Hydrodynamic aspect of caves Prelovšek, Mitja; Turk, Janez; Gabrovšek, Franci
International journal of speleology,
01/2008, Letnik:
37, Številka:
1
Journal Article
Recenzirano
Odprti dostop
From a hydrological point of view, active caves are a series of connected conduits which drain water through an aquifer. Water tends to choose the easiest way through the system but different ...geological and morphological barriers act as flow restrictions. The number and characteristics of restrictions depends on the particular speleogenetic environment, which is a function of geological, geomorphological, climatological and hydrological settings. Such a variety and heterogeneity of underground systems has presented a challenge for human understanding for many centuries. Access to many underground passages, theoretical knowledge and recent methods (modeling, water pressure-resistant dataloggers, precise sensors etc.) give us the opportunity to get better insight into the hydrodynamic aspect of caves. In our work we tried to approach underground hydrodynamics from both theoretical and practical points of view. We present some theoretical background of open surface and pressurized flow in underground rivers and present results of some possible scenarios. Moreover, two case studies from the Ljubljanica river basin are presented in more detail. The approach and methodology in each case is somewhat different, as the aims were different at the beginning of exploration. However, they both deal with temporal and spatial hydrodynamics of underground waters.
V prispevku predstavljamo del rezultatov raziskovalnega projekta, ki je bil usmerjen v študij poplavne ravnice Ižice na Ljubljanskem barju, v katero sta umeščeni arheološki najdišči Maharski in ...Resnikov prekop. Z LiDAR meritvami površja in neposrednim datiranjem opuščenih rečnih korit dokazujemo, da je najdišče Maharski prekop stalo na rečnem bregu in ne na 'mostiščarskem' jezeru.
The third publication in which an international group of researchers, under management of collaborators of the Institute of Archaeology at the Scientific Research Centre of the Slovenian Academy of ...Sciences and Arts (ZRC SAZU) from Ljubljana, studies problems of pile-dwelling inhabitation of the Ljubljansko barje, introduces results of researches performed at pile-dwelling settlements Stare gmajne, Blatna Brezovica and Veliki Otavnik Ib, i.e. settlements dating to the 2nd half of the 4th millennium BC.
Na Ljubljanskem barju smo izvedli 4-letno raziskavo z namenom, da ugotovimo, kako vplivata košnja in gnojenje na botanične karakteristike travne ruše. Travniška poskusa v obliki deljenk s štirimi ...ponovitvami smo zasnovali na zvezah Arrhenatherion (T1) in Molinion (T2) v letu 1999. Glavne parcele so predstavljale pogostnost rabe (2 košnji na leto z zapoznelo in običajno 1. košnjo, 3 košnje in 4 košnje), podparcele pa stopnjo gnojenja (negnojeno – kontrola, PK in NPK z različnimi odmerki N). Po štirih letih sta gnojenje in raba zelo spremenila izgled in botanično sestavo travne ruše v obeh zvezah. Intenzifikacija pridelovanja pa ni zmanjšala rastlinske pestrosti. Na T1 se je s številom košenj povečeval delež trav na račun zeli in nasploh malo prisotnih metuljnic. Povečan delež trav se je na T1 pojavil tudi pri NPK gnojenju v primerjavi z negnojeno ali PK gnojeno travno rušo. Gnojenje je močno zmanjšalo prisotnost močvirske preslice na T1 (maks. 25 %, min. 1 %). Ta učinek je bil bolj izrazit pri 3- in 4-kosni rabi. Na T2 je po razmerju med botaničnimi skupinami odstopala travna ruša pri zapozneli 2-kosni rabi. Ta je vsebovala povečan delež zeli tako pri negnojeni kot pri gnojenih variantah. Na T2 se je delež metuljnic povečal pri PK gnojenju, vendar je bil tudi tu v povprečju manjši od 6 %. Gnojenje je na obeh poskusih prevladujoče vplivalo na vrstno sestavo travne ruše. Pri intenzivnejši pridelavi so se na T1 namesto na stres tolerantnih vrst uveljavile konkurenčne, na T2 pa so se namesto na stres tolerantne modre stožke uveljavile konkurenčne in hkrati na stres tolerantne vrste.
