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| Elements | Water flows | ||
|---|---|---|---|
A | = area | P_atm | = precipitation |
atm | = atmosphere | E_atm | = evaporation |
PR | = paved roof | T_atm | = transpiration |
CP | = closed paved | R_up | = decoupled runoff |
OP | = open paved | R_ow | = runoff to open water |
UP | = unpaved | I_uz | = infiltration |
OW | = open water | P_gw | = percolation |
UZ | = unsaturated zone | D_ow | = drainage |
GW | = groundwater | S_out | = downward seepage |
MSS | = mixed sewer system | R_mss / R_swds | = runoff to sewer systems |
SWDS | = stormwater drainage system | SOF | = sewer overflow on street |
SO | = sewer overflow | Q_ow | = discharge to open water |
WWTP | = waste water treatment plant | Q_out | = discharge to outside / WWTP |
History
Originally the time step was 1 day. That way time series of more than 100-year rainfall and evaporation could be managed in EXCEL. A smaller time step could also be applied (1 hour, 15 minutes, 5 minutes). However, because of the limitations of EXCEL, a smaller time step implies much shorter time series. Transforming the water balance tool to a set of Python scripts solved this limitation. This set of Python scripts that has been combined in the Urbanwb model. This documentation describes the Urbanwb model.
Model purpose
This tool has been developed to determine the return periods of runoff events for relatively small urban areas in which the basic hydro(geo)logic conditions are assumed to be similar for the entire area. Determination of runoff return periods requires large time series of rainfall and evaporation, preferably at least 30 years.
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