Rose, Michael T.

Watershed delineations in low topographic relief landscapes with canal networks require hydrography. This hypothesis was tested by utilizing digital elevation models (DEMs). Seven DEMs were processed using two automated delineation methods. Both methods include filling of localized sinks, but an enhanced method incorporated incremental "tipping" to provide flow direction. In two watersheds studied, DEMs with only topography delineated watersheds within 24% and 84% of the manual delineation. With the addition of hydrography, including canals, both watersheds were delineated to within 85% and 92% of the manual delineation. Contrary to the assumption that tipping would improve delineation, tipping decreased the delineated area by removing a water flow path. Based on this research, DEM input data and delineation method strongly influence automated watershed delineations in low relief conditions.