enhancing water availability for the region. It is seen as an essential development to help manage the region’s water resources more effectively, particularly as the urban population grows and water demand increases.

Conclusion

Thika Dam is an essential infrastructure project that supports the water needs of Nairobi and its surrounding areas. Although the dam has faced environmental and operational challenges over the years, its role in ensuring a consistent water supply is invaluable. Ongoing projects like the Thika 3A Dam highlight the government’s commitment to addressing water scarcity in Kenya and improving the resilience of the region's water supply systems.