Undergraduate Thesis - Feasibility of Rainwater Harvesting in Paarden Island

The area that will be used to capture rainwater must be established to help with quantity calculations as well as identifying what the possible contaminants might be. Roof area is calculated by establishing the roof footprint. In most cases the rain will fall on the roof vertically down wards and as such the effective collection area would be the area that the roof projects on to the ground surface (Krishna, 2005) which is known as the roof footprint as shown in figure 3-2.

 

 

Figure 3‑2: Footprint of a building

Source: (Oregon Department of Consumer & Business Services, 2009)

 

Ground surface area is calculated to be the area that contributes to a single drainage point that is usually the where the water is collected and stored. This area is determined similarly to the way in which catchment areas are determined in hydrology.

 

 

Figure 3‑3: Sample of a delineated catchment used for hydrology calculations

 

Groundwater surface catchment is determined by the available areas within a catchment that will allow infiltration to occur. The rate of infiltration will depend on the type of soil that is present within the area.