Ecosystem Services Delivery in Sub-Saharan Africa

Hello all!

In my previous post, I elaborated a bit on the physical characteristics of Sub-Saharan Africa. In this post, I will be using two case studies to illustrate the ecosystem benefits from water resources, from the previously mentioned wetter areas that span across Sub-Saharan Africa (western and central Africa).

The Hadejia-Nguru Wetlands, Western Africa (Barbier and Thompson, 1998: 435)

Figure 3. Hadejia-Nguru River Basin, comprising of the Hadeija-Nguru Wetlands (circled in blue) and the upstream irrigation projects of Hadejia Valley Project and Kano River Project (circled in red).

The Hadeija-Nguru wetlands are formed where the Hadejia and Jama'are rivers converge to form the Yobe River in Nigeria, circled in blue in Figure 3. Extensive areas up to 1000km² are inundated in August and September during the rainy seasons when the ITCZ shifts northwards as Nigeria lies at a latitude of 9°N (recall: physical characteristics of Africa); outside of these rainy months, the floodplains remain dry. Here is a brief list of the floodplain ecosystem benefits using the CICES framework:

1. Provisioning services: Earnings from sales and food consumption from agricultural products, grazing, fuelwood and fishing. Dry-season grazing for nomadic pastoral farmers. Agricultural surpluses for other cities. Migratory habitats for wildlife (eg. wader birds).

2. Regulation and maintenance services: Recharge of the aquifers within the Chad formation.

3. Cultural services: Ecotourism for educational and scientific purposes due to its rich habitat.

With increasing pressure from droughts and dam construction in the Sub-Sahara African region, it has been found that existing wetlands in Africa have increasingly fragmented into isolated pockets; natural wetland connectivity with the annual floods have therefore been lost (Stratford et al. 2011). I will expand more on the valuation of these ecosystem services for the management of wetlands later, as they are currently beyond the scope of understanding of this entry.

The Mara River Basin, Central Africa (Dessu et al. 2014)

Figure 4. The Mara River Basin, with the lakes and rivers outlined in blue (Dessu et al. 2014: 105).

The Mara River drains a combined area of 13,750 km² spanning across Kenya and Tanzania as seen in Figure 4. The Nyangores and Amala rivers are perennial due to the orographic effect from higher altitudes in the north, while the Talek and Sand rivers are ephemeral due to lower altitudes in the west. The livelihoods in the Mara River Basin rely heavily on these rivers for the provision of ecosystem services as seen below:

1. Provisioning services: Economic benefits from farming, livestock husbandry (major economic activity of Massai Tribe), and high-grade gold mining. Tea plantations, rain-fed wheat farms and commercial irrigation farms contribute to food security of Kenya. Forests contribute to economy through logging and charcoal burning.

2. Regulation and maintenance services: Recharge of sub-basins in low flow months of February and March. Carbon sequestration by the forest reserves in the north.

3. Cultural services: Tourism (accounting for 8% of all tourist bed nights, revenue of $20 million).

Similarly, loss of native forest cover, agricultural intensification, growing tourist facilities and pollution have altered the river's natural hydrological regime, resulting in lower low flows and higher peak flows. The population in the Mara River Basin however, is projected to increase through the 21st century, and the basin may therefore experience severe pressure on water resources.

In these two case studies, I have briefly covered the ecosystem benefits delivered by wetlands and rivers to the human population in two regions of Sub-Saharan Africa. In my next post, I will talk about methods of ecosystem valuation of water, and subsequently cover case studies of examples doing so.

See you next week!