In a first-ever “world-wide synthesis”, an international team of scientists has analyzed data on 23 “drivers of environmental stress” that impact the health and quality of the world’s major rivers. The findings: 65% of the world’s riverine ecosystems are “moderately to highly threatened”.
The team’s assessment is the first to “jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts.”
Owing to a concomitant failure to invest in river protection, along with continuous pollution (mostly agriculture run-off), wetland conversion (for housing), dam building and other “waterworks” engineering projects, the threats facing our world’s rivers stand to impact the “water security” of an estimated 5 billion people — nearly 80% of the world’s population.
Reporting in last week’s edition of the journal Nature (‘Global threats to human water security and river biodiversity’, Vorosmarty et al), the scientific team’s data analysis also revealed that the most threatened rivers are those found in the most developed (“richest”) nations — the United States and several European states. However, according to the report, these nations are “able to off-set high stressor levels without remedying the underlying causes” through massive water technology investments. Poorer nations cannot afford this, and consequently, are more vulnerable.
Rivers are sometimes referred to as the “arteries” of the planet, as they link up continents, through coastal zones, with the world’s seas and oceans. Collectively, it is estimated that rivers provide the world’s human population with several trillions of dollars in ‘ecosystem services’, the most crucial of which is water for drinking and agricultural uses. In addition, riverine ecosystems provide habitat for over 120,000 species of animals and plants, with nearly 1/6 of this total threatened with extinction.
The team describes their findings as “conservative” since data was lacking for other stressors such as mining wastes, pharmaceutical compounds, large-scale, inter-basin water transfers (such as with the Colorado River), as well as the impacts from climate change (e.g., changing precipitation patterns due to greater aerosol accumulation).
Protecting river watersheds can not only save enormous amounts of money through flood protection and lessening the need for drinking water treatment, but also, such protections can generate income for rural peoples through preserving fish spawning grounds, amongst other services.
In regards to flood protection, this point was tragically made by the devastation wrought by Hurricane Katrina. Contrary to popular belief, the failed levies were not the primary cause of the devastation to New Orleans. Rather, the systematic removal of wetlands (salt marshes) and barrier islands from the mouth region of the Mississippi River allowed the storm surge to achieve greater impact than it would have with the marshes left intact. Spartina grass-covered marshes, which are typically built-up by downstream river sedimentation, act as vast, natural “sponges” that absorb excess water and serve as a buffer to storm surges, protecting coastal populations. As of 2010, approximately 50% of coastal wetlands in the U.S have been destroyed.
Quoting from the paper’s abstract: “The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity.”
For further reading on this issue, check out the IPS story by Stephen Leahy, Engineering a Water Crisis in Rivers.
To follow the on-going assessment of the world’s rivers, check out riverthreat.net
Related Story: Unsafe Water Kills More People than War: Study
Chart source: riverthreat.net; also, supporting on-line material for the Vorosmarty et al paper (Nature.com), see links above.
Bottom photo: USCG