The team approached the hydraulic design of the irrigation and stormwater management system as a water balance problem. There are several process streams in this system, including: rainfall, evapotranspiration, runoff/drainage from the green roof to the cisterns, water pumped from the cisterns to the green roof, inflow from Calvin’s irrigation system to the cisterns, and emergency outflow from the cisterns to the storm sewer. Daily flows of water within these process streams were quantified and analyzed in an Excel spreadsheet (Appendix A shows how this spreadsheet was set up). This spreadsheet acted as a tool to make design decisions. A process schematic diagram of the system is shown in Figure 2.
See design report for more details and calculations