Web Service for Extracting Stream Networks from DEM Data

Stream networks are important features for hydrologic modeling, geomorphologic analysis of landscape, and many other applications. Automatic extraction of stream network from digital elevation model (DEM) has been implemented in major GIS software such as ArcGIS and GRASS based on flow direction along steepest descent and using some threshold criteria to separate channels and hillslope. However, these hydrology based algorithms often tend to produce results that are spatially uniform, not correctly reflecting the spatial variability in stream dissection patterns. In addition, the traditional paradigm of storing and processing everything on a local machine with locally owned software makes it time-consuming and expensive to process and analyze large quantity of geospatial data, which is often required for Earth System Science research. This paper describes the implementation of a morphology based algorithm for extracting stream networks from DEM data as a Web Service within the framework of GeoBrain, an open, interoperable, distributed, standard-compliant, multi-tier web-based geospatial information services and knowledge building system. This is made possible with recent advances in Service-Oriented Architecture (SOA), geospatial Web Services, and interoperability technologies and allows widest possible accessibility, because the only requirement for the user is an Internet connection and a standard web browser.