Vpliv načinov gospodarjenja s travišči na ptice gnezdilke Ljubljanskega barja (osrednja Slovenija)
In spite of the extensive drainage works carried out in the bogs of Ljubljansko barje, the area is ...still important for breeding birds, particularly wet meadow species. Existence of these meadows nowadays depends very much on human management, which can be more or less intensive. Lately, more and more wet meadows are being transformed into pastures. The aim of this research was to find out how different grassland management regimes affect breeding birds at Ljubljansko barje. Intensively managed meadows, extensively managed meadows, pastures and litter meadows were compared. As birds were counted by a method adapted to pastures, counts were made from the edge of the plots. From the end of April till mid June 2003, every plot was visited four times in the morning and once during the night. Management intensity of the plot was determined by the beginning and extent of the area being mown or grazed, speed of mowing progress, number of irrigation ditches and proportion of area fertilized. The largest numbers of breeding birds were recorded in litter meadows, slightly fewer in extensively managed meadows and the least in intensively managed meadows. Considering the numbers of breeding birds, pastures were more similar to intensively than to extensively managed meadows. The beginning of mowing, extent of area mown and proportion of fertilised area were in significant negative correlation with density of nesting birds. It turned out that grazing, as practiced in the year of the research, is not suitable for maintaining wet meadows as habitats for grassland birds. The question remains, however, would less intensive grazing be a suitable alternative solution for maintaining conservationally very important wet grasslands at Ljubljansko barje, which would otherwise be abandoned.
V prispevku je prvikrat objavljen izbor naključno pobra-nih najdb z dveh novoopredeljenih koliščarskih naselbin na Ljubljanskem barju: Gornjega mostišča in Strojanove vode. ...Najdbe kažejo na podobnost z gradivom s Hočevarice, kar pomeni, da gre za naselbini horizonta keramike z brazdastim vrezom. Absolutno kronološko govorimo o času druge četrtine 4. tisočletja pr. Kr.Uvrstitev Gornjega mostišča in Strojanove vode v omenjeni časovni horizont horizontalno stratigrafsko gledano potrjuje staro Ložarjevo tezo, da lahko na Ljubljanskem barju izbiro lokacij koliščarskih naselbin povezujemo z dinamiko krčenja holocenskega jezera, kar pomeni, da je najmlajše med njimi v glavnem iskati v smeri umika jezera oz. na jugovzhodnem delu v smeri proti središču Ljubljanskega barja.
The Ljubljanica River with its tributaries has witnessed no less than a quarter of a century of organised underwater research. The latter has shown that the archaeological complex there ...unquestionably ranks among the most interesting ones in Slovenia with the finds from the beds and banks of the waterways speaking of nearby settlements, cemeteries, forts, control points or places of cult.These, together with various types of river vessels and other traces of water exploitation, improve in many ways the knowledge of the phenomenon that is the Ljubljansko barje as a cultural landscape as well as its specific dynamics closely related to the natural changes in the environment from the early periods of the prehistory onwards.
V prispevku so predstavljene arheološke najdbe z mlajše-oziroma zgodnjepoznobronastodobnega planega naselja IškaLoka, ki leži na trdini na obrobju Ljubljanskega barja.
The monograph presents the entire course of archaeological and dendrochronological investigations of two pile dwelling cycles at the Hočevarica site in the Ljubjansko barje, which occurred ...approximately in the 37th and the first half of the 36th century BC.In addition to artefacts from Hočevarica (A. Velušček), the results from paleobotanical investigations (M. Jeraj), a classification of the material from a necklace ring (D. Skaberne and A. Mladenovič), analyses of metallurgic instruments (Ž. Šmit) as well as organic remains of mammals (B. Toškan and J. Dirjec), fish (M. Govedič, J. Pavšič and J. Dirjec) and birds (F. Janžekovič and V. Malez) are also presented.
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