The water-ecological problems of territorial development

The resolution of the issues related to the prevention of ecological problems having a technogenic as well as a natural character relies on a knowledge of the formation patterns of hydrological processes, which makes it possible to rationally manage water resources, ecologically transform landscapes, and minimize the consequences of socio-economic development of the territory. The theoretical foundations of landscape-hydrological analysis, combined with the principles of instrumental landscape planning, determine the system of basin management, and some methods for tackling the water-ecological problems.     

Neural network modelling of planform geometry of headland-bay beaches

The shoreline of beaches in the lee of coastal salients or man-made structures, usually known as headland-bay beaches, has a distinctive curvature; wave fronts curve as a result of wave diffraction at the headland and in turn cause the shoreline to bend. The ensuing curved planform is of great interest both as a peculiar landform and in the context of engineering projects in which it is necessary to predict how a coastal structure will affect the sandy shoreline in its lee. A number of empirical models have been put forward, each based on a specific equation. A novel approach, based on the application of artificial neural networks, is presented in this work. Unlike the conventional method, no particular equation of the planform is embedded in the model. Instead, it is the model itself that learns about the problem from a series of examples of headland-bay beaches (the training set) and thereafter applies this self-acquired knowledge to other cases (the test set) for validation. Twenty-three headland-bay beaches from around the world were selected, of which sixteen and seven make up the training and test sets, respectively. As there is no well-developed theory for deciding upon the most convenient neural network architecture to deal with a particular data set, an experimental study was conducted in which ten different architectures with one and two hidden neuron layers and five training algorithms – 50 different options combining network architecture and training algorithm – were compared. Each of these options was implemented, trained and tested in order to find the best-performing approach for modelling the planform of headland-bay beaches. Finally, the selected neural network model was compared with a state-of-the-art planform model and was shown to outperform it.     

Einfluß der Gezeitenstromturbulenz auf die hydrographische Schichtung der Nordsee

Zusammenfassung Es wird das kritische vertikale Dichtegefälle ermittelt, das die Gezeitenstromturbulenz, die vom Meeresboden ausgeht, zum Erliegen bringt (Abb. 2). Ihm wird jenes vertikale Dichtegefälle gegenübergestellt, das der tägliche Wärmestrom durch die Turbulenz der winderzeugten Oberflächenströmungen bewirkt (Abb. 3). In derjeningen Tiefe, in der beide Gefällswerte gleich werden, liegt die Obergrenze der bodennahen Mischungsschicht, deren Verteilung in der Nordsee auf zwei ozeanographischen Schnitten verfolgt wird, die mit dem Vermessungs- und Forschungsschiff Gauss im August 1953 ausgeführt wurden (Abb. 1). Der eine Schnitt verläuft vom Nordausgang der Nordsee zu den westfriesischen Inseln, der andere von der schottischen zur norwegischen Küste (Abb. 4). Durch diese Anordnung konnten alle charakteristischen sommerlichen Lagen in der Nordsee erfaßt werden: der Übergang von der unbedeutenden bodennahen Mischungsschicht in der nördlichen Nordsee zur mächtigen Mischungsschicht der mittleren Nordsee, die dort in den Gebieten mit höheren Gezeitenströmen die normale sommerliche Sprungschicht zu einer wenige Dezimeter dicken Schicht zusammendrängt und die in den Gebieten mit starken Gezeitenströmen in die oberflächennahe Mischungsschicht übergreift. Als Folge davon wird in ausgedehnten Gebieten Schichtungslosigkeit während des ganzen Jahres aufrechterhalten. Die weitreichenden, verschiedenartigen Einflüsse dieser Mischungsvorgänge machen sich unter anderem auf den Jahresgang der Oberflächentemperatur der Nordsee deutlich bemerkbar (Abb. 5 und 6).

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Summary The critical vertical density gradient for suppressing the tidal current turbulence which originates from the bottom of the sea is determined (fig. 2). It is compared with the vertical density gradient caused by the daily heat transport in consequence of the turbulence of the wind-produced surface currents (fig. 3). At the depth where the two gradients become equal there lies the upper limit of the mixed ground layer. Its distribution in the North Sea is shown by two oceanographic profiles on the basis of measurements carried out by the survey and research ship Gauss in April 1953 (fig. 1). One profile extends from the northern exit of the North Sea to the West-Frisian islands, the other one from the Scotch to the Norwegian coast (fig. 4). By this arrangement all characteristic summer situations in the North Sea could be included: the change from the small mixed ground layer in the northern North Sea to the mighty mixed ground layer of the central North Sea compressing there, in regions with higher tidal currents, the normal summer discontinuity layer to a few decimeters and, in regions with strong tidal currents, reaching into the mixed surface layer. As a consequence in vast regions a state without stratification is maintained during the whole year. The far-reaching and various influences of these mixing processes, e. g. on the annual variation of the surface temperature of the North Sea, are evident (fig. 5 and 6).

