The definition of stream channel head location using digital elevation data

We examine the practicalities of estimating stream channel head location fr om digital elevation data using single and multiple flow direction algorith ms within the context of field observations for two small catchments in nor thern Italy. The main conclusions were: (a) field observed contributing are as to channel heads vary significantly and suggest that a constant contribu ting area is not a good assumption; (b) field evidence confirmed an inverse relationship between drainage area and local slope immediately upslope of the channel head for one catchment but not the other; (c) when best fit par ameters for field observed channel heads were used to define slope dependen t thresholds in the DEM algorithms the resulting drainage densities were to o high; (d) the single direction algorithms generally produced more extensi ve channel networks with shorter hillslope flow pathways.