Export with consideration of upstream flow detention – new automation with improved functions
The developed export function now facilitates the export of upstream sub-catchments, including flow detention to downstream areas. This capability supports designs that consider upstream flow detention and enables the simulation of sequential sub-catchment detention facilities.
This development allows for the evaluation of interactions between detention volumes across various rainfall durations and the optimization of design outflows for both upstream and downstream facilities. In some cases, this can significantly impact the efficiency of these facilities.
Transport time, calculated for the flow path between the upstream and the downstream facility, is a new parameter implemented to refine accuracy in calculation of downstream flow detention volume when considering upstream flow detention. The transport time determines how the upstream flow impacts the downstream facility for different rainfall durations. It is also used to calculate the longest flow path within the composite catchment area, relevant for longer durations where flow detention does not occur upstream.
The results will indicate when upstream detention effectively influences downstream areas and when it does not. This optimization considers varying runoff times within sub-watersheds, transport times between upstream and downstream facilities, and outflows, in line with the methodologies of Giudice et al. (2014) and Ngo et al. (2016).