Natural habitats and vegetated ecosystems are vital to maintaining the health and quality of urban water resources. Environmental restoration and conservation practices such as reforestation, stream bank restoration, erosion control and agricultural best practices can go a long way towards improving water quality for millions living in urban areas. The Nature Conservancy in collaboration with the International Water Association and the climate leadership group, C4O Cities have developed the Urban Water Blueprint which analyzes and evaluates water quality in upwards of 2,000 watersheds and 530 cities. Their aim is to provide science-based recommendations to help develop natural solutions which can be integrated into infrastructure to improve urban water quality.
More than half of the world’s population lives and works in cities, all of which, regardless of size or population density, require a clean, safe, reliable water supply. Demand for water rises and with it so does spending, neither of which help with the growing scarcity and insecurity of this vital resource. Weather patterns have become less predictable, while multiple users compete for depleted and degraded resources while mistrust grows among them. The Urban Water Blueprint report discusses how addressing these challenges via investing in nature will produce positive returns. Specifically evaluated within this document is source watershed conservation as a solution to the growing urban water crisis.
Scientists from the contributing organizations noted above present findings from their research on how and where watershed conservation strategies can have a significant impact on drinking water—drawing on three years of comprehensive, in-depth analysis of the source watersheds that serve over 500 medium and large cities worldwide. Cities occupy only 1% of the planet’s actual land area while their supporting watersheds sprawl over 12%. This translates to approximately 1.7 billion hectares of land which collects, filters and transports water to almost a billion dependant people before even reaching man-made infrastructure.
Land use heavily influences the availability, quality and cost to treat and transport this water supply. Currently, on average, source watershed lands are occupied by 40% forest, 30% cropland and 20% grassland and pasture. In developing areas land is likely to be used most often for agriculture. When there is no buffer between agricultural land and water bodies, water quality can easily be degraded by nutrient-enriched runoff. With cropland projected to increase by at least 10% over the next 15 years this problem may become more severe. When forest lands are converted to cropland and pastures sedimentation into streams and rivers is increased further degrading water quality. The trajectory of this development is unsustainable for water quality in the U.S. and around the world.
The Urban Water Blueprint proffers watersheds as natural infrastructure as a conservation strategy to combat this current trajectory. In order to determine the efficacy of watershed conservation as a means of securing water quality for cities researchers evaluated 5 common conservation strategies: land protection, reforestation, riparian restoration, agricultural best management practices, and forest fuel reduction. Each strategy was analyzed for its effectiveness in reduction of sedimentation and nutrient pollution in more than 2,000 source watersheds that serve over 500 cities:
- Forest Protection: Purchase of easements, land rental, fencing out cattle, and funding for park guards to
maintain watershed services,
- Reforestation: Restoration and planting of native trees, grasses, and shrubs in critical areas to
reduce erosion and related sediment transport,
- Agricultural Best Management Practices: Implementation of cover crops, contour farming to prevent—and wetland and terrace
construction to trap—sediment and nutrient runoff,
- Riparian Restoration: River bank restoration and protection to reduce erosion and improve water quality,
- Forest Fuel Reduction: Conducting controlled burns and/or mechanical treatment to reduce wildfire severity
and related sediment and ash pollution.
For more information on watershed conservation and protection and what you can do to help, visit: http://water.nature.org/.