MODEL SELECTION AND APPLICATIONS FOR TOTAL MAXIMUM DAILY LOAD DEVELOPMENT

This chapter presents an approach to model selection for total maximum daily load (TMDL) determination, allocation, and implementation planning to attain the water quality standards in impaired waterbodies. Determination of a TMDL is the numerical quantification of the total allowable load or waste assimilative capacity of the receiving waterbody. Model sophistication is the degree of development defined by reliable process integrity of the underlying physical, chemical, or biological processes being simulated. The chapter also presents an overview of the major considerations for a holistic approach to model selection for TMDL determination, allocation, and implementation planning. Several technical and management considerations affect the TMDL model selection process. The chapter highlights how model selection should consider model calibration and validation after the selection. It provides a concise overview of TMDL model calibration, validation, sensitivity, and uncertainty analysis to define technical criteria that must be considered in model selection.