Image: De Urbanisten and Studio Marco Vermeulen
Two Dutch architects want to alter the storm drainage system of the city of Rotterdam to redirect water into playgrounds. The water will be used to fill fanciful ponds and moats for children to play in/around:
In Florian Boer and Marco Vermeulen's proposal, rainwater runoff isn't funneled into a complex system of underground pipes, a system that is rather expensive to build and maintain, but is managed instead through a network of surface reservoirs, the Waterpleinen, or Watersquares. These storage spaces will be dry for most of the year, but during storm events, they will collect water from the surrounding neighborhood. If one reaches capacity, excess water will overflow into another basin. After the rain, the collected water will slowly recede into nearby bodies of water or seep into the soil.
So instead of being buried in concrete, excised from the daily life of the city and only experienced by municipal workers, urban hydrology is visibly, even prominently, incorporated into the surface fabric of the city. Programmed with recreational opportunities when its dry and even while inundated, its infrastructure provides active public spaces for the local area, not dark playgrounds for a handful of urban explorers. It even becomes an event, its frolicking rivulets and interior lakes staged for the young and old.
Link via Fast Company
BTW - the two examples you provided look like great implementation of water and concrete, but the intention of the space is different. I don't think there is anything wrong with those spaces because I suspect people realize there is reason to take caution, whereas the space proposed in this project would encourage different behavior.
When I was a kid, playgrounds were made of huge wooden beams, metal poles, chains and tires, surrounded by yards of gravel, all potentially injury-inducing. I survived and so did all my friends. We also learned to look where we were going, that splinters wouldn't kill us, that crushed rock wasn't something to wrestle on, and most important, sliding down the slide in shorts during the height of summer was a very bad idea.
When I was a little bit older, I enjoyed running around the Leonhardt Lagoon in Dallas (http://tinyurl.com/ydtknty) and the Fort Worth Water Gardens (http://en.wikipedia.org/wiki/Fort_Worth_Water_Gardens), both of which comprised -- guess what -- concrete and water.
I know I'm turning into a crotchety old man, but frankly today's plastic-bubble playgrounds make me sad. Raising kids in an entirely padded environment produces adults with no coping skills the same way raising them in a sterile, antibacterial setting produces adults with weak immune systems.
Let your kids get a few bruises and scrapes! Concrete only hurts when you aren't careful.