HR: 0800h
AN: H11C-0638    [Abstracts]
TI: River junction and reach vulnerability prediction in urban watershed: a methodology for identifying structural uncertainty
AU: * He, Y
EM: yhe@mail.sdsu.edu
AF: San Diego State University, Civil and Environmental Engineering, 5500 Campanile Drive, San Diego, CA 92182, United States
AU: Beighley, R E
EM: beighley@mail.sdsu.edu
AF: San Diego State University, Civil and Environmental Engineering, 5500 Campanile Drive, San Diego, CA 92182, United States
AB: The mixing of water, solutes and sediments from two or more tributaries of urban watershed produces streamflow possessing unique biogeochemical, hydrological, morphological, and ecological signatures. To understand and predict these signatures, confluence locations within river networks are commonly used to divide a watershed into individual modeling units where hydrologic characteristics are spatially averaged and used to parameterize process models. In this context, model parameters from an individual unit directly influence the simulated hydrograph at its corresponding downstream junctions and reaches. However, the uncertainty of model predictions at and between junction locations due to parameter variability within individual modeling units is poorly understood. This research develops a methodology to map junction and reach locations that are sensitive to model parameter variability. The results can be used for risk assessment in sensitive applications such as the design of bridges, culverts and channels to convey flood flows. This paper presents (a) a methodology for identifying stream junctions and reaches that are potentially vulnerable to model uncertainty due to the structural arrangement of their drainage network, (2) two dimensionless indices: junction ratio and reach ratio to quantify drainage characteristics and the vulnerability of junction and reach to parameter uncertainty, (3) a case study of urban catchments in coastal southern California, using a rainfall-runoff model to explore the relationships between changes in peak discharge at junctions and along reaches with varying junction and/or reach ratios. Preliminary results show that 7 percent of junctions and 4 percent of reaches are vulnerable to model parameter uncertainty based on a threshold of 10 percent changes in peak discharge.
UR: http://spatialhydro.sdsu.edu
DE: 1805 Computational hydrology
DE: 1816 Estimation and forecasting
DE: 1819 Geographic Information Systems (GIS)
DE: 1847 Modeling
DE: 1873 Uncertainty assessment (3275)
SC: Hydrology [H]
MN: 2007 Fall Meeting