Collection of water in Independent Quarry
Situated on beds of limestone, the restored Independent Quarry will,like all other quarries on Portland, be a very dry place. Any pond will only be sustainable if it continuously receives an input of water from the landscape.
Elevated structures such as the planned stone summits would provide ideal surfaces for the collection of atmospheric water on foggy mornings. This would be greatly enhanced if the structures were made of appropriate materials and in an appropriate shape.
Like glass, limestone is naturally hydrophilic, which is to say that water will tend to collect on it. In contrast hydrophobic materials such as wax tend to resist water and provide ideal surfaces for encouraging water run-off. If hydrophilic limestone collecting areas were combined with hydrophobic channels you would have the ideal water-collecting system. This is the principle employed by the Darkling Beetle in the Namib Desert. These beetles survive without water by climbing up to the tops of the sand dunes each morning and pointing their abdomen upwards into the moist winds that blow in from the nearby ocean. Water collects on their hydrophilic abdomens and is channelled through waxy hydrophobic grooves towards their mouths. The best solutions are often found in nature.
The ideal shape for a water-collecting structure would be tree-like, branching up into the atmosphere from a single trunk. Such a shape would not be practical if made out of stone, being too fragile to resist weather and the attentions of vandals. Alternative designs would still need to maximise surface area, whilst encouraging run-off into channels. I would suggest vertical surfaces arranged in a variety of directions to intercept prevailing winds. A traditional stack of cuboid stones would work, particularly if there were wide channels between the stones to provide greater surface area. There is plenty of potential for other more artistically-inspired designs.
Running down from these structures would be channels cut into the stone. These could be made to be hydrophobic with a layer of wax, or lined with some other material so as to provide a visible design. In turn these channels would lead into some sort of piping or gutter system taking the water into the pond area. Ideally these would be made to look like natural streams and waterfalls (on a tiny scale, we're not talking Niagara here!). If glass beads could be embedded into the wax, the combination of the hydrophilic glass and the hydrophobic wax would make a surface even more efficient at harvesting water, closer to the beetle's design.
Here's a reference from Oxford University on the Darkling Beetle:
http://www.netzeitung.de/wissenschaft/166251.html
Bob Ford.