Study Region: Cerkniško Polje, (SW Slovenia) - regularly flooded polje with a complex recharge and partly disturbed due to human interventions. Study Focus: We focus on the long-term flooding ...dynamics on the polje, including analyses of trends over time, seasonal changes and identification of the impact of climate change and human construction activities on the flooding dynamics. For this purpose, we used a 70 years long dataset of continuous hydrological and meteorological measurements, and analysed documents about past human activities on the polje. New Hydrological Insights for the Region: Comprehensive analyses have revealed notable changes in the flood dynamics over past decades which mostly reflect a general drop of the water level. This is linked to both changes in the climate (lower effective precipitation) and human construction activities (regulation of the river beds, construction of dams, widening or reclogging of swallow holes). In the 1970s floods were longer and more extensive due to experimental permanent lake formation but since the partial removal of constructions, floods have become shorter and less extensive, although extreme events are more frequent than in the past. These changing patterns further impact on biodiversity, which is one of the most remarkable elements of the polje.
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•Cerkniško Polje experiences higher frequency of extreme floods and droughts.•Long-term climatological trends show stagnant rainfall but higher evapotranspiration.•There were human activities for both shortening and prolonging flooding events.•Water level is recently more dependent on meteorological events than human activities.•Due to changeable flooding dynamics over time changes in habitat types are present.
Koncept geodiverzitete obstaja že več kot 20 let. Večina metod vrednotenja geodiverzitete se uporablja za ugotavljanje geokonzervatorskega ali geoturističnega potenciala. Metode, s katerimi bi lahko ...vrednotili izobraževalni potencial geodiverzitete, so zelo redke. Glavni cilj našega članka je podati novo metodo vrednotenja geodiverzitete za določanje izobraževalnega potenciala proučevanega območja. Metoda je uporabna za učne namene, ko učitelji načrtujejo organizacijo strokovnih ekskurzij ali terenskega dela.
Abstract
Agriculture has a great impact on biodiversity in Europe. Populations of farmland birds are declining due to both intensification and abandonment of agriculture. The purpose of this study ...was to determine the effects of overgrowing on the diversity of birds at Cerknica Polje. Six vegetation types were identified on eight survey plots (15.2-31.6 ha each): Short grass - regularly mown wet meadows; Tall herbs - stands of Common Reed Phragmites australis and Reed Canary Grass Phalaris arundinacea; Sparse bushes - stands of low woody plants; Dense bushes - dense stands of bushes; Meadows with trees - mown meadows with scattered trees; Bushes with trees - hedges, trees and dense stands of bushes. In total, 34 species were registered. The heterogeneity of vegetation types correlated positively with the heterogeneity of bird species. The highest density of breeding territories and species was established in Bushes with trees, the lowest in Short grass. No species were registered in all vegetation types, and only Tree Pipit was recorded in five out of six types. Twelve species were registered in only one vegetation type. Cerknica Polje is an important breeding locality for species with the highest breeding density at the national level (e.g. Corncrake Crex crex, Curlew Numenius arquata, Skylark Alauda arvensis, Whinchat Saxicola rubetra, Sedge Warbler Acrocephalus schoenobaenus). These species breed in specific habitats with different stages of succession. A managing plan for the area should therefore combine abandoned plots in different stages of succession and large regularly mown areas. Abandonment of agriculture at Cerknica Polje has led to the emergence of areas with bushes in different succession stages. Efforts should be directed at preserving large complexes of mown wet meadows.
Between the end of February 2007 and mid-February in 2008, 73 systematic surveys of waterbirds and raptors were carried out during 10-day periods at Cerknica polje (Southern Slovenia). The main ...objectives of our research were: to ascertain the abundance and temporal dynamics of the species occurring here, to specify their status, to make a comparison with the past period of systematic data gathering in the 1991-1992 period, to present estimates of the breeding, migrating and wintering populations, as well as to make, on these bases, a nature-conservancy evaluation of the area. Other ornithological data, acquired till the end of 2010, were gathered as well. Between the beginning of May and the beginning of September 2007, the water in the area virtually ran dry (it was retained only in the channels of the streams), while the surface itself was partially or fully icebound from mid-November 2007 till the beginning of February 2008. By the end of 2010, a total of 129 waterbird and raptor species were recorded at Cerknica polje, while in the 2007-2008 period 83 were registered. Dynamics of the species occurrence with more than nine observations made in the area is presented in a greater detail in the species overview. The breeding status was held by 27 bird species, while further seven were forage guests that bred in the vicinity of the study area. Most of the species (118) had the status of passage visitor, whereas those with the status of summer visitor (34) and winter visitor (40) were fewer. Among the recorded species, 34 were accidental and 21 rare visitors. There were 16 winter and seven summer residents, while year-round residents were six. In all 10-day periods of the research period, four species were recorded: Mallard Anas plathyrhynchos, Grey Heron Ardea cinerea, Buzzard Buteo buteo and Kestrel Falco tinnunculus. In more than 90% of 10-day periods, the Great Egret Ardea alba was recorded as well. In the 2007-2008 period, two species were eudominant (Mallard 27.2%, Buzzard 10.1%), whereas another two were dominant (Garganey Anas querquedula 7.4%, Coot Fulica atra 6.4%). Most individuals were registered at the end of March and in early April (up to 1,978 ind.), whereas the greatest numbers