Quantitative assessment of the tradeoffs between conventional “hard” civil infrastructure and nature-based solutions for climate change adaptation

The fundamental water resources problem to be solved in adaptation to climate change is increasing rainfall variability: generally, flood peaks are increasing, and dry-season water availability is decreasing. Large, centralized adaptation strategies such as reservoirs impounded behind tall dams typically perform well at both attenuation of flood peaks, and augmentation of dry season flows. They come with substantial costs, however, in terms of capital cost outlays and damages to local ecological and human environments. The Intergovernmental Panel on Climate Change, the United States (US) Government, the European Union, the United Nations, and many other institutions and agencies are currently advocating for the adoption of “nature-based solutions” (NbS), which are believed able to reduce adverse climate change impacts at community scale, while supporting biodiversity and securing ecosystem services. However, the potential of NbS to provide the intended benefits has not been rigorously assessed. This talk presents a preliminary assessment of climate change vulnerabilities for the Chimanimani biosphere reserve in Zimbabwe, and an evaluation of the tradeoffs between conventional “hard” civil infrastructure and decentralized NbS.