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Calculates states and fluxes on Paved Roof during current time step.
Parameters:
- p_atm (float) – rainfall during current time step [mm]
- e_pot_ow (float) – potential Open Water evaporation during current time step [mm]
Returns: A dictionary of computed states and fluxes of Paved Roof during current time step
- int_pr – Interception storage on Paved Roof after rainfall at the beginning of current time step [mm]
- e_atm_pr – Evaporation from interception storage on Paved Roof during current time step [mm]
- intstor_pr – Remaining interception storage on Paved Roof at the end of current time step [mm]
- r_pr_meas – Runoff from Paved Roof to measure during current time step (not necessarily on Paved Roof itself) [mm]
- r_pr_swds – Runoff from Paved Roof to storm water drainage system (SWDS) during current time step [mm]
- r_pr_mss – Runoff from Paved Roof to combined sewer system (MSS) during current time step [mm]
- r_pr_up – Runoff from Paved Roof to Unpaved during current time step [mm]
Return type: (dictionary)
2.2 Closed Paved
Closed Paved areas are mainly areas with paved covers like roads, parking lots, driveways, etc. that are made of impermeable material like cement and bituminous concrete pavement. In terms of conceptual modelling mechanisms, Closed Paved is quite similar to Paved Roof. On the surface of a typical impermeable paved area, a small amount of rainwater is intercepted as surface ponding which can only be emptied through evaporation. Rainfall exceeding the interception storage capacity will generate runoff, which flows to the sewer system (SWDS and/or MSS). The disconnected fraction of runoff is assumed to flow to the Unpaved area (UP). Figure 5 provides a schematic overview.
Figure 5 Schematic overview of Closed Paved (CP) in Urbanwb
2.2.1 Assumptions
- Rainwater falling on the Closed Paved is first ponded as surface interception storage and depleted by evaporation, then the excessive rainwater becomes runoff. In other words, only rainfall exceeding the interception storage capacity runs off. Provided that a very large interception storage capacity on Closed Paved is predefined, there is no runoff generated.
- Runoff on the Closed Paved is redistributed to sewer system (SWDS and MSS) and Unpaved (UP) by predefined ratios. If part of Closed Paved area is disconnected to the sewer system, that disconnected fraction of runoff flows to Unpaved area by assumption. Connected runoff on Closed Paved flows to the storm water drainage system (SWDS) or (and) combined sewer system (MSS) at predefined proportions.
2.2.2 Calculation order
- Initial interception storage on Closed Paved at the beginning of current time step is the remaining interception storage on Closed Paved at the end of previous time step plus rainfall at current time step, and it is limited by predefined interception storage capacity on Closed Paved.
- (Actual) evaporation from interception on Closed Paved during current time step is limited by potential Open Water evaporation and available initial interception storage on Closed Paved during the same time step. Evaporation is possible only if the interception storage contains water.
- (Final) interception storage on Closed Paved at the end of current time step is evaporation subtracted from initial interception storage.
- (Total) runoff from Closed Paved during current time step is rainfall subtracting actual evaporation and the change in interception storage between the same time step and previous time step. Total runoff from Closed Paved is redistributed to the measure (Meas), sewer system (SWDS and MSS) and Unpaved (UP) at predefined ratios.
- Subtracting the runoff to the measure from the total runoff is the remaining runoff. Connected remaining runoff is reallocated to storm water drainage system (SWDS) and combined sewer system (MSS) at predefined proportions while disconnected remaining runoff flows to Unpaved area (UP) at predefined ratios.
2.2.3 Code and input arguments
class urbanwb.closedpaved.ClosedPaved(intstor_cp_t0, cp_no_meas_area, cp_meas_area, cp_meas_inflow_area, intstorcap_cp=1.6, swds_frac=1.0, discfrac_cp=0.0, **kwargs) [source]
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