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...

The evaporite formations (in outcrop and at shallowdepth) cover an extensivearea of the Spanish territory. These soluble sediments are foundin diversegeological domainsand recorda widetimespan fromthe Triassicup to the presentday. Broadly,the Mesozoic and Paleogene formations (Alpinecycle) are affected by compressional structures, whereasthe Neogene (post-orogenic) sedimentsremain undefonned.The subsidence caused by subsurface dissolution ofthe evaporites (subjacentkarst)takesplace in three maintypes of stratigraphical settings: a) Subsidence affectingevaporite-bearing MesozoicandTertiarysuccessions (interstratalkarst);b) Subsidencein Quaternaryalluvialdeposits relatedto the exorheicevolutionofthepresent-dayfluvialsystems(alluvialor mantledkarst);c) Subsidencein exposedevaporites(uncovered karst). These types may be represented by paleosubsidence phenomena (synsedimentary and/or postsedimentary) recognizable in the stratigraphical record, or by equivalentcurrentlyactive or modemexampleswith surfaceexpression.The interstratal karstification of the Mesozoic marine evaporitesand the consequent subsidenceof the topstrata is revealedby stratiform collapsebrecciasand wedge-outs in the evaporitesgrading intounsoluble residues.InseveralTertiarybasins,the sedimentsoverlyingevaporiteslocallyshowsynsedimentary and/orpostsedimentary subsidencestructures. The dissolution-induced subsidence coeval to sedimentation gives place to local thickenings in basin-like structures with convergent dips and cumulative wedge out systems. This sinkingprocesscontrolsthe generation of depositional environments and lithofaciesdistribution. The postsedimentary subsidenceproducesa greatvarietyof gravitational deformations in the Tertiarysupra-evaporitic units includingbothductile and brittle structures(flexures, synfonns,fractures,collapseand brecciation).The Quaternary fluvial terrace deposits on evaporite sedimentsshow anomalous thickenings (>150 m) caused by a dissolution-induced subsidence process in the alluvial plain which is balanced by alluvial aggradation. The complex space and time evolutionpattern of the paleosubsidence gives place to intricate and anarchical structures in the alluvium which may be erroneously interpreted as pure tectonic deformations. The current subsidence and generationof sinkholes due to suballuvialkarstification constitutesa geohazardwhich affectsto largedenselypopulatedareas endangering human safetyand posinglimitationsto the development. An outstandingexamplecorresponds to Calatayud historicalcity, where subsidence severelydamageshighlyvaluablemonuments. The subsidenceresultingfrom the underground karstification of evaporiteshas determinedor influencedthe generation of some importantmodem lacustrinebasins like Gallocanta, Fuente de Piedra and Banyoles lakes. The suddenformationof sinkholes due to the collapse of cave roofs is relatively frequentin some evaporite outcrops. Very harmful and spectacularsubsidence activity is currently occurring in the Cardona salt diapir where subsidence has been dramatically exac...

Anthropogenic activities in urban, agrarian, or industrial areas are the main cause of heavy metals in sediments worldwide. Since the 1960s, there have been submarine discharges through outfalls of poorly treated or untreated wastewater on the south coast of Mallorca island (Mediterranean Sea). In this study, the pollution of marine sediments is analyzed at a great number of points on the south of the seacoast. Heavy metal concentrations of As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn, total inorganic carbon (TIC), sulfur, mineralogy, and grain size were analyzed. The objective is to evaluate the concentrations of toxic substances and their spatial distribution and ranges that can negatively affect marine ecosystems and human health. In addition, the results obtained have been compared with standardized indices for marine sediments, and a regional index has been developed with the background values of heavy metals obtained in the sediments of the study area. To obtain consistent conclusions, concentrations of heavy metals were classified with the Igeo Index. The concentrations of heavy metals obtained show that a great number of samples exceeded the limits considered for uncontaminated sediments according to the index applied. Elements such as Hg, Ba, Pb, and Cu showed high concentrations close to the outfalls and lower concentrations in zones far from these points. To support the assessment, chemical processes such as dissolution or chemical precipitation have been studied. The results also show that marine sediments can be a good trap for chemical elements and a good proxy to analyze the impact of anthropogenic activities in areas heavily pressured by humans, and the risk to the environment and human health.

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Management of water resources, implying their appropriate protection, calls for a sound evaluation of recharge. Such assessment is very complex in karst aquifers. Most methods are developed for application to detrital aquifers, without taking into account the extraordinary heterogeneity of porosity and permeability of karst systems. It is commonly recommended to estimate recharge using multiple methods; however, differences inherent to the diverse methods make it difficult to clarify the accuracy of each result. In this study, recharge was estimated in a karst aquifer working in a natural regime, in a Mediterranean-type climate, in the western part of the Sierra de las Nieves (southern Spain). Mediterranean climate regions are characterized by high inter-annual rainfall variability featuring long dry periods and short intense wet periods, the latter constituting the most important contribution to aquifer water input. This paper aims to identify the methods that provide the most plausible range of recharge rate during wet periods. Six methods were tested: the classical method of Thornthwaite-Mather, the Visual Balan code, the chloride balance method, and spatially distributed methods such as APLIS, a novel spatiotemporal estimation of recharge, and ZOODRM. The results help determine valid methods for application in the rest of the unit of study and in similar karst aquifers.