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A DEM-based method for refining delineated stream networks using a longitudinal incision index
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DOI：10.1080/13658816.2026.2693884.png)
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Abstract
En 中文
Accurate delineation of stream networks is fundamental for hydrologic modeling, watershed analysis, and geomorphological studies. However, traditional delineation methods, particularly those based on constant flow accumulation thresholds, often generate spurious flow paths (pseudo streams) that follow local gradients but lack the geomorphic structure of genuine channels, especially in headwater areas. This study presents a geomorphically informed postprocessing method that uses a longitudinal incision index to refine DEM-derived stream networks. The index quantifies topographic dissection by comparing each flow path’s elevation profile to a synthetic straight reference line representing uniform descent. Flow paths with incision values below a user-defined threshold are identified as pseudo streams and removed. Through tests in two representative watersheds and additional validation across 292 headwater watersheds, the incision index proved effective in eliminating pseudo streams while retaining genuine drainage structures, improving the geomorphic consistency of the extracted networks. The results demonstrate that the optimal incision threshold varies systematically with topographic relief, with lower values in high-relief terrains and higher values in low-relief areas, providing practical guidance for threshold selection.
Keywords:
Incision index
stream network extraction
pseudo stream
DEM
flow accumulation threshold
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