Channels, ponds, reservoirs, culverts, and other natural or constructed drainage features in a watershed affect the runoff from the watershed. Thus data that describe those must be collected.

For a conceptual model, data about the features are needed to make a decision about which model to use and configure the model appropriately. For example, with a , data describing channels are needed to select, calibrate, and use a routing method that accounts for the impact of a channel on the design flood peak.

For an empirical model, data on drainage features is needed first to enable wise decisions about which model(s) to use, and second, to estimate model parameters. For example, require that the streamflow records be without significant regulation. To determine if this is so, the designer must have information on regulation in the watershed, including descriptions of ponds, reservoirs, detention structures, and diversions in the watershed.