Dear Ms Suzette Schreuder,
Thank you for your question.
Coping with the decline of natural resources, like water scarcity, is a vital challenge of Making Cities Water Resilient. As addressed by the Asian Development Bank (ADB), solutions imply raising resilience to national water security (Asian Water Development Outlook 2013) in following key dimensions:
- Household – supply of drinking water,
- Economic – fresh water supply for food production,
- Water-related disasters – recharge groundwater to limit ground subsidence.
Connecting thread is the implementation of dynamic water resource management in the built environment. This is an attractive ambition and is further justified by the 1st pillar of the Water Sensitive City framework: building flexibility and adaptability in our water sources - “Cities as Water Supply Catchments”.
This means achieving self-sufficiency of cities by considering the re-use of supplied (potable) water and the use of alternative water sources to limit groundwater extractions. At the same time many cities are sensitive to ground subsidence because of large scale groundwater extractions. Among these so-called “sinking cities” are the urban dense areas of Bangkok, Jakarta, Ho Chi Minh City, Mexico City, Manila and West Netherlands. In the 1970s the Japanese managed to slow down and even stop the Tokyo subsidence rate. This was only possible through an extreme decision: by ending ground water extractions and transferring to other water sources, like: rain, sea and surface water.
Especially rainwater harvesting & use on a large scale is recognized as potential opportunity to deal with water scarcity and achieve self-sufficiency and more regenerative cities of tomorrow. Front-runner examples in urban dense areas are found in Japan (building scale), Australia (building and district scale) and Singapore (city scale).
Kind regards, Nanco Dolman