HR: 15:10h
AN: H13I-07    [Abstracts]
TI: Use of traditional and novel statistics to calibrate of hydrological model for TMDL analysis in the Calleguas Creek Watershedfor the TMDL analysis in the Calleguas Creek Watershed
AU: * Foglia, L
EM: lauraf@lwa.com
AF: Civil and Environmental Eng., UC Davis, One Shields Ave., Davis, CA 95616, United States
AU: * Foglia, L
EM: lauraf@lwa.com
AF: Larry Walker Associates, 707 Fourth Street, Davis, CA 95616, United States
AU: Mysliwiec, M
EM: mitchm@lwa.com
AF: Larry Walker Associates, 707 Fourth Street, Davis, CA 95616, United States
AB: A hydrologic model was developed using Hydrologic Simulation Program – Fortran (HSPF) for the Calleguas Creek Watershed (CCW) in Ventura County, Southern California, for flood control analysis. To provide decision support in total maximum daily load (TMDL) development, the model was expanded to simulate suspended sediment and particle associated and dissolved fractions of select metals and selenium all of which were also manually calibrated. A Pathogen TMDL is required for the CCW and it is desired to modify the available HSPF model of the watershed to simulate fate and transport of bacteria. Bacteria are difficult to measure and model and they can be attached to suspended sediment; thus, a detailed simulation of the sediment is required. For a Pathogen TMDL, it is commonly accepted that quantification of the uncertainty in the predictions is as or more important than the predicted value. In the present work, we decided to re-analyze the calibration of the hydrological model, and then add calibration of sediment and bacteria. The goal of the new model is to better match the low flow periods of record, sediment transport, and indicator bacteria than would be possible using the available model and hand calibration. The HSPF model was recalibrated using the automatic inversion code UCODE-2005. Furthermore, the utility of local sensitivity analysis, parameter-estimation using single objective-function optimization methods, and tests against new data to evaluate a fully distributed hydrological model are explored. The approach considered differs from other recent publications on analysis of hydrologic models in the weighting of observations based on an analysis of observation errors, the sensitivity analysis methods used, the single objective-function used for parameter estimation, and the combination of traditional and unusual (for hydrologic models) statistics considered to evaluate model fit. Traditional statistics, such as Nash and Sutcliffe coefficient, provide information on the overall result of the calibration and not on the single observation used. In the specific case, measures of leverage, Cook's D and DFBETAs, commonly used for groundwater models, are applied to the CCW hydrological model to evaluate the importance of the different hydrological observations used (here, daily values, monthly volumes and exceedance times) and to provide guidelines for the more complicated sediment and bacteria calibration.
DE: 1846 Model calibration (3333)
DE: 1871 Surface water quality
DE: 1873 Uncertainty assessment (3275)
SC: Hydrology [H]
MN: 2007 Fall Meeting