Fixing past failures to incorporate nature into infrastructure investments is costly. In another example, from the Komadugu Yobe basin upstream from Lake Chad in Nigeria, engineers built dams in the 1960s and ’70s to supply fresh water to the expanding urban population of Nigeria’s second largest city, Kano. Altered streamflow patterns downstream devastated ecosystems and a reduction in annual flooding meant a lack of water for crops. Fisheries, agricultural and pastoral livelihoods were destroyed. To overcome this ecological imbalance and restore the basin and food and water security for the 23 million people living there, in 2006 the Government of Nigeria and the governments of the six riparian states set up a US$125 million trust fund for the Komadugu Yobe Basin. Investment in the natural infrastructure of the basin means that river channels are being cleared, wetlands and fisheries restored and navigation is once again possible (Krehnak et al. 2011).
The key to working with ecosystems in the nexus is to be able to quantify the services they provide and estimate their economic value. Economic valuations from the infrastructure benefits of ecosystem services are based on market prices for products (e.g. wetland fisheries), the cost of replacing ecosystems through engineering (e.g. water filtration) or the costs of damage avoided (e.g. flood attenuation).
Strategies for investing in natural infrastructure can readily be incorporated into broader infrastructure packages but appropriate mechanisms for investment are needed. The major forms of investment in natural infrastructure