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An Instructional Framework for Introducing Spatially Distributed Hydrologic Design Concepts Joshua M. Peschel and Patricia K. Haan Texas A&M University, College Station, Texas 77843-2117

Introduction

Spatially distributed information technologies are emerging as an integral component of decision-making and design practices within the biological and agricultural engineering community (Mohtar and Engel, 2000; Ouyang and Barthoic, 2001; Choi et al., 2002). Several hydrologic and water quality models, such as the Soil and Water Assessment Tool (SWAT) (Di Luzio et al., 1997), the Better Assessment Science Integrating Point and Non-point Sources (BASINS) program (Di Luzio et al., 2002), the Automated Geospatial Watershed Assessment (AWGA) model (Miller et al., 2002), and the Hydrologic Engineering Center (HEC) software packages (USACE-HEC, 2000a; USACE-HEC, 2000b), are now constructed within geographical information system (GIS) frameworks. These types of GIS-based tools allow an engineer to better visualize problems and to design with spatially distributed data sets. With the increasing trends in availability and use of spatially distributed data, it is imperative that basic distributed modeling techniques be introduced to undergraduate students in a biological and agricultural engineering curriculum.

One of the core output parameters in any hydrologic or water quality model is surface runoff. Undergraduate students in biological and agricultural engineering are primarily taught traditional weighted average or “lumped” approaches to determine surface runoff in hydrologic-related problems. The often-standard procedure introduced for direct surface runoff calculation is the Natural Resources Conservation Service Curve Number (NRCS-CN) method (Chow et al., 1988; Haan et al., 1994; Gupta, 1995; Bedient and Huber, 2003). Originally developed in 1954 by the Soil Conservation Service (now known as NRCS) and later expanded upon, the NRCS-CN method is a time-averaged, direct runoff calculation that utilizes hydrologic soil group, land cover type and management practices, and antecedent moisture condition as input parameters (Rallison, 1980; Rallison and Miller, 1981; USDA-SCS, 1985 and 1986). The NRCS-CN basis parameters can easily be determined from publicly available digital spatial data sets using any standard GIS program (Melesse and Shih, 2002).

The pedagogical rationale associated with the NRCS-CN method is sound. Problems are more tractable and easier to solve by hand. However, the variability and orientation of spatial elements that may exist within a system of study motivates a distributed approach to problem solving. A simplified example is the construction of a suburban neighborhood (impervious surfaces) within a rural watershed. Given that flow calculations are based on soil type land cover, will there be a difference in the surface runoff calculation for the watershed that depends on the spatial location of the neighborhood? Using the traditional surface runoff calculation method, this question cannot be adequately answered.

Proceedings of the 2004 American Society for Engineering Education Annual Conference & Exposition Copyright © 2004, American Society for Engineering

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Haan, P., & Peschel, J. (2004, June), An Instructional Framework For Introducing Spatially Distributed Hydrologic Design Concepts Paper presented at 2004 Annual Conference, Salt Lake City, Utah. 10.18260/1-2--13487