A new triangular multiple flow direction algorithm for computing upslope areas from gridded digital elevation models

Terrain analysis is the quantitative analysis of topographic surfaces. The purpose of a digital terrain system is to provide the digital representation of terrain so that environmental problem like soil erosion may be approached accurately and efficiently through automated means. Traditionally this was (and still is!) being done manually by using topographic/contour maps. With the availability of Digital Elevation Models (DEM) and GIS tools, watershed properties can be extracted by using automated procedures. Remote Sensing and Digital elevation models (DEMs) are known to be very useful data sources for the automated delineation of flow paths, sub watersheds and flow networks for hydrologic modelling and watershed characterization. The digital terrain model was extracted from a 90m resolution Shuttle Radar Topographic Mission (SRTM) of the study area. The SRTM data was corrected by removing voids, striping, tree offsets and random noise. The SRTM DEM data was projected from geographic coordinate WGS 84 to UTM zone 32 of the study area. The 3-D analysis tool of the ArcGIS 10.1 was used for this process. The DEM was processed to obtain the Slope, Contour, Flow direction, Flow accumulation, Flow length, Stream power Index of the study area. The study proved that SRTM elevation dataset has the ability to obviate the lack of terrain data for hydrologic modelling using ArcGIS where appropriate data for terrain modelling and simulation of hydrological processes is unavailable.

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A Variant of the Planchon and Darboux Algorithm for Filling Depressions in Raster Digital Elevation Models

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi8040164 ◽

2019 ◽

Vol 8 (4) ◽

pp. 164

Author(s):

Hongqiang Wei ◽

Guiyun Zhou ◽

Wenyan Dong

Keyword(s):

Surface Topography ◽

Flow Direction ◽

Digital Elevation Models ◽

Analysis Software ◽

Memory Space ◽

Software Packages ◽

Hydrologic Analysis ◽

Digital Elevation

Depression (pit or sink) filling is a key preprocessing step for the automatic hydrologic analysis of surface topography. The Planchon and Darboux (P&D) algorithm is a widely used depression filling algorithm. In this study, we propose an improved variant over the fastest sequential variant of the P&D algorithm for depression filling. Our variant introduces two important improvements compared with the fastest variant of the P&D algorithm, and greatly reduces redundant computation, as well as requires less memory space. Our algorithm can be easily integrated into many of the existing hydrologic analysis software packages. Moreover, our algorithm shares the same versatility as the P&D algorithm. Depressions can be replaced with surfaces either strictly horizontal, or slightly sloping. In the latter case, it is easier to calculate the flow direction matrix.

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