The initial states for 2D mesh elements are based on a basic inverse distance interpolation method following Modified Shepard's Method.
The state variables for each 2D element are based on the variables on the neighbour elements within radius specified by the user, weighted by a weighting function of the type:
where i is the index of the elements whose centre is located within a distance R from the target element.
The radius and weighting are specified in the State search radius and State power parameter fields in the InfoWorks and SWMM 2D Parameters dialog.
The final value for a variable v in an element j will be given by:
The interpolation algorithm estimates an elevation for each element in the 2D mesh, compares it with the ground level of the element. If the resulting depth is positive, then it interpolates other variables such as velocity, solutes, etc.
Elements in the network which is being initialised, that do not have any source element within the radius distance, will not be initialised with any data, and a warning is included in the log file. If there are 2D IC zones in an InfoWorks network, they are applied after the initialisation is performed, and will overwrite initial state data.