Equal Area Slope

Creator: Andrew Campbell Email: andrew.j.campbell@aecom.com Webpage: https://github.com/D-a-s-h-e-r/EAS This plug-in estimates the equal area slope of polylines using an underlying topography raster. Estimating the equal area slope of a catchment or flow path is a necessary step in many hydrological calculations. While not a particularly difficult calculation, it can be time-consuming and hard to document, especially when doing rework. This plug-in aims to streamline the process by providing a method for estimating the equal area slopes of all features in the input vector layer. The algorithm creates a virtual layer with the calculated results in its attribute table. Mathematically equal area slope (EAS) can be expressed as EAS = (2 * A) / (L ^ 2) - (z / L) Where, A = area under line, which can be estimated by the trapezoidal rule L = length of line z = elevation of line at its downstream end Current limitations • vector and raster layers must be in the same coordinate reference system; • vector layer extents must reside within raster layer extents; • vector layer must be a polyline or polygon layer; • assumes some thought has been put into digitising the flow paths; • samples only the first band of raster. Subsequent revisions will improve the plug-in to better handle aforementioned limitations. Please email me at andrew.j.campbell@aecom.com with any suggested improvements!