Coupling Tritium Release Data with Remotely Sensed Precipitation Data to Assess Model Uncertainties

Abstract

An accidental tritium release (570 L, 210 TBq) from the K-Reactor at the Savannah River Site (South Carolina, USA) occurred between December 22- 25, 1991. Observed tritium concentrations in rivers and streams, as well as in the coastal estuary, are used to calibrate a hydrologic flow and transport model, BASINS 4.0 (Better Assessment Science Integrating Point and Non- Point Sources) environmental analysis system and the HSPF hydrologic model. The model is used to investigate complex hydrometeorological and source attribution problems. Both source and meteorologic input uncertainties are evaluated with respect to model predictions. Meteorological inputs include ground-based rain gauges supple-mented with and several NASA products including TRMM 3B42, TRMM 3B42RT, and MERRA (Modern Era Retrospective-Analysis for Research and Applications) reanalysis data. Model parameter uncertainties are evaluated using PEST (Model-Independent Parameter Estimation and Uncertainty Analysis) and coupled to meteorologic uncertainties to provide bounding estimates of model accuracy.