The Probability Distributed Model (PDM) is a general-purpose, lumped conceptual model for continuous rainfall-runoff simulation (Moore, 2007). The PDM model incorporated within InfoWorks ICM is based on the model developed by the UK Centre for Ecology and Hydrology (CEH) © 2000 NERC CEH Wallingford.
General form of the PDM rainfall-runoff model
Using the PDM model
To use the PDM runoff volume model, set the Runoff volume type field of the Runoff surface to PDM.
Subcatchments referencing a PDM runoff surface must also reference a PDM Descriptor object. The descriptor is used to define the PDM rainfall-runoff model parameters.
A PDM Descriptor's parameters can be automatically calibrated using observed rainfall, flow, potential evaporation and temperature from a Scalar TSD object to optimise the values used by the PDM descriptor.
Using the PDM model for warming up the network
The PDM model can also be used to warm-up the network before any hydraulic simulations are run. This allows it to reach a steady state and thus provide more realistic hydraulic conditions when a simulation starts. See Schedule Hydraulic Run View for further information.