Unit Hydrograph Derivation Using Geographic Information Systemby W. C. Hughes, Univ of Colorado, Boulder, CO, USA,
L. E. Johnson, Univ of Colorado, Boulder, CO, USA,
K. S. Medde, Univ of Colorado, Boulder, CO, USA,
L. Tunnell, Univ of Colorado, Boulder, CO, USA,
Abstract: Geographical information system (GIS) data management and processing functions are used to develop synthetic unit hydrographs using input data consisting of digital elevation models (DEM) and stream path digital line graphs (DLG). The time-area method, a precursor to modern unit hydrograph theory, provides the theoretical basis for determination of overland and channel flow velocities. GIS processing directly incorporates the velocity determinations in a spatially distributed manner, converts the velocities to flow time, and then performs the spatial integration over the watershed to obtain the isochrones and interval areas. Processing of the resultant time-area curve to obtain the S-curve and adjust for watershed storage effects completes the unit hydrograph development process.
Subject Headings: Geographic information systems | Information systems | Data processing | Hydrographs | Systems management | Fluid velocity | Information management | Hydrologic models
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