A phosphorus index that combines critical source areas and transport pathways using a travel time approach

Evaluating topographic wetness indices across central New York agricultural landscapes

“…Computed as ln(α/tan β), where α is the upslope contributing area per unit contour length and tanβ is the local slope, the index provides a relative, not absolute, measure of the moisture status of a particular area or pixel. Since its introduction, the TWI concept has been integrated into many popular hydrologic models (e.g., TOPMODEL, Beven and Kirby, 1979;VSLF, Schneiderman et al, 2007;SWAT-VSA, Easton et al, 2008) and pollution risk indices (Agnew et al, 2006;Reaney et al, 2011;Marjerison et al, 2011;Buchanan et al, 2013). Despite its wide application, large-scale corroboration of TWI-based predictions of landscape-scale soil moisture patterns using actual field observations are the exception rather than the rule.…”

Index models to evaluate the potential metal pollution contribution from washoff of road-deposited sediment

“…The RDS index was based on the phosphorus index that is used for modeling diffuse pollution in agricultural areas (Sharpley et al, 2008;Buchanan et al, 2013), but the RDS index was designed specifically to deal with the RDS characteristics found in diffuse pollution in urban areas. The RDS index is used in this study not only to identify critical source areas by quantifying relative pollution risks, but…”

“…Index models have been widely used for identifying diffuse critical source areas of phosphorus (P) on farms, and are less likely than other models to be constrained by a lack of input data (Heathwaite et al, 2005;Sharpley et al, 2008). Index models allow critical source areas to be identified by quantifying the relative pollution risk (e.g., as a probability) as opposed to the actual pollutant loading, because it is difficult to quantify transport factors (Buczko and Kuchenbuch, 2007;Buchanan et al, 2013). The index models mentioned above were initially devised for diffuse pollution in agricultural areas, and no index model has yet been specifically designed for diffuse pollution in urban areas that can be used to identify critical source areas of urban runoff.…”

A hierarchical pyramid method for managing large-scale high-resolution drainage networks extracted from DEM

“…Both the vector (i.e., geographical features) and property (i.e., topographical parameters) information for drainage networks extracted from Digital Elevation Models (DEMs) are important for physically based distributed hydrological modeling (Hung and Wang, 2007;Moretti and Montanari, 2008;Li et al, 2011;Åkesson and Wörman, 2012;, non-point source pollutant simulation Buchanan et al, 2013;, and geomorphological analysis (Li et al, 2009;Millares et al, 2012). With the development of Remote Sensing (RS), Global Positioning System (GPS), and Geographical Information System (GIS) technologies, DEM with higher accuracy and resolution can be obtained (Wilson, 2012).…”