|Nejadhashemi, Amir - UNIV. OF MD|
|Shirmohammadi, Adel - UNIV. OF MD|
|Montas, Hubert - UNIV. OF MD|
Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2009
Publication Date: December 1, 2009
Citation: Nejadhashemi, A.P., Shirmohammadi, A., Sheridan, J.M., Montas, H.J. 2009. Case Study: Evaluation of Streamflow Partitioning Methods. Journal of Irrigation and Drainage Engineering. 135:6 pp791-801. Interpretive Summary: A number of methods are available for estimation of the relative proportioning of total streamflow into storm runoff and baseflow. To date, the effectiveness of these approaches has not been rigorously tested because of the general lack of separately-measured storm runoff and baseflow data. Five of the more promising methods for streamflow partitioning were selected for testing using 12 years of separately-measured surface runoff and baseflow data from a small (0.34 ha) field in the southern US Coastal Plain. Statistical testing showed that the Boughton method, based on a standard manual flow-separation technique, consistently produced the best predictive results and tha the technique was among the easier methods for incorporation into large-scale natural resource and environmental models. Future work is planned to relate the "fraction" coefficient required by the approach to watershed-specific physical and hydrologic characteristics. This information will permit development of improved capabilities for estimation of the relative partitioning of streamflows. Improved understanding of the relative proportioning of streamflows is critical for accurate assessment and management of our natural resources, and for developing better solutions to environmental problems such as point and non-point source pollution, ecosystem response, and global warming.
Technical Abstract: Understanding water flow and its relative quantities through different pathways is vital for watershed management. Like many problems in hydrology, a number of methods have been proposed for streamflow partitioning. Numerous hydrograph-partitioning techniques, including three-component, analytical, empirical, graphical, geochemical, and automated methods were reviewed (Nejadhashemi et al., 2003). Five methods were identified as being the most relevant and less input intensive. This study tested performance of these methods against separately measured surface and subsurface flow data from the Coastal Plain physiographic region of southeastern United States. Separately measured surface and subsurface flow data were collected for twelve years (1970-1981) in a field scale watershed (about 0.345 ha in area) by the Southeast Watershed Research Laboratory of the USDA-Agricultural Service. Results of comparative analyses indicated that method IV proposed by Boughton (1988) performed best. Results also indicated that accuracy of this method is highly dependent upon the proper estimation of the “fraction coefficient” that is based on many physical and hydrologic characteristics of the watershed. This study concluded that deterministic/empirical methods, such as Boughton’s method IV, require proper parameter values for increased accuracy.