Editing Hydrograph (section)

==Raster hydrograph==
[[Image:Raster hydrograph.png|thumb|A raster hydrograph. The entire flow record and patterns representing different timescales can be visualized.]]

'''Raster hydrographs''' are pixel-based plots for visualizing and identifying variations and changes in large multidimensional data sets. Originally developed by Keim (2000)<ref>Keim, D.A. 2000. Designing pixel-oriented visualization techniques: theory and applications. IEEE Transactions on Visualization and Computer Graphics, 6(1), 59-78.</ref> they were first applied in hydrology by Koehler (2004)<ref>Koehler, R. 2004. Raster Based Analysis and Visualization of Hydrologic Time Series. Ph.D. dissertation, University of Arizona. Tucson, AZ, 189 p.</ref> as a means of highlighting inter-annual (long-term) and intra-annual (e.g., [[seasonality]]) changes in streamflow. 

The raster hydrographs in the USGS WaterWatch, like those developed by Koehler, depict years on the y-axis and days along the x-axis. Users can choose to plot streamflow (actual values or log values), streamflow percentile, or streamflow class (from 1, for low flow, to 7 for high flow), for Daily, 7-Day, 14-Day, and 28-Day streamflow. For a more comprehensive description of raster hydrographs, see Strandhagen et al. (2006).<ref>Strandhagen, E., Marcus, W.A., and Meacham, J.E. 2006. Views of the rivers: representing streamflow of the greater Yellowstone ecosystem (hotlink to http://geography.uoregon.edu/amarcus/Publications/Strandhagen-et-al_2006_Cart_Pers.pdf). Cartographic Perspectives, no. 55, Fall.</ref>