Regional Stormwater Quality Model Calibration using the National Stormw ater Quality Database

Many stormwater managers are frustrated by the large amount of data needed to calibrate and verify stormwater quality models. These data needs are usually divided into several broad categories: • development characteristics for the land uses of interest • rainfall and runoff data needed for describing the urban hydrology for the area • stormwater quality data for the land uses and complete range of rain conditions • performance data for the stormwater controls to be investigated It is a daunting (time-consuming and expensive) task to collect this information. However, the investment is usually worthwhile for an area that desires to make cost-effective and robust decisions concerning stormwater management for their area. Unfortunately, if the will and budget are available, it still requires a substantial amount of time to obtain the necessary information. One approach that can be taken as a preliminary step is to use available data from the National Stormwater Quality Database (NSQD) (Pitt, et al. 2004). This paper describes how information about regional land development characteristics for different land uses from throughout the country were integrated with the stormwater quality data contained in the NSQD to develop regional calibration files describing stormwater quality characteristics useful for water quality modeling calibration. These calibration sets can then be used in an area for preliminary analyses in the design of a local sampling program for verification of these calibration data for the area and for initial stormwater control design evaluations.