of species (48) were recorded in mid-April. Between May and August, the numbers of individuals and species were low owing to the dried up lake. The smallest area of occurrence was occupied by the Cormorant Phalacrocorax carbo and a group of ducks of the genera Aythya, Bucephala and Mergellus. Gulls, egrets, herons, waders, harriers Circus sp. and the Red-footed Kestrel Falco vespertinus occurred in the greater part of the research area. 10 breeders fulfilled the criteria of the species of the greatest conservation importance, two of which (Ferruginous Duck Aythya nyroca and Curlew Numenius arquata) are species of global conservation concern, whereas seven are of conservation concern on a European scale. Among non-breeders, 14 waterbird species and raptors occurred in significant numbers (> 0.1% biogeographical population), five of which occurred at least occasionally with more than 1% of their biographical population. Two species (Red-necked Grebe Podiceps grisegena and Snipe Gallinago gallinago) breed in Slovenia only at Cerknica polje, while further six species have here at least 40% of their Slovenian breeding population
Various multivariate statistical techniques (MST) can provide valuable insights into water quality variability. Despite numerous studies in which these methods have been used, their potential has not ...been fully exploited. This paper presents an improved approach to better understand the hydrodynamics of karst systems. The integrated application of hierarchical cluster and principal component analysis in combination with factor analysis allowed the construction of an advanced multivariate chemograph. The analytical procedure was applied in a binary karst aquifer known for its complex hydrodynamics and mixing of water with similar hydrochemical composition. In addition, the study area provides access to an integral groundwater flow system (ponor‐cave‐spring) and offers extensive prior hydrogeological knowledge. The approach allowed reduction and discrimination of the main parameters affecting water quality characteristics. Their identification enabled recognition of three predominant recharge components: (a) stored water impact with Cl and electrical conductivity, (b) sinking stream impact with turbidity and bacteria composition and (c) karst aquifer impact with Ca/Mg ratio as principal parameters. The results supported innovative characterization of the dominant processes and isolation of temporal hydrodynamic phases of individual monitoring points within the aquifer system. On this basis, a spatio‐temporal conceptual model was developed and the hydrodynamic behavior of the main springs was revealed. The applied methodology demonstrated to be useful in ascertaining functioning of a complex karst system under flood event conditions.
Plain Language Summary
Karst aquifer systems contain important water resources. The quality of karst springs can deteriorate significantly after rain events, but it is difficult to distinguish how water flows and mixes in the subsurface, especially in large and complex systems. Statistical methods are powerful tools for studying these issues, but most common approaches are inadequate in some cases to reveal the origin of the water and its fate. In this paper, we present an approach in which we combined different statistical methods to explain the dynamics of water flow based on the physicochemical and microbiological properties of water. The application of these methods led to the discrimination of parameters most useful for a reliable interpretation of statistical results, such as turbidity, bacteria, Cl, EC, and Ca/Mg, and to the construction of an advanced diagram that we called a multivariate chemograph. This diagram allowed us to see where the water was coming from at any given time to our monitoring points, which allowed us to construct a detailed explanation of water flow dynamics in space and time. Our contribution is important to better predict the fate of contaminants in karst underground and to develop an early warning system for better water supply management.
Key Points
A new approach to study and explain hydrodynamics of karst aquifers was developed
It offers an innovative solution to distinguish influential monitoring parameters
Multivariate chemographs allowed spatio‐temporal detection of recharge phases
Karst ground water dynamics between the Planinsko polje and the springs of Ljubljanica (Slovenia) was studied based on the monitoring of stage and temperature of ground water in four caves. The Unica ...River, which flows over the Planinsko Polje, and sinks at its E and N rim, is considered as the main input to the observed system. At small flood events its role is none or questionable. At medium and large events, when the discharge of Unica exceeds 25 m super( 3)/s, it becomes an important and/or the dominant input to the system. When the capacity of the primary (eastern) ponors in the polje is exceeded, the stage in a cave, which is fed solely through these ponors, reaches the plateau followed by a very slow recession. The surplus flow goes towards northern ponors causing a fast rise of the stage in adjacent to them. In two of the northernmost caves, the stage response is almost identical, but the temperature variations are different. The uniform water level suggests a highly permeable region bounded by a low permeability barrier in the down-flow direction, while different temperature behavior indicates a different origin of the waters for each cave.
Hydrodynamic aspect of caves Prelovšek, Mitja; Turk, Janez; Gabrovšek, Franci
International journal of speleology,
01/2008, Volume:
37, Issue:
1
Journal Article
Peer reviewed
Open access
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.
Detailed study of the upper Cerkni super(1)e, ica's catchment and its sediments in Cerkni super(1)ko polje revealed that the river turned this direction in the middle Wuerm, while in the more remote ...past, the input to Cerkni super(1)ko polje (and to the caves) was completely karstic. Its alluvial fan cut the main vertical ponors, and deflected the main polje outflow westwards, indirectly into Planinsko polje. Consequently, recent hydrogeological conditions in Planinska jama are a direct consequence of development in Cerkni super(1)ko polje.
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