Center for Research in Water Resources, University of Texas at Austin
View an animated map of moisture flow over North America (June, 1991 - July, 1993)
This page describes research and educational material related to water balance calculations in the atmosphere and in the soil. Much of the material in this module was also present on the GISHydro97 CD-ROM produced for the 1997 ESRI User's Conference and is just organized in a different way. The highlights of last year's "Atmosphere" and "Soilwater" modules were instructional exercises showing how simple water balance calculations can be made within ArcView GIS. Project reports added this year describe more complex hydrology models run using external codes. ArcView and Arc/Info are used to prepare input data sets for these models.
New materials include (1) a master's thesis written by Kris Martinez to investigate the effects of climate change on the Edward's Aquifer in Central Texas by linking a simple soil water balance model to a recharge and groundwater model, and (2) a term project by Karen Mohr which describes data assimilation for a physically based model that couples the energy, momentum, and water fluxes at the land surface. In these projects, ArcView and/or Arc/Info were used for pre-processing rather than making the actual hydrologic computations because useful FORTRAN and/or C codes already existed and because GIS macro languages are slow when compared with compiled languages like FORTRAN and C.
Exercise on the 1993 Midwest Flood
This exercise takes a generalized border of the Upper Mississippi Basin and part of the Missouri Basin and does an atmospheric water balance using 12 hour time intervals from March to July 1993, during the great flood which occurred in the Midwest at that time.
Exercise for processing a boundary
This exercise takes the polygon boundary of Texas, approximately 7000 km in length and originally consisting of about 25,000 line segments, and simplifies it into approximately 70 line segments of about 100 km each so that atmospheric moisture flow calculations can be done segment by segment in a reasonable way. This exercise can be used to prepare boundary line data for water balance calculations like those done for the 1993 Midwest Flood Exercise (above).
Instructional exercises are provided here to demonstrate how simple soil-water balance calculations can be made in ArcView GIS using Avenue. Exercises for two sample study areas are available, one in Morocco and one in Texas. The input data for these exercises are taken from global data sets and therefore similar exercises can be run at any location in the world. The Morocco exercise uses a "traditional" scheme for estimating evaporation while the algorithm used in the Texas exercise is more experimental. The Texas exercise illustrates how to make calculations using just Avenue or using a combination of Avenue and FORTRAN.
Primary Contact
Seann M. Reed
seann@crwr.utexas.edu
http://www.ce.utexas.edu/prof/maidment/gishydro/seann/seann.htm
These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin. All commercial rights reserved. Copyright 1998 Center for Research in Water Resources.
