Channel forms recovery in an ephemeral river after gravel mining (Palancia River, Eastern Spain)

During the 1970s, the Palancia River was intensively affected by gravel mining instream. This activity completely destroyed the fluvial forms, devastating the original wandering pattern. At the end of the 1980s, gravel mining ceased and the river started a process of recovery, only altered by several clearing operations. The aim of this work is to describe these processes of change, analyzing the river's morphosedimentary conditions through a GIS analysis of aerial photographs previous to, simultaneous with, and subsequent to the intense gravel mining activity. Results explain the current difficulties of some ephemeral rivers to recover their original forms, because of the sediment and water deficit conditions, the critical role of channel incision and inappropriate actions of river clearing and channelization for flood prevention

Stable oxygen isotopes in Romanian oak tree rings record summer droughts and associated large-scale circulation patterns over Europe

We present the first annual oxygen isotope record (1900 – 2016) from the latewood (LW) cellulose of oak trees (Quercus robur) from NW Romania. As expected, the results correlate negatively with summer relative humidity, sunshine duration and precipitation and positively with summer maximum temperature. Spatial correlation analysis reveals a clear signal reflecting drought conditions at a European scale. Interannual variability is influenced by large-scale atmospheric circulation and by surface temperatures in the North Atlantic Ocean and the Mediterranean Sea. There is considerable potential to produce long and well-replicated oak tree ring stable isotope chronologies in Romania which would allow reconstructions of both regional drought and large-scale circulation variability over southern and central Europe

Researches on the ice jam formation in the upstream of Izvoru Muntelui reservoir

The current work provides a description of the ice jam phenomena along the riverof Bistrita, which has the longest mountainous course in Romania (216km). During the coldseason of the year, in the upstream of the Izvoru Muntelui Reservoir over a length of 25-30km, there are generated with a almost yearly frequency ice blocks accumulations known asice jams. Analysis of the hidroclimatical and morphological conditions of the river bed hasrevealed that they are favorable to formation of ice jam provided there is present a certaincombination of their temporal variations. Hidraulic geometry of the Bistrita river bed isfavorable to flow of frazil slush, frazil pans and ice floes while the air temperature is -7 oC aslong as the level of Izvoru Muntelui Reservoir is below 500 m. Over this level, the river bed isblocked with ice jam during the submerse phase of the lake and this blockage advancesupstream with velocities of several hudreds of meters per day. The most dramatic phenomenahas been recorded during the winter of 2002-2003 when the thickness of the ice was of 6meters and it caused floods that provoked damages and claimed human lives. Aparition in2003 of the Topoliceni Reservoir, placed 6 km upstream of the Izvoru Muntelui Reservoir, hascomplicated the evolution of the phenomena, the lake itself acting as an accumulation poolfor the ices in the upstream.</p

L' évaluation du risque géomorphologique dans le bassin hidrographique Suha Mică (droit affluent de la riviere Moldova)

La cartographie des aires qui présentent un risque géomorphologique est devenue une nécessité sociale. Dans le domaine de la recherche des processus concernant le versant et le canal (le lit de la rivière) des éléments indicateurs ont été signalés, et qui peuvent conduire à faire l’inventaire des facteurs de risque locaux. Parmi les nombreuses ossibilités de combinaison des facteurs géomorphologiques qui déterminent la susceptibilité au risque d’un territoire, on a considéré comme étant édifiants pour la zone ’étude les suivants : géologie, pente, l’exposition des versants, l’utilisation des terrains. La carte à risque montre le niveau de l’exposition des certaines aires à un grand dangeret implique une évaluation quantitative stricte. Un niveau élevé de prédisposition au risque d’un territoire s’identifie en plan physique par une susceptibilité accrue aux processus géomorphologiques actuels spécifiques. Sur la base de plusieurs éléments cartographiques on a réalisé la carte de l’expansion des aires avec les processus géomorphologiques actuels dominants, et puis, sur la base des paramètres géographiques mentionnés antérieurement (ci-dessus), on a réalisé la carte du sque géomorphologique pour le bassin hydrographique Suha Mică. Notre étude est originale parce que, par la cartographie géomorphologique détailléeui a été réalisée avant la carte à risque, on a eu la possibilité de vérifier sur le terrain quel facteur est plus important pour l’exposition au risque des différentes unités des aires dansa zone étudiée. Par rapport aux autres réalisations de ce type, où la lithologie a un pourcentage maximum, dans notre cas, le facteur déterminant est la pente du versant. Cefait a mené à une réalisation cartographique plus véridique, fait qu’on a pu voir lors de la vérification de la carte à risque géomorphologique, sur la base de la carte de l’extensiondes aires affectés par les processus géomorphologiques actuels dominants.</p

Subfossil oaks from alluvial deposits and their role in past fluvial activities analysis: case study East Carpathian rivers, Romania

Dendrochronological research was conducted in Europe in several centers whereby oak trees, regardless of species, originating from various archaeological sites were studied. Thereby, several shronologies were assembled in Ireland, Germany and the UK, covering the past 7000 to 8000 years. The environment impacts on tree growth by generating higher / lower growth ratescompared to the multinannual average, thus indicating extreme years. The patterns of extreme years pertaining to individual sequences are subsequently synchronized by cross-dating.The study area consists of two rivers with different typologies but comparable in terms of size: river Moldova (braided to wandering channel in the lower reach) and river Siret (sinuosmeandering channel). Along the 100 km-long floodplain of the former and the 144 km-long floodplain of the latter we found and sampled 77 subfossil trunks from which 26 were subjectedto 14C dating</p

New data concerning the Late Quaternary drainage evolution on the Someş River alluvial fan

The study area is located in the north-eastern part of the Pannonian Basin, on the romanian teritory, with a surface of over 3,600 square kilometers. With elevations of 20-30 m above the Timiş and Criş plains, is the highest low-western romanian plains (100 – 160 m absolute altitudes), the surface extending on both sides of Someş River. This study aims to report new information on Late Quaternary evolution of fluvial discharge on the surface of Someş alluvial fan.Numerous relict fluvial morphologies were recognized on the surface ofSomeşRiveralluvial Plain, by analyzing mainly the fluvial morphologies visible on the second austro-hungarian military maps (reference moment: ca. 1860), and on recent ortophotoplans (reference moment: 2005). The identified palaeochannel types (braided, meandering) and morphometry (large scale meanders vs. small scale meanders), the concentration of these relict features on distinct palaeodrainage directions, the relation of them with the recent fluvial drainage of the area (intersected, partly/ totally used by present day misfit channels), suggest a complex Late Quaternary history of the lower course ofSomeşRiver. </p