The Breadbasket of Tanzania

The focus of this blog post is policy documentation from the International Union for Conservation of Nature (IUCN) Water and Nature Initiative (WANI) case study, looking at the Pangani River Basin (PRB) in North-East Tanzania (Welling et al 2011). The basin covers an area of 56,300 km² (95%) in Tanzania, with 4,880 km² (5%) of this situated within Kenya (Welling et al 2011). In order to improve management of the limited water resources available for the basin's 3.4 million inhabitants and gather technical information, with an overarching aim of strengthening Integrated Water Resources Management (IWRM), the Pangani River Basin Management Project (PRBMP) was set up in 2002.

A map of the Pangani River Basin (Source: Pangani River Basin, Tanzania Report)

Fertile soils and abundant rainfall mean this basin has been referred to as the 'breadbasket of Tanzania' (Welling et al 2011). In 2011, it was estimated by the WANI case study that ~55,000ha of the basin was being intensely irrigated with inefficient furrow irrigation. As well as irrigation, water from the multiple rivers constituting the basin serve several hydroelectric power (HEP) stations, collectively providing 17% of Tanzania's electricity demand (Welling et al 2011). Together, irrigation and HEP use nearly 90% of surface flow in the Pangani (Barchiesi et al 2011).

Problems within the basin

The basin is already defined as water-stressed (<1200m3 water per person, per year), and thus climate change is exacerbating the problem of there not being enough water supply to meet demands (PRBMP 2015; Welling et al 2011). We saw in my last post that Mount Kilimanjaro's glaciers are receding at dramatic rates due to impacts of climate change, and this is impacting flows in the nearby PRB (IUCN 2011). Flows which used to be several hundreds of metres per second have diminished to below 40m3 (Welling et al 2011; IUCN 2011)! The combined effects of 1.8-3.6°C temperature rise in Tanzania, intensified and unpredictable precipitation patterns, and increased evaporation and evapotranspiration are expected to cause a 6-10% decline in annual basin flows (PRBMP 2015). The reduction in river flow has already caused seawater intrusion 20km upstream from the estuary (PRBMP 2015) and thus future additional reduction will put livelihoods, industry and the economy of Tanzania at stake.

A warming world, with urbanisation, population growth, intensified agriculture, and rising energy demands have all led to increased competition and overexploitation of water resources in the basin (Barchiesi et al). This has caused conflicts to emerge between various stakeholders, such as large-scale and small-scale farmers, livestock keepers, coastal communities, and HEP producers downstream (Welling et al 2011; PRBMP). There is not enough physical water available in the basin to meet the allocations made, thus over-allocation of limited supplies is a key issue to be resolved by the PRBMP.

How to manage these issues?

A growing awareness of problems in the PRB has stimulated action, both in the form of governments and stakeholders. The PRBMP have undertaken climate change modelling assessments, groundwater studies, and integrated flow research in order to improve understanding of environmental flows and thus to better inform decision making for allocation of water in the basin. I believe that encouraging community participation and IWRM, getting opinions and perspectives from all stakeholders, will hopefully reduce conflict between users of the basin in a modifying climatic future.