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Résumé On recherche le gradient vertical critique de densité capable d'annuller le remous dû à la marée au fond de la mer (fig. 2) et on le compare au même gradient produit par le réchauffement diurne combiné avec la turbulence des courants de surface dûs au vent (fig. 3). La profondeur à laquelle ces deux gradients sont identiques fixe la limite supérieure de la couche de mélange voisine du fond. La distribution de cette couche dans la Mer du Nord ressort de deux profils relevés par le navire océanographique Gauss en août 1953 (fig. 1). L'un des profils va de l'extrémité septentrionale de cette mer jusqu'aux îles occidentales de la Frise; l'autre s'étend de la côte écossaise à celle de la Norvège (fig. 4). De cette façon une étude de tous les caractères estivaux de la Mer du Nord met en évidence le passage de la faible couche de mélange dans le Nord à la couche très importante dans la région moyenne; cette dernière couche a pour effet de réduire à quelques décimètres la couche de transition estivale normale dans les régions à courants de marée profonds tandis qu'elle pénètre dans la couche de mélange de surface dans les régions à forts courants de marée. En vertu de ces processus, l'absence de stratification se maintient pendant toute l'année dans de vastes régions. Les effets variés et lointains de ces phénomènes de mélange se font nettement sentir, entre autres, sur la variation annuelle de la température de surface dans la Mer du Nord (fig. 5 et 6).

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Mit 6 Textabbildungen.     

The ethnocultural component of tourism development in the Altai Republic

A characterization is provided for the recreation resources of the Altai Republic. The diversity of the national-ethnical composition of the population of the Altai Republic is determined as well as analyzing the spatial distribution of the ethnoses on its territory. The coefficients of ethnical diversity are calculated for all administrative districts. The territories with a different level of ethnical diversity and a different combination of ethnical groups are determined. The study revealed a connection of ethnical diversity and natural conditions of the territory and the concentration of separate ethnoses in definite landscapes. A characterization is provided for the ethnocultural tourism and recreation resources of the Altai Republic within the context of administrative districts. Information is provided concerning the territorial distribution of separate ethnical groups, traditional kinds of their nature management, religion, main national dishes, elements of national costume, national festivities and rites, etc. An analysis of the spatial distribution of the ethnocultural recreation resources identified promising clusters (nodes) or destinations for the arrangement of special ethnocultural tourist routes. Schematic maps are provided, which display the ethnical diversity in the districts of the region, and promising districts for the organization of ethnocultural tourist routes.     

Soil erosion,climatic vagary and agricultural change on the Downs around Lewes and Brighton,autumn 1982

Farmland on the Downs between Lewes and Brighton suffered severe erosion during the autumn of 1982. The erosion was widespread and affected a variety of topographic situations, but it was confined to areas of arable land and recently-sown grass leys. Erosion on the scale recorded during the autumn of 1982 has never previously been recorded from this area. Three major sites of erosion are described and explanations for the erosion are sought through an analysis of rainfall conditions experienced during autumn 1982 and in recent changes in agricultural land use on the Downs. It is concluded that, whilst total rainfall and the intensity of rainstorms were both unusually high, similar events are likely to recur several times a century. Evidence is presented which suggests that the ploughing up of permanent pasture, the removal of field boundaries and the increased adoption of autumn-sown cereals have all contributed to the onset of severe erosion. It appears that a major re-activation of erosion on the Downs may be commencing which threatens the long-term viability of farming in the area.     

Linking Tarim Basin sea retreat (west China) and Asian aridification in the late Eocene

The Tarim Basin in western China formed the easternmost margin of a shallow epicontinental sea that extended across Eurasia and was well connected to the western Tethys during the Paleogene. Climate modelling studies suggest that the westward retreat of this sea from Central Asia may have been as important as the Tibetan Plateau uplift in forcing aridification and monsoon intensification in the Asian continental interior due to the redistribution of the land‐sea thermal contrast. However, testing of this hypothesis is hindered by poor constraints on the timing and precise palaeogeographic dynamics of the retreat. Here, we present an improved integrated bio‐ and magnetostratigraphic chronological framework of the previously studied marine to continental transition in the southwest Tarim Basin along the Pamir and West Kunlun Shan, allowing us to better constrain its timing, cause and palaeoenvironmental impact. The sea retreat is assigned a latest Lutetian–earliest Bartonian age (ca. 41 Ma; correlation of the last marine sediments to calcareous nannofossil Zone CP14 and correlation of the first continental red beds to the base of magnetochron C18r). Higher up in the continental deposits, a major hiatus includes the Eocene–Oligocene transition (ca. 34 Ma). This suggests the Tarim Basin was hydrologically connected to the Tethyan marine Realm until at least the earliest Oligocene and had not yet been closed by uplift of the Pamir–Kunlun orogenic system. The westward sea retreat at ca. 41 Ma and the disconformity at the Eocene–Oligocene transition are both time‐equivalent with reported Asian aridification steps, suggesting that, consistent with climate modelling results, the sea acted as an important moisture source for the Asian continental interior.