Development Aspects Impressum Editors

Sustaining broader system-wide ecosystem services

The topic of managing natural infrastructure to meet water-related goals often extends well beyond addressing water quantity and quality issues for direct human use. Water underpins all ecosystem functions, so water management potentially affects all ecosystem services. One of the greatest needs is to expand the thinking on water management beyond immediate-use issues into the broader context of balancing the delivery of all ecosystem services. This is a big topic, but an example of the need to think more broadly, demonstrating the value and importance of natural infrastructure, is illustrated by water-management issues and solutions for the Mississippi River delta (Box 5).

Box 5: Rethinking water management through an ecosystem services framework: disaster risk transfer and mitigation in the Mississippi Delta, USA

River deltas are dynamic and complex ecosystems driven largely by hydrology, in- cluding the regular transfer of sediments and nutrients from the catchment into lowlands and the estuary. Their functioning underpins numerous ecosystem ser- vices, in particular land regulation and formation. This, in turn, delivers benefits through the maintenance of coastal stability and erosion regulation, thereby, for example, reducing disaster vulnerability. The Mississippi River Delta, in common with many rivers, has been highly modified: its hydrology has been changed through water abstraction, principally for agriculture, while reservoir construction, also for hydropower, has interrupted sediment transfer. Additional infrastructure has had to be added, with high investment and operational costs, which effectively are required to compensate for losses in the services originally provided by natural infrastructure; examples include continual dyke and coastal defence development and maintenance in order to deal with a de-stabilizing estuary.

The resulting degradation of associated wetlands infrastructure is now widely re- garded as a major contributing factor to the scale of economic and human losses re- sulting from hurricanes. Hurricane Katrina (2005), in particular, was a catastrophic reminder of the pitfalls of paying insufficient attention to managing natural infra- structure as an asset. If treated as an economic asset, the minimum asset value of the natural infrastructure provided by the delta would be US$330 billion to US$1.3 tril- lion (at 2007 values) in terms of hurricane and flood protection, water supply, water quality, recreation and fisheries. Importantly, studies suggest that rehabilitation and restoration of this natural infrastructure would have an estimated net benefit of US$62 billion annually. This includes reduced disaster-risk vulnerability and savings in capital and operational costs for physical infrastructure-based solutions (includ- ing factoring in the economic costs for existing users of reallocating water use).
Agriculture has historically been a key driver of water-allocation policy. Yet the value of food and fibres produced by agriculture represents only a fraction of the value of the multitude of other services provided by the ecosystem, particularly by wetlands. Historically, planning has achieved reduced risks to agriculture (i.e., by a more stable water supply for crops), using physical infrastructure, at the expense of transferring risks downstream by undermining natural infrastructure there.



Source: Batker and others (2010).

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