1. General Model Information

Name: Spatial Water Budget Model

Acronym: SWBM

Main medium: terrestrial
Main subject: hydrology
Organization level: Landscape, Ecosystem
Type of model: 3D
Main application:
Keywords: hydrology, water balance, streams, watershed, land use, grid, raster, GIS, Arcview, Avenue, Spatial Analyst, Latin America


Joep C. Luijten
Natural Resources Defence Council, 1200 New York Avenue NW, Suite 400, Washington, DC 20009-6166, USA
Phone: +1.202.2892379
Fax: +1.202.2891060
email: joepluijten@yahoo.com
Homepage: http://www.geocities.com/joepluijten/


J.C. Luijten, J.W. Jones, E.B. Knapp


The Spatial Water Budget Model (SWBM) is a continuous, distributed parameter, watershed scale model that simulates water supply and demand over space and time on a daily basis using Geographical Information System (GIS) data structures. SWBM delineates streams and computes availability of stream water as it flows down slope or is (partially) extracted to for domestic, industrial and agricultural uses. It is a tool for assessing water availability and use under different development pathways at a watershed scale to determine whether water security is a potential problem, and if so, when and where it occurs. Processes that are simulated by SWBM are: (i) land unit water balance, (ii) water flow to streams, (iii) stream water flow balance, (iv) water storage in dams and small reservoirs, and (v) water extraction from reservoirs and streams for domestic, agricultural and industrial uses. The model does not simulate peak flow, sediment loading, soil erosion and vegetation growth. SWBM is intended for supporting local decision-making processes and for teaching local stakeholders about basic functions of multiple community watershed components such as relationships between land and water resources, effects of water use, and upstream-downstream relationships. SWBM has been developed in particular for application in agricultural hillside watersheds in Latin America and the Caribbean of up to approximately 50,000 ha in size and for which few biophysical data are available, but it can be applied to watersheds in other areas as well. SWBM fills the gap between current needs of rural communities in developing countries and data demands of established, more complex models designed for application in developed countries. The model was not designed for engineering specific hydrologic projects or for describing the movement of water based on detailed physical processes. The SWBM model has been programmed in Avenue (ESRI, 1996), the scripting language of ArcView GIS software (ESRI, 1997). It runs on Windows and Unix based systems on which ArcView GIS 3.1 or higher along with the Spatial Analyst v1.1 extension have been installed. Routing an accumulation of water as it flows down slope is computed using the intrinsic Flow Direction and Flow Accumulation functions. Data requirements are relatively low compared to those of existing hydrological models. Data are inputted as ARC/INFO grids and through user-friendly menus. Simulation results, which are saved in ARC/INFO grids and in dBase-IV files, can be processed using Avenue scripts and spreadsheet software.

II. Technical Information

II.1 Executables:

Operating System(s): The model is available as an ArcView project file (.apr). It can be used on any Windows or Unix-based system on which ArcView GIS v3.1 or higher has been installed. contact author

II.2 Source-code:

Programming Language(s): contact author
Avenue contact author

II.3 Manuals:

contact author
Spatial Water Budget Model and Hydrological Tools: an ArcView GIS extension. User's Manual. ABE report No. 00-1. Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL, and International Center for Tropical Agriculture (CIAT), Cali, Colombia. (downloadable from http://www.icasanet.org/toolkit/swbm.html)

II.4 Data:

contact author
This is explained in the user manual as well as in the dissertation that contains the complete mathematical information of the model.

III. Mathematical Information

III.1 Mathematics

The following document is the full scientific documentation of the Spatial Water Budget Model: Luijten, J.C., 1999. A tool for community-based water resources management in hillside watersheds. Ph.D. dissertation. University of Florida. Gainesville, FL. 303 pp.

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

Luijten, J.C., 1999. A tool for community-based water resources management in hillside watersheds. Ph.D. dissertation. University of Florida. Gainesville, FL. 303 pp. http://etd.fcla.edu/etd/uf/1999/amp7392/luijten.pdf

Luijten, J.C., J.W. Jones, and E.B. Knapp, 2000. Dynamic modeling of strategic water availability in the Cabuyal River, Colombia: The impact of land cover change on the hydrological balance. Advances in Environmental Monitoring and Modelling 1(1):36-60. http://www.kcl.ac.uk/kis/schools/hums/geog/advemm/vol1no1.html

Luijten, J.C., E.B. Knapp and J.W. Jones, 2001. A tool for community-based assessment of the implications of development on water security in hillside watersheds. Agricultural Systems (in press)

V. Further information in the World-Wide-Web

VI. Additional remarks

Last review of this document by: Joep Luijten, Feb. 10, 2001
Status of the document: Contributed by Joep Luijten
last modified by Tobias Gabele Wed Aug 21 21:44:51 CEST 2002

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