Climate change to trigger more rain in Kenya’s Tana River Basin

Wednesday January 24 2018

A boda boda rider wades through a flooded

A boda boda rider wades through a flooded section of Sultan Hamud-Kasikeu road in Makueni County on November 11, 2017. The Kenyan coast is expected to experience increased rains in the coming months. FILE PHOTO | NATION 

By KENNEDY SENELWA
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Rainfall in the Tana River Basin in Kenya — which has in recent years grappled with erratic weather — is likely to increase by up to 43 per cent annually.

According to the International Water Management Institute (IWMI), the likely floods will make water management in Tana Basin tricky.

Fisheries, agriculture and cattle keeping are major sources of food and employment for about seven million residents living in greater Tana River Basin.

IWMI recommends that Kenya works with resource managers to help residents adapt to changing conditions for sustainable water management.

“How Kenya responds to both the opportunities and challenges will make an enormous difference,” said Prof Eric Odada of African Collaboration Centre for Earth System Science (Access) at the University of Nairobi.

Erratic weather conditions

He said there is a need for building an infrastructure that can withstand the erratic weather conditions to ensure sustainable development in the area.

“Large increase in amount of water available will translate into opportunities for deriving benefits from dams and other built infrastructure, meaning potentially more hydropower, water supplies and irrigation,” said Matthew McCartney, leader of IWMI’s Water Futures Research Group.

Ecosystems in the Tana River Basin, including forests, arid and semiarid lands, mountain vegetation, freshwater and wetlands, marine and coastal areas provide a range of benefits to human beings.

In the report titled Understanding the Hydrological Impacts of Climate Change in the Tana River Basin, Kenya said water flow and groundwater recharge are critical elements for well being of rivers.

Tana, Kenya’s longest river, originates in Aberdares in Central Kenya and flows over 1,000 kilometres to meet Indian Ocean in Ungwana Bay in Kipini area. It drains a catchment area of 95,000 square kilometres.

The Basin supplies 80 per cent of drinking water to Nairobi, Kenya’s capital.

Source of country’s hydro power

Tana River hosts Seven Fork’s Dams complex — a primary source of about 70 per cent of country’s hydro power and 38 per cent of total electricity supply.

“Knowing how climate change may affect hydrology and performance of these costly investments is important for water managers and policy makers. Climate change is threat to future development,” said Mr Odada.

Researchers used Soil and Water Assessment Tool (SWAT) hydrological model to simulate processes affecting river flows. Results for 2020 to 2049, 2040 to 2069 and 2070 to 2099 were compared with 1983 to 2011 baseline.

Climate change input came from ensemble of six models, simulating different greenhouse gas emission scenarios. Researchers evaluated climate change impacts comparing scenarios with basin’s current situation.