Every time heavy rains pound the upper Tana catchment, communities living downstream face the same threat of a rising river that bursts its banks and sends water across homes, farms and grazing land.
The rain falling around the Aberdares and Mount Kenya turns into a flood threat for residents of Tana River and Garissa counties. Water, Sanitation and Irrigation Cabinet Secretary Eric Mugaa says this occurs partly because of the huge volume of water entering the River Tana and the Seven Forks dams.
The reservoirs are designed to hold large volumes of water, but when they reach capacity, excess water has to be released through spillways and eventually finds its way back into the river system. This cycle, which repeats itself almost every year, is expected to worsen during the predicted October-November-December above average rainfall due to the El Niño phenomenon.
“Our people in Tana River, Garissa and the lower belt of the Tana catchment, which receives a lot of water because of the Aberdares and Mt Kenya, one thing that is inevitable, if the rains are predicted as they are, our Seven Forks will spill,” Mr Mugaa said.
Access To Accessible Water || Eric Mugaa
Although he noted that spillage is good because it protects the dams from being swept off, which could cause more disasters, the CS added that the problem comes downstream, where the river channel may not be wide enough to accommodate the increased volume.
“What makes it flood is that the watercourse is so small to accommodate the volume. The moment the banks are broken, you cannot control it; the water goes anywhere,” Mr Mugaa said.
However, Mr Mugaa, a civil engineer specialised in water resources, said the government is working on ways to give excess water alternative routes and reduce pressure on the main river channel.
He said the State Department of Irrigation has started constructing a hydraulic canal to divert part of the River Tana, although the project is not yet complete.
“We need to do a hydraulic canal that is a diversion of the river. The State Department of Irrigation had started it; it is not complete partly,” he said.
Speaking during an interview with Fixing the Nation, Mr Mugaa said the diverted water would be channelled to an inland swamp.
Another intervention is at the Bura Irrigation Scheme, where the government has constructed a canal capable of carrying 11,000 litres of water per second. Mr Mugaa said the canal could be opened to reduce the amount of water flowing through the River Tana if flooding worsens.
“If the worst comes to worst, we also open that canal to reduce the flow of water in the river,” he said.
More than 20 homes marooned by water at Bula Jebesa as a result of spillage at the Bura Canal in Tana River County.
Photo credit: Stephen Oduor I Nation Media Group.
“For the posterity of this nation, because these are cyclic challenges we are having, we now need to build those many storages, because one dam is supposed to be filling and then we let the water into another one in a series,” Mr Mugaa said.
The proposed system, he explained, would allow water to be released in a controlled manner after the flood peak has passed.
“By the time the flood is gone, in case we have a three- or two-hour break of no rain, it is when you open the gates, controlled flow,” he said.
For residents living along the lower Tana, the immediate concern is whether the forecast heavy rains will push the river beyond the capacity of its channel. Mr Mugaa warned communities in low-lying areas of Tana River and Garissa counties to prepare to move to higher ground if the rains materialise as forecast.
