A GIS Based Geomorphic Approach for the Digital Computation of Time-Area Curvesby Jayanta K. Sircar, Univ of Md, Coll Pk, United States,
Robert M. Ragan, Univ of Md, Coll Pk, United States,
Edwin T. Engman, Univ of Md, Coll Pk, United States,
Russell A. Fink, Univ of Md, Coll Pk, United States,
Abstract: Hydrologists routinely operate simulation models to approximate the runoff process. A popular strategy is the routing of a 'time-area' histogram. In addition, state-of-the-art hydrologic simulation and analysis must often include spatial variability. A common requirement to perform such analysis is the segmentation of the terrain to a series of isolated sub-basins and their individual hydrographs routed through the channel network. However, inspite of recent advances in technology, the derivation of the time-area curves, taking into account spatial variability, has remained a manual process. Consequently, the tediousness and time consuming efforts required in time-area computations is a critical roadblock that seriously limits the operational use of the approach. The goal of the present research is to exploit the power of automated terrain analysis using desktop microcomputer technology to design a system to provide a subdivision of the watershed into small subbasins, and develop estimates of channel characteristics. The designed automated approach for estimating channel-cross-sections, slopes, and velocities are demonstrated to greatly reduce the complexity in computing the time-area curve for a watershed. A key element of the developed system is an innovative use of classical geomorphology coupled to a 'rasterization' of maps into a Geographic Information System framework. The success of the present research clearly provides a practical strategy to use digital techniques to develop the time-area curve for a small watershed.
Subject Headings: Curvature | Watersheds | Geographic information systems | Information systems | Terrain | Mapping | Hydrologic models | Runoff
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