Baseline review and ecosystem services assessment of the Tana River Basin, Kenya

Ecosystem services are commonly defined as the benefits received by humanity via functioning ecosystems. They can be broadly categorized as provisioning, regulating, cultural, and habitat services; with many services co-occurring and most ecosystems providing a wide range of services across several categories. Water mediates many ecosystem services and is in turn heavily influenced by land management decisions made at different scales from local to basin. Taking a holistic ecosystem services approach that focuses on maintaining healthy ecosystems as primary mechanisms for ensuring sustainable services delivery has been slowly mainstreamed into land management decision making worldwide. In addition, it is now often an important guiding principle in research for development programs. In many water-rich basins found in less developed countries, efforts are under way to increase energy resources via hydropower production as well as expand irrigation potential to increase food security. However, climate change threatens to undermine these goals - meant to spur development and alleviate poverty - by imposing risks and requiring decision makers to act under significant levels of uncertainty. Within Kenya, the Tana River Basin serves as an example where there are significant development targets for hydropower, domestic water provision, and irrigation; planned as part of Kenya's 2030 Vision. Currently, the basin supplies Nairobi with hydropower and nearly all of its domestic water resources through a series of water transfers and dams in the Upper Tana Basin. Historically, authorities have struggled to develop sustainable large-scale irrigation projects in the middle and lower basin, while the upper basin continues to be one of the most agriculturally productive regions within the country. Both hydropower production and irrigation expansion have been plagued by controversy with historical efforts leading to relocations and increased conflict. At present, the country is working to balance its need for water, energy, and food security with the preservation of ecosystems and ensuring the sustainability of the services they provide. The basin is home to two major biodiversity hot spots. At its headwaters, the Kenyan government actively manages the Afromontane forests of the Aberdare Mountain Range, which serves as one of Kenya's five main water towers by ensuring water quantity and quality of the waters supplied to downstream users. At the terminus of the Tana River, lies its rich delta providing numerous livelihood opportunities as well as supporting several endemic and endangered plant and animal species. There are critical concerns regarding how hydropower and irrigation development may affect this rich delta. In addition, alarms have been raised regarding how upstream land management practices may have deleterious effects on current and planned built infrastructure (e.g., hydropower and large-scale irrigation) in the basin. Under the WISE-UP to Climate project, natural infrastructure is explored as a 'nature-based solution' for climate change adaptation and sustainable development. The project is developing knowledge on how to use portfolios of built water infrastructure (e.g., dams, levees, and irrigation channels) and natural infrastructure (e.g., wetlands, floodplains, and watersheds) in tandem for poverty reduction, water-energy-food security, biodiversity conservation, and climate resilience. This paper presents a basin-scale summary of natural resources within the Tana River Basin and illustrates an overview of how people living within the basin rely on a wide variety of ecosystem services. In addition, the paper puts forth a first approximation of the key role natural infrastructure plays in supporting efforts to ensure water-energy-food security in the Tana River Basin. © 2012, by IWMI.