Rainwater harvesting: TTT

Subcatchment element as displayed in the TT menu

Storage element as displayed in the TTT menu

Once the size of cistern has been determined, it can easily be modeled in many open source and proprietary applications. For planning purposes, a RWH system can be integrated into a site plan as a storage element, using the TTT.

1. Create subcatchment for harvesting rainwater.

Stage Storage Stage Storage Storage type No removal Catchment In many scenarios this will be the roof area, delineated on the map as a 'subcatchment'. ? Lined Underlying soil Any:This doesn't matter for RWH cistern systems Evaporation factor 0 Suction head (mm) 0 Saturated conductivity (mm/hr) 0 Initial soil moisture deficit (fraction) 0 The dimensions of the rainwater cistern can be placed into the fields: Bottom elevation (m) Maximum depth (m) Initial water depth (m) The Curves table is designed to accommodate ponds of roughly conical dimensions. A rainwater cistern is usually cuboid or cylindrical in shape, so that the area (m2) will remain the same throughout the depth.

Tank used to store rainwater (typically roof runoff) for later use.

Rainwater harvesting.

The land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale.

Abiotic transfer of water vapour to the atmosphere.