THIBA: THE MAKING OF KENYA’S FIRST IRRIGATION DAM.

A mega project that has generated spirited discussions around irrigation success, agriculture, and food security in Kenya and the region, Thiba Dam has been completed. We sat down with the Deputy General Manager; Irrigation Infrastructure Development Services, Eng. Charles Muasya, for its facts and figures. Here are the excerpts.

How was Thiba Dam conceptualized?

The construction of Thiba Dam was informed by a study carried out in 1988 which also proposed the rehabilitation of the existing Mwea Irrigation Scheme and expansion by 10,000 acres within the Mutithi area. In addition, there was a recommendation to do an inter-basin water transfer through the construction of a link canal from Nyaminthe di River to the Thiba River. The link canal was constructed in 1991 and the design work of the dam was completed in 2012.

When did the construction start and end?

The construction started on March 1, 2018, after the completion of a detailed design of the dam and irrigation area and completed on May 2022.

Any challenges encountered during the whole process of construction?

Yes, there were a few, including a budget, tax exemptions, and ground rock formation of the site. However, with teamwork and the right expertise, we were able to get solutions to all the challenges.

Please take us through the stages of filling the dam to its capacity of 15.6 million cubic meters.

The capacity of Thiba Dam is 15.6 million cubic meters including dead storage of four million cubic meters. Dam filling commenced on May 24, 2022, when the stop log gates were closed. The filling of the dam will depend on inflow from the catchment and the water demand on the Scheme downstream. With the current inflow of 4.5m3 per second, the dam, without any discharge downstream, takes 2.5 months to fill but with an inflow of 9m3 per second, in a normal rainy season, the dam can fill in slightly more than a month.

At what point will Mwea Irrigation Scheme farmers start using its waters for irrigation?

The release of water for irrigation activities on the Scheme has started and is being guided by demand. Water is released through the regulated outlet gates.

Which milestones will the Authority achieve in Mwea Irrigation Scheme with water from the dam?

Before the construction the dam, the Authority was able to command 25,000 acres of rice production with water from Nyamindi and Thiba River. The 25,000 acres produced around 114,000 metric tonnes of rice with an economic value of KSh10 billion per year. About 250,350 job opportunities were also created in the farms. Now with water from the dam, the Authority will be able to command an additional 10,000 acres, hence increasing the production by 86,000 metric tonnes, growing the economy of Kenya by an additional KSh6 billion per year, and creating an additional 100,000 jobs in the farms.

What was the magic behind completing Thiba Dam within the set timelines?

I will attribute the achievement to proper contract management, administration, and proper institutional implementation mechanism at the Authority.

Now that the facility is complete, which is the next big dam project?

Currently, we do not have any under construction but the Authority is pursuing several dam projects, namely Thuci, Gogo, Rwabura, and Thiririka.

Is this your main achievement in your engineering career while serving under the Authority?

Indeed, it is the biggest achievement. I am very happy that I was part of the team involved in the implementation of the project.

What message do you have for the team behind this dream?

First of all, congratulations on the achievement. Let us maintain the same spirit to ensure that we perform even better in the future. The list is endless, but allow me to name a few people: Mr. Gitonga Mugambi, EBS – the Chief Executive Officer of NIA; Eng. Loise Kahiga, the Chief Engineer (Planning and Design); Eng. Stephen Mutinda, Senior Irrigation Engineer/Project Manager at Thiba Dam; Mr. Innocent Ariemba, the Mwea Irrigation Scheme Manager; and all the contractors and consultants. Thank you for the role played and continue to play.

Message to Mwea farmers?

Now that you have sufficient stored water, use it efficiently. Play your rightful roles to make Kenya food-secure