Abstract

 Parameter Sensitivity in Hydrologic Modeling

 By

 Tanya Nicole Hoogerwerf, M.S.E.

The University of Texas at Austin, 2002

SUPERVISOR: David R. Maidment

 The computation of discharge from a watershed depends on the lag time between rainfall and runoff, while, in turn the lag time depends on watershed parameters, such as length of the longest flow path, watershed slope and the SCS curve number describing the effects of land use and soils.  This research explores the variation in lag time and discharge resulting from traditional and automated methods of calculating hydrologic parameters.  Four levels of extracting hydrologic parameters are explored:  (1) measurement from paper maps, (2) on-screen extraction from raster maps, (3) using GIS and two different resolutions of grid-based digital elevation models (DEMs), and (4) using a triangulated irregular network (TIN).  Results show that variations in watershed area and curve number most directly impact the computed discharge, while variations in slope and flow path length are relatively insignificant.