Automatic detection and delineation of karst terrain depressions and its application in geomorphological mapping and morphometric analysis

Abstract

UDC 551.435.8:528 E. Pardo-Igúzquiza, J. J. Durán and P. A. Dowd: Automatic detection and delineation of karst terrain depressions and its application in geomorphological mapping and morphometric analysis Digital elevation models (DEM) are digital representations of topography that are especially suitable for numerical terrain analysis in earth sciences and engineering. One of the main quantitative uses of DEM is the automatic delineation of flow networks and watersheds in hydrology and geomorphology. In these applications (using both lowresolution and precision DEM) depressions hinder the inference of pathways and a lot of work has been done in designing algorithms that remove them so as to generate depressionfree digital elevation models with no interruptions to flow. There are, however, geomorphological environments, such as karst terrains, in which depressions are singular elements, on scales ranging from centimetres to kilo metres, which are of intrinsic interest. The detection of these depressions is of significant interest in geomorphologic map ping because the development of large depressions is normal in karst terrains: potholes, blind valleys, dolines, uvalas and poljes. The smallest depressions that can be detected depend on the spatial resolution (pixel size) of the DEM. For example, depressions from centimetres to a few metres, such as some types of karren, cannot be detected if the raster digital eleva tion model has a spatial resolution greater than, say, 5 m (i.e., square 5m pixel). In this work we describe a method for the au tomatic detection and delineation of terrain depressions. First, we apply a very efficient algorithm to remove pits from the DEM. The terrain depressions are then obtained by subtract ing the depressionfree DEM from the original DEM. The final product is a digital map of depressions that facilitates the cal IzvlečekUDK 551.435.8:528 E. Pardo-Igúzquiza, J. J. Durán and P. A. Dowd: Avtomatska zaznava in omejitev kraških kotanj in njena uporaba v geomorfološkem kartiranju in morfomertrični analizi Digitalni model reliefa (DMR) je oblika predstavitve topografije, ki je še posebej primerna za numerično analizo površja. DMR je odlična podlaga za analizo rečnih mrež in njihovih zaledij. Pri takih analizah so (zaprte) kotanje pro blem, ker lahko predstavljajo lažno točko odtoka, zato je eden prvih korakov izdelava DMR brez zaprtih oblik. Na kraških območjih pa so kotanje različnih dimenzij in oblik ena glavnih značilnosti površja in predmet številnih študij. Računalniška zaznava brezen, slepih dolin, vrtač, uval, udornic in polij, je torej lahko velika pomoč pri analizi kraških površij. Velikost, ki jo lahko zaznamo, je navzdol omejena z ločljivostjo DMR; tako na primer kotanje velikosti od nekaj centimetrov do nekaj metrov (npr. različne vrste škrapelj) ne moremo določiti z DMR, ki ima prostorsko ločljivost 5 m. V tem delu predsta vimo metodo za avtomatsko zaznavanje in omejevanje kraških kotanj. Najprej predstavimo učinkovit algoritem, ki kotanje odstrani iz DMR. Tak, "br...

Karst Depression Detection Using ASTER, ALOS/PRISM and SRTM-Derived Digital Elevation Models in the Bambuí Group, Brazil

“…Several studies employ terrain attributes to characterize and describe karst processes [21][22][23]. In karst-depression detection studies a promising terrain attribute is the sink depth derived from the depression-filling algorithm [24][25][26][27]. Such algorithms are an integral component of spatially distributed hydrological models that delineate watersheds, drainage networks and overland flowpaths [28][29][30][31][32].…”

Geomorphological Dating of Pleistocene Conglomerates in Central Slovenia Based on Spatial Analyses of Dolines Using LiDAR and Ground Penetrating Radar

“…The increasingly available high-resolution LiDAR (Light Detection and Ranging) method for obtaining elevation data and creating digital elevation models (DEMs) is still in early stages of ability and reliability testing compared to traditional topographic and aerial surveying methods in modern karst geomorphology [5]. Researches applying high-resolution DEMs are mainly focused on automation of dolines detection and delineation [5][6][7][8], rather than on interpretations of the acquired geomorphological data [4,9].…”

Modelado fractal de la distribución del tamaño de dolinas en el macizo kárstico de la Sierra de las Nieves (Málaga, España)

“…El citado procedimiento proporciona una cartografía de alta resolución de la batimetría de las dolinas como las que se muestran en la Figura 6, donde se ha representado la profundidad de las dolinas con respecto al borde de la depresión. Asimismo, puede verse el fuerte control estructural reflejado en cómo las dolinas se han desarrollado en la intersección de fracturas, de modo que las dolinas tienen una forma alargada a lo largo de las principales direcciones de la fracturación regional (Pardo-Igúzquiza et al, 2013;Pardo-Igúzquiza et al, 2014b). Figura 5.…”