Researchers work to restore critical Kenya watershed

Scientists from the CGIAR Research Program on Water, Land and Ecosystems (WLE) are using sophisticated mapping tools and land restoration cost analyses in efforts to improve ecosystem health in Kenya, which faces complex problems such as uncontrolled open-pit mining.

The work in the Upper Tana basin is part of an integrated research program designed to protect the watershed, reduce degradation of land and increase the resilience of smallholder farmers. It is being led by The Nature Conservancy (TNC), which has created a water fund for the conservation efforts. The International Center for Tropical Agriculture (CIAT) is a founding partner.

Restoring the Tana River watershed

"Our goal is to restore and protect the condition of the Upper Tana River watershed, improve water security for Nairobi, which depends on the river for clean water, and secure the country's principle hydropower source," said Fredrick Kihara, TNC's Nairobi Water Fund outreach manager.

The Upper Tana provides 90 percent of the water to Nairobi and contributes two-thirds of Kenya's power supply through hydropower generation. The upper watershed comprises a densely populated agricultural zone inhabited predominantly by smallholder farmers.

TNC and CIAT are utilizing the latest research and modeling tools in order to prioritize restoration and conservation work in the watershed.

CIAT researchers, together with the Water Resources Management Authority in Kenya (WRMA), are conducting periodic river gauging and sediment discharge monitoring in critical parts of the watershed and are also producing maps from high-resolution satellite images that show where and how the watershed is being degraded by quarry chains, upstream farming and other development. Quarries typically do not occur in isolation, but appear as an interconnected series of open pits called quarry chains.

Preserving ecosystem services benefits people and environment

Based on cost-benefit analyses, researchers are able to recommend ecosystem-based approaches to mitigate sedimentation and erosion in the predominantly rural upstream watersheds that can safeguard the quantity and quality of water for downstream users.

"The goal of the project is to inform investment decisions and encourage public policies that will ensure the sustainable use and restoration of ecologically important areas," said Fred Kizito, senior soil scientist for CIAT in Kenya.

Exploring incentives for change

The methodology developed for the Upper Tana River basin is expected to be replicated in other watersheds across Africa. The idea is that a comparative analysis of ecosystem services in different landscapes and among different livelihood scenarios can help scale up work.

Researchers are also assessing possible incentives for farmers and governments to invest in land restoration efforts. Scientists will be exploring new approaches to understand, monitor and evaluate land degradation and will consider incentive schemes such as carbon credits, subsidies and rewards for ecosystem services. Women, youth and marginalized groups will be brought into the discussions through direct participation in conservation activities and joint planning workshops.

New technologies pave the way

WLE scientists are using state-of-the-art techniques to produce land-use maps and classify vegetation. This also involves very high-resolution satellite imagery and remote sensing tools. Simulations are being done to forecast how degraded areas are likely to impact the sedimentation of rivers in the watershed.

Quarry locations are being mapped, and scientists are studying the biophysical and socioeconomic variables and putting together statistical profiles that will help identify crop lands at risk of being converted into quarries.