Flow Accumulation
The calculation of how much flow accumulates in each cell of a raster, used to identify drainage patterns and stream networks (standard GIS usage).
What does Flow Accumulation mean?
A fundamental idea in hydrology and GIS, flow accumulation describes the way water moves across a terrain. It shows how much water would collect in each raster grid cell depending on the drainage patterns and slope of the land. In essence, flow accumulation determines the number of upstream cells that contribute to the water flow into a specific cell. Water from numerous cells converges in areas with high flow accumulation values, which frequently indicate streams, rivers, or drainage channels. Cells with limited flow accumulation, on the other hand, get little or no water from external sources. This data aids in stream network identification, flood zone prediction, and watershed boundary identification. A digital elevation model (DEM) is typically used to calculate flow accumulation by first figuring out which way water flows from each cell and then adding up the upstream cells that contribute. It is an essential tool for managing water resources, planning the environment, and comprehending how water flows across a landscape.
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The path that water takes across a surface is determined by the flow direction in GIS, which displays the steepest downhill direction from each cell. Flow accumulation helps locate streams and watershed areas by calculating the number of upstream cells that pour into each cell. When combined, they are crucial for watershed study and hydrological modelling.
Using a digital elevation model (DEM), hydrological analysis employing flow accumulation determines the total water flow across a terrain. In GIS-based hydrological modelling, it supports flood prediction, watershed management, and soil erosion research by assisting in the identification of drainage patterns, stream networks, and runoff-prone locations.
The cumulative flow to every cell in a DEM is displayed via a flow accumulation raster in GIS. In order to identify streams, drainage patterns, and watershed zones—all of which are important for runoff and erosion analysis—it draws attention to places where water converges.
Watershed analysis and hydrological studies are aided by drainage network extraction from a DEM, which maps water flow routes and identifies stream channels using topography elevation data.