Abstract

CAMARGO ROA, Cristopher Edgar; ANDRADES GRASSI, Jesús Enrique  and  VIDAL GARCIA, Raúl Oswaldo. Evaluation of digital elevation models for estimating erosion volumes by using spatial autocorrelation analysis in a catchment of the Venezuelan Andes, a case study in the torrential micro-watershed La Machirí. Colomb. for. [online]. 2014, vol.17, n.1, pp.40-59. ISSN 0120-0739.

Digital elevation models -DEM- as a visual representation of landforms and altitude have been very useful in the study of topography. This research took place in a 3.39 km2 area of the La Machirí torrential micro-watershed (Táchira State, Venezuela). Its purpose was to evaluate a DEM generated through a process of digital photogrammetry that was also checked against a DEM edited from existing level curves in topographic charts. Exploratory Spatial Data Analysis (ESDA) and the Multiple-Point Geostatistics (Minimal Distance Analysis, Special Pattern Analysis, Variogram, and Variographic Analysis of Surfaces) methods were used. Differences between the two models were identified generated by the sum of the errors caused by the spatial distribution of checkpoints marked for the photogrammetric process (less than the number of checkpoints of a normal distribution, possible spatial bias between checkpoints and indications of spatial dependence phenomena), the error generated from the interpolation method applied during the process, and by the error caused by local erosion processes. The first assessment indicated a difference in the surface area of 0.57 ha and of 9.41 hm³ in volume in both DEMs. A zoned analysis indicated that at least three more checkpoints are necessary in order to get a more accurate DEM.

Keywords : Exploratory spatial data analysis -ESDA; multiple- point geostatistics; digital elevation model (DEM); La Machirí; volume.

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