By Vladimir Smakhtin | Inter Press Service
TOKYO, Japan—Almost every day we hear news about catastrophic flooding or drought somewhere in the world. And many nations and regions are on track for even more extreme water problems within a generation, the latest Intergovernmental Panel on Climate report warns.
Extreme floods and droughts have a profound impact on development, particularly in less developed parts of the world. About 140 million people are affected—displaced by the loss of incomes or homes—and close to 10,000 people worldwide die annually from these twin calamities.
Global annual economic losses from floods and droughts exceeds $40 billion; add in damages from storms like America’s recent Hurricanes Florence and Michael, and cost numbers balloon.
Flood and drought economic losses—comparable in dollar terms to all global development aid—strongly affect the water, food and energy security of nations.
To help cope with these problems, massive investments continue to be made in large reservoirs.
However, in certain regions it has started to make little engineering sense to build additional “gray [concrete and steel] infrastructure” due to a lack of suitable sites and/or rapid evaporation.
In others, aging gray infrastructure may no longer provide their originally envisioned benefits because hydrological parameters and patterns are changing.
The appropriate response is to recognize the benefits of “green [natural ecosystems] infrastructure” and to design gray and green infrastructure in tandem to maximize benefits for people, nature and the economy.
Such “Nature-Based Solutions” were the theme of this year’s UN World Water Development Report.
Nature-Based Solutions, include, for example:
- Soil moisture-retention systems, and groundwater recharge to enhance water availability;
- Natural and constructed wetlands and riparian buffer strips to improve water quality; and
- Floodplain restoration to reduce risks associated with water‐related disasters and climate change.
The role of green water-storage infrastructure is particularly important. The enormous potential of such approaches are being fully understood only now but its clear that green infrastructure can directly improve the performance of gray infrastructure for disaster risk reduction.
Indeed, large-scale managed aquifer recharge efforts can, in certain conditions, alleviate both flood and drought risks in the same river basin.
Recent studies suggest that, in a river basin greater than 150,000 km2 in area, with only 200 km2 of land converted for accelerated groundwater recharge in wetter years, agricultural income could be boosted by about $200 million per year.
Not only is additional water made available to farmers in drier periods, downstream flooding costs can be eliminated. And the capital investment required could be recouped in a decade or less.
Such sustainable, cost-effective and scalable solutions may be especially relevant in developing countries, where water-related disaster vulnerability has risen to unprecedented levels and the impacts of climate change will be most acutely felt.
Nature-Based Solutions are not feasible everywhere and, where they would help, they alone are not the silver bullet solution for water risks and variability—they cannot be counted on to replace or achieve the full risk reduction effect of gray infrastructure.
Nevertheless, Nature-Based Solutions need to be considered in all water management planning and practiced where possible. Especially at river basin and regional scales, management planning should consider a range of surface and subsurface storage options, not just large concrete